Patterns of Reading Impairments in Cases of Anomia - Dr Christopher Williams

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TABLE OF CONTENTS

List of Figures .............................................................................................................. iv

List of Tables................................................................................................................. v

Acknowledgements ...................................................................................................... vii

Abstract........................................................................................................................ ix

Chapter 1. General introduction..................................................................................1:1

Cognitive models of language processing ...................................................................1:1

A simple model to explore language abilities: The ‘basic model’ ................................1:2

Two lexicons or four? ............................................................................................. 1:8

Different accounts of reading aloud ........................................................................ 1:9

The relationship between reading aloud and oral picture naming........................... 1:11

Research Aims...................................................................................................... 1:14

Chapter 2. Method ..................................................................................................... 2:17

Participants.............................................................................................................. 2:17

Recruitment of aphasic participants ...................................................................... 2:17

Recruitment of unimpaired controls ...................................................................... 2:18

Materials.................................................................................................................. 2:19

Procedures ............................................................................................................... 2:23

Scoring..................................................................................................................... 2:25

Analyses ................................................................................................................... 2:25

Chapter 3. Control group – results and discussion ................................................... 3:31

Regularity effects of unpublished tests ...................................................................... 3:31

Oral naming versus written naming.......................................................................... 3:32

Methodological issues .............................................................................................. 3:33

Chapter 4. A simple case to explain? ......................................................................... 4:37

Case description....................................................................................................... 4:37

Results...................................................................................................................... 4:37

Input processes ..................................................................................................... 4:38

Reading and repetition of words and nonwords..................................................... 4:38

The semantic system............................................................................................. 4:38

Picture naming...................................................................................................... 4:39

Discussion ................................................................................................................ 4:40

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Chapter 5. Three cases of phonological dyslexia ...................................................... 5:45

Case 1 – RPD........................................................................................................... 5:45

Results for RPD........................................................................................................ 5:45

Input processes..................................................................................................... 5:46

Reading and repetition of words and nonwords .................................................... 5:46

The semantic system ............................................................................................ 5:47

Picture naming ..................................................................................................... 5:48

Discussion – RPD .................................................................................................... 5:49

Case 2 – DHT .......................................................................................................... 5:53

Results for DHT ....................................................................................................... 5:53

Input processes..................................................................................................... 5:53



Picture naming ..................................................................................................... 5:56

Item consistency and comparisons........................................................................ 5:57

Discussion – DHT .................................................................................................... 5:58

Case 3 – DPC .......................................................................................................... 5:62

Results for DPC ....................................................................................................... 5:62

Input processes..................................................................................................... 5:63



Picture naming ..................................................................................................... 5:65

Discussion – DPC .................................................................................................... 5:67

Phonological dyslexia – general discussion.............................................................. 5:70

Chapter 6. Interpreting results for a bilingual aphasic ............................................ 6:73


Control M2........................................................................................................... 6:74

Results ..................................................................................................................... 6:74

Input processes..................................................................................................... 6:74



Picture naming ..................................................................................................... 6:77

Discussion................................................................................................................ 6:80

Chapter 7. A case of deep dyslexia ............................................................................ 7:87

Deep dyslexia........................................................................................................... 7:87


Results ..................................................................................................................... 7:89

Input processes..................................................................................................... 7:89



Picture naming ..................................................................................................... 7:92

Item consistency................................................................................................... 7:95

Discussion................................................................................................................ 7:96

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Chapter 8. Collective results for aphasic participants ............................................ 8:101

Collective results .................................................................................................... 8:101

Severity of aphasia and dissociations...................................................................... 8:105

Severity .............................................................................................................. 8:105

Dissociations and double dissociations................................................................ 8:106

Chapter 9. General discussion ................................................................................. 9:109

The basic model - conclusions ................................................................................ 9:109

Reading aloud..................................................................................................... 9:109

Semantic errors on oral naming........................................................................... 9:110

Comments on methodological issues....................................................................... 9:113

References.................................................................................................................... 117

Appendices................................................................................................................... 123

Appendix 1. Materials................................................................................................ 124

Appendix 2. Analyses................................................................................................. 132

Appendix 3. Control group results ............................................................................. 133

Appendix 4. Nonword reading ................................................................................... 135

Appendix 5. Error analysis for aphasic participants .................................................. 136

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List of Figures

Figure 1:1. The ‘basic model’ of language processing. ............................................... 1:3

Figure 1:2. The three reading routes of the basic model: ........................................... 1:5

Figure 1:3. The central components of any four-lexicon model. ................................ 1:8

Figure 1:4. The hypothesis described by Orpwood and Warrington (1995). .......... 1:12

Figure 2:1. Example Item from the comprehension test: ......................................... 2:21

Figure 3:1. Control group performance on repetition tasks. ................................... 3:36

Figure 4:1. The basic model, showing MWN’s proposed lesion site. ....................... 4:41

Figure 5:1. The basic model as it applies to RPD...................................................... 5:49

Figure 5:2. The basic model as it applies to DHT. .................................................... 5:59

Figure 5:3. The basic model as it applies to DPC...................................................... 5:68

Figure 6:1. Sample of written naming responses for JWS. ...................................... 6:79

Figure 6:2. Attempted alphabet by JWS................................................................... 6:80

Figure 6:3. The basic model as it applies to JWS...................................................... 6:82

Figure 7:1. The basic model as it applies to SJS. ...................................................... 7:97

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List of Tables

Table 2:1. Descriptive data for the aphasic participants. ......................................... 2:18

Table 2:2. List and order of tests in each session. ..................................................... 2:24

Table 3:1. Summary of control results on published tests. ....................................... 3:31

Table 3:2. Summary of control group results on unpublished tests. ........................ 3:32

Table 3:3. Most frequently incorrect items on PPT for controls. ............................. 3:34

Table 4:1. MWN’s performance on tests of input processes..................................... 4:38

Table 4:2. MWN’s performance on reading and repetition tests. ............................ 4:38

Table 4:3. MWN’s performance on semantic tests. .................................................. 4:39

Table 4:4. MWN’s performance on the oral naming test. ........................................ 4:39

Table 4:5. MWN’s performance on the written naming test. ................................... 4:40

Table 5:1. RPD’s performance on tests of input processes. ...................................... 5:46

Table 5:2. RPD’s performance on reading and repetition tests................................ 5:47

Table 5:3. RPD’s performance on semantic tests...................................................... 5:47

Table 5:4. RPD’s performance on the oral naming test............................................ 5:48

Table 5:5. RPD’s performance on the written naming test. ..................................... 5:48

Table 5:6. DHT’s performance on tests of input processes....................................... 5:54

Table 5:7. DHT’s performance on reading and repetition tests. .............................. 5:54

Table 5:8. DHT’s performance on semantic tests. .................................................... 5:55

Table 5:9. DHT’s performance on the oral naming test. .......................................... 5:56

Table 5:10. DHT’s performance on the written naming test. ................................... 5:57

Table 5:11. Item consistency between tests of verbal output for DHT..................... 5:58

Table 5:12. DPC’s performance on tests of input processes. .................................... 5:63

Table 5:13. DPC’s performance on reading and repetition tests.............................. 5:64

Table 5:14. DPC’s performance on semantic tests. ................................................... 5:65

Table 5:15. DPC’s performance on the oral naming test.......................................... 5:65

Table 5:16. DPC’s performance on the written naming test..................................... 5:66

Table 5:17. Item consistency between oral naming and other tasks for DPC.......... 5:67

Table 6:1.JWS’ performance on tests of input processes.......................................... 6:75

Table 6:2. JWS’ performance on reading and repetition tests. ................................ 6:76

Table 6:3. JWS’ performance on semantic tests. ...................................................... 6:77

Table 6:4. JWS’ results on the oral naming test........................................................ 6:78

Table 6:5. JWS’ performance on the written naming test. ....................................... 6:79

Table 7:1. SJS’ performance on tests of input processes. ......................................... 7:90

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Table 7:2. SJS’ performance on reading and repetition tests. ................................. 7:90

Table 7:3. Reading errors for SJS. ............................................................................ 7:91

Table 7:4. SJS’ performance on semantic tests......................................................... 7:92

Table 7:5. SJS’ performance on the oral naming test............................................... 7:93

Table 7:6. Examples of oral naming errors for SJS.................................................. 7:93

Table 7:7. SJS’ performance on the written naming test. ........................................ 7:94

Table 7:8. Examples of written naming errors for SJS. ........................................... 7:95

Table 7:9. Item consistency between comprehension and naming for SJS.............. 7:95

Table 7:10. Item consistency between several tests for SJS...................................... 7:96

Table 8:1. Performance of aphasic participants on tests of input processes.......... 8:101

Table 8:2. Performance of aphasic participants on reading and repetition tests. . 8:102

Table 8:3. Performance of aphasic participants on semantic tests......................... 8:103

Table 8:4. Performance of aphasic participants on the oral naming tests. ............ 8:104

Table 8:5. Performance of aphasic participants on the written naming test ......... 8:105

Table 8:6. Comparison of the regular and exception word groups........................ 8:105

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Acknowledgements

First and foremost, I would like to thank all of the wonderful people who participated in

this project, without whom none of this would have been possible. For most of these

individuals, the assessment procedure involved several hours of testing, and I am eternally

grateful for the time and effort that you all devoted to the project. I must also thank two

participants, TB and FME, whose results were not included in the final report but who

gave there time nevertheless.

Second, I would like to acknowledge the professional assistance I received from various

people. In particular, my supervisors, Professor Max Coltheart and Associate Professor

Lindsey Nickels, who gave their time and effort over a period of many years, and who

never lost faith that I would eventually submit. For your time, advice, and understanding, I

cannot thank you enough. I am also grateful to the speech pathologists as St Joseph’s

Hospital and the Royal Rehabilitation Centre Sydney for their assistance in referring

patients and for being extremely accommodating in providing me with their time and other

resources. I am also indebted to many other academics and support staff of the Macquarie

Centre for Cognitive Science and the Psychology Department of Macquarie University for

their professional advice and assistance with resources.

Third, I would like to thank the many amazing people in my life who I am lucky enough to

have as family and friends. I am especially grateful to my parents, who not only provided

me with the love and support that they always have, but who also went out of their way to

help me with finding control participants. To all of my friends, including student peers,

team mates, work colleagues, flat mates, and long-term friends, I cannot express how

grateful I am for your professional support (including assistance with proof reading,

material preparation and other advice) and, more importantly, your moral support – I

would not have attained this feat without your compassion, reassurance, and

understanding.

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Abstract

Over recent decades, research-based cognitive models of language have become

increasingly sophisticated. However, with increasing sophistication has come an equivalent

increase in complexity, to the extent that it is now more difficult than ever for clinicians to

utilise the model for testing hypotheses about patients and devise appropriate therapeutic

interventions. A series of six cases is presented to explore the capacity of the ‘basic model’

to account for various aphasic profiles, with a particular focus on hypotheses about reading

pathways. To this end, a series of experiments was designed using a single set of picture-

word items, with a focus on the balance between words with and without regular spelling-

sound correspondence. Various theoretical positions are discussed including the lexical

non-semantic route, the summation hypothesis, and the hypothesis that reading aloud and

oral naming are subserved by different phonological output lexicons (e.g. Orpwood &

Warrington, 1995).

Most of the aphasic participants presented with ‘output’ anomia, but for some this was in

the context of mild semantic deficits that may have contributed to their poor oral naming.

One of the participants was also completely unable to read nonwords, yet his reading of

real words, although impaired, did not contain semantic errors. This is an uncommon

finding and one that is incongruent with the summation hypothesis. Other participants

demonstrated intact reading of exception words despite being impaired on the oral naming

task, which further supports the inclusion of the lexical non-semantic route.

Another of the aphasic participants was considered in the context of being a late-acquired

bilingual speaker. He was compared not only to the main control group, but also to an

unimpaired, late-acquired bilingual speaker with the same language background. The basic

model was unable to account for his pattern of deficits, but it was determined that most

cognitive models, no matter how intricate, are inadequate to account for aphasic syndromes

in bilingual speakers.

The final case examines the profile of a participant with deep dyslexia. Although the basic

model is able to account for this participant’s profile, consideration is given to the right-

hemisphere hypothesis and to the notion that, due to wide ranging and as yet unknown

variables, standard cognitive models of language processing may again be inappropriate

for use with these cases.

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It was concluded that the evidence supported the potential of the basic model and the

assumptions associated with it, including the lexical non-semantic route and the depiction

of only two lexicons, one each for spoken and written lexical entries. Additionally, several

methodological issues are discussed including poor sensitivity of several tests.

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Chapter 1. General introduction

Anomia is usually characterised as general word-finding difficulties. It can exist as a

syndrome in itself or, more often, as a feature of a more general aphasic disorder (Garman,

1990). Almost every aphasic individual experiences some degree of impaired word

retrieval (e.g. Garrett, 1992; Weigel-Crump & Koenigsknecht, 1973), which is made

evident by the fact that the most common finding of aphasic research is the inability to

name pictures correctly (Goodglass, 1983). Analysis of the various causes of naming

failure, and the myriad of other lexical deficits associated with it, can reveal a great deal

about the cognitive architecture of language processing. This chapter introduces and briefly

discusses a range of issues surrounding cognitive models of language processing. In the

chapters that follow, some of these issues will be explored through a case series involving

six individuals with various anomic syndromes and degrees of impairment. In particular,

the potential for a ‘basic’ model of language processing to account for the deficits of these

individuals will be examined, and it will be argued that this relatively uncomplicated

model is sufficient to explain and understand acquired language deficits at a clinical level.

Cognitive models of language processing

In any cognitive model of lexical processing, the ability to perform normal linguistic

functions is explained by an array of processing modules linked to each other by a network

of pathways. These models do not aim to account for neural processing centres and

connections, rather, they are attempts to explain the processes involved in normal lexical

functioning, and are often constructed around hypotheses that are generated from case

studies of individuals with language impairments. Such hypotheses are generally based on

dissociations (i.e. when a certain process is impaired while another is intact) and, more

importantly, double dissociations (i.e. when two separate processes can be differentially

impaired) – for example, there are cases of impaired written naming with intact oral

naming and vice versa, indicating a double dissociation between the process involved in

each form of naming.

Whilst there are many ways in which the various models differ, by their very nature there

are many aspects that they must have in common. Specifically, all lexical models must be

able to explain the different processes involved in understanding and producing language,

at least at the level of single words. Therefore, all models must account for orthographic

processing (the way we process written words), phonological processing (spoken words),

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recognition of 2- and 3-dimensional objects, and semantic processing (comprehension of

words and objects). The full range of everyday skills encompassed by a model should

include: Confrontation naming (naming of pictures and objects), both oral and written;

spontaneous speech and writing; recognition and comprehension of pictures, written words

and spoken words; reading aloud; written ‘copying’ and verbal repetition; and writing to

dictation. Also, models must account not only for our ability to process words that are

known to us, but also words that are novel or made up.

A simple model to explore language abilities: The ‘basic model’

The primary objective of this report is to show that a simple cognitive model of language is

sufficient to account for most aphasic individuals. Being able to precisely identify a

patient’s deficit within the context of a cognitive model can have significant implications

for the design of therapeutic intervention. However, due to their complex nature, the

practical application of the more sophisticated research-based models are often difficult for

clinicians to apply and interpret. Therefore, simplifying models to a degree that they can be

easily applied to the majority of cases could have significant implications for clinical

practice.

Keeping in mind the language abilities of normal speakers, in addition to the most

commonly reported and generally agreed upon aspects, the simplest model that could be

considered for clinical application is presented in Figure 1:1 (e.g. Allport, 1984; Allport &

Funnell, 1981; Jackson & Coltheart, 2001). The most peripheral, non-language features

such as initial acoustic processing and motor output are omitted, and internal processing of

modules is not defined.

At the centre of the basic model in Figure 1:1 is the semantic system, which stores and

processes conceptual information about the meanings of words and objects; it represents an

intricate network of semantic features (i.e. all the characteristics of the things that an

individual knows). To either side of the semantic system are the phonological lexicon and

orthographic lexicon, stores of all the spoken and written words (respectively) that an

individual knows.

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Figure 1:1. The ‘basic model’ of language processing.

Input to the model can be auditory or visual. Auditory information first reaches the

phonological input buffer, which temporarily stores and processes phonemes (small units

of sound) before forwarding the information on to the phonological lexicon for activation

of the appropriate word forms, and to the phonological output buffer, where phonological

information is reorganised as speech. The pathway between the phonological input and

output buffers is the sublexical repetition route, and allows auditory input to be re-

processed as speech output – this is the mechanism that allows us to quickly repeat verbal

information (both real words and nonwords). Repetition of known words can also occur via

the phonological lexicon. Information from the phonological lexicon is also forwarded to

the semantic system where relevant semantic nodes are activated, enabling comprehension

of spoken words.

Visual input to the system can take two forms. Firstly, 2- and 3-dimensional objects are

identified and processed by the object recognition system, which then activates relevant

nodes in the semantic system. Naming of these objects is then made possible via the

phonological lexicon and phonological output buffer (for oral naming) or the orthographic

lexicon and orthographic output buffer (for written naming). Secondly, written input is

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processed initially by a stage of letter identification, which associates the almost infinite

array of forms that each letter of the alphabet can take with the single letter that they

represent (i.e. no matter how the letter a is written – e.g. a, a, A, or A – it is usually

recognisable).

According to the basic model, reading aloud is made possible by three different routes, all

beginning at the stage of letter identification. The first, called the semantic route (Figure

1:2a), proceeds to the orthographic lexicon, through the semantic system, and on to the

phonological lexicon and phonological output buffer. The second (Figure 1:2b) is called

the lexical non-semantic route, and also proceeds to the orthographic lexicon. At this point

however, information is sent directly to the phonological lexicon, bypassing the semantic

system, before being forwarded on to the phonological output buffer. This pathway allows

for written words to be read aloud without necessarily activating semantic representations,

and is discussed in greater detail later in the chapter. The third route (Figure 1:2c) is a

direct connection from letter identification to the phonological output buffer via grapheme-

phoneme conversion. This pathway, also known as the sublexical route, allows for the

processing of strings of graphemes (a grapheme is a letter or group of letters that represent

a single phoneme) that do not have entries in the lexicons – that is, unfamiliar words,

foreign words and nonwords (i.e. plausible made-up words such as ploon and chup).

a.

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b.

c.

Figure 1:2. The three reading routes of the basic model:

(a) the semantic route; (b) the lexical non-semantic route; and (c) grapheme-phoneme conversion.

From the perspective of the basic model, reading aloud is made possible by these three

pathways. Words with regular spelling (i.e. those that have predictable grapheme-phoneme

correspondence and therefore sound the way they are spelled, such as dog and arm) can be

read via any of the three routes. In contrast, exception words (words that do not sound the

way they are spelled, such as bowl and yacht) cannot be read via grapheme-phoneme

conversion – since grapheme-phoneme conversion only allows for direct translation of

graphemes into phonemes, this would cause regularisation errors (e.g. bowl would be read

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as ‘bowel’ and yacht would be read as ‘yatched’ or ‘yacked’). However, exception words

can be read using either the semantic or lexical non-semantic route, since all words are

represented in the lexicons and simply need to be activated, first in the orthographic

lexicon, then in the phonological lexicon. Finally, novel words and nonwords can only be

read via grapheme-phoneme conversion, since these letter strings are not represented in the

lexicons. Damage to grapheme-phoneme conversion impairs the individual’s ability to read

nonwords, which will often (but not always) be read as lexicalisations (e.g. ploon might be

read as ‘plume’ or ‘prune,’ while chup might be read as ‘chap’).

Finally, the model needs to include components that can process novel words not only in

their written form, but also via auditory input. Repetition of novel words is achieved by the

sublexical repetition route, which connects the phonological input and output buffers.

Written dictation of novel words is achieved via phoneme-grapheme conversion, which is

responsible for converting sequences of phonemes into graphemes, thus allowing a person

to write novel strings of sounds that are heard. This process is not examined in the case

series, but is shown in the model because its existence is well supported by evidence in the

literature (e.g. Alario, Schiller, Domoto-Reilly, & Caramazza, 2003; Miceli, Capasso, &

Caramazza, 1999).

Damage to the model will result in a variety of deficits, depending on which component or

components are damaged, and the degree to which the components are still able to function

(see Allport, 1984; Allport & Funnell, 1981; Jackson & Coltheart, 2001). In broad terms,

there are two ways that lesions might affect the functioning of the core components of the

language system (i.e. the semantic system, phonological lexicon and orthographic lexicon)

– damage to the representations within the process, or reduced activation of those

representations. Generally, damage to the representations should lead to consistency of

errors. In other words, if the actual representations are damaged, then the same errors will

appear repeatedly, and for all tasks that rely on that module. On the other hand, reduced

activation, which is generally conceptualised as damage to the connections between

modules, is less likely to result in error consistency.

Damage to individual components will obviously lead to a particular set of impairments. If

the semantic system is damaged, comprehension will be impaired regardless of the method

of input (i.e. the individual will have difficulty understanding the meanings of pictures,

spoken words and written words). However, the most distinctive feature of ‘semantic

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anomia’ is bimodal naming failure to all forms of input (Rothi, Raymer, Maher,

Greenwald, & Morris, 1991). That is, an impaired ability to name words both orally and in

writing, whether the stimuli are presented as pictures, written definitions or auditory

definitions. Semantic errors (meaning-related errors e.g. naming a car as a truck) should be

common because damage to particular semantic representations increases the likelihood of

lexical entries that are related by meaning being activated in the relevant lexicon (Miceli,

Amitrano, Capasso, & Caramazza, 1996).

Damage to a lexicon will lead to the inability to activate representations within that

lexicon. From the perspective of the basic model, this will lead to: a) reduced ability to

name pictures in that modality, with a range of error types including semantic and

phonological errors; b) difficulties with lexical decision (i.e. distinguishing between real

and made-up words) in that modality; and c) difficulties with comprehension of words

input from that modality. Other abilities might be partially affected. In particular, reading

aloud of exception words should lead to regularisation errors if either lexicon is damaged,

and if grapheme-phoneme conversion is intact. Likewise, writing of exception words to

dictation should be affected by damage to the phonological lexicon. However, nonword

reading, repetition and writing to dictation should all be possible, even if both lexicons are

damaged. In contrast, reduced activation of the lexicons from the semantic system should

lead to impaired picture naming of that modality, without affecting any other language

skill. Errors should be similar in nature to those seen for lexicon damage, including

semantic errors, but with less consistency predicted.

Post-lexical damage should also have similarities to lexical damage. In particular, damage

to the connection between the phonological lexicon and phonological output buffer should

impact on oral naming and reading of exception words. For naming, semantic errors would

not be expected since the lexical entry has already been selected. On the other hand,

auditory lexical decision should still be possible, as should repetition of words (via the

sublexical repetition route). Damage to the connection between the orthographic lexicon

and orthographic output buffer should mirror this pattern for writing. Finally, damage to

the input or output buffers should affect all input or output for that modality, while damage

to the object recognition process should affect all tasks that involve some aspect of

interpreting pictures or objects.

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Two lexicons or four?

Perhaps the most audacious argument presented in the basic model is that only two

lexicons are defined, one each for spoken and written words. In contrast, the majority of

mainstream models describe separate lexicons for input and for output for each modality,

as depicted in Figure 1:3 below. Only the central components are shown, with peripheral

features omitted (e.g. input and output buffers, grapheme-phoneme conversion and direct

links between the lexicons), as are any hypothesised feedback mechanisms and

connections between the lexicons. This is because of the diverse range of configurations

that the various models hypothesise. On the other hand, the central features that are

pictured are common to most cognitive models of language processing (e.g. Hillis &

Caramazza, 1991; Martin & Saffran, 2002; Miceli et al., 1996; Nickels, 2000; Southwood

& Chatterjee, 2001).

Figure 1:3. The central components of any four-lexicon model.

A considerable number of debates surround this issue (refer to Howard, 1995, for an

extensive discussion on the topic; also see Martin & Saffran, 2002). However, despite the

general consensus of four lexicons, the objective of this report is to show that a simple

model is sufficient to account for the language of people with aphasia in a clinical setting.

Therefore, judgments as to whether or not aspects of particular models are fundamental

should not be restricted to peripheral components and pathways; determining the relevance

of core components, in particular the number of lexicons, is just as crucial. A

demonstration that two lexicons are sufficient would considerably decrease the complexity

of cognitive models of language. The majority of evidence that favours the position of a

distinction between input and output lexicons is not based on cases for which

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representations are clearly lost in one but preserved in the other. Rather, the arguments are

based primarily on findings from intricate research methodology such as ‘dual-task

decrement’ (Shallice, McLeod, & Lewis, 1985) and research findings as they relate to

certain theoretical assumptions (see Howard & Franklin, 1988). However, at a clinical

level there is often a lack of distinction between input and output modules when

identifying deficits. Therefore, for the sake of simplicity the lexicons were not divided into

input and output processes, in accordance with previous advocates of this approach (e.g.

Allport & Funnell, 1981; Funnell, 1983; Jackson & Coltheart, 2001)

Different accounts of reading aloud

At first glance, the lexical non-semantic reading route might appear to be redundant.

Indeed, it is not entirely clear what purpose it serves for normal language, and is not

included in many models, such as the summation hypothesis (e.g. Hillis & Caramazza,

1991) and Plaut’s computational model (Plaut, McClelland, Seidenberg, & Patterson,

1996). However, omission of the lexical non-semantic route leads to certain predictions

concerning word reading for individuals with damage to the semantic reading route. First

of all, if grapheme-phoneme conversion is impaired, then reading aloud of real words

should include frequent semantic intrusions or omissions (Miceli et al., 1996). Indeed, this

is the profile observed for deep dyslexia. However, not all individuals with impaired

semantic processing and non-functional grapheme-phoneme conversion produce semantic

errors on word reading. For example, WB (Funnell, 1983) performed poorly on tests of

semantic processing and was completely unable to read nonwords, to the extent that he was

unable to generate a response for more than half of the items. Nevertheless, he performed

reading tasks with very few semantic errors or omissions.

The second prediction is that even if reading aloud is impaired (and includes semantic

errors) in addition to non-functional grapheme-phoneme conversion, as is generally the

case in deep dyslexia, then this function should be just as severely compromised as oral

naming, since the absence of grapheme-phoneme conversion should lead to a complete

reliance on the semantic reading route. However, reading aloud is consistently reported to

be superior to oral naming provided orthographic input is intact, even for individuals with

deep dyslexia. This phenomenon is “only consistent with the partial operation of (the

lexical non-semantic route)” (Howard, 1985, p403).

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A third prediction is that if grapheme-phoneme conversion is intact or at least partially

active, then regularisation errors should occur on reading of exception words. In other

words, surface dyslexia should be evident (Patterson, Marshall, & Coltheart, 1985).

However, Weekes and Robinson (1997) report BP, whose performance on semantic tasks

such as word-picture and picture-picture matching was impaired. Furthermore, he was able

to name barely more than half of the picture items in the Snodgrass and Vanderwart

corpus, and nearly half of his errors were semantic errors. His nonword reading was also

impaired, though he successfully read approximately half of the items on a nonword

reading task. Nevertheless, on a set of 40 exception words, BP made only one error

(reading thumb as thump, most likely a visual error). This is considered by Weekes as

strong evidence that BP is reading via a lexical pathway that does not involve semantic

processing. This prediction also applies to post-semantic naming impairments – MRF was

considered to have an intact semantic system but was impaired on oral naming, with

partially active grapheme-phoneme conversion, yet there was no effect of regularity

observed (Orpwood & Warrington, 1995).

Although the predictions made by most cognitive models of language processing with only

two reading pathways are not supported by the literature, the summation hypothesis (e.g.

Hillis & Caramazza, 1991; Hillis, Rapp, & Caramazza, 1999; Miceli et al., 1996; Miceli,

Capasso, & Caramazza, 1994; Miceli, Giustolisi, & Caramazza, 1991), considers reading

aloud of real words to be achieved by the ‘summation’ of lexical and sublexical processes.

If the semantic reading route is only partially operational but the sublexical process is also

providing full or partial activation, reading of words, both regular and irregular, is still

possible. Partial semantic activation means that semantically appropriate representations in

the phonological output lexicon, including the target, are partially activated (e.g. the word

yacht will activate representations such as boat, mast, sail, and of course yacht). At the

same time, the sublexical process activates all phonologically appropriate representations

in the phonological lexicon (so yacht might activate representations for words such as yet,

yurt and, again, yacht). Therefore, the only node in the phonological output lexicon that

will be activated above threshold is the target word, yacht. All other representations that

are activated will fail to reach threshold.

However, an important assumption of the summation hypothesis is that a complete lack of

input from the sublexical process, in conjunction with a lesion at some stage of the

semantic reading route, should lead to frequent semantic errors in word reading (i.e. deep

1:11

dyslexia). On the other hand, partial activation from the sublexical process should all but

eliminate semantic errors (and reduce total errors), as seen in phonological dyslexia. As

mentioned, however, evidence from the phonological dyslexic WB (Funnell, 1983)

suggests that this distinction between phonological and deep dyslexia does not always hold

true. This debate is examined further in the case of DHT, who is presented in Chapter 5.

The relationship between reading aloud and oral picture naming

While there are many different interpretations of how word reading can be achieved

through lexical, sublexical and lexical non-semantic processes, language researchers agree

almost universally that the phonological process of reading words aloud overlaps with the

phonological process of oral picture naming. However, a challenge to this principle was

the suggestion that reading and oral naming have distinct phonological stores that can each

be selectively damaged. The first clear presentation of this hypothesis appeared in a 1995

article by Orpwood and Warrington. They described MRF, an individual with poor oral

naming of pictures and poor naming to definition, with frequent semantic errors. As

demonstrated by his poor nonword reading, MRF had only partial access to grapheme-

phoneme conversion. MRF was able to read real words, with no difference between regular

and exception items, and his repetition of nonwords was intact; therefore he must have had

a lesion affecting the grapheme-phoneme conversion process. Comprehension was also

intact, suggesting a lesion of the phonological output lexicon. However, from the

perspective of most serial models, this should also impair word reading.

As can be seen in Figure 1:4, the authors propose that the lesion affecting oral naming is

located at a phonological output lexicon that is unique for oral naming tasks (lesion a).

Grapheme-phoneme conversion is also impaired (lesion b), but all other processes are

intact, including an additional phonological output store for word reading; the presence of

semantic errors in oral naming, and complete absence of them in reading, is considered

further justification for their position. The authors reject the summation hypothesis as a

plausible account on the basis that his grapheme-phoneme conversion is too severely

impaired to adequately contribute to reading.

Support for this hypothesis was provided by an apparent double dissociation between

reading and oral naming. BF was described by Goldblum (1985), and was remarkable in

that he was described as having intact oral naming yet impaired word reading (despite

intact comprehension for words). According to Breen and Warrington (1995), BF contrasts

with the many individuals reported for whom reading is intact while oral naming is

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impaired, thus representing a double dissociation between these two abilities. In the

context of most mainstream models, there is no way to account for this phenomenon. The

solution, according to the authors, is independent stores for each task. Extending this

hypothesis, the authors conducted a series of priming experiments with participant NOR.

They found that priming by first reading the word had very little effect on NOR’s oral

naming unless the delay was extremely short. Although they concede that very little is

known about the specific effects of priming at the level of the phonological lexicon, they

consider this finding to represent a possible dissociation between the phonological

processes involved in reading aloud and oral naming.

Figure 1:4. The hypothesis described by Orpwood and Warrington (1995).

Green boxes and arrows indicate intact processing; red boxes and arrows represent the hypothesised

lesions. Only relevant processes are shown.

The most significant feature of the hypothesis of independent phonological stores is the

claim of a double dissociation between oral naming and reading aloud. However, this

position is challenged by Lambon Ralph, Cippoloti and Patterson (1999), who argue that

BF’s naming was not necessarily superior to oral reading, as purported by Goldblum

(1985). Three reason are given for this challenge: First, BF’s profile represented a complex

pattern of various dyslexic syndromes, rather than a single syndrome that could be

accounted for by an isolated lesion of output phonology; second, and most significantly,

1:13

reading and oral naming were not compared for the same set of words; finally, Goldblum

considered BF’s naming to be less impaired than reading partly because the majority of his

errors were almost always corrected – Lambon Ralph and colleagues (1999) argue that this

is far from a clear demonstration of normal functioning.

The claim that the summation hypothesis is unable to account for NOR and MRF is also

disputed by Lambon Ralph and colleagues. Rather, the presence of semantic errors in

naming but not in reading can be attributed to direct input from sublexical processes

because only minimal orthographic information is needed to block semantic errors. For

their participant MOS, who also performed poorly on oral naming and well on reading

aloud, they suggest that the phonological output lexicon itself is preserved, as is the

semantic system. Instead, it is the connection between these systems that is severed, with

reading aided by the sublexical process.

In accordance with the summation hypothesis, Lambon Ralph and colleagues (1999) go

further by suggesting that the reason why oral naming is frequently found to be impaired in

the context of intact reading is that oral naming is simply more vulnerable. There are two

factors that contribute to this vulnerability. First, there is no direct correspondence between

conceptual knowledge about an object and the phonological representation of that object’s

name, while reading is largely aided by the ‘quasi-regular’ mapping between orthography

and phonology. Second, only one source of phonological activation is available to oral

naming, while reading has at least two. In support of this claim is evidence that oral

naming in anomic participants can be improved by an additional source of phonological

activation such as phonemic cueing, making it as robust as reading aloud with its two

sources of phonological activation (Lambon Ralph, 1998; Lambon Ralph et al., 1999).

In a third article aimed at supporting the notion of multiple phonological output stores,

Crutch and Warrington (2001) present VYG, whose spontaneous speech was intact, but

whose oral naming and reading aloud were both impaired. Oral naming responses

consisted mostly of circumlocutions, with few phonological errors, while reading errors

were all phonological. Since VYG was able to comprehend words that he was unable to

read aloud, the authors concluded that the site of damage must be at the level of a

phonological output store, or perhaps access to the output store from semantics. Despite

the fact that VYG’s naming was more severely impaired than his reading, the authors

claim that damage to the ‘stronger’ reading process should affect naming in the same way

1:14

– the high number of phonological errors in reading, and almost complete absence of them

in naming, is therefore considered evidence for a double dissociation between the tasks.

However, there are several flaws in the logic of the articles discussed above. Firstly, if

reading aloud and oral naming are enabled by separate phonological stores, then the double

dissociation between them should not be restricted to differences in error patterns. There

should be individuals reported in the literature for whom reading is worse than oral naming

for the same items, a phenomenon which has not yet been described. Secondly, Crutch and

Warrington (2001) claim that VYG’s comprehension of words that he is unable to read

aloud indicates that his semantic system is unaffected. They fail to observe the principle

that receptive tasks such as word-picture matching place considerably less strain on the

semantic system than do expressive tasks (e.g. Howard, 1985; Laine, Kujala, Niemi, &

Uusipaikka, 1992; Lambon Ralph, Sage, & Roberts, 2000). If VYG does have a mild

semantic deficit, this could have a noticeable impact on oral naming, including generation

of semantic errors, with less of an impact on reading, which is assisted by partially intact

grapheme-phoneme conversion – thus leading to more phonological errors. Thirdly, many

authors argue that discrepancies of error types should actually be expected for the same

reason that reading aloud is considered to be less vulnerable to impairment than oral

naming (e.g. Newcombe & Marshall, 1980; Southwood & Chatterjee, 2000, 2001). If

additional phonological input constrains the responses, then more phonological errors, and

less semantic/circumlocutory errors should be evident.

Research Aims

The general aim of this report is to demonstrate that the basic model of language

processing, as described in this chapter, could be a useful clinical tool to aid the

understanding of aphasic patients. To this end, the following predictions were made:

1) The basic model will be sufficient to account for each individual’s profile, or at least as

capable as any existing model.

2) Two lexicons, one each for phonological and orthographic representations, are

sufficient to explain the majority of aphasic participants.

3) The lexical non-semantic route is an essential component of serial models. Therefore:

a) Participants with significantly impaired oral naming (that is not caused by pre-

semantic damage) but with intact reading are best accounted for by the existence of

this pathway.

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b) If grapheme-phoneme conversion is completely abolished for an individual with

damage to the semantic reading route, deep dyslexia will only result if the lexical

non-semantic route is also damaged.

c) Reading impairments exhibited by anomic participants will conform to models of

language retrieval that assume a shared phonological process for reading aloud and

for oral naming (i.e. Orpwood and Warrington’s (1995) hypothesis of distinct

phonological stores will not be supported).

The critical motivation for this study was the paucity of literature in which a single set of

stimuli is used for a variety of language tasks. By developing a range of tests with a single

set of words-picture items, aphasic participants could be assessed in such a way that intact

and defective functions could be determined with much greater confidence than if a variety

of different tests had been used, thus providing insight into what aspects of cognitive

architecture are required to account for the participants. Furthermore, by carefully

balancing the group of items so that half would have word names with regular spelling and

the other half irregular, it was expected that a great deal more might be revealed about the

process of reading aloud.

The next chapter describes the processes involved in material preparation, recruitment of

suitable participants, assessment procedures and analysis of results.

1:16

2:17

Chapter 2. Method

As was described in the previous section, one aim of this project was to assess the validity

of claims made initially by Orpwood and Warrington (1995) that reading aloud and oral

naming are subserved by distinct phonological stores. This chapter describes the

recruitment of participants and the tests used, including the development of the five

unpublished tests that were designed to investigate the Orpwood and Warrington (1995)

hypothesis. It also describes the procedures that were followed for administration, scoring

and analysis of the battery of tests. As will be made clear, the lack of evidence for or

against this hypothesis did little to diminish the value of the results.

Participants

Recruitment of aphasic participants

Aphasic participants were recruited with the assistance of Speech Pathologists at the Royal

Rehabilitation Centre Sydney and St Joseph’s Hospital, through the Macquarie University

Psychology Clinic, and researchers at the Macquarie Centre for Cognitive Science. The

criteria for recruitment were adults with aphasia sustained at least 6 months prior to the

assessment, who presented primarily with anomia, without excessive interference from

complicating factors such as impaired hearing or vision, global cognitive dysfunction or

prominent motor-speech deficits, including dysarthria or verbal dyspraxia. Individuals with

mild complicating deficits were still requested with the understanding that they would be

excluded if necessary, though none were excluded on this basis. Individuals were also

excluded if they were identified as having recent psychiatric risk factors such as suicidal

ideation, depression or heightened anxiety.

A total of 12 potential participants were recruited. Of these, 7 were considered appropriate

based on the inclusion and exclusion criteria. One was excluded due to a near-ceiling

performance on most tests, two had recovered to the point that they were speaking fluently

in conversational speech, and two individuals who showed interest were excluded on the

basis of psychiatric conditions as it was considered unethical to risk placing them into a

potentially stressful situation. One participant, FME, was described in a separate report in

relation to her diagnosis of herpes simplex encephalitis, and is not discussed any further in

this dissertation. Descriptive data for the six remaining participants appear in Table 2:1

below. Each participant is described in detail in the following chapters.

2:18

Ch

ap

ter

Part

ic-

ipan

t

Ag

e

Ed

uca

tio

n

Sex

Description of injury/illness

Months Since Injury

Acute deficits (immediately post-onset)

Relevant Medical History

Vision/ Glasses

4 MWN 76 10 F

LMCA ischaemic with minor cortical atrophy

8

Broca's aphasia; dysarthria; mild verbal dyspraxia; mild right arm weakness

AMI 1990; mitral valve repair; TIA; hypercholesterolemia

Bifocals

5 RPD 65 10 M LMCA infarct 29 Unknown

Right meningioma and debulking surgery; CABG; high cholesterol

Glasses (short and reading)

5 DPC 51 11 F LMCA haemorrhagic

56 Confusion; aphasia

Type II DM; migraines; anxiety disorder

Reading

5 DHT 62 9 M LMCA cerebral embolic infarct

35

Right hemiplegia; non-fluent aphasia, agrammatism

Infective endocarditis; CABG

Bifocals

6 JWS 69 9 M LMCA ischaemic

24 Right hemiparesis; hemisensory loss; global aphasia

Unknown Reading

7 SJS 43 10 M

LMCA haemorrhagic with bifurcation aneurism

83

Severe frontal headache; vomiting; global aphasia/dysphonia

Hypertension Glasses (short)

Table 2:1. Descriptive data for the aphasic participants.

Education = total years of formal education; LMCA = left middle cerebral artery; CABG = coronary

artery bypass graft; AMI = acute myocardial infarction; TIA = transient ischaemic attack; DM =

diabetes mellitus.

Recruitment of unimpaired controls

Unimpaired controls were recruited through personal contacts, and were seen in two

groups. The first group took part in the validation stage, and consisted of 10 age

appropriate controls (M = 59.63, SD = 4.35) with appropriate anticipated years of

education (M = 11.7, SD = 2.63). These participants were selected on the basis of expected

age and education levels of the ABI participants, who had not yet been identified. For the

second control group, 16 unimpaired participants were initially recruited, of which two had

also been involved in the validation stage. One participant, M2, emigrated from the

Netherlands at the age of 21. Because English is his second language, he was excluded

from the main control group. However, his data are presented in Chapter 6 as a comparison

for JWS, an aphasic participant with a similar background.

2:19

The remaining 15 individuals, 8 females and 7 males, were included in the main group.

Independent t-tests revealed no significant difference between the seven original aphasics

and the control group for either age (aphasics M = 61.00, SD = 12.08; controls M = 60.20,

SD = 6.35; t(19) = 0.20, p = 0.84) or years of formal education (aphasics M = 9.83, SD =

0.75; controls M = 10.07, SD = 1.16; t(19) = 0.45, p = 0.66).

Many of the control participants wore glasses, and several had mild visual impairments

(e.g. cataracts) though testing did not reveal any obvious visual difficulties (i.e. they did

not perform any worse than other controls on tests that might be sensitive to visual

impairment). Also, four members of the main control group (three males, one female)

reported mild hearing difficulties, which were not identified until nonword repetition was

attempted. The justification for including these individuals is that such mild hearing loss

and visual difficulties are clearly common in this population, and difficult to identify.

Therefore, similar difficulties cannot be eliminated as a cause of poor performance for

some of the aphasic participants; the effect of mild hearing loss on repetition tasks is

discussed in Chapter 3. Two participants emigrated from England about 25 years ago, and

the results of these individuals are also examined more closely in Chapter 3.

Materials

One of the key predictions made by the Orpwood and Warrington (1995) hypothesis is that

if oral naming is impaired, and the cause of this impairment can be localised to the

phonological output lexicon, then words with regular spelling should be less affected on a

reading task than words with irregular spelling, assuming that grapheme-phoneme

conversion is still involved. Determining the effects of regularity on reading performance

is also tantamount to hypotheses relating to the lexical non-semantic route. Therefore, the

primary objective when preparing the materials was to focus on this contrast between

regular and exception words by gathering two word lists that differed only in this respect.

That is, the word items needed to be matched on criteria such as frequency and linguistic

complexity. In order to further limit potential differences in linguistic complexity, only

monosyllabic words were chosen. Since the items also needed to be named, only words

that could be easily elicited by their pictures were appropriate, which considerably limited

the number of appropriate items. For example, a picture of a yacht will just as often be

named as a boat; pictures of a buoy and a raft proved to be difficult to identify for many

people.

2:20

After an extensive period of item selection and refinement, including informal testing and

discussion with peers, 104 items were selected from the list of monosyllabic words in the

CELEX lexical database (Baayen, Piepenbrock, & Van Rijn, 1993). The pictures were

obtained primarily from Hemera Photo Objects (Hemera, 1997-2000), with gaps filled by

non-copyright pictures obtained from the internet. Alterations were made where necessary

to exclude distracting aspects of the images or to highlight the relevant part of the picture.

The regular and exception word sets were matched for spoken and written frequency

(Baayen et al., 1993), number of phonemes, number of letters, the number of plural words

(only one item in each set (shorts/blinds) was a plural word), and whether the item was

animate or inanimate. Since many nouns also act as verbs (e.g. axe, bowl, or comb), which

can have a considerable impact on frequency effects, only items that were deemed to be

used most often as nouns were selected. Comparisons were analysed using t-test and

Fisher’s exact calculations, with the results presented in Appendix 1. Following the

validation phase of the research (see the Procedures section that follows) the final

word/picture set included 40 items with regular spelling and 40 exception items, with

classification determined by the set of grapheme to phoneme correspondence rules listed

by Rastle and Coltheart (1999).

These 80 items were used for four simple tests of language ability: Oral naming, written

naming, reading aloud and repetition. As it was anticipated that some participants might

have considerable difficulties with written picture naming and that they would be unable to

complete the test, the first 20 items on this test were also matched as per the criteria listed

above. Again, comparisons were by way of t-tests and Fisher’s exact, with the results

appearing in Appendix 1. Presentation order of items in each test was pseudorandom –

items were selected at random but relocated to ensure that no more than three consecutive

items were related by regularity, semantic field or phonological similarity.

Additionally, a word-picture matching task was designed to determine whether or not

participants had intact access to the semantic representations of the test items from the

written word. A multiple-choice format was used. For each item, the target word appeared

in the middle, with four pictures around the word. The pictures were equated in size as

much as possible, but often needed to be slightly different to remain size appropriate (e.g. a

picture of a cat needs to be larger than a picture of a mouse). An example item from the

2:21

comprehension test appears in Figure 2:1. For each written word item, the pictures

included:

a) The target picture;

b) A semantic distractor – the regular and exception word groups were matched for

degree of semantic relatedness between the distractor and the target based on

figures sourced from Maki, McKinley and Thompson (2004) as well as the type of

semantic relationship (each pair was broadly classified as either related by

association, such as bowl and spoon, or simply being members of the same

category, such as an axe and a saw);

c) A phonological/orthographic distractor – the two groups were matched for degree

of phonological relatedness; and

d) An unrelated distractor.

bowl

Figure 2:1. Example Item from the comprehension test:

The given word item (bowl), the target picture, the semantic distractor (spoon), the phonological

distractor (bell), and the unrelated distractor (tricycle).

Most pictures appeared more than once throughout the test, though none appeared more

than three times in total (including once as the target, for many of the pictures). The full

list of items for the comprehension test appears in Appendix 1, along with relatedness

figures and classifications, and statistical calculations.

Other tests: Aphasic participants were also assessed on several published tests in order to

assess the integrity of other aspects of the lexical system. The following tests were

administered:

• Tests from the Psycholinguistic Assessment of Language Processing in Aphasia

(PALPA, Kay, Lesser, & Coltheart, 1992):

2:22

o Visual lexical decision (subtest 25) – spelling-sound regularity

(distinguishing real words (regular and exception) from nonwords

(pseudohomophones and non-homophonic nonwords)). This test was used

to assess the integrity of the orthographic lexicon and input to it. Chance is

50% on this test.

o Homophone decision (subtest 28) – judging whether or not pairs of words

(with regular and irregular spelling) or nonwords sound the same. This test

relies on the integrity of multiple components of lexical processing,

including the orthographic lexicon, phonological lexicon, grapheme-

phoneme conversion and the phonological output buffer. The error pattern

of this task, in particular the contrast between real word and nonword pairs,

is often more important than the total score. Chance is 50% for this test also.

o Nonword reading and repetition (subtest 36) – grapheme-phoneme

conversion and the sublexical repetition route can potentially play an

important role in processing of words, particularly when other abilities are

impaired. Therefore, assessment of nonword reading and repetition was

vital. To enable relevant comparisons, it was also crucial that the nonword

items be comparable to items used for the unpublished tests (i.e. the 80

regular and exception words discussed previously). Indeed, two-tailed

independent t-tests revealed no significant difference between the 80 test

items and the 24 nonwords used in PALPA for either number of letters (for

real words M = 4.30, SD = 0.79; for nonwords M = 4.50, SD = 1.14, t (102)

= 0.98, p = 0.33) or number of phonemes (for real words M = 3.30, SD =

0.80; for nonwords M = 3.42, SD = 0.72, t (102) = 0.64, p = 0.52).

o Cross-case matching (subtest 19) and, for participants who made errors on

this test, mirror reversal (subtest 18). These tests were intended to eliminate

an impairment of letter identification as the cause of a participant’s

difficulties with processing written words.

• Pyramids and Palm Trees test (PPT, Howard & Patterson, 1992) – this test requires

the participant to match the stimulus item (picture, written word or spoken word) to an

associated item from a choice of two semantically related pictures. Three versions

were utilised in order to assess the integrity of the semantic system and input to it:

o 3 pictures version – poor performance relative to the other versions might

suggest reduced input from object recognition.

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o 2 pictures + 1 written word version – relatively poor performance suggests

reduced input to the semantic system from the orthographic lexicon.

o 2 pictures + 1 spoken word version – relatively poor performance suggests

reduced input to the semantic system from the phonological lexicon.

Equal difficulty with all three versions is indicative of damage to representations

within the semantic system.

• From the Birmingham Object Recognition Battery (BORB, Riddoch & Humphreys,

1993):

o Subtest A (hard). This subtest is comprised of 32 black and white drawings

of which half are real and half are made up from two different objects (e.g.

the body of a cow with the head of a horse). This tests the integrity of the

object recognition process.

Procedures

Validation phase: The original 104 pictures were shown to the validation group of controls

on the screen of a 17” laptop computer using Microsoft PowerPoint. In cases where the

target was provided in conjunction with an appropriate non-target word (e.g. ‘crow, bird’

for the desired target of crow), the target was considered to have been achieved (on testing,

aphasic participants and members of the second control group were prompted to provide

another response if they answered with an appropriate non-target word). Likewise, if the

target response was included as part of a larger, similarly appropriate response (e.g. steak

� ‘t-bone steak’; plane � ‘aeroplane’), the item was considered appropriate for inclusion,

and hence correct if produced by the aphasic participants and members of the second

control group. Items were only included if the target word was achieved by nine out of ten

controls in the validation group, and the two word groups (regular/exception words) were

matched for the number of participants who named each word correctly (mean number

correct out of 10 for the regular group was 9.85 (SD = 0.33) and for the exception word

group 9.75 (SD = 0.44), t(78) = 0.42; p = 0.68).

Experimental phase: The items for four tests were shown to all participants on a 17” laptop

screen using Microsoft PowerPoint – the items for the repetition task were read by the

examiner. For picture naming (oral and written) and reading, five seconds was allowed for

the response, with the timing controlled by the computer (a further 5 seconds was allowed

if the participant was prompted to provide a different response, as described for the

validation study). For written naming, the time limit only applied to the commencement of

2:24

writing a name to allow for any motor difficulties (i.e. extra time was allowed for slow

writing, within reason). For repetition, the 80 items were read to the participant, with 5

seconds allowed for each response. Ten seconds was allowed for each item on the

comprehension test. A five second gap (a blank screen) separated each item on all tests

except for repetition, for which one to two seconds separated each response from the

following item. Participants were permitted to move through the computerised tests faster

by pressing an appropriate key on the keyboard.

The assessments with all participants were conducted over four sessions, with each session

a week apart (or within 2 days). The tests administered in each session are listed in Table

2:2 below. The unpublished tests were spread out over the sessions to reduce the effects of

priming. The exception was the last session, during which written naming was followed

soon after by repetition; it was considered too impractical and burdensome on the

participants to extend testing beyond four sessions. Controls were assessed on all tests

except for cross-case matching, on which unimpaired individuals are assumed to be 100%

accurate.

Session 1 � Interview

� Comprehension test

� PPT (3 pictures)

Session 2

� Oral naming test

� PPT (2 pictures, 1 written word)

� Visual lexical decision – regularity (PALPA: 25)

� Object decision (BORB: Subtest A – Hard)

� Homophone decision (PALPA: 28)

� Nonword reading (PALPA: 36)

Session 3

� Reading test

� PPT (2 pictures, 1 spoken word)

� Nonword repetition (PALPA: 36)

� Cross-case matching (PALPA: 19)

Session 4 � Written naming test

� Repetition test

Table 2:2. List and order of tests in each session.

Italics indicate unpublished tests.

The structure of testing was not varied between participants; all aphasic and unimpaired

participants completed the tests in the same order. This was to ensure consistency with, and

therefore enable accurate interpretation of, practice effects and priming.

2:25

Scoring

For the unpublished tests, clarification of certain error types is needed:

• Phonological error was scored when at least half of the target phonemes were

produced in the correct position.

• Spelling error was scored for written naming if at least half of the target letters were

produced in the correct position (e.g. chef�chark).

• Mixed errors were considered unrelated unless there was an obvious connection

with the target item (e.g. bone � dag (presumably dog) in written naming was

considered a semantic error).

• Errors that were self-corrected within the time limit were considered correct without

further consideration.

• Morphological errors were primarily inflectional errors (mostly addition or deletion

of the plural –s).

• Based on the responses of controls, plural variation in picture naming was

considered acceptable for two items, blind/s, for which both variants are common, and

gate/s (which was generally named as the singular, but since the picture was of a two-

part gate this could not be considered an error). Also, the pronunciation of vase varied

(either pronounced /vaz/ or /veIs/).

• No response errors included items for which some effort was made but nothing

meaningful (i.e. only one phoneme or letter) was generated.

Finally, although errors on the comprehension test appear fairly straightforward, there is at

least two ways that the actual error types could reflect problems such as reduced visual

acuity or scanning. First, the phonological distractors more often than not had names that

were visually similar to the target (e.g. ball/bell; nose/hose) – therefore, many phonological

errors could actually be visual or orthographic errors. Second, many of the semantic

distractors were not only visually similar to the target, but in some cases were actually

more prominent (especially when the distractor picture, but not the target, had the

background removed) – therefore, some semantic errors could actually reflect failure to

adequately scan all components of the item, which might account for the rare control

errors.

Analyses

Measures of impairment: To ascertain whether or not an aphasic participant performed

significantly worse than the control group, the Bayesian methodology of Crawford and

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Garthwaite (2007) was employed (using the software for simple difference, cited in the

same article). This was the primary calculation used for determining whether or not a

participant had performed significantly worse than the control group on a particular task.

Because the regular and exception groups were so well matched in terms of control

performance, Fisher’s exact test (an unstardardised method of comparing independent

groups) was used to determine differences, rather than Crawford and Garthwaite’s

standardised calculation, which was influenced by ceiling effects.

For certain participants, the discrepancy between two unpublished tests was measured with

McNemar’s Test, with the obvious caveat that the tests differ slightly in their levels of

difficulty, meaning a certain level of subjective interpretation was unavoidable. The

Crawford and Garthwaite method (2007) proved to be inappropriate for judging these

discrepancies and dissociations due to the differing influences of ceiling effects on the

different tests.

Item consistency: An important consideration for error analysis is item consistency, or the

comparison between two tasks for a particular set of items. Since language based entries

are conceptualised as representations stored within the semantic system and each of the

lexicons, damage to particular representations should lead to errors on the relevant items

regardless of the task, assuming that the same processing module is necessary for each of

the tasks being compared. For example, damage to representations in the semantic system

might lead to item consistency for oral naming, written naming and word-picture matching

for particular items, but not necessarily for repetition or reading; damage to representations

in the orthographic lexicon might lead to consistency for reading, word-picture matching

and written naming, but not repetition or oral naming. On the other hand, a lesion that

causes reduced activation of a processing module, rather than damage to the

representations in the module, would not be expected to result in such consistency.

Therefore, item consistency can, in certain conditions, provide an indication of the extent

to which two deficits might be related by a single lesion.

However, there are several aspects of item consistency that warrant caution when

interpreting the results. First of all, not all tasks have the same ‘degree of difficulty’ – even

for unimpaired individuals, written naming is usually performed less well than oral

naming, at least for English in which written naming entails not only naming the picture,

but also retrieving details about complex spelling rules and a large number of memorised

2:27

word spellings that do not abide by rules or even a consistent exception to the rule (for

example, it would not be unusual for some unimpaired individuals to be unable to spell

words such as yacht). Furthermore, impaired participants could easily have multiple lesion

sites affecting particular abilities, yet it is still relevant to investigate the possibility that

one of the lesions is at least partially responsible for two or more of the deficits. Therefore,

calculation of item consistency between different tasks should include an element of

maximum consistency or ‘maximum overlap,’ which is discussed shortly.

The second caution relating to item consistency is that a certain level of similarity is often

expected between two tasks even if the difficulties on the tasks are not the result of a single

lesion. This argument relates most prominently to the relationship between oral and written

naming, and arose from observations that certain participants with post-semantic naming

impairments would demonstrate statistical consistency between the two tasks, suggesting

to many that there could be an additional process after the semantic system but before the

lexicons (e.g. Levelt et al., 1991; Raymer et al., 1997; Raymer, Maher, Foundas, Rothi, &

Heilman, 2000). However, several authors have questioned the need for this additional

process in accounting for item consistency. For example, Miceli and colleagues (1991)

consider a certain level of consistency to simply represent deficits resulting from co-

occurring lesions affected by the same linguistic factors such as word frequency,

imageability and linguistic complexity. That is, for any particular set of words, it is likely

that the least frequent and most complex words will be the most vulnerable. This can lead

to consistency between any tasks that happen to share the same common pressures.

Furthermore, the particular common pressures are different for different pairs of tasks. For

example, for oral and written naming, word frequency and imageability are likely to play a

role, while for reading aloud and written naming, word frequency and grapheme-phoneme

regularity might lead to consistency, and the effect of imageability is perhaps less

predictable. Therefore, it is important to keep in mind that a certain level of consistency

between tasks, even beyond what would be predicted from mathematical chance, could

simply be the result of the factors that affect both tasks.

Despite these cautions about interpreting item consistency, the benefit of being able to

judge the relationship between two deficits makes this form of analysis extremely

worthwhile. There are numerous methodologies for calculating and interpreting

consistency (see Howard, 1995, for a statistical procedure that attempts to negate the

effects of some of the variables that affect word retrieval). Although it is theoretically

2:28

possible to use or devise a procedure for determining statistically significant consistency

that takes into account frequency, visual complexity, phonological and orthographic

complexity and so on, the nature of comparing the results of two different tests is so

complex that it is not reasonable to consider such a method to be entirely accurate.

Furthermore, attempting to compare five different tests with such a methodology would

mean calculating the effects of the various factors for up to ten comparisons, each with

different common factors with varying degrees of impact for each. For these reasons, a

straightforward method was used to allow qualitative judgement of item consistency

between tests.

Simply put, the actual overlap (of correct plus incorrect responses) is compared to the

maximum overlap and the chance overlap. The maximum overlap is the greatest that the

overlap between two tests can be, given the difference in test scores, and is found by

adding the number of errors of the more accurate test to the number of correct responses on

the less accurate test. For example, if the score on oral naming is 60/80 and the score on

written naming is 30/80, then the maximum overlap is 50 (20 errors on oral naming plus 30

correct on written naming). In other words, the overlap between the two tests, given the

difference in performance, cannot be higher than 50. The closer the scores are for two tests,

the higher the maximum overlap. The chance overlap, which is derived from Cohen’s

Kappa, is the overlap that would be predicted by chance alone, given the difference in

scores (assuming complete independence). This figure is found by multiplying the number

of errors on test a by the percentage of errors on test b, added to the number correct on test

a multiplied by the percentage correct on test b. Since the figure does not attempt to

incorporate item frequency or complexity, there is no illusion that the comparison can

render a statistically sound comparison. Rather, it simply allows an estimate that can be

used for all of the comparison regardless of the common pressures that would be expected.

This allows for a more honest comparison by allowing a much greater depth of

interpretation and debate, instead of relying on a statistical procedure that may or may not

encompass all of the relevant factors. Calculation of overlap is explained further in

Appendix 2.

By considering the actual overlap as it compares with the chance overlap and maximum

overlap, a qualitative judgement can be made about the relationship between two tasks: An

overlap closer to chance than to the maximum suggests little or no relationship; a score

midway between chance and the maximum suggests a possible relationship, with possible

2:29

involvement from common pressures; finally, an overlap that is close to the maximum is a

good indication of a relationship between the tasks, provided the maximum is reasonably

high (if tests differ too greatly in score, the maximum overlap can be too low to allow a

meaningful interpretation).

Nonword reading and repetition: In addition to presenting the results of the two nonword

tasks in terms of number of items correct, an additional calculation was performed to

assess the level of accuracy of the individual phonemes produced. This phoneme overlap is

a simple method of displaying a participant’s accuracy when their total score on the test is

below normal levels. For each item, the number of phonemes in the target response is

compared with the number of correct phonemes in the actual response. The lesser of the

two is then divided by the greater to achieve a figure that represents the percentage of

correct phonemes that were achieved for that item. For example, if ploon is read as ‘foon,’

two of the 4 target phonemes have been achieved, or a 50% overlap. The mean overlap for

all 24 items can then be calculated.

The number of lexicalisations is also recorded. These are items that are generated as real

words that are similar to the target (usually within a single phoneme or grapheme of the

target). A relatively high number of lexicalisations for a particular test suggests that the

lexicons are being employed to process novel grapheme or phoneme sequences, rather than

grapheme-phoneme conversion (for nonword reading) and the sublexical repetition route

(for nonword repetition). A high number of lexicalisations also reduces the relevance of

phoneme overlap; for example, DHT (Chapter 4) had an overlap of 31% on nonword

reading, but it came almost entirely from his lexicalisations suggesting that nonwords were

being read via lexical processes and not at all by grapheme-phoneme conversion. On the

other hand, a reasonable overlap with a lower number of lexicalisations would suggest at

least partial access to grapheme-phoneme conversion.

The following chapter presents and discusses the results of the 15 unimpaired participants

whose data allowed enabled effective analysis of the aphasic participants.

2:30

3:31

Chapter 3. Control group – results and discussion

Before reporting and discussing each of the aphasic participants, several issues arose from

the control group data that are worth discussing. Summary data of testing with control

participants appear in Tables 3:1 and 3:2. Full results are reported in Appendix 3.

BORB PALPA PPT

Object

decision Lexical

decision Homophone

decision Nonword reading

Nonword repetition

Mean 3P 2P1W 2P1S

n 32 60 60 24 24 52 52 52 52

Mean 25.93 58.33 55.65 22.94 21.73 50.44 50.07 50.73 50.53

StDev 2.66 2.38 3.46 1.18 3.16 1.42 1.94 1.33 1.30

Lowest 20 53 50 21 13 46.33 45 47 47

Table 3:1. Summary of control results on published tests.

Mean, standard deviation (StDev) and lowest score for each of the published tests. For PPT, Mean =

mean of all 3 versions; 3P = 3-picture version; 2P1W = 2-picture/1-written word version; 2P1S = 2-

picture/1-spoken word version.

Regularity effects of unpublished tests

Since one of the aims of the research focused on the issue of regularity effects, the first

comparison was between regular and exception words for the unpublished tests. Although

there is a slight discrepancy between word groups for each test, efforts to match the groups

were fairly successful. The only meaningful difference was for written naming,

presumably due to less predictable spelling of some words. This was a significant

discrepancy (t(14) = 2.69, p = 0.02). Since the balance of imageability between the two

groups was based only on the oral naming performance of the validation control group, it

was not surprising that differences were revealed for the written naming test, for which

regularity should, theoretically, play a much greater role. Having said that, the effect of

regularity should only be evident in spelling errors. While there mean of spelling errors

was higher for the exception words (0.93 to 0.53), so too was the mean of semantic errors

(0.67 to 0.20).

The only other significant discrepancy was for the comprehension test (t(14) = 2.26, p =

0.04), though the actual difference was minimal (summed across the 15 participants, there

were 4 errors on regular words and none on exception). Means and standard deviations for

these tests, as well as the discrepancy between means of the regular and exception word

groups, appear in Table 3:1.

3:32

Compre- hension

Oral Naming

Reading Written Naming

Repetition

n 80 80 80 80 80

Mean 79.73 79.00 79.87 77.07 79.20

Standard Deviation 0.46 1.00 0.35 2.63 1.08

Regular - exception -0.27 0.33 0.13 1.07 0.40

Table 3:2. Summary of control group results on unpublished tests.

Descriptive data for each test and for the discrepancies between regular and exception word groups on

each test (mean of total scores for each participant on regular words minus mean for exception words).

Oral naming versus written naming

It was not unexpected that some aphasic participants would have greater difficulty with

written naming than with oral. Therefore, it is important to be able to judge whether this

discrepancy is the result of differing effects of lesions, or the effects of a single lesion

affecting both output modalities, with the written naming score lower simply because this

task is more difficult. Indeed, control data suggest that written naming is significantly more

difficult, with the range of scores much lower (lowest control score 72 for written naming,

77 for oral). Therefore, a small difference between scores might simply relate to the degree

of difficulty on each task, and this needs to be taken into account when comparing

participants’ scores for each task. On the other hand, a significant difference in the

opposite direction is a strong indication that oral naming is defective, and more so than

written naming if both are impaired. Written naming was significantly more difficult than

oral naming for the control group t(14) = 3.08, p < 0.01. Strangely, however, it was not just

spelling errors that distinguished the two naming tasks (a mean of 1.47 compared with 0

phonological errors on oral naming) – the mean number of semantic errors also increased

from oral naming (0.47) to written naming (0.87). Other error types were fairly consistent

between the two tasks. In terms of item consistency across participants, one item on written

naming (scroll) was scored incorrectly by three participants, while 10 other items were

incorrect for two different participants.

Written naming was also significantly more difficult than comprehension (t(14) = 3.73, p <

0.01), reading (t(14) = 2.85, p = 0.01), and repetition (t(14) = 4.05, p < 0.01), though on

each of these tasks the mean number of errors was less than one, as can be seen in Table

3:1.

3:33

Methodological issues

Several methodological issues became apparent when the results of the control group were

analysed:

1. Written naming: One problem with the added difficulty of written naming is a reduction

of sensitivity for the test. Some people are simply ‘bad spellers,’ which lowers the mean

and range of the control scores. Unfortunately, this erodes the test’s ability to detect mild

deficits of written naming amongst aphasic participants who were premorbidly ‘good

spellers.’ If an individual who would have premorbidly scored close to 100% on written

naming then sustains an injury that reduces their performance to the level of unimpaired

‘bad spellers,’ any assertion of a deficit is much less conclusive. This problem can be

addressed to some extent with error patterns: Errors of unimpaired individuals with low

scores should be predominantly spelling mistakes, with ‘appropriate’ misspellings (e.g.

wasp�wosp). A high number of semantic errors (no control made more than 2) or very

unusual spellings (e.g. bee�eeb; kite�kert) might indicate that a lesion is affecting this

process.

2. PPT: Two members of the control group, F6 and M6, emigrated from England about 25

years ago. Despite performing at similar levels to the rest of the control group on most

tests, there was an obvious advantage for F6 and M6 on PPT, achieving 100% accuracy on

all three versions. Only one other control, F5, achieved full scores on all three version –

predictably, F5 was also educated in England. Only one Australian educated control

achieved a perfect score, and only on one version. The difference between controls

educated in England and those educated in Australia was significant (t (13) = 2.47, p =

0.03), Nevertheless, merging the scores of all 15 control participants had only a small

impact on group scores – the mean for the 12 Australian-educated controls across all three

versions was 50.06 (SD = 1.32) compared with 50.44 (SD = 1.42) when the three England-

educated participants are included.

For most of the aphasic participants, the inclusion of the England-educated controls made

little difference. Nevertheless, the apparent cultural bias in PPT suggests that there should

be concern as to the appropriateness of using English norms for a clinical population

educated in Australia. Howard and Patterson (1992) report a mean score of 98-99% (less

than one error) for the 3-picture and 3-word versions, with no participant making more

than three errors. In contrast, three of the twelve unimpaired, Australian-educated

3:34

participants made more than three errors on at least one occasion, and the mean for the 3-

picture version was considerably lower than that given by the authors of the test (95%, or

about 2 errors more on average). This finding should serve as a warning to clinicians who

use the PPT in practice that the results of the PPT, although very useful, need to be

interpreted within the context of this possible cultural bias. On the other hand, lowering the

cut-off score for PPT reduces its sensitivity, so it is important to balance these

considerations. The items that were most unreliable for the Australian educated members

of the control group are listed below. While most items were unreliable on just a few

occasions and for only two to three participants, the most noticeable difficulty was on the

acorn item, for which Australian-educated controls consistently chose the distractor.

Percent accuracy

Item number

Given item Target Distractor

14 40 acorn pig donkey

86 16 windmill tulip daffodil

89 4 thimble needle cotton

92 31 puddle cloud sun

92 32 rocket moon star

94 12 pyramid palm tree pine tree

94 14 ticket bus car

94 26 nun church house

Table 3:3. Most frequently incorrect items on PPT for controls.

Only items that were incorrect for at least two different control participants are included.

3. Object decision: Perhaps the most concerning test result was for the object recognition

task from BORB (Riddoch & Humphreys, 1993). The performance of the control group on

this task varied so greatly that it effectively had very little capacity for detecting

impairments, with the worst-performing control scoring just 20/32 (chance is 16/32). The

mean of 25.93 was also noticeably lower than that of the original normative sample (M =

27.0, SD = 2.2). Fortunately, the lack of sensitivity of this test did not matter for the

aphasic participants, for whom the lowest score was 26/32.

Although an English advantage might again be predicted, given that many of the animals

represented in the test might be unfamiliar to people raised and educated in Australia, this

was certainly not the case – three of the Australian-educated controls outperformed their

England-educated peers. However, the clearest outcome of error analysis was the obvious

response bias towards real objects (M = 95%, SD = 5%; for unreal objects, M = 67%, SD =

13%). This lack of ability for unimpaired controls to reliably identify made-up pictures

suggests possible problems with the materials. Feedback from the controls who found the

3:35

test difficult indicated that the drawings were not clear enough, and it is important to note

that the lowest scoring control did not report any diagnosed visual problems (aside from

the need to wear glasses). A qualitative observation was that participants appeared to

improve as the test proceeded, suggesting that practice items or coaching might improve

reliability, validity and sensitivity.

4. Nonword repetition: Lastly, it was noted in Chapter 2 that several control participants

had minor hearing difficulties which were considered age appropriate and were not

obvious in conversation. These difficulties seemed irrelevant on all of the tasks with the

exception of nonword repetition. As can be seen in Figure 3:1, those with minor hearing

loss performed considerably worse on this task (for the 4 hearing impaired controls, out of

24, M = 16.75, SD = 2.87, for the 11 unimpaired controls M = 23.55, SD = 0.69). This is in

contrast to word repetition, on which the score out of a possible 80 differed only slightly

(hearing impaired M = 78.25, SD = 1.26; for unimpaired M = 79.55, SD = 0.82). A two-

way analysis of variance revealed a significant effect of hearing on the tests (F(1, 13) =

55.67, p < 0.01).

The inclusion of these participants was justified on the grounds that they were considered

representative of the general population. The advantage of this decision is that allowances

can be made for aphasic participants with mild hearing difficulties (to the extent that it

seems relatively ‘normal’ for this age group). The disadvantage is the lack of sensitivity in

detecting impairments of nonword repetition in participants with good hearing. Although

the outcome of nonword repetition is therefore somewhat less transparent, the results are

nevertheless useful. Obviously, a good score on this task (22/24 or higher) is indicative of

intact abilities (within the confines of the basic model, which means intact auditory input,

phoneme input and output buffers, and speech/motor output). Scores below this point were

interpreted within the context of the basic model (which in this instance complies with

most mainstream language models), and are examined more closely in the relevant

chapters.

3:36

0

20

40

60

80

100

Words Nonwords Words Nonwords

Hearing impaired Normal hearing

Perc

ent corr

ect

Figure 3:1. Control group performance on repetition tasks.

Mean scores in percent for word and nonword repetition for the 4 members of the control group with

minor hearing loss and the 11 without.

4:37

Chapter 4. A simple case to explain?

The first aphasic participant to be presented is MWN, a woman with an apparently isolated

deficit of oral naming. The basic model can account for her straightforward profile, though

closer examination of her data reveals several issues that are not so easily resolved. The

issues raised include the lack of sensitivity of written naming and the tests of the semantic

system, and whether or not the production of semantic errors on oral naming can be

attributed to a post-semantic lesion. The significance of the lexical non-semantic route is

also discussed.

Case description

MWN was a 76-year-old woman with 10 years of formal education and five years part-

time nursing training. She worked as a nurse until she retired at age 65. Medical records

indicate that MWN was admitted to hospital in July 2006 with aphasia and right-sided

weakness. She was diagnosed as having sustained an ischaemic infarct of the left middle

cerebral artery. CT brain scan revealed minor cortical atrophy with no evidence of mass,

haemorrhage, infarction or hydrocephalus. In August 2006 she was admitted to a

rehabilitation facility, where a speech pathology assessment noted word-finding difficulties

with frequent phonemic errors, and moderate-severe verbal dyspraxia characterised by

hesitations, false starts and articulatory errors. However, her auditory comprehension was

good for complex instructions. Relevant medical history includes acute myocardial

infarction 15 years before the injury, mitral valve repair, a transient ischaemic attack, and

hypercholesterolemia.

Results

MWN was assessed approximately eight months after her admission to hospital. Her

spontaneous speech was slow and she initially appeared to lack confidence on testing.

However, she was quick to complete the tests and seemed to grow in confidence as testing

proceeded. MWN’s results are summarised in the following sections. Significance (simple

difference of her performance relative to controls) was calculated using the Bayesian

standardised difference method (Crawford & Garthwaite, 2007). Her responses to

particular tests are listed in Appendix 5:a.

4:38

Input processes

MWN scored higher than the mean score for controls on all tests of input processes,

indicating that her object recognition, letter identification and orthographic lexicon are all

intact.

Object

decision X-case

matching Lexical

decision Homophone

decision

n 32 26 60 60

MWN 26 26 60 57

Control M 25.93 58.33 55.65

2SD below M 20.62 53.57 48.72

Lowest control 20 53 50

Significance ns

\

ns ns

Table 4:1. MWN’s performance on tests of input processes.

Results of object decision, cross-case matching, visual lexical decision, and homophone decision.

Reading and repetition of words and nonwords

MWN made one error in her reading of test items (reading mast as ‘mask’). Although this

was significantly different to controls, it was within the control range and was probably the

result of mild dyspraxia, suggesting that the processes involved in reading of exception

words (most importantly the lexicons) are otherwise intact. Reading of nonwords was also

normal in comparison to controls, indicating that grapheme-phoneme conversion is intact,

and repetition of both words and nonwords was performed better than the mean of the

controls, suggesting that the phonological input and output buffers and sublexical

repetition route are intact.

Reading Repetition


n 80 24 80 24

MWN 79 22 80 22

Control M 79.87 22.94 79.2 21.73

2SD below M 79.16 20.57 77.04 15.42

Lowest control 79 21 77 13

Significance 0.02 0.23 \ \

Table 4:2. MWN’s performance on reading and repetition tests.

The semantic system

MWN performed well on all tests of the semantic system. She achieved 100% on the

comprehension test, and performed well on PPT with scores from 49/52 on the 3-picture

version to 51/52 on the other versions. Therefore, there was no indication of a semantic

deficit.

4:39

Comprehension

Test PPT mean

score

n 80 52

MWN 80 50.33

Control M 79.73 50.44

2SD below M 78.82 47.60

Lowest control 79.00 46.33

Significance ns ns

Table 4:3. MWN’s performance on semantic tests.

Picture naming

Oral picture naming was the only task on which MWN had obvious difficulties. She

performed significantly worse than controls, with 6 of her 16 errors phonological

approximations (addition or substitution of a single phoneme – on 5 occasions involving

the phoneme /r/) and 4 of her errors semantic errors (flask � ‘cigarette lighter’ (which may

have been a visual error); crow � ‘currawong;’ noose � ‘rope;’ skull � ‘skeleton’).

There was a small difference between regular and exception words (31 and 33 correct

respectively), with both impaired relative to controls.

Oral picture naming

Correct Errors

n=80 Delay Phon Morph Sem Circ P/U NR

MWN 64 2 6 1 4 0 0 3

Control M 79.00

2SD below M 77.00 Most control errors

Lowest control 77 1 0 0 2 1 2 0

Significance <0.01

Table 4:4. MWN’s performance on the oral naming test.

Delay = correct after time limit; Phon = phonological error; Morph =morphological error (including

plural errors); Sem = semantic error; Circ = circumlocution; P/U = perceptual or unrelated error; NR

= no response.

MWN’s overall score on written naming was not significantly different to the control

group, and was considerably better than her oral naming score. Although her performance

on the two naming tasks did not differ significantly, (McNemar’s test, p = 0.08), the

difference in total scores, and in the opposite direction to that which would be expected

based on control scores, does suggest that her oral naming is impaired relative to her

written naming. Her 7 written naming errors consisted mostly of semantic errors and no-

response errors (3 of each). Although written naming appeared to be normal, the majority

4:40

of her errors were semantic or no-response errors with only 1 spelling mistake, suggesting

an abnormal error pattern (low scores for controls was mostly due to spelling errors –

MWN made more semantic and no-response errors than any control). There was also

evidence of item consistency between the naming tests, with an overlap (67) closer to the

maximum (71) than to chance (59.8; refer to the calculations section of Chapter 2).

Furthermore, all three of her semantic errors on written naming were amongst the four

generated for oral naming, and two of these errors were the same response. Therefore, the

status of her written naming process is not entirely clear.

Written picture naming totals

Correct Errors

n=80 Delay Spell Sem P/U NR

MWN 73 0 1 3 0 3

Control M 77.07


Lowest control 72 2 5 2 1 1

Significance ns

Table 4:5. MWN’s performance on the written naming test.

Delay = correct after time limit; Spell = spelling error; Sem =semantic error; P/U = perceptual or

unrelated error; NR = no response.

Discussion

MWN performed within normal limits on all tests except for oral naming. This single

deficit will now be discussed in relation to the basic model, which is recreated in Figure

4:1 below. However, before attempting to identify the cause of her poor oral naming,

possible lesion sites can be eliminated by considering what she does well. Firstly, the

integrity of her object recognition and semantic system is indicated by normal

performances on tests of object recognition, comprehension and written naming. Not only

is oral naming impaired while written naming is intact, but the latter was performed better

that the former – which is the opposite pattern to that of controls. Therefore, her defective

oral naming appears to be the result of damage to post-semantic processing.

Secondly, she performed well on the reading test, with only one minor error, suggesting

that her ability to read exception words is intact. According to the model, this would

indicate that the phonological lexicon, phonological output buffer and the connection

between the two must be intact (the integrity of the phonological output buffer is further

indicated by her good performance on repetition tasks). She also performed better than the

4:41

mean of the control group on the 2-picture/1-spoken word version of PPT, providing

further evidence of an intact phonological lexicon. Therefore, the assumptions of the model

stipulate that the only plausible lesion site is the connection between the semantic system

and the phonological lexicon, as indicated by lesion a, thus disrupting oral naming without

affecting reading of exception words.

Figure 4:1. The basic model, showing MWN’s proposed lesion site.

The lesion is represented by the letter ‘a.’ Green boxes and arrows represent modules and pathways

that are considered intact based on results of tests and assumptions of the model. Functioning of

phoneme-grapheme conversion is unknown.

One important outcome of MWN’s assessment is that her pattern of results cannot be

explained without referring to the lexical-nonsemantic route that is discussed in Chapter 1.

That is, for oral naming to be impaired while reading of exception words is intact, the only

explanation is one that involves a direct route between the orthographic and phonological

lexicons, allowing for exception word reading, with the lesion located at a point in the oral

naming process prior to the phonological lexicon (in this case, input to the phonological

lexicon from the semantic system). This argument holds not only for this basic, 2-lexicon

model, but for all models that propose a shared lexicon for reading and oral naming,

though of course the hypothesis of dissociable lexical stores for reading and for oral

naming (e.g. Orpwood & Warrington, 1995) could also account for the data.

4:42

Alternatively, since MWN generated more semantic errors than the controls on both

naming tasks, the error patterns might represent a very mild deficit of semantic or pre-

semantic processing that was not detected on semantic tests but became evident on the

naming tasks due to the greater sensitivity of expressive over receptive tasks (e.g. Howard,

1985; Laine et al., 1992; Lambon Ralph et al., 2000). Of course a semantic deficit should

lead to noticeably defective written naming relative to controls, yet MWN scored within

the range of the control group. However, this does not necessarily mean than written

naming is intact. It is quite possible that MWN does indeed have difficulty with written

naming but that the test lacks sensitivity due to the poor spelling of some control

participants (see Chapter 3). In this view, her one spelling error might be considered a

perfectly normal occurrence, while most of her remaining seven errors would reflect a mild

lesion. Although not exactly conclusive, this pattern does suggest a possible organic cause

for her low written naming score as well as a possible relationship between the two naming

tasks, which is further evidenced by the similarity in errors. Therefore the possibility of a

semantic impairment underlying her poor naming cannot be disregarded.

While many authors would support the notion that lesion a might be responsible for

MWN’s semantic errors (e.g. Beaton, Guest, & Ved, 1997; Laine & Martin, 1996; Lambon

Ralph et al., 2000), can it also explain the phonological approximations she produced?

There are two ways that these errors might be accounted for. First, they could be the result

of mild dyspraxia (i.e. a lesion after the phonological output buffer) that, for some reason,

does not have a noticeable effect on other verbal tasks. For example, repetition and reading

might produce stronger activation of the target phonemes in the phonological output buffer

due to multiple sources of input, reducing interference. This account would therefore imply

that the phonological approximations are independent of lesion a shown in Figure 4:1, or

that her remaining errors on oral naming and most of her errors on written naming are

caused by a single, mild semantic deficit, with phonological errors on oral naming caused

by this additional lesion. The second explanation is that on some occasions lesion a allows

the target phonological representations to be activated above threshold, but with

competition from phonologically similar representations, leading eventually to interference

in the phonological output buffer (which would perhaps be experienced by MWN as a

degree of uncertainty about the word); on tasks of reading and repetition, multiple sources

of input constrain responses in the phonological output buffer, reducing the likelihood of

errors.

4:43

In summary, although MWN’s data represent what is superficially a straightforward profile

of lexical abilities, her single obvious impairment raises several theoretical questions that

are not easily answered. Nevertheless, the basic model is able to account for MWN’s

performance without the need for any adjustments. Evidence was also found for the

existence of the lexical non-semantic route and for the possibility that semantic errors in

oral naming can result from post-semantic lesions.

5:44

5:45

Chapter 5. Three cases of phonological dyslexia

Phonological dyslexia is a pattern of results in which the individual’s ability to read

nonwords is impaired relative to his or her ability to read real words, without the semantic

errors on word reading that are observed in deep dyslexia. This chapter is devoted to three

participants who presented with phonological dyslexia. The description of phonological

dyslexia is not of great importance, given the wide range of potential causes of this

‘symptom-complex.’ However, it does serve as a reference point, and although each case is

quite unique, there are certain similarities that allow a unified discussion. Each case is

presented and interpreted individually, with a collective discussion at the end of the

chapter.

Case 1 – RPD

RPD was a 65-year-old man with 10 years of formal education. He managed a transport

company before retiring at the age of 54. In June 2004, RPD sustained an infarct of the left

middle cerebral artery. Previous medical history includes a right-sided meningioma which

required debulking surgery 17 years before current testing, a coronary artery bypass graft

11 years earlier, high cholesterol, and retinal detachment (his mild visual impairment is

corrected by reading and distance glasses).

A speech pathology report from approximately six weeks after his stroke indicates that he

demonstrated a moderate impairment of comprehension, including moderate difficulties

with auditory comprehension and following sequential commands, and inconsistent

performance on reading comprehension tasks involving increased length and complexity of

passages, despite reasonable comprehension of single words and sentences. Nevertheless,

comprehension was considered a strength in comparison to his expressive language –

verbal output was characterised by dyspraxia and phonemic errors, while written language

conveyed little or no meaning, and was characterised by letter substitutions and jargon

words.

Results for RPD

RPD was assessed 2 years, 5 months post-injury. His spontaneous speech at the time of the

assessment was non-fluent; nevertheless he tried extremely hard to express himself, and

although he produced frequent semantic and phonological errors, he was able to maintain a

conversation, albeit somewhat stilted. Although he was generally quite slow to respond to

5:46

test items, he applied himself well on testing, and seemed to be aware of his errors in most

cases. RPD’s results are outlined in the following sections. Significance (simple difference

of RPD’s performance relative to controls) was calculated using the Bayesian standardised

difference method (Crawford & Garthwaite, 2007). His responses to particular tests are

listed in Appendix 5:b.

Input processes

RPD’s object recognition ability seemed to be intact based on his excellent performance on

BORB object decision. He also completed the cross-case matching task without making

any errors indicating that letter identification is intact. However, he performed significantly

worse than controls on lexical decision (though just outside the normal range), suggesting

either a breakdown in processing within the orthographic lexicon or reduced activation of

the lexicon. All of the errors were due to RPD identifying nonwords as real words (5

pseudohomophones and 3 non-homophonic nonwords) suggesting that his likely

impairment of orthographic lexical processing is accompanied by either response bias or

additional difficulties involving grapheme-phoneme conversion. He also had difficulties on

the homophone decision task, supporting the notion that the orthographic lexicon is either

failing to receive or adequately process information.

Object

decision X-case

matching Lexical

decision Homophone

decision

n 32 26 60 60

RPD 29 26 52 41

Control M 25.93 58.33 55.65

2SD below M 20.62 53.57 48.72


Significance ns

\

0.01 <0.01

Table 5:1. RPD’s performance on tests of input processes.



RPD made 2 phonological errors on the reading test (1 each for regular and exception

words), which was significantly worse than controls, and again just outside the normal

range. This result was not unexpected given RPD’s difficulties with visual lexical decision,

and suggests a common, mild impairment affecting the two tasks. Reading of nonwords

was much more impaired, with less than a third of the items read correctly. Since letter

identification appears to be intact, this would indicate that the processes involved in

grapheme-phoneme conversion are dysfunctional. Of his 17 errors, 12 were lexicalisations

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suggesting a tendency to read nonwords via the lexical reading routes (despite a possible

impairment of the orthographic lexicon suggested by difficulties with lexical decision).

Repetition of both words and nonwords was within normal limits, indicating that the

phonological input and output buffers, and their direct connection, are intact. Although it

will be argued in later sections that a nonword repetition score this low might reflect a

deficit, there is no reason to believe this is the case for RPD, particularly given his age.

Even if nonword repetition was impaired, this would merely suggest damage to the

sublexical repetition route and have no impact on other aspects of lexical processing.

Reading Repetition


n 80 24 80 24

RPD 78 7 79 17

Control M 79.87 22.94 79.2 21.73

2SD below M 79.16 20.57 77.04 15.42


Significance <0.01 <0.01 ns ns

Table 5:2. RPD’s performance on reading and repetition tests.

The semantic system

RPD made 3 errors on the comprehension test, all of which were because he chose the

semantic distractor (crab � lobster; clown � juggler; fork � knife). Although he

performed significantly worse than controls on the 2-picture/1-spoken word version of

PPT, he was within the range of the control group, and his scores on the other two

versions, and mean score for all three versions, were all normal. Therefore, results of

semantic tests were mixed, but might indicate a mild deficit that is perhaps only evident

under certain test conditions.

PPT

Comprehension Test Mean 3P 2P1W 2P1S

n 80 52 52 52 52

RPD 77 48.00 48 49 47

Control M 79.73 50.44 50.07 50.73 50.53

2SD below M 78.82 47.60 46.18 48.06 47.93

Lowest control 79.00 46.33 45 47 47

Significance <0.01 ns ns ns <0.01

Table 5:3. RPD’s performance on semantic tests.

Mean = mean of all 3 versions; 3P = 3-picture version; 2P1W = 2-picture/1-written word version; 2P1S

= 2-picture/1-spoken word version.

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Picture naming

RPD performed significantly worse than controls on oral naming. He made a total of 17

errors of which 12 (71%) were semantic errors. Regular and exception words were close to

even (30 and 29 correct respectively).

Oral picture naming

Correct Errors

n=80 Delay Morph Sem Circ P/U

RPD 59 2 6 13 0 0

Control M 79.00



Significance <0.01

Table 5:4. RPD’s performance on the oral naming test.

Delay = correct after time limit; Morph = morphological error (including plural errors); Sem =

semantic error; Circ = circumlocution; P/U = perceptual or unrelated error.

RPD’s written picture naming was slightly (but not significantly) better than oral naming

(McNemar’s Test, p = 0.59) with 4 fewer errors. Again, most errors were semantic (54%)

but to a lesser degree. Regular and exception words were very similar (6 and 7 errors

respectively).

Written picture naming

Correct Errors


RPD 67 0 2 7 0 4

Control M 77.07


Lowest control 72.00 2 5 2 1 1

Significance <0.01

Table 5:5. RPD’s performance on the written naming test.

Delay = correct after time limit; Spell = spelling error; Sem = semantic error; P/U = perceptual or


In terms of consistency, the total overlap between the two versions (64) was closer to

chance (55.5) than to the maximum (76; refer to the calculations section of Chapter 3). Of

the 13 errors made on written naming, only 5 had also been produced on oral naming (from

a total of 17). Of these, 1 item was the same response (skull�skeleton) and a further 2

were the same type of error (semantic error) but different responses

(bee�wasp/‘mosquito’; chalk�blackboard/ ‘crayon’). Of the three errors produced on the

5:49

comprehension task, 2 appeared again on oral naming, while none were repeated on

written naming. Although there is a degree of similarity, a relationship between the naming

tasks seems unlikely. Instead, the low-moderate overlap is probably best explained as

being due to the common pressures of imageability, linguistic complexity and so forth.

Discussion – RPD

RPD had difficulties on several tests, revealing likely impairments of reading (of both

words and nonwords), visual lexical decision and picture naming in both modalities, with

mixed results on tests of the semantic system. He produced a high number of semantic

errors on both oral and written picture naming, though a comparison between errors on

each version suggests limited consistency between the two. These impairments and errors

patterns will now be discussed in relation to the basic model, which is recreated in Figure

5:1 below.

Figure 5:1. The basic model as it applies to RPD.

Proposed lesions are labeled and indicated by red boxes and arrows. Green boxes and arrows

represent modules and pathways that are considered intact based on results of tests and assumptions

of the model. Black boxes and arrows represent features for which functioning is unclear.

In terms of intact functioning, RPD’s normal performance on tests of word and nonword

repetition suggests that the phonological input and output buffers are all intact. He

produced an error-free performance on cross-case matching, indicating that his letter

5:50

identification process is intact. He also performed well on the test of object recognition,

indicating that this function is intact.

At least one of the difficulties that RPD had on testing was also quite easy to reconcile

with the basic model. His performance on nonword reading was extremely poor. Since

letter identification and the phonological output buffer are both intact, the likely

explanation is a lesion at some point during the grapheme-phoneme conversion process, as

indicated by lesion a. The high number of lexicalisations suggests that RPD has a tendency

to rely on lexical processes when he reads nonwords.

The integrity of RPD’s semantic system is not at all clear. On the one hand, his

performance on PPT suggests that his semantic system is intact. However, his score on the

comprehension test is, by itself, indicative of mildly impaired processing. One explanation,

given his difficulties with visual lexical decision, is that he has trouble processing the

words in the comprehension test. However, this would lead to a prediction of poor

performance on the 2-picture/1-written word version of PPT relative to the other versions.

On the contrary, this was RPD’s best PPT result.

Another explanation for the contrast between the comprehension test and PPT is the test

conditions: PPT is untimed and has only two possible choices for each item, while the

comprehension test is time-limited and has four choices for each item. The hypothesised

explanation for RPD’s results is that the semantic representations themselves are

reasonably intact (explaining PPT) but access to them (or perhaps between them) is

inefficient and slow, a deficiency that is revealed when he is put under the pressure of

timed tests. Alternatively, this might be labelled by Crutch and Warrington (e.g. 2001;

2003; 2005) as a disorder of refractory access. In their view, it is not the time allowed for

each item that is the problem, but the time between items. Each time a semantic

representation is activated, activity within the semantic system becomes restricted, either

by inhibitory processes or impaired activation.

Unfortunately, the time between items was not considered to be a relevant variable during

preparation of the materials so was not controlled for. Therefore, there is no way to

determine exactly how timing conditions might have impacted on RPD’s results. However,

it certainly seems plausible to ascribe his low score on the comprehension test to the

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influence of the time limitation. Lesion b represents this mild impairment of semantic

processing.

If it is the time restriction that causes a problem for RPD, then other timed tasks that

involve semantic processing should also be negatively impacted by time constraints.

Indeed, both naming tests, which are the only other tasks that depend on the semantic

system, are certainly impaired. Although this might lead to a prediction of item consistency

between the tasks, this assumption would only apply if the representations are damaged,

which does not seem to the case.

Another issue raised by RPD’s results concerns orthographic processing. Judging from his

poor results on the lexical decision task and supported by his difficulties with the

homophone decision and reading tests, it seems likely that orthographic processing (or its

input) is mildly impaired. Although the comprehension test result is compatible with this

claim, RPD’s best PPT result was on the 2-picture/1-written word version. Although there

is not a convincing explanation for this apparent contradiction, it should be noted that tasks

involving the orthographic lexicon were all performed very close to control levels, so any

deficit would have to be extremely mild – and perhaps simply overcome by RPD’s good

reasoning, and the small degree of variation across PPT results. Therefore, a mild lesion of

the orthographic lexicon (lesion c) is suggested to explain these results, though the

integrity of the lexicon is not certain. Although these results alone could also be explained

by reduced access to the lexicon (from letter identification), a lesion of the lexicon itself is

also able to explain his poor written naming, while a lesion of the input pathway cannot.

Therefore, written naming is hypothesised to be reduced due to a combination of two mild

impairments – inefficient semantic processing which affects performance on timed tests,

and mild damage to the orthographic lexicon.

The only remaining impairment to explain is RPD’s poor oral naming. Although his

impaired semantic processing would have had an impact, the severity of his oral naming

deficit suggests an additional, post-semantic lesion. Since the phonological output buffer

appears to be intact, then the breakdown must be either in the phonological lexicon, output

from the lexicon to the phonological output buffer, or input to the lexicon from semantics,

with the latter the most likely site for a lesion (lesion d in the model). The most convincing

evidence for this conclusion is that reading of exception words was very close to normal

despite his mild impairment of orthographic lexical processing. Presumably, an additional

5:52

lesion of the phonological lexicon or its output would leave reading much more obviously

impaired. The locus of lesion d, on the other hand, allows for his almost perfect reading of

exception words to be achieved by the lexical non-semantic route. Also, the observation

that he produced more semantic errors on oral naming than on written suggests that not all

of his semantic errors on oral naming were caused by a semantic impairment. Therefore,

this discrepancy in error type also provides moderate support for the assertion that

semantic errors can occur secondary to post-semantic lesions, though with the obvious

caution that a semantic deficit might be expressed differently by each naming task.

Although the results of testing with RPD are not the easiest to reconcile, adding features

that are common to other models does not make his profile any easier to explain. That is,

none of the major models could better account for the discrepancy between the

comprehension test and PPT, or explain why reading and the 2-picture/1-written word

version of PPT was performed so well despite difficulties with lexical decision. Therefore,

although further explanation was required on certain issues, the basic model was as capable

of accounting for these as any other model. Furthermore, additional, tentative evidence was

found for the lexical non-semantic route, as well as for the hypothesis that semantic errors

can result from post-semantic lesions. Finally, a new principle was hypothesised: That

time-limited comprehension tasks can be more sensitive to semantic deficits than

intuitively more difficult but untimed taks.

The next section discusses DHT, whose performance resembled RPD’s is at least one

important way: He too performed considerably worse on the comprehension test than

would be predicted from his PPT scores.

5:53

Case 2 – DHT

DHT was a 62-year-old retired man with nine years of formal education, who had worked

as a typesetter. In June 2004, DHT sustained an embolic infarct of the left middle cerebral

artery secondary to infective endocarditis. According to medical records, he presented with

right-sided hemiplegia and a ‘significant communication impairment.’ DHT was attending

group and individual speech therapy sessions and meetings at the local spasticity centre,

and receiving regular botulinum toxin injections in his right arm. He wore bifocal glasses

but was otherwise not visually impaired. As recently as 3 months before current testing,

DHT was reported by Speech Pathologists as demonstrating severe non-fluent agrammatic

aphasia. He was previously a keen reader, though he reported finding it difficult now to

maintain attention for long enough to read books, despite having reasonable

comprehension when reading in short bursts. However, he continues to enjoy using his

computer and the internet.

Results for DHT

DHT was assessed approximately 2 years and 11 months after his cerebral infarct.

Although his comprehension for conversation seemed intact, his ability to express himself

was severely impaired, often relying on his wife to communicate his ideas. DHT’s results

are outlined in the following sections. Significance (simple difference of his performance

relative to controls) was calculated using the Bayesian standardised difference method

(Crawford & Garthwaite, 2007). His responses to particular tests are listed in Appendix

5:c.

Input processes

DHT scored better than the mean of the control group on all tests of input processes apart

from homophone decision, indicating that object recognition, letter identification and the

orthographic lexicon are all intact. It is not clear why he had difficulty with homophone

decision, though it may have reflected a problem with his ability to compare and judge

how two words should sound, a skill that is subserved primarily by the phonological output

buffer.

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Object

decision X-case

matching Lexical

decision Homophone

decision

n 32 26 60 60

DHT 27 26 59 44

Control M 25.93 58.33 55.65

2SD below M 20.62 53.57 48.72


Significance ns

\

ns <0.01

Table 5:6. DHT’s performance on tests of input processes.



DHT performed significantly worse than controls on all reading and repetition tasks.

Reading and repetition of real words was impaired. Reading errors were either

phonological in nature (13/19 errors) or failures to respond (7/19 errors). A few of the

‘phonological’ errors were possibly visual errors (e.g. drum � grum) but most either

differed quite significantly from the target response (e.g. chalk � core; blinds � blounds)

and were often accompanied by an indication that he knew he was incorrect (e.g. bib �

“big, no…”). There was no regularity effect (10 errors for each word type) and no

regularisations. Repetition errors were mostly phonological in nature (10/12 errors), with

most involving substitution of 1 to 2 phonemes. There was a reasonably high rate of item

consistency between the two tasks, with a total overlap of 66, which was midway between

chance (54.3) and the maximum (76). Of the 9 overlapping errors, 7 were the same type of

error (phonological), suggesting a possible common source of impairment for reading and

repetition.

Reading Repetition


n 80 24 80 24

DHT 60 0 66 15

Control M 79.87 22.94 79.2 21.73

2SD below M 79.16 20.57 77.04 15.42


Significance <0.01 <0.01 <0.01 0.03

Table 5:7. DHT’s performance on reading and repetition tests.

DHT found reading of nonwords so difficult that he was unable to correctly read any of the

24 stimuli. He managed just 31% overlap (i.e. phonemes correct) between the target

stimuli and his responses, which came almost entirely from the 10 lexicalisations he

produced – of his remaining 12 responses, 10 did not even share a single phoneme with the

5:55

target. This indicates that his grapheme-phoneme conversion process is severely impaired,

to the extent that it is practically non-functional.

Finally, his nonword repetition was significantly worse than controls. Since he was within

the range of the control group it could be argued that his low score reflects poor hearing

comparable to the controls with mild hearing difficulties. However, if this were the case

and his low nonword repetition score was entirely due to poor hearing, his repetition score

for real words should have been much higher than it was – even controls who struggled

with nonword repetition due to mild hearing deficits were able to repeat real words

reasonably well (at least 77/80). Therefore, DHT’s low scores on both word and nonword

repetition suggest a lesion that has impacted on both abilities at a point after auditory input.

If his hearing is intact, then comparing his nonword repetition score with the remaining 11

control participants (range 22-24, mean = 23.55, standard deviation = 0.69) leads to the

conclusion that his nonword repetition ability is significantly worse than controls (p<0.01)

and well outside the control range.

The semantic system

PPT


n 80 52 52 52 52

DHT 77 51.00 52 51 50

Control M 79.73 50.44 50.07 50.73 50.53

2SD below M 78.82 47.60 46.18 48.06 47.93

Lowest control 79.00 46.33 45 47 47

Significance <0.01 ns ns ns ns

Table 5:8. DHT’s performance on semantic tests.



Tests of the semantic system were performed with mixed results, akin to RPD. He

performed better than the mean of the control group on PPT (with individual scores of 50-

52, also providing further evidence that object recognition, the orthographic lexicon, and

the phonological lexicon are all intact). However, his 3 errors on the comprehension test

resulted in a score significantly worse than that of the controls. All 3 of his errors were

because he chose the semantic distractor and all were regular words (i.e. the deficit cannot

be attributed to a problem with reading of exception words). The contrast between the

comprehension test and PPT is similar to RPD’s performance on these tests, and again it is

5:56

argued that the participant’s semantic system contains intact semantic representations but

that inefficient semantic processing becomes evident on timed tasks.

Picture naming

DHT’s oral picture naming was significantly worse than controls, naming barely more than

half of the pictures correct. Errors were mostly no-response, phonological errors (in most

cases due to substitution of a single phoneme), and semantic errors, listed below. Of his 4

morphological errors, one was an irregular pluralisation (tooth � ‘teeth’) and the

remainder were addition or deletion of the plural -s. There was a relatively large difference

between regular (24 correct) and exception words (19 correct) on oral naming, though this

discrepancy was not significant (Fisher’s exact, p = 0.19) and due mostly to semantic

errors (4 more on exception words).

Oral picture naming

Correct Errors


DHT 43 3 10 4 8 0 0 12

Control M 79.00



Significance <0.01

Table 5:9. DHT’s performance on the oral naming test.

Delay = correct after time limit; Phon = phonological error; Morph = morphological error (including


= no response.

DHT’s semantic errors on oral naming were:

• crow � ‘bird’ (when asked what type his response was ‘evil’)

• cork � ‘bottle opener’

• flask � ‘whiskey’

• book � ‘bible’

• pear � ‘apple’

• wasp � ‘bee’

• ice � ‘water’

• vase � ‘bowl’

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These errors suggest that some features of the target semantic representations were

activated, but competing nodes with overlapping semantic features were selected in their

stead.

Written naming was intact and significantly better than oral naming (McNemar’s test, p <

0.01), the opposite direction to the controls. His extremely poor oral naming and intact

written naming is strongly indicative of a post-semantic impairment affecting phonological

output processes. If the semantic system is impaired, it appears to have only a minimal

effect on picture naming. Of his five errors on written naming, 2 were semantic in nature (1

of which was book � ‘bible,’ overlapping with oral naming) and the remaining 3 were no-

response errors; the high number of no-response errors and complete absence of spelling

errors makes the pattern somewhat unusual in comparison to the control group, whose

worst performing member made a single no-response error. However, his low number of

total errors makes a deficit seem unlikely.


Correct Errors


DHT 75 0 0 2 0 3

Control M 77.07



Significance ns

Table 5:10. DHT’s performance on the written naming test.



Item consistency and comparisons

DHT was moderately consistent on tasks of verbal output, with overlaps on all

comparisons midway between chance and maximum. Since the only locus of a common

lesion would be the phonological output buffer, consistency should not be expected to be

any higher as the word form has already been selected by this stage; the consistency seen is

more likely to represent the influence of factors common to all verbal tasks, such as spoken

word frequency and phonemic complexity.

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Chance overlap

Actual overlap

Max overlap

Oral naming vs reading

41.65 50 61

Oral naming vs repetition

41.95 51 57

Repetition vs reading

54.3 66 76

Table 5:11. Item consistency between tests of verbal output for DHT.

In addition to written naming being preserved relative to oral naming, it was also

significantly better than both reading (McNemar’s test, p < 0.01) and repetition

(McNemar’s test, p < 0.05), his other impaired processes.

Discussion – DHT

DHT performed poorly on several tests, especially those involving spoken output.

Although the source of his difficulties is not clear, many aspects of his performance are

indicative of intact processes within the language network. He performed well on all three

versions of PPT, indicating the integrity of: The phonological input buffer and

phonological lexicon (and the connection between the two); letter identification and the

orthographic lexicon (supported by written naming and lexical decision – his poor

homophone decision is likely influenced by other factors, which will be considered

shortly); and object recognition (supported by the object decision test and written naming).

As with RPD, his semantic processing is considered to be reasonably intact when given

sufficient time, but perhaps unable to cope with the time constraints of the comprehension

test. Finally, since written naming is intact, all orthographic output processes appear to be

intact. His intact performance on written naming does not necessarily contradict the

assertion of a very mild semantic deficit. Again, this could be a case of a ‘good speller’

with a mild impairment being compared to controls that include some ‘bad spellers’

without acquired deficits, as with MWN. His complete lack of spelling errors and

relatively high number of no-response errors seems to support this conclusion. Another

possibility is that the five seconds allowed for each item on written naming is less

restrictive than the ten seconds for items on the comprehension test, which are visually

much more complex. Alternatively, Crutch and Warrington (e.g. 2005) might argue that his

intact written naming reflects more time between the items than for the comprehension and

oral naming tests, since sufficient time for completing responses was always permitted on

written naming but was generally not an issue for other tests. Since this factor was not

controlled for, there is no way to be sure.

5:59

DHT’s most notable difficulties on testing were for oral naming, reading and repetition (of

words and nonwords), and homophone decision. In other words, based on the current

testing, DHT appears to be impaired on all tasks involving phonological output, while

orthographic input and output and phonological input are all intact. DHT’s profile, as it

relates to the basic model, is depicted in Figure 5:2, with his semantic impairment

represented by lesion a.

Figure 5:2. The basic model as it applies to DHT.

Proposed lesion sites are marked in red and labeled. Green boxes and arrows represent modules and

pathways that are considered intact based on results of tests and assumptions of the model. Black

boxes and arrows represent features for which functioning is unclear.

Only one lesion (lesion b) is needed to explain DHT’s difficulties on all verbal tasks,

though additional lesions are likely to be involved. This single lesion is able to capture

DHT’s language deficits by asserting that all tasks that require processing at the level of

the phonological output buffer will be impaired to some extent. Having said that, his ability

to convert letters into sounds appears to be so completely inaccessible that an additional

lesion affecting grapheme-phoneme conversion is highly likely, thus lesion c. Also, lesion

b is unable to account for his eight semantic errors on oral naming, since by this stage the

phonological representation has already been selected. Therefore, only phonological

approximations, delayed responses and no-responses should be evident (the latter two

5:60

when internal monitoring successfully blocks illegitimate responses). There are three

plausible explanations for his semantic errors. First, they could be the result of his mild

semantic impairment. However, a similar number of semantic errors would then be

expected on written naming, which was not the case. Second, they could be due to an

additional, relatively minor lesion between semantics and the phonological lexicon, as per

MWN and as indicated by lesion d in Figure 5:2. This explanation is further justified since

DHT generated more than twice the number of errors on oral naming than on reading or

repetition, and produced no semantic errors for the latter two tests. The discrepancy in

semantic errors between the two versions of naming provides some support for the concept

that semantic errors can result from post-semantic lesions, as previously argued by many

other authors (e.g. Beaton et al., 1997; Laine & Martin, 1996; Lambon Ralph, 1998;

Lambon Ralph et al., 2000).

Although this is the simplest explanation, a third possibility is worth mentioning: Active

production of semantically related words as a coping strategy. The proposition is that

semantic errors arise, on some occasions and for particular individuals, when the individual

has rejected responses that are phonologically inaccurate; the high number of no-response

errors suggests that he is indeed able to reject many of his incorrect responses. The

semantic errors, therefore, could be a conscious attempt to produce a response that conveys

a certain level of semantic information about the target, when he has recognised that the

response he was trying to generate is clearly wrong.

If this is a coping strategy, how effective would it be at conveying the desired information?

One significant point is that phonological approximations, even when they differ by only a

single phoneme, generally convey no relevant information at all, or are simply confusing

(e.g. ‘grum,’ ‘bled’) unless they are in context (which in itself is difficult for a severely

agrammatic aphasic, such as DHT). On the other hand, semantically related substitutes will

at least convey some aspects of what the participant is trying to generate (e.g. book �

‘bible;’ wasp � ‘bee;’ pear � ‘apple’ are all examples of DHT’s semantic errors) and

could often be sufficient, as in these examples, to relate their message to the listener. One

problem with this hypothesis is that semantic errors should also be evident on reading and

repetition of real words. However, both of these tasks were performed much more

accurately, and both involve multiple sources of information helping to constrain responses

generated by the phonological output buffer, which may act to reduce the need for

semantically related responses.

5:61

In sum, DHT demonstrates mildly inefficient semantic processing with damage to his

phonological output buffer, affecting all verbal tasks, with additional lesions affecting

particular verbal tasks more than others. Also, the high number of semantic errors on oral

naming relative to his intact written naming provides support for the argument that

semantic errors can result from post-semantic lesions, though his mild semantic deficit

makes this conclusion less certain.

One notable feature of DHT’s results is the remarkable preservation of written naming in

contrast to severely impaired oral naming (32 more errors), reading (15 more errors) and

word repetition (9 more errors), along with completely non-functional nonword reading

and possible semantic impairment.

DHT is also one of the rare cases of phonological dyslexia for which nonword reading is

almost completely impossible (at least one case, WB (Funnell, 1983), has been described

previously). This finding counters the assertion that the abolition of grapheme-phoneme

conversion in conjunction with damage to or reduced activation of the phonological

lexicon should lead to semantic errors on word reading, as occurs in deep dyslexia (e.g.

Newcombe & Marshall, 1980). On the other hand, advocates of the summation hypothesis

would perhaps argue that DHT’s semantic impairment is considerably less severe than

what would be seen in deep dyslexia, particularly given his excellent scores on PPT, and

indeed, DHT’s results are much less conclusive than they would be if he had a more

profound semantic impairment. Nevertheless, his results do seem to favour a model that

includes the lexical non-semantic route.

The next section describes DPC, a third case of phonological dyslexia with similarities to

both RPD and DHT.

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Case 3 – DPC

DPC was a 51-year-old woman with 11 years of formal education who had worked mostly

as a claims inspector for an insurance company. She was admitted to hospital in March

2002 following sudden onset of confusion, speech difficulties and rapid atrial fibrillation.

A brain CT scan revealed a haemorrhagic infarct of the left middle cerebral artery.

Relevant medical history included type II non-insulin dependent diabetes, anxiety disorder,

migraines and non-Hodgkins lymphoma.

A speech pathology report approximately three months after her stroke indicated non-

functional expressive communication, with some use of gestures. She was also noted to

have severe, global semantic deficits. A further investigation nine months later indicated

dramatic improvements in this area: She was noted to have mild-moderate difficulties with

auditory comprehension, with 100% accuracy in responding to yes/no questions and mild

difficulties with following sequential commands of more than two instructions. Reading

comprehension was comparable to auditory comprehension. Expressive communication

was more severely impaired, however: She demonstrated moderate to severe difficulties

with verbal expression, including spontaneous speech that was hesitant, non-fluent and

limited to single words and basic phrases. Confrontation naming was extremely poor, even

with cues, and repetition was poor for anything but single, high frequency words. Reading

aloud and written expression were both similar in nature to spontaneous verbal output. A

neuropsychological report two months later, which focused on her capacity to return to

driving, concluded that DPC demonstrated “inefficient visual scanning, reduced spatial

attention span, reduced attention to visual detail, weak complex attention skills, and

questionable visual acuity,” as well as left-right disorientation and difficulty following

sequential commands with three stages or more.

Results for DPC

DPC was assessed 4 years and 8 months after her admission to hospital. Her spontaneous

speech was comparable to the description by speech pathologists a year after her stroke.

She was extremely slow and unsure on most tests, even those for which she achieved high

scores. DPC’s results are outlined in the following sections. Significance (simple

difference of DPC’s performance relative to controls) was calculated using the Bayesian

standardised difference method (Crawford & Garthwaite, 2007). Her responses to

particular tests are listed in Appendix 5:d.

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Input processes

DPC performed better than the mean of the control group on the object decision task and

achieved 100% on cross case matching, indicating that her object recognition and letter

identification processes are intact. Her score on lexical decision was normal in comparison

to controls, suggesting that her orthographic lexicon is also intact. However, the

homophone decision task proved extremely difficult, with DPC achieving less than chance.

She performed significantly worse than controls and at chance levels on all three types of

word pairs (regular words = 12/20; exception words = 7/20; nonwords = 9/20; p<0.01 for

each) suggesting a major disruption in the processes involved in judging the sounds of both

real words and nonwords.

Object

decision X-case

matching Lexical

decision Homophone

decision

n 32 26 60 60

DPC 26 26 55 28

Control M 25.93 58.33 55.65

2SD below M 20.62 53.57 48.72


Significance ns

\

ns <0.01

Table 5:12. DPC’s performance on tests of input processes.



DPC had difficulties with both reading tasks. She made 3 phonological errors on word

reading, 2 of which were real words differing by a single phoneme (e.g. mast � ‘mask’) or

letter (e.g. noose � ‘nose’). Two of her errors were for regular words, three for exception

words (with no regularisations). The third was a neologism that shared only the initial and

final phonemes. Her remaining 2 errors were failures to respond. For nonwords, reading

was extremely disordered with 9 of her 19 errors lexicalisations, suggesting severe

disruption to grapheme-phoneme conversion, with many of the nonwords being produced

via the lexical reading routes. However, she managed to produce at least one correct

phoneme for all but one item, with an overlap of 59%. In addition to producing 5 words

correctly, this observation suggests that she has retained a limited (though inconsistent)

capacity to convert letters into sounds.

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Reading Repetition


n 80 24 80 24

DPC 75 5 66 14

Control M 79.87 22.94 79.2 21.73

2SD below M 79.16 20.57 77.04 15.42


Significance <0.01 <0.01 <0.01 0.02

Table 5:13. DPC’s performance on reading and repetition tests.

Word repetition was also impaired, with 11 phonological errors (mostly substitution of a

single phoneme), an inflectional error, and 2 failures to respond. However, her score on

nonword repetition was within the range of controls, similar to DHT. Again, it is argued

that DPC is probably impaired on both repetition tasks. Although the state of her hearing is

unknown, her young age makes it much less likely that she has impaired hearing, excepting

a neurological cause. More importantly, the sublexical repetition route, if intact, should

enable word repetition. Therefore, DPC’s difficulties with repeating both words and

nonwords most likely indicates intact hearing, with a single lesion that is responsible for

both deficits. Comparing her nonword repetition score with the 11 controls with intact

hearing (range 22-24, mean = 23.55, standard deviation = 0.69) leads to the conclusion that

her score is significantly worse (p<0.01) and well outside the control range.

A comparison between the reading and repetition tests suggests little consistency, with the

actual overlap (66) closer to chance (62.75) than to the maximum (71). However, since the

locus of a single lesion affecting both tasks would have to be at the phonological output

buffer or later, item consistency should not be expected, and the low-moderate level of

consistency is likely the result of common pressures such as word frequency and linguistic

complexity.

The semantic system

As with the two other cases reported in this chapter, DPC’s results on tests of the semantic

system were mixed. On the comprehension test she made 5 errors (1 regular word, 4

exception) which was significantly worse than controls. Error types were mixed, with 2

semantic (wolf � dog; chalk � duster) and 1 phonological distractor (glass � grass,

perhaps an orthographic or visual error) chosen, and 2 items not responded to. For PPT she

performed well on the 3-picture version in comparison to controls. For the other two

versions her scores were borderline. Despite her mixed performances on PPT, she was

extremely slow on all versions. Together with the comprehension test, it seems likely that

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DPC has a mild semantic deficit, reflecting either damage or reduced activation to the

semantic system, or perhaps a difficulty in processing that has lead to slow and inefficient

processing of semantic information, as was argued for RPD and DHT. The latter of these

seems more likely, even if her PPT performance is considered to reflect a semantic

impairment; her score on the comprehension test is much worse than would be expected

from her borderline PPT performance.

PPT


n 80 52 52 52 52

DPC 75 47.00 48 47 46

Control M 79.73 50.44 50.07 50.73 50.53

2SD below M 78.82 47.60 46.18 48.06 47.93

Lowest control 79.00 46.33 45 47 47

Significance <0.01 0.02 0.16 <0.01 <0.01

Table 5:14. DPC’s performance on semantic tests.



Picture naming

DPC performed significantly worse than controls on both picture naming tasks. For oral

naming there was minimal difference between regular (25 correct) and exception words

(23 correct). She produced only 2 semantic errors, which is normal compared to controls.

The majority of her errors were no-response, phonological and delayed, with a range of

other error types and several mixed errors. She occasionally struggled to produce the

desired response, resorting to spelling out some ‘phonological’ errors (incorrectly on all

occasions, e.g. dice � ‘L.I.C.E.’) or producing some sounds but giving up and producing a

semantic error (e.g. crow � ‘cr…cr…bird’).

Oral picture naming

Correct Errors


DPC 48 7 8 3 2 2 1 9

Control M 79.00



Significance <0.01

Table 5:15. DPC’s performance on the oral naming test.

Delay = correct after time limit; Phon = phonological error and spelled out responses; Morph =

morphological error (including plural errors); Sem = semantic error; Circ = circumlocution; P/U =

perceptual or unrelated error; NR = no response.

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DPC found written picture naming so difficult that the test was discontinued to avoid

distress after the initial 20 words. She was extremely slow and unsure of herself. Her

mistakes were mostly classified as spelling errors, though in most cases the words were

only half correct and most could not be considered reasonable spellings of the words (e.g.

chalk � calb; shorts � shorh; witch � wick). In total, 75% of her responses contained at

least partial orthographic similarity to the target word, indicating some access to

orthographic output.


Correct Errors


DPC 3 0 9 0 2 6

Control M 19.00



Significance <0.01

Table 5:16. DPC’s performance on the written naming test.



Item consistency calculations for DPC, apart from the comparison between oral naming

and repetition, should be interpreted cautiously, since the maximum in most cases is barely

above chance. Comparisons between oral naming and other tasks are presented in Table

5:17. There was a relatively high degree of consistency between oral naming and the

comprehension test, and the overlap between oral naming and the reading test was at the

maximum. A comparison between written naming and the same 20 items on oral naming

suggests a high degree of consistency between the two versions of naming as well.

However, the small number of items requires additional caution when interpreting this

finding, especially given how high chance was. In contrast, the overlap between oral

naming and repetition was not far above chance, suggesting limited overlap between these

tasks. Comparisons between written naming and other tasks produce figures too low to be

interpreted, with maximum overlaps between 4 and 6.

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Overlap between oral naming and other tests

Chance overlap Actual overlap Maximum overlap Degree of overalap

Comprehension 47.00 51 53 Moderate/high

Reading 47.00 53 53 Maximum

Written naming 8.75 13 *13 Maximum

Repetition 45.20 48 62 Low

Table 5:17. Item consistency between oral naming and other tasks for DPC.

*From a reduced set of items (20).

Discussion – DPC

The results of testing with DPC suggest a wide range of impairments with multiple

potential lesion sites. Nevertheless, she performed well on several tests, indicating that she

has not sustained ‘global’ loss of lexical-semantic processing. Her performance on the

object decision and visual lexical decision tests indicate that her object recognition process

and orthographic lexicon are both intact, as are letter identification (also supported by

cross-case matching) and visual input. On the other hand, she had difficulties with reading

and repetition of words and nonwords and both naming tasks, with mixed results on tests

of the semantic system. Her multiple areas of difficulty and mixed results on semantic tests

make it somewhat difficult to localise the lesion sites.

As with RPD and DHT, the question of greatest importance is whether or not semantics is

impaired. Although her performance on PPT is not a conclusive demonstration of an intact

semantic system, her performance was at worst mildly impaired, and not to the extent that

would predict her relatively low score on the comprehension test, an intuitively simpler

task. Again it is argued that DPC has sustained damage to her semantic system in a manner

such that the representations themselves are generally preserved, but her ability to process

semantic information is slow and inefficient, having a greater impact on tests with time

constraints. This deficit is indicated by lesion a in Figure 5:3. On the other hand, of the

three cases presented in this chapter, DPC seems to be the most likely to have sustained

damage to the actual representations in her semantic system. Her visual difficulties, as

reported following a neuropsychological assessment shortly after her stroke, could also

have contributed to her low scores.

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Figure 5:3. The basic model as it applies to DPC.

Proposed lesion sites are indicated in red and labeled. Green boxes and arrows represent modules and



Again, both naming tasks are also impaired, and quite severely. Compared to RPD, whose

performance on semantic tasks was only marginally better, DPC’s naming was

considerably worse, suggesting that any semantic impairment is merely one factor involved

in her poor naming. Reading and repetition are also impaired, for both words and

nonwords. Therefore, the simplest and most effective explanation is a lesion of the

phonological output buffer (lesion b). Additionally, comparisons between verbal tasks and

error analysis of each task – specifically the high rate of phonological errors and scarcity of

semantic errors – are congruent with damage to output phonological processing. Thus,

lesions a and b are able to account for DPC’s poor oral naming, while lesion b alone is

responsible for her impaired reading and repetition, as well as her poor performance on the

homophone decision task. Given that nonword reading was performed considerably worse

than the other tasks, an extra lesion of grapheme-phoneme conversion is possible.

However, it is also plausible that nonword reading is simply more sensitive to a lesion of

the phonological output buffer, since only once source of activation is provided. Therefore,

since grapheme-phoneme conversion appeared to be at least partially active, an additional

lesion within this process does not seem necessary, as it was with DHT.

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Written naming appeared to be more severely affected than oral naming for DPC. On the

limited sample of words that she was asked to name, she was extremely slow and appeared

to become increasingly frustrated as the test proceeded. Although she only managed to

correctly name three of the 20 pictures that were presented, for most of the items she did

demonstrate at least partial access to orthographic information. However, it is clear that

DPC’s difficulties with written naming are beyond what can be explained by mildly

inefficient or impaired semantic processing. Since her letters are well formed, her difficulty

does not seem to relate to impaired motor functioning. Since the orthographic lexicon is

intact (based on lexical decision), the lesion would have to be either in the connection

between semantics and the orthographic lexicon, or at a point after the orthographic

lexicon. The lack of semantic errors and her ability to consistently access partial

orthographic information suggests the latter; it seems that she is able to accurately select

the orthographic word form but is unable to assemble it correctly. This deficit is indicated

by lesion c; without data from a dictation task, it is not clear whether this would be the

output buffer or access to it from the orthographic lexicon.

In sum, the basic model is able to account for DPC’s profile, with similar conclusions and

assumptions as those already discussed in relation to RPD and DHT.

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Phonological dyslexia – general discussion

There seems to be little evidence in the literature to support any notion that phonological

dyslexia represents a genuine clinical symptom-complex, let alone a distinct syndrome,

and the interpretation of results from RPD, DHT and DPC does not challenge this view.

The only criteria for a ‘diagnosis’ of phonological dyslexia are that 1) nonword reading is

more severely impaired than real word reading, and 2) reading of real words does not

include semantic errors. The second criterion is necessary to distinguish phonological

dyslexia from deep dyslexia. The first criterion, however, is somewhat flawed. With

multiple routes to achieve reading of real words, it is reasonable to assert that this ability is

more resilient to brain injury, since a single lesion of grapheme-phoneme conversion is

enough to disrupt nonword reading, while multiple lesions are often needed to account for

defective reading of real words.

Even if a single lesion disrupts both processes it should impact word reading less because

there are multiple sources of activation providing input to enable the correct phonological

assembly. If so, then there are many ways that the first criterion can be met, at least from

the perspective of cognitive models. Lesions could be localised to: The grapheme-phoneme

conversion processes, as proposed for RPD; the phonological output buffer, as per DPC; a

wide range of combinations of different lesions affecting reading of both words and

nonwords, but with the latter more severely disrupted, such as the explanation for DHT’s

profile; or quite possibly a mild impairment of letter identification, which theoretically

should have less of an impact on activation of existing lexical entries than on accurate

conversion of novel letter strings. With such a variety of causes, the degree of impairment

relative to word reading seems quite irrelevant; rather, it is simply any degree of

impairment to nonword reading with a complete absence of semantic errors on word

reading, regardless of the extent of reading impairment, and including individuals for

whom word reading is intact.

Having said that, the label ‘phonological dyslexia’ is still useful provided it is only applied

as a clinical description, and not as a diagnosis. It is an efficient method of describing the

many individuals for whom nonword reading is impaired but without the characteristics of

deep dyslexia, and grouping participants in this way still enables certain predictions to be

explored even if, as is apparent here, the outcome suggests that have little in common.

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The most striking similarity for the cases presented in this chapter is the contradiction in

results for the semantic tests. PPT performance ranged from borderline to excellent, yet

their scores on the comprehension test suggest that they have all sustained damage of some

nature that has impacted on their semantic processing. The account given in this chapter,

which also applies to JWS (Chapter 6), is that the semantic system can be damaged in such

a way that specific nodes remain intact, but the transmission of information within the

system, or perhaps the information entering the system, is now slower and/or less efficient.

It is not suggested that they have not experienced significant loss of semantic functioning –

ten seconds should be ample time to match a word with the correct picture – rather, the

suggestion is that for all of these individuals the damage is not to the semantic

representations themselves but to their ability to interact with each other. On this account,

the high number of semantic errors reflects running out of time and choosing the first

plausible picture, while the less common phonological/visual errors might indicate poor

working memory, reduced concentration and attention, confusion, or simply failing to look

closely at the printed word due to the pressure of time constraints. Once again, it is worth

noting that the concept of refractory access disorders (Crutch & Warrington, 2005) is

another suitable explanation for these participants. It is also possible that the answer lies in

the actual items used for each test, or more specifically differences in associations between

the various components of each item.

Of course, the concept that the semantic system can be rendered inefficient without

necessitating the assumption that the semantic representations themselves are degraded

requires an understanding of the internal structure of the semantic system, a theoretical

argument that is beyond the scope of this paper. However, it is an argument that needs to

be explored if the semantic system and cases like those presented in this chapter are to be

fully understood. Presumably the answer to this question could be resolved with

investigation of the semantic system that involves a variety of tests under timed and

untimed conditions.

In summary, this chapter has explored the language profiles of three aphasic individuals,

each of whom might be described as having phonological dyslexia. For all participants, the

central issue was the discrepancy between timed and untimed tests of the semantic system.

Other issues include the lack of sensitivity to neurological impairments for some tests, in

particular nonword repetition and written naming. However, the basic model was able to

account for the profiles of all of these participants. Furthermore, evidence was found for

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the concept that semantic errors can relate to post-semantic lesions and to support the

existence of the lexical non-semantic route over the summation hypothesis.

A fourth case of phonological dyslexia, JWS, is discussed in the following chapter (with

the added complication that English is his second language). Interestingly, the

contradiction between semantic tests was again apparent, along with other patterns that are

much more difficult to explain than those discussed in this chapter.

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Chapter 6. Interpreting results for a bilingual aphasic

Are cognitive models of language appropriate for use with aphasic individuals who

acquired English at a late age? There are observable neurological differences between first

and second languages, and these differences appear to vary according to age of acquisition.

In distinguishing between early and late acquisition of a second language, the ‘critical

period’ appears to be puberty, not only for functional ability but also hemispheric

lateralization and other neuroanatomical variations (Birdsong, 1999; Hull & Vaid, 2007;

Lenneberg, 1967; Marian, 2000; Marian, Spivey, & Hirsch, 2003). Furthermore, these

functional and neural distinctions between first and second languages appear to vary

according to the language task being performed (e.g. Weber-Fox & Neville, 1999).

Since an individual’s second language is theoretically stored and processed differently to

their first language, disruption of a second language is potentially more difficult for a

lexical model to explain. As a further complication, it seems reasonable to assume that

some (but not all) lexical tasks would be more difficult for a bilingual participant even

before an injury is sustained. Therefore, when an aphasic participant for whom English is

the second language is compared to normative data it must be in the context of what is

expected of a second-language speaker; this is achieved, in this case, by comparing the

participant’s data not only to the control group but also to an unimpaired speaker of the

same first language.

Case description

JWS was a 69-year-old man who moved to Australia from the Netherlands when he was

13. His wife reported that he had a slight Dutch accent premorbidly, which was not

exaggerated following the injury. He had a total of 9 years education (mostly in the

Netherlands), and had worked as a plumber and bobcat driver before retiring at age 55.

In October 2004, JWS presented to hospital with right-sided hemiparesis, hemisensory loss

and global aphasia. He was diagnosed as having sustained an ischaemic stroke of the left

middle cerebral artery. He reported no history of hypertension, hypercholesterolemia or

diabetes, though he did smoke until about 10 years prior to his stroke. Investigations one

year post-stroke revealed bilateral proptosis (bulging of the eyes) and Bell’s palsy, though

he had normal extra-ocular movements and full visual fields. There was no evidence of

verbal dyspraxia; dysarthria was not reported. In May 2006 he was reported to have

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ongoing right-sided motor deficits including hemiparesis and evidence of upper motor

neuron spasticity in his hand.

Control M2

Control M2 was excluded from the main control group due to his mild difficulties with

English (compared to the rest of the group). He migrated from the Netherlands at age 21.

He received 9 years of education (in the Netherlands) and was employed on farms, at a

chemist shop and in an iron foundry. He reported mild hearing loss (which was not obvious

in conversation) and early macular degeneration in one eye, but is still able to read

newspaper font with the aid of glasses. Therefore, in terms of education, employment

history and perceptual abilities, M2 is a reasonably good match for JWS, particularly since

they both acquired English after puberty. Tests on which JWS scored significantly worse

than the control group were only considered indicative of an impairment if the score was

also significantly worse than M2’s result.

Results

JWS’ spontaneous speech was non-fluent and he relied heavily on his wife in conversation.

He also often failed to fully comprehend relatively lengthy or complex questions and

statements. A similar difficulty was observed on testing, when he often needed the

instructions repeated and occasionally proceeded without a clear understanding of the task

requirements (e.g. despite being told to mark all the correct letters on the mirror reversal

task, he marked all of the reversed letters instead). He was unable to use his right hand for

any task that required fine motor control. He was slow on all tasks, often failing to respond

quickly enough to items that were timed. Results for JWS are outlined in the following

sections. Significance (simple difference of performance relative to controls, for both JWS

and M2) was calculated using the Bayesian standardised difference method (Crawford &

Garthwaite, 2007). His responses to particular tests are listed in Appendix 5:e.

Input processes

On the object decision task, JWS outperformed the mean of the controls, indicating that

object recognition processes are intact. He made one error on cross-case matching, pairing

the capital ‘D’ with the lower case ‘b’ (unimpaired individuals are expected to perform this

task error free). He also made one error (from 36 items) on the mirror reversal task,

suggesting a possible minor impairment of letter recognition.

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Object

decision X-case

matching Lexical

decision Homophone

decision

n 32 26 60 60

JWS 29 25 35 36

M2 25 56 43

Control M 25.93 58.33 55.65

2SD below M 20.62 53.57 48.72


Significance ns

\

<0.01 <0.01

Table 6:1.JWS’ performance on tests of input processes.


On the other hand, he performed extremely poorly (and barely above chance) on lexical

decision, suggesting severely impaired processing of, or access to, the orthographic lexicon

(in contrast, M2’s performance was comparable to the native English speakers). The main

reason for JWS’ low score was his tendency to identify nonwords as words, though this

might have been due to response bias. He also struggled with the homophone decision task,

which again was not much better than chance. M2 also performed poorly on this task (and

significantly worse than the native English speaking controls: p < 0.01). Furthermore, JWS

and M2 did not differ significantly (McNemar Test, p = 0.23) suggesting a possible

influence from their language background.


On the word-reading test, JWS made 3 errors. He made one regularisation error (bear �

‘beer,’ which was not due to dialect difference since M2 read this word to rhyme with

‘pear,’ while JWS did not). He made 1 other exception word error (mask � ‘mast,’ a fairly

common phonological error made by several aphasic participants, on several different

tests), and 1 regular word error (noose � ‘nose,’ which is perhaps better described as a

visual error). Although significantly worse than controls, this result is comparable to M2,

who made 2 errors on exception words, both of which were regularisations (he enunciated

the silent letters in comb and sword). Therefore, reading might be intact for JWS in the

context of his language background. Alternatively, his errors on the reading test might

relate to the mild difficulties he encountered on the tasks of letter identification, since his 3

erroneous responses are visually quite similar to the relevant targets. Either way, his

reading of real words, in particular exception words, was considerably better than would be

predicted from his extremely impaired lexical decision performance.

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Reading Repetition


n 80 24 80 24

JWS 77 13 71 13

M2 78 21 67 9

Control M 79.87 22.94 79.2 21.73

2SD below M 79.16 20.57 77.04 15.42


Significance <0.01 <0.01 <0.01 <0.01

Table 6:2. JWS’ performance on reading and repetition tests.

In contrast, nonword reading was extremely poor for JWS, with an overlap between

response and target phonemes of 83.13%, compared with 96.39% overlap for M2, whose

total score was equal to the lowest scoring of the native English-speaking controls. His

score was significantly lower than M2’s (McNemar’s test, p = 0.02). Although his ability

to convert letters to sounds is impaired, his phoneme overlap indicates that he is still

reasonably capable of processing novel letter strings, though with reduced accuracy.

On word repetition, JWS made a total of 9 errors of which 7 were phonological (1 error

was morphological and 1 unrelated). However, this was a better result than that achieved

by M2. For repetition of nonwords, his score of 13 (with 5 lexicalisations and 86.04%

overlap) was not only better than the score achieved by M2 (with 8 lexicalisations and

76.53% overlap), but was also within the range of the control group. Although M2 reported

mild hearing difficulties, which might have affected his nonword repetition performance,

this should not have had such an impact on repetition of real words, which seems to be less

sensitive to hearing impairments. Therefore, there does appear to be an element of

disadvantage for bilingual speakers on repetition tests, for which JWS appeared to be intact

relative to M2. Therefore, his phonological input and output buffers and sublexical

repetition route must be intact. Additionally, if his phonological output buffer is intact,

then his difficulties with nonword reading must be due to either his mild impairment of

letter identification, or to the grapheme-phoneme conversion process itself.

The semantic system

JWS made a total of 8 errors on the comprehension test, which was well outside the range

of the control group, though not significantly worse than M2 (McNemar’s test, p = 0.23).

Two errors seemed to be visual in nature: glass, was probably misread as the phonological

distractor (grass), and bread he misread (aloud) as ‘breed,’ and did not respond. For the

remaining 6 errors JWS chose the semantic distractor. Since M2 was also significantly

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below the level of the native English speaking controls (p < 0.01) with 3 semantic errors,

the result of this test is difficult to interpret. However, although some of his errors on the

comprehension test could perhaps be attributed to his bilingual background, there are

indications that JWS is either experiencing impaired semantic processing or receiving

reduced input to the semantic system.

PPT


n 80 52 52 52 52

JWS 72 46.33 46 45 48

M2 77 48.00 49 48 47

Control M 79.73 50.44 50.07 50.73 50.53

2SD below M 78.82 47.60 46.18 48.06 47.93

Lowest control 79.00 46.33 45 47 47

Significance <0.01 <0.01 0.03 <0.01 0.04

Table 6:3. JWS’ performance on semantic tests.



On PPT, JWS’ scores were reasonably consistent and similar to the lowest scores of the

native English-speaking controls. His scores across the three versions was not significantly

different to M2 (t(51) = 1.40, p = 0.17). It would be difficult to justify a semantic deficit

from these results alone, particularly since he performed within the range of controls on

two versions. Also, his relatively low score on the 2-picture/1-written word version appears

to be consistent with his difficulties on other tasks that involve orthographic processing.

On the other hand, his score on the 2-picture/1-spoken word version suggests that his

phonological lexicon at least is probably intact. Overall, however, the integrity of his

semantic system is not clear, with a pattern similar to the cases presented in Chapter 5, and

is therefore best considered another example of intact semantic representations with

inefficient processing on time-constrained tasks.

Picture naming

Oral picture naming was severely impaired for JWS. M2 also had difficulty with this task,

with a score significantly below that of the native English-speaking controls (p < 0.01).

However, M2 only made three errors more than other controls, in contrast to JWS who was

only able to correctly name approximately half of the pictures, and was significantly worse

than M2 (McNemar’s test, p < 0.01). While many of his errors were correct but out of time

(supporting the hypothesis of inefficient processing rather than complete loss of semantic

representations) semantic errors were the most common type. There was a significant

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discrepancy between regular and exception words (16 and 25 correct respectively; Fisher

exact, p = 0.04), in the opposite direction to that which can be readily explained by most

cognitive models.

Oral picture naming

Correct Errors


JWS 41 13 2 0 17 3 0 4

M2 74 0 1 1 3 0 0 1

Control M 79.00



Significance <0.01

Table 6:4. JWS’ results on the oral naming test.



= no response.

Written naming was also extremely impaired, and was discontinued after the initial 20

items. Using his non-dominant left hand, his responses were extremely slow and effortful.

He generated just 3 correct regular words and 1 correct exception word. Many of his letters

were malformed suggesting a considerable influence from damage to the late stages of

orthographic output (e.g. apraxia). However, other factors also seem to have been

involved. Of his 6 spelling errors, 3 were omission of a single letter (e.g. watch � wath,

and the regularisation error sword � sord), while the remainder were only barely related to

the target (drum � dump; kite � kert; axe � ars). Many of his errors were mixed

(including both of his semantic errors) and others bore little, if any, resemblance to the

target word. Some were only interpretable because he was asked to verbalise these

responses after writing them. These errors appear to reflect severely disrupted orthographic

processes, far beyond what can be explained by a motor deficit alone. In contrast, M2

performed significantly better (McNemar’s test, p < 0.01) and was not significantly worse

than the native English-speaking controls (p = 0.09).

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Correct Errors

n=20 Delay Spell Morph Sem P/U NR

JWS 4 0 6 1 2 3 4

M2 17 0 2 0 0 0 1

Control M 19.00


Lowest control 16 1 3 0 1 1 1

Significance <0.01

Table 6:5. JWS’ performance on the written naming test.

Delay = correct after time limit; Spell = spelling error; Morph = morphological error (including plural

errors); Sem = semantic error; P/U = perceptual or unrelated error; NR = no response.

A sample of JWS’ responses on written naming appear in Figure 6:1 below, with the target

response to the right of each and, where relevant, the semantic relative he attempted to

produce in brackets.

Response Target (and intended response)

Figure 6:1. Sample of written naming responses for JWS.

When asked to print the alphabet (see Figure 6:2 below), he was quite slow and messy. He

missed 4 letters (L, N, Q, V) and some of his letters were malformed (e.g. ‘W’ was upside

down, ‘F’ was missing a line). His performance supports the hypothesis of a defect late in

the processing of letters (i.e. orthographic output buffer or later), or perhaps

miscommunication between orthographic output and the right-sided motor areas

responsible for writing with his left hand.

chef (cook)

road

shorts (pant)

kite

glove

dog

axe

drum

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Figure 6:2. Attempted alphabet by JWS.

By reducing oral naming to the 20 items tested on written naming, these two tasks can be

compared. JWS made 6 errors on the reduced set of oral naming items, all of which

overlapped with the 16 errors on written naming – that is, the overlap is as high as it could

possibly be, suggesting a possible relationship between the two deficits, even though the

data set is too small to be convincing.

Since the locus of a single deficit for both versions of naming would have to be the

semantic system (or access to it from object recognition), an overlap between the

comprehension test and each version of naming might also be expected. Reducing the

comprehension test to the 20 items completed on written naming yields an overlap of just

8, which is below chance (8.8). The overlap between comprehension and oral naming is

also less than chance (actual overlap of 39, compared with chance of 40.8 – the maximum

is 49). This suggests that if there is a common lesion responsible for all three impairments,

its effect might be similar to the inefficient semantic processing described in Chapter 5,

and the consistency between the naming tasks simply a coincidence.

Discussion

Results for JWS are presented graphically in Figure 6:3, in the context of the basic model.

Tests on which JWS performed well relative to either the controls or to M2 have been

considered intact in the context of his bilingual background. With this consideration in

mind, several processes seem to be intact: The integrity of object recognition was well

supported by an excellent score on the object decision task; repetition of both words and

nonwords was performed well enough to suggest that his phonological input and output

buffers, and the sublexical repetition route that links them, are all intact; letter

identification seems to be reasonable, though perhaps slightly defective; and finally, his

reasonable score on the 2-picture/1-spoken word version of PPT suggests that processes

linking his phonological input buffer and semantic system, including his phonological

lexicon, are probably intact. Since the phonological output buffer is intact and letter

identification reasonable, his poor nonword reading can only be accounted for by a lesion

of grapheme-phoneme conversion (lesion a in the model). Once again, however, it is not

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clear what impact his probable impairment of letter identification might have had on later

processing. As was discussed in the previous chapter, it is theoretically possible that

damage to the letter identification process would have a greater impact on nonword

reading than on word reading.

Before discussing other potential lesion sites, JWS’ pattern of results raised several issues

that need to be clarified. As with the cases presented in Chapter 5, scores for JWS on tests

of the semantic system were mixed, with a borderline performance on PPT contrasting

with a score on the comprehension test that was indicative of a fairly obvious semantic

impairment. Again, it is suggested that the differing results are due to the contrast in test

conditions, and that JWS has a mild impairment of the semantic system (lesion c in the

model) that becomes evident on timed tests due to inefficient processing of semantic

information despite the representations within the system remaining intact.

The most striking observation concerns the orthographic lexicon. JWS made three errors

on the reading test, one more than M2 and two more than the worst performing member of

the control group. Although this result might reflect the impact of a lesion, the impairment

is, at worst, very mild. In contrast, JWS’ ability to distinguish between real words and

nonwords on a visual lexical decision task was severely impaired, and this deficit is

accounted for by lesion b in the model. Since M2 performed within the range of the control

group on this task, language background does not seem to have influenced the result.

Astonishingly, this impairment represents defective processing of a component that is

crucial to the reading of exception words, the orthographic lexicon (or perhaps input to it

from letter identification). Although it is possible that JWS was reading regular words via

the slightly impaired grapheme-phoneme conversion process, regularisation errors should

have been common in his reading of exception words if the orthographic lexicon is as

defective as it appears to be.

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Figure 6:3. The basic model as it applies to JWS.

Questions marks indicate areas where the model is unable to account for his results. Proposed lesions

are labeled and indicated by red boxes and arrows. Green boxes and arrows represent modules and



Do other tests provide any evidence for or against the integrity of the orthographic lexicon?

Some support for a lesion of the orthographic lexicon appears in JWS’ results on tests of

the semantic system. The only version of PPT on which JWS performed worse than the

control group was the 2-picture/1-written word version, which does suggest a difficulty

with orthographic input to the semantic system, particularly since he also performed very

poorly on the comprehension test. However, once again the extent of damage suggested by

his poor lexical decision is far beyond what was observed for the comprehension test and

PPT. Other tests that involve the orthographic lexicon are inconclusive. Homophone

decisions were just as difficult for JWS as was the lexical decision task, though M2 also

struggled on this test. Although written naming could be argued to stem from damage to

the orthographic lexicon from his lexical decision results alone, there is, once again, the

question of why written naming, like lexical decision, is so much more impaired than

reading.

All mainstream models conceptualise normal reading as being accomplished via a pathway

that involves a process that is also responsible for lexical decision (initially the

orthographic lexicon or orthographic input lexicon), with regular word reading also

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possible via grapheme-phoneme conversion. So how is reading possible with near-normal

accuracy (with no discrepancy between regular and exception words) when lexical

decision and nonword reading are both severely impaired? One possibility is that his

reading is improved by the process of grapheme-phoneme conversion. Even though his

nonword reading is well below normal in terms of total correct, the high overlap between

his responses and the targets makes this a reasonable proposition. However, this should

lead to a discrepancy between regular and exception words. It is possible that the common,

monosyllabic exception words used for this research are simply not irregular enough (i.e.

do not conflict enough with the rules of grapheme-phoneme conversion) to cause a

discrepancy between the two word groups. Supporting this interpretation is the observation

that no participant performed significantly worse on exception word reading than on

regular word reading (the biggest discrepancy was two errors more on exception words

from a total of 42 errors).

A more concise explanation might be the summation hypothesis (Hillis & Caramazza,

1991), which would argue that partial activation of the phonological output lexicon by both

grapheme-phoneme conversion and the lexical non-semantic route combine to activate the

target word above threshold. For both of these explanations, however, the most obvious

criticism is that if lexical decision is only performed at the level of chance, then the

orthographic lexicon must be practically non-functional. Even with input from grapheme-

phoneme conversion (which is only partially operational), reading should be extremely

difficult and, furthermore, a pattern of surface dyslexia should be evident.

Could this dilemma be resolved by modifying the model? Separate lexicons for input and

output would certainly not help to resolve this problem. One feasible solution would be to

suggest that the orthographic lexicon is constructed in such a way that the highly

imageable words on the reading test are better preserved than the less imageable words of

lexical decision, or perhaps that feedback from the semantic system somehow boosts high

imageability words more so than less imageable words.

Alternatively, JWS’ language background could be the answer. If first and second

languages are stored differently in the mind, then it is possible that separate processes are

able to interact for some tasks but not others. The complex nature of multiple interacting

neurological and premorbid linguistic factors mean that cognitive models of language

might be insufficient to fully understand bilingual aphasics, particularly those such as JWS,

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who acquired his second language at a relatively late age. To further elaborate on the

complex interplay between first and second languages, Marian and colleagues (2003)

discuss the ‘parallel access position,’ which stipulates that the two languages can operate in

parallel, even if language input is only for one of the languages. Although the degree of

interaction varies according to factors such as age of acquisition and proficiency, they

report that sublexical processing, for example, is language independent on initial

presentation of spoken language. Neurologically, this initial phonological processing

activates simultaneous, overlapping areas; however, activation of lexical representations is

less clear, and appears to activate larger (though still overlapping) areas of the brain. This

concurs with the observation that the functional patterns established during acquisition of a

first language will underlie the learning of the second (Hull & Vaid, 2007).

According to Hull and Vaid (2007), the cognitive neuropsychological approach to

bilingualism assumes a functional distinction between first and second languages, either

for the lexicons or the entire language network. Marian and colleagues (2003) observe that

the question of bilingual distinctions no longer concerns whether or not the two languages

are shared, but what is the nature of the overlap and interaction between the languages, and

what are the factors that influence this relationship. Therefore, it is not surprising that

cognitive neuropsychology is criticised in its approach to understanding bilingual aphasics.

According to Hull and Vaid (2007), language profiles of bilingual aphasics should not be

considered in terms of damage to a processing module (or even to a neural structure) that is

devoted to the defective language, whether that be the first or the second language. The

authors instead support a functional approach, by trying to determine patterns of

fluctuating damage to the individual’s inhibitory or activation processes. The authors site

the work of Paradis (2000), who observed that some bilingual aphasics are able to speak

capably in one of their languages but not the other on a particular day, but might

demonstrate the opposite the next day.

Therefore, there are myriad ways in which first and second language processes (and,

perhaps, left and right hemisphere processes) might interact to allow exception word

reading for a person with impaired lexical processing. Alternatively, his pattern might

simply reflect fluctuating abilities from one day to the next. Either way, it seems unlikely

that any standardised cognitive model of language processing could account for the diverse

range of bilingual aphasics given the widely varying influences of age of acquisition,

proficiency, hemispheric lateralisation and other differences in neural processing,

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fluctuations between abilities in the languages, overlapping and interacting processes at

both the neural and functional levels, and a wide array of possible individual differences

such as personality, intelligence and learning strategies.

Nevertheless, other aspects of JWS’ profile are less complex, and can be understood in

terms of the basic model. Oral and written naming are both severely impaired. As

discussed above, this could relate to inefficient semantic processing. Alternatively, given

the severity of his naming impairments, any semantic deficit underlying both oral and

written naming are probably exacerbated by additional, post-semantic lesions. For oral

naming, there are two candidates for the location of such a lesion. The first is the

connection between the semantic system and the phonological lexicon, with reading of real

words achieved primarily by the lexical non-semantic route. The second is the connection

between the phonological lexicon and the phonological output buffer, with repetition of

real words achieved by the sublexical repetition route. Precedents established by the

literature would suggest that the error patterns in his oral naming, in particular the high

number of semantic errors, are more consistent with the former, which is indicated by

lesion d.

Written naming, however, appears to be more severely impaired than oral and beyond what

would be predicted from his semantic impairment. The low number of semantic errors

complies with this assertion, and furthermore suggests that any additional lesion is

probably located at the orthographic lexicon, which has already been identified as a lesion

site. However, closer inspection of his written naming performance suggests other lesions

could also be involved. Many of his letters were malformed (in written naming and when

asked to write the alphabet) suggesting a considerable influence from damage to the late

stages of written output (e.g. poor motor coordination). However, the high number of

spelling errors (35% of total responses, including mixed errors), suggests JWS is also

experiencing difficulty assembling the words correctly, suggesting a possible lesion of the

orthographic output buffer (lesion c)or input to it from the orthographic lexicon. Needless

to say, JWS’ written naming appears to reflect a complex interplay of different lesions

(semantic, orthographic lexicon or output buffer, and motor coordination) with a

contribution from his language background.

Finally, there was a significant discrepancy between regular and exception words on oral

naming, in a direction that does not correspond with any standard explanation (even one

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that takes into account the relationship between first and second languages). If the

discrepancy was for written naming, the explanation could perhaps involve the suggestion

that exception word items can be less vulnerable because they rely more on memory of

word spellings learnt by rote and less on normal spelling rules – rules that can be impaired,

leaving regular words more vulnerable. However, even if this explanation could be

justified it is difficult to see how it could relate to oral naming. Once again it is difficult to

rule out the complex interaction between his two languages as making representations of

exception words in the phonological lexicon somehow less vulnerable than regular words.

In conclusion, the basic model might be able to explain some bilingual aphasic

participants, but it was not able to account for the pattern of results observed for JWS.

However, the one contradiction that could not be accounted for is probably inexplicable for

any model that fails to account for the interaction between his first and second languages.

As suggested by Hull and Vaid (2007), it could simply be the case that cognitive models of

language are unsuitable for bilingual aphasics, and that a more appropriate perspective is a

functional approach that takes into consideration the complexities of failed inhibition and

activation of various processes from the two languages.

The following chapter is devoted to SJS, an individual whose results fit the profile of deep

dyslexia.

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Chapter 7. A case of deep dyslexia

Deep dyslexia

As its name suggests, deep dyslexia is a profound form of acquired dyslexia. It is generally

associated with extensive left-hemisphere damage, usually resulting in aphasia and right-

sided hemiparesis. The hallmark of deep dyslexia is the production of semantically related

errors when reading aloud, such as horse being read as ‘cow.’ In addition to semantic

errors, visual errors (eg. dice � ‘ice’) and morphological errors can be produced during

reading aloud. Abstract words are more susceptible than concrete words, function words

are difficult to read, and nonwords are practically impossible to read. Writing, if possible at

all, will reflect all of these symptoms (see Coltheart, 1987 for a comprehensive review).

The first comprehensive attempt to explain the various impairments associated with deep

dyslexia posited damage to six separate components of the lexical-semantic system

(Morton & Patterson, 1987). However, the strikingly obvious drawback of this account is

that if six isolated areas of the brain must be damaged to produce the syndrome of deep

dyslexia, then there should be cases demonstrating a myriad of combinations of the six

deficits (e.g. the first five symptoms, the first two and last two symptoms and so on). An

alternate hypothesis that appeared at the same time proposed that deep dyslexia was not the

result of a damaged left hemisphere reading system, it was instead the outcome of normal

reading processes in the right hemisphere, which become dominant when the left

hemisphere reading system has become non-functional (Coltheart, 1987; Saffran, Bogyo,

Schwartz, & Marin, 1987). Indeed, radiological investigations have provided evidence that

severe damage to Broca’s area can lead to greater activation of homologous areas of the

right hemisphere, as well as peripheral language areas of the left hemisphere during

language tasks (e.g. Calvert et al., 2000).

There is now a growing volume of neurological evidence to support the right hemisphere

hypothesis (e.g. Schweiger, Zaidel, Field, & Dobkin, 1989; Weekes, Coltheart, & Gordon,

1997). Although measuring hemispheric lateralization would seem to be a relatively

straightforward matter for radiological investigation, the issue is somewhat more

complicated than that (see Coltheart, 2000; Laine, Salmelin, Helenius, & Marttila, 2000;

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Price et al., 1998). Therefore, despite the mounting evidence for differential lateralization

in deep dyslexia compared to other syndromes, the issue is far from resolved.

If deep dyslexia does represent right hemisphere language processing, then it could be

argued that it would be inappropriate to apply the results of a deep dyslexic’s language

assessment to a model of ‘normal’ language since it is unclear what components of the

reading processes would and would not contribute to lexical processing (e.g. does the

orthographic lexicon still function normally, or does all orthographic input occur in the

right hemisphere). Having said that, the benefit of cognitive language models is that they

are able to map out an individual’s profile for the purpose of better understanding, and

ideally treating, the complex interaction of the various components that comprise normal

language, irrespective of the neuroanatomical explanation. Indeed, it is still common for

researchers to attempt to map deep dyslexia onto existing cognitive language models

(Morton & Patterson, 1987; Nolan & Caramazza, 1982; Plaut & Shallice, 1993;

Southwood & Chatterjee, 1999, 2001). Therefore, attempting to explain a case of deep

dyslexia within the confines of the basic model is certainly a worthwhile goal.

Case description

SJS was a 43-year-old man with 10 years of formal education, as well as electrician and

telecommunications certificates. He was working in a managerial role for a

telecommunications company at the time of his injury. SJS was admitted to hospital in

April 2000 following the sudden onset of severe frontal headache, vomiting and aphasia.

Cerebral CT scans revealed extensive subarachnoid haemorrhage in the vicinity of the

Circle of Willis and in the left sylvian fissure, with evidence of intracerebral haemorrhage

within the left frontal lobe. The following day he underwent craniotomy and clipping of

the left middle cerebral artery. Post-operative complications included vasospasm and right-

sided hemiparesis, and he was also later diagnosed with hyperlipidemia.

He was transferred to a rehabilitation facility one month later, at which time he had a dense

right-sided hemiplegia, verbal dyspraxia and global aphasia. His initial speech pathology

assessment revealed unreliability with yes/no responses (using a combination of gestures

and written cues), complete lack of spontaneous vocalisations, inability to imitate oral

movements, and inability to participate in activities due to poor comprehension, even with

visual modelling. On discharge from rehabilitation about six weeks later, yes/no responses

remained inconsistent, though his verbal dyspraxia had improved slightly and he was

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occasionally able to produce an appropriate word orally – written output was completely

non-functional. He had difficulties with gesture and communication boards, and he

demonstrated impairments of both conceptual and lexical semantics, with degraded access

from both phonological and orthographic input lexicons.

In February 2003, almost three years post-injury, a neuropsychological assessment

revealed a general reduction in cognitive abilities, including slowed speed of information

processing, difficulties with higher level planning and problem solving, and reduced

memory for complex visual information. This was in addition to his profound expressive

and receptive language deficits and a number of behavioural concerns.

An orthoptic report in June 2001 reported an earlier finding of right homonymous

hemianopia with macular sparring, though there was no evidence of this at the time of the

orthoptic assessment, nor were there any signs of neglect, ocular motor nerve palsy or gaze

palsy. His shortsightedness is corrected by glasses, and he was considered to be within

medical guidelines for driving.

Results

Spontaneous language for SJS was as expected based on speech pathology reports. He was

extremely non-fluent, with mostly single word utterances. The words that he did produce

were often generic, high frequency words that were semantically related to the concepts

that he was trying to express. He used a communication book at times, but conveying

information around the images was extremely effortful for him, and often ended without

success. He often initiated conversation, though he seemed to be limited to just a few

topics that he could convey (i.e. he often mentioned his cat, daughter, computer or work,

all words that he was able to produce reliably).

SJS’ results are outlined in the following sections. Significance (simple difference of his

performance relative to controls) was calculated using the Bayesian standardised difference

method (Crawford & Garthwaite, 2007). His responses to particular tests are listed in

Appendix 5:f.

Input processes

SJS performed better than the mean of the control group on the object decision task,

indicating that his object recognition abilities are intact. He did not make any errors on

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cross-case matching and performed normally on lexical decision, indicating that letter

identification and the orthographic lexicon are both intact. However, he performed close to

chance on the homophone decision task, with an even spread of error types, perhaps

reflecting damage to later phonological processes.

Object

decision X-case

matching Lexical

decision Homophone

decision

n 32 26 60 60

SJS 29 26 55 32

Control M 25.93 58.33 55.65

2SD below M 20.62 53.57 48.72


Significance ns

\

ns <0.01

Table 7:1. SJS’ performance on tests of input processes.



SJS was severely impaired on both reading tasks. He was able to read less than half of the

test words aloud, with no regularity effect (22 errors from each word group) or

regularisations of exception words. The most remarkable aspect of his reading was the high

number of semantic errors (17) compared with other error types, indicating a reading

pattern of deep dyslexia. Examples of his reading responses appear in Table 7:3, with a full

list of responses in Appendix 5. He generally seemed aware of his errors, often shaking his

head or saying “no” after producing a response.

Reading Repetition


n 80 24 80 24

SJS 36 0 80 16

Control M 79.87 22.94 79.2 21.73

2SD below M 79.16 20.57 77.04 15.42


Significance <0.01 <0.01 ns ns

Table 7:2. SJS’ performance on reading and repetition tests.

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Error type Error

number (n=45)

Target Response

ice dice Phonological/visual 2

nose hose

Inflectional 3 shoe shoes

bowl soup

brick book, no, wood

cloud rain

clown easter show

goat bull

salt pepper

Semantic 17

tent camp

gate lock, up there (g) Circumlocution 4

pear fridge (g)

crow flowers

fork wine

noose duck Unrelated/mixed 8

shield lawn

No response 11

Table 7:3. Reading errors for SJS.

Bracketed (g) indicates he gestured or pointed as part of his response.

Nonword reading was almost impossible for SJS. He was unable to read any of the words

accurately, though he did manage to produce some of the appropriate sounds in the stimuli

(there was an overlap of 19.65% between his responses and the targets, which was almost

entirely from lexicalisations). Although he responded to 22 of the 24 items with real words,

only 5 of these were actually lexicalisations (e.g. ked � ‘bed’). The remainder of his

responses bore little, if any, resemblance to the stimuli (e.g. nar � ‘washing;’ grest �

‘flowers’). As with other tests, many responses appeared more than once (e.g. ‘flowers’

was produced in response to 3 different items, none of which bore any resemblance to this

word). A full list of his nonword reading errors appears in Appendix 5.

Repetition of real words was flawless, indicating that the phonological input and output

buffers are both intact. It is also unlikely, based on this result, that his hearing is impaired.

Therefore, his relatively poor result in nonword repetition suggests that the sublexical

repetition route is not completely functional, which would suggest that the phonological

lexicon is probably intact since word repetition is so good. If this is the case, then similar

results should be evident in the control data. Indeed, for the controls that performed word

repetition without error, the average score on nonword repetition was 23.22 (standard

deviation 1.64), suggesting that a flawless performance on word repetition along with a

relatively low score on nonword repetition is a good indication that the latter is probably

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impaired (allowing for 1 error on repetition makes no difference to this conclusion –

controls who performed poorly on nonword repetition all made 2-3 errors on word

repetition). Therefore, a discrepancy as large as that demonstrated by SJS strongly suggests

an impairment specific to nonword repetition. He produced a high number of

lexicalisations on nonword repetition (6), though this was not unusual in comparison to

some controls (up to 9 lexicalisations).

The semantic system

SJS performed poorly on all tests of the semantic system. He made 9 errors on the

comprehension test (6 semantic, 3 phonological), which is high even in comparison to the

other aphasic participants. The distinct lack of ‘unrelated’ errors despite the high number

of total errors (relative to both controls and to other participants) suggests that, rather than

a complete lack of understanding of the stimulus words (and guessing of the answers),

certain aspects of the items were being processed, but inaccurately. Also, they did not

appear to be perceptual errors since the words representing the phonemic distractors were

perceptually quite dissimilar to the targets (e.g. flask�mask; glass�glove) and most of

the semantic errors were not in any way perceptually similar (e.g. key�lock; dice�cards;

witch�broom). SJS also performed significantly worse than controls on all versions of

PPT, with scores falling 2-3 below the range of controls, and consistent across the three

versions. Results of these tests suggest that SJS is experiencing impaired semantic

processing.

PPT


n 80 52 52 52 52

SJS 71 44.00 43 45 44

Control M 79.73 50.44 50.07 50.73 50.53

2SD below M 78.82 47.60 46.18 48.06 47.93

Lowest control 79.00 46.33 45 47 47

Significance <0.01 <0.01 <0.01 <0.01 <0.01

Table 7:4. SJS’ performance on semantic tests.



Picture naming

SJS performed poorly on both naming tasks, though he generally indicated that he was

aware of his errors in a similar fashion to word reading. For oral naming, the majority of

his errors were semantic errors and circumlocutions, and in many cases it was quite

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difficult to distinguish between these two error types due to his non-fluent output. He used

a lot of gestures, often in conjunction with generic words including ‘immature’ descriptive

words (e.g. yuck, yummy), and often described the target word by giving 2-3 semantically

related words, or a single word accompanied by a gesture (these were considered ‘single-

word circumlocutions’).

Oral picture naming

Correct Errors


SJS 32 0 2 2 18 15 4 7

Control M 79.00



Significance <0.01

Table 7:5. SJS’ performance on the oral naming test.



= no response.

Examples of his errors appear in table 7:6 below, with a full list in Appendix 5. Of his 48

errors, 21 were for regular words and 27 for exception words. Although a relatively large

discrepancy, it was not significant (Fisher exact, p = 0.13). The main reason for the

discrepancy was the difference in semantic errors and circumlocutions (19 for exception

words, 14 for regular words).

Error type Subtotal (n=48)

Target Response

ball bowl Phonological/visual 2

key chee

tooth teeth Morphological 2

worm worms

bee fly

beer glass

bread toast

chalk pencil

dog cat

Semantic 18

nose eye

blinds open/doors (g)

hose grass (g) Circumlocutions 15

scroll old, long time

bear yuck

brick foot Unrelated/mixed 4

cake nice

Table 7:6. Examples of oral naming errors for SJS.

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Written naming was extremely difficult for SJS, achieving just over 10% accuracy. Despite

his low number of semantic errors and complete absence of morphological errors, this

pattern is not necessarily in conflict with previous accounts of deep dyslexia. Rather, many

of the unrelated errors could simply be of mixed error types, making the actual responses

indecipherable. A total of 21 errors were spelled correctly, including semantic and

unrelated errors, though as many as 18 of these might have been perseverations (they had

appeared previously as responses, either correct or incorrect, earlier in the test). As many

as 5 of his responses on oral naming might have been perseverations. He made more errors

on regular words (38) than he did on exception words (33), though the difference was not

significant (Fisher exact, p = 0.08).


Correct Errors


SJS 9 0 8 5 45 13

Control M 77.07



Significance <0.01

Table 7:7. SJS’ performance on the written naming test.



Only 1 of his spelling errors was spelled with normal orthographic-phonological rules

(plane � plain). The remaining 8 spelling errors were all rather atypical (i.e. they were not

the type of spelling errors that an unimpaired ‘bad speller’ or someone with a mild

orthographic deficit might occasionally make) and many contained only half of the correct

phonemes or letters, the minimum required to be included as a spelling error. His spelling

errors included inappropriate vowel substitutions (e.g. tent � tant; book � bouk),

incorrect letter order (e.g. bee � eeb) and letter additions and deletions (e.g. watch �

switch; cloud � cud). These errors suggest that he was able to access some aspects of

orthography but in an extremely haphazard manner. Examples of other errors appear

below, with the full list displayed in Appendix 5.

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Error type Subtotal (n=48)

Target Response

bone dag (dog)

crab claw Semantic 5

tongue eye

ball cab

chef chark

dice rarrd

gate bickle

road door

skull stuke

soup cad

Unrelated/mixed

45

wolf clart

Table 7:8. Examples of written naming errors for SJS.

Item consistency

The overlap between the two versions of naming was quite low, as was the overlap

between comprehension and each version of naming. Furthermore, there was a large (and

in one case significant) discrepancy between regular and exception words in opposite

directions for each test. This suggests that either there are separate lesions impacting on

each of these tests, there is a common lesion that is affecting his abilities in an

unpredictable fashion (e.g. impaired access to the semantic system), or, if there is a

common lesion, its effects are minimal in comparison to additional lesions affecting each

naming modality independently.

Chance overlap

Actual overlap

Max overlap

Oral naming vs written naming

46.31 49 57

Comprehension vs oral naming

34.69 34 41

Comprehension vs written naming

15.98 16 18

Table 7:9. Item consistency between comprehension and naming for SJS.

There was moderate consistency between reading and each version of naming, though in

each case the overlap was only midway between chance and the maximum overlap and

could reflect common pressures such as frequency. The overlap between reading and

comprehension was below chance, suggesting no relationship between his impairments on

these tasks.

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Chance overlap

Actual overlap

Max overlap

Reading vs oral naming

40.80 50 76

Reading vs written naming

43.10 49 53

Comprehension vs reading

36.90 36 45

Table 7:10. Item consistency between several tests for SJS.

Discussion

SJS performed well on several tests of early lexical processing. In particular, his object

recognition, letter identification and orthographic lexicon all appear to be intact. His

perfect score on word repetition further indicates that his auditory input and phonological

input and output buffers are intact; his relatively poor score on nonword repetition suggests

a mild deficit of the sublexical repetition route (lesion a in Figure 7:1), and further suggests

that his phonological lexicon is probably intact. Since his letter identification process and

phonological output buffer both appear to be intact, his failure to accurately read any

nonwords indicates that the grapheme-phoneme conversion process is almost completely

non-functional (lesion b in the model). Finally, his difficulties on tests of the semantic

system, and relatively consistent scores across the different versions of PPT, suggest

damage to the semantic system. A lesion of the actual semantic module is the favoured

position, which is justified shortly.

The remaining deficits identified for SJS – reading of real words, and oral and written

picture naming – require further analysis. For reading, the semantic route and lexical non-

semantic route must both be severely damaged. Both of these routes include the

orthographic lexicon and the phonological output buffer, both of which seem to be intact.

The deficit could also be explained by a single lesion of the phonological lexicon or its

connection to the phonological output buffer. However, the latter can be discounted on the

basis of the high number of semantic errors on word reading (and oral naming), which

suggests that the representations in the phonological lexicon are consistently failing to be

activated by the semantic system.

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Figure 7:1. The basic model as it applies to SJS.

Proposed lesions are labeled and coloured red. Green boxes and arrows represent modules and


boxes and arrows represent features for which functioning is not clear.

The integrity of the phonological lexicon is not so certain. The contrast between his scores

on repetition tasks suggest that it is intact. However, the principle of the summation

hypothesis for reading could also be applied to repetition and could account for this pattern

by proposing that partial activation from both routes could lead to accurate assembly in

word repetition. However, the severity of SJS’ reading disorder is such that if damage to

the phonological lexicon were responsible, then it seems unlikely that a perfect score

would be possible on word repetition.

A lesion of the semantic system (lesion c), rather than input to it from object recognition,

and an additional lesion of the lexical non-semantic reading route (lesion d) are indicated

in Figure 7:1. While the severity of his reading impairment (relative to semantic

processing) suggests an additional lesion, perhaps of the connection between semantics and

the phonological lexicon, this could also be accounted for by the argument that tests of the

semantic system are less sensitive to semantic deficits than are tests that require active

generation and output of a semantic representation (Laine et al., 2000). Nevertheless, an

additional post-semantic lesion cannot be dismissed (indicated by the question-marked

lesion e in the model).

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It would be plausible to argue that his compromised semantic system is also responsible for

his difficulties on both naming tests. However, the low overlap between oral and written

naming, and between each of these and the comprehension test, as well as the large

discrepancy in total scores between the naming tests, suggests possible additional lesions.

An additional lesion has already been suggested for oral naming. However, the locus for an

additional lesion impacting on written naming is more obscure due to the severity of the

impairment and the extremely high number of unrelated and indecipherable errors. The

few semantic errors probably reflect his semantic impairment, while his spelling errors

suggest a post-lexical impairment (since the lexical entry seems to have been accurately

selected – rather than an orthographic relative – but cannot activate the appropriate

orthographic coding in the output buffer), as indicated by lesion f in the model. However,

the source of his 45 unrelated errors is not clear. Many of them are probably the combined

result of lesions c and f. However, it seems unlikely that all of these errors are simply

misspelt semantic errors, and some do not even obey the normal rules of English spelling

(e.g. rarrd; dekeey; edde; cuk). Therefore, from the perspective of the basic model, the

extremely high number of indecipherable responses and perseverations in written naming

suggests a complex interaction of at least two lesions, and perhaps more.

In conclusion, SJS presents with a pattern best described as deep dyslexia, including

extremely poor word and nonword reading, with semantic errors on word reading,

impaired semantic processing, and impaired oral and written picture naming. It has been

demonstrated in this chapter that the basic model can account for the variety of lexical

impairments associated with deep dyslexia. On the other hand, it is pertinent to again note

that if deep dyslexia is caused by the combined effect of all of these lesions, then cases

should exist that demonstrate some but not all of the relevant symptoms. Since no such

case has been reported, the preferred explanation remains that of Coltheart (1987) and

Saffran and colleagues (1987): That deep dyslexia is the result of a single, destructive

lesion of the left hemisphere language area, with some or all aspects of processing

compensated for by equivalent areas of the right hemisphere. Therefore, it could be argued

that any cognitive model of language, even those that can account for cases of deep

dyslexia, are perhaps inadequate simply because they are unable to explain why all deep

dyslexics have exactly the same array of impairments.

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Since the interactive functioning of right and left hemisphere language areas is unclear, it

might also be impossible at this stage to fully understand the syndrome from the

perspective of hemispheric lateralization, which could explain some of the variability in

radiological results (e.g. Coltheart, 2000; Laine et al., 2000). It is possible that there are

simply too many variables influencing the specific outcomes of deep dyslexia. For

example, individuals might differ in hemispheric lateralization, the degree of lesion

damage, the specific location of the lesion, and the differences in orthography between the

various languages studied (Laine et al., 2000). Another approach to understanding deep

dyslexia is to consider the symptoms in terms of defective inhibitory mechanism and

interference from competing lexical entries (e.g. Colangelo & Buchanan, 2005, 2006;

Colangelo, Buchanan, & Westbury, 2004; Colangelo, Stephenson, Westbury, & Buchanan,

2003; Katz & Lanzoni, 1997).

The following chapter collates and compares the data presented for the six aphasic

participants.

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Chapter 8. Collective results for aphasic participants

This chapter collates some of the data collected from the aphasic participants in an attempt

to uncover any common patterns in the results, as well as to compare group results (for the

aphasic participants) to the normal data obtained from the control group. Issues

surrounding some of these patterns are then considered in greater detail in the final chapter.

Collective results

As can be seen in Table 8:1, the aphasic participants all performed better than the mean of

the control group on the object decision task. The significance of this result is that visual

processing is intact for all of the aphasic participants, and therefore difficulties on other

tasks cannot be attributed to a disturbance of visual processing.

Object

decision X-case

matching Lexical

decision Homophone

decision

n 32 26 60 60

MWN 26 26 60 57

RPD 29 26 52 41

DHT 27 26 59 44

DPC 26 26 55 28

JWS 29 25 35 36

SJS 29 26 55 32

Mean of Ps 27.67 25.83 52.67 39.67

Control M 25.93 58.33 55.65

2SD below M 20.62 53.57 48.72


Significance ns

\

0.04 <0.01

Table 8:1. Performance of aphasic participants on tests of input processes.

While most aphasic participants performed reasonably well on lexical decision,

homophone decision proved to be much more challenging, with only MWN performing at

a normal level. Three of the four aphasic participants who were intact for lexical decision

were significantly impaired on homophone decision (DHT, DPC and SJS). This might

reflect the multifaceted nature of homophone decision, which relies on the functioning of

multiple language processes to be performed well and might therefore be more vulnerable

to damage.

One of the most notable findings is the high accuracy of word reading (Table 8:2) relative

to oral naming (Table 8:4). On average, aphasic participants were able to correctly read

almost 20 more items than they could name. Given their good results on the object decision

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task, this indicates that, as expected, oral naming is indeed more vulnerable to damage than

is spoken word reading. This is despite the fact that many of the participants struggled with

nonword reading. Although there is an obvious relationship between reading of words and

nonwords in these results (with a correlation for the aphasic participants of 0.68), even

those participants for whom nonword reading was impossible still managed to achieve

higher scores on word reading than on oral naming (17 higher for DHT and 4 higher for

SJS).

Reading Repetition


n 80 24 80 24

MWN 79 22 80 22

RPD 78 7 79 17

DHT 60 0 66 15

DPC 75 5 66 14

JWS 77 13 71 13

SJS 36 0 80 16

Mean of Ps 67.50 7.83 73.67 16.17

Control M 79.87 22.94 79.2 21.73

2SD below M 79.16 20.57 77.04 15.42


Significance <0.01 <0.01 <0.01 ns

Table 8:2. Performance of aphasic participants on reading and repetition tests.

The generally high levels of accuracy in the word-reading task suggest that the task might

not have been challenging enough, and might therefore be masking minor reading

impairments. Furthermore, the low number of errors for most participants made it difficult

to detect any possible regularity effects (see Table 8:6 and Chapter 9 for further discussion

of this topic).

On repetition tasks, three participants, MWN, RPD and SJS, all performed well (1 error or

less) on word repetition. On the other hand, results for nonword repetition were much

worse, with only MWN achieving a high score. In particular, JWS and DPC achieved less

than 60% accuracy on nonword reading, while RPD, SJS and DHT all achieved 63-71%.

However, considering the wide range of performances by controls (54-100%), it is very

difficult to argue that this constitutes a deficit for these participants. It would seem that the

most likely explanation for this is that nonword repetition is extremely sensitive to mild

hearing loss, which is relative common in this age group. In contrast to word repetition, in

which items activate whole entries in the lexicon (and in this case, items that have already

been presented to the participants on four previous occasions, and are probably still primed

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from the written naming task just minutes earlier), the ability to perform nonword

repetition relies on an individual being able to detect variations between different

phonemes, which may differ by a characteristic as subtle as voicing.

For semantic tests, it was necessary for the purpose of this project to make the assumption

that a normal performance on both the comprehension test and on PPT was indicative of an

intact semantic system, though it is possible that the sensitivity of these tests is not high

enough to detect a relatively minor impairment that may nevertheless impact on other tests,

particularly picture naming. The only participant for which this could have been an issue

was MWN, who made no errors on the comprehension test and very few on PPT. All other

participants made 3 or more errors on the comprehension test (compared to a maximum of

1 error from controls) suggesting, at the least, a mild semantic deficit.

Comprehension

Test PPT mean score

n 80 52

MWN 80 50.33

RPD 77 48.00

DHT 77 51.00

DPC 75 47.00

JWS 72 46.33

SJS 71 44.00

Mean of Ps 75.33 47.78

Control M 79.73 50.44

2SD below M 78.82 47.60

Lowest control 79.00 46.33

Significance <0.01 <0.05

Table 8:3. Performance of aphasic participants on semantic tests.

An unusual pattern emerged in the comparison between the comprehension test and PPT.

Many of the aphasic participants achieved good scores on the latter (relative to the control

group) yet made several errors on the former. Collectively, the mean of the participants

was well within the range of the controls on PPT, but well outside the range on the

comprehension test. Despite the intuitive ease of the comprehension test, these results

suggest that it might actually be more sensitive to semantic impairments than the PPT. The

contrast between the comprehension test and PPT is discussed in greater detail in the final

chapter.

In oral naming, the most common error type was semantic errors, with a fairly even spread

of other error types. Semantic errors were also common on written naming, though the

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error means on this test were distorted by the extremely high number of unrelated errors

produced by SJS.

Oral picture naming

Correct Errors


MWN 64 2 6 1 4 0 0 3

RPD 59 2 0 6 13 0 0 0

DHT 43 3 10 4 8 0 0 12

DPC 48 7 8 3 2 2 1 9

JWS 41 13 2 0 17 3 0 4

SJS 32 0 2 2 18 15 4 7

Mean of Ps 47.83 4.50 4.67 2.67 10.33 3.33 0.83 5.83

Control M 79.00 0.13 0.00 0.00 0.40 0.13 0.33 0.00



Significance <0.01

Table 8:4. Performance of aphasic participants on the oral naming tests.

Another notable contrast is that, while the best performance on oral naming was MWN

with 16 errors, two participants, MWN and DHT, actually scored within the range of the

control group on written naming, while a third, RPD, also made less errors on the written

format. Since written naming should be more difficult than oral naming (on average,

controls made approximately 2 errors more on written naming than on oral), these results

suggest that post-semantic damage is largely responsible for the oral naming deficit

demonstrated by at least three of the aphasic participants. This dissociation between the

tasks is most apparent for DHT, who made just 5 errors on written naming but 37 on oral

naming, as well as 20 errors and 14 errors on the reading and repetition tasks respectively.

This was the only case for which a single output function was well preserved despite

considerable deficits on the other three output tasks.

As per the discussion for MWN, the written naming test, by its very nature, lacks

sensitivity. As was evident in the scores for the control group, spelling of some words is

simply a difficult task. The low scores of some control participants therefore meant that

some possible deficits were not clearly identified. Nevertheless, consideration of errors in

these cases did aid interpretation of the results.

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Correct Errors

n=80 Delay Spell Morph Sem Circ P/U NR

MWN 73 0 1 0 3 0 0 3

RPD 67 0 2 0 7 0 0 4

DHT 75 0 0 0 2 0 0 3

SJS 9 0 8 0 5 0 45 13

Mean of Ps 56.00 0.00 2.75 0.00 4.25 0.00 11.25 5.75

Control M 77.07 0.07 0.53 0.00 0.33 0.00 0.00 0.07


Lowest control 72.00 2 5 0 2 0 1 1

Significance <0.01

Table 8:5. Performance of aphasic participants on the written naming test (for the four who completed

the test).

In regard to regularity effects, the aphasic participants did not, as a group, differ greatly on

accuracy between the regular words and the exception words for any task. The only task on

which the groups differed by more than an error was the repetition test, which was mostly

due to the results of JWS. For oral naming, SJS and DHT made considerably more errors

on exception words (a difference of 6 and 5 respectively), though this was countered by the

reverse pattern for JWS, with 9 more errors for regular words.

Reading Repetition Comprehension Oral naming Written naming

Reg Ex Reg Ex Reg Ex Reg Ex Reg Ex

n 40 40 40 40 40 40 40 40 40 40

MWN 40 39 40 40 40 40 31 33 36 37

RPD 39 39 39 40 37 40 30 29 34 33

DHT 30 30 34 32 37 40 24 19 39 36

DPC 38 37 34 32 39 36 25 23

JWS 39 38 38 33 37 35 16 25

SJS 18 17 40 40 36 35 19 13 2 7

Mean 34.00 33.33 37.50 36.17 37.67 37.67 24.17 23.67 27.75 28.25

Reg - Ex 0.67 1.33 0.00 0.50 -0.50

Controls 0.13 0.40 -0.27 0.33 1.07

Table 8:6. Comparison of the regular and exception word groups for aphasic participants.

Severity of aphasia and dissociations

Severity

Along with a variety of contrasting patterns of performance, the participants also

demonstrated varying degrees of overall severity, with some obvious examples. MWN was

clearly the least impaired – her performance was normal on all tests except for oral naming

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(and on many tests better than the mean of the control group). Even her score on oral

naming was higher than any other aphasic participant.

Qualitatively, SJS and DPC were much more disabled than the other participants. While

both had reasonably intact comprehension (at the conversational level) both were

extremely impaired in their production of spontaneous speech, and SJS was almost

completely reliant on his communication book to express himself. For DPC, this general

language dysfunction was quite apparent on testing, with scores generally lower than most

other aphasics. While this was generally true of SJS as well, he was one of only two

aphasic participants to perform without error on the word repetition task, a remarkably

preserved function in the context of a wide range of significant language deficits.

The remaining three participants, RPD, DHT and JWS, appeared to be functionally in

between these two extremes. They were still socially active and able to converse, though

quite restricted by the quality of their verbal output. Once again, this functional ability was

reflected in their scores, with all participants demonstrating strengths and weaknesses and

all performing reasonably well on a few tasks.

Dissociations and double dissociations

The importance of double dissociations in cognitive neuropsychological research supports

the need to identify these when they appear. While there were many dissociations revealed

by the results, double dissociations were not so common.

The most apparent dissociations were evident in comparisons between DHT and his fellow

participants. For example, DHT (along with MWN) does well on written naming but

poorly on oral naming. This contrasts best with SJS who, whilst severely impaired on oral

naming, is much more impaired on written naming (this is not a double dissociation since

he was impaired on both and written naming is a more difficult task). Since the participants

were all recruited based on their anomia, a true double dissociation was never possible

between oral and written naming (within this project).

Another dissociation for DHT is between his intact written naming and his poor reading.

Once again, however, there is no clear double dissociation since only MWN performed

within normal limits on reading. The same was true of the comprehension test. Similarly,

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SJS performed the repetition task perfectly, with a poor performance on reading and oral

naming, but a double dissociation does not exist due to the lack of intact results for the

latter two tasks.

Since double dissociations cannot be considered for the comprehension and reading tests,

because only MWN did well on these, nor for the oral naming test since no aphasic

participant did well, then the only remaining comparison (for the unpublished tests) is

between written naming and repetition. Indeed, a double dissociation does exist in these

results, between DHT (intact and impaired, respectively) and SJS (the reverse). This is the

only certain double dissociation in the results of the unpublished tests and, unfortunately,

the least relevant since there is no suggestion that the two processes are in any way related.

However, another comparison between SJS and DHT is much more significant. Both

participants were completely unable to read nonwords, a hallmark of deep dyslexia. While

SJS did indeed present with the characteristics of deep dyslexia, DHT, like Funnell’s case

WB (1983), presented with phonological dyslexia – although his reading of real words was

severely impaired, he did not make any semantic errors. Therefore, DHT provides direct

evidence against one of the crucial predictions of the summation hypothesis, that non-

functional grapheme-phoneme conversion should lead to semantic errors on word reading.

Rather, DHT’s data help to justify the lexical non-semantic route, which is further

supported by the results of MWN and RPD, for whom reading of exception words, despite

impaired oral naming, is best explained by the presence of this route. The pattern of results

for SJS are also compatible with this assertion.

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Chapter 9. General discussion

The basic model - conclusions

The primary objective of this case series was to assess the practical application of a simple,

easy-to-understand cognitive model of language, the ‘basic model.’ With the exception of

JWS, a late-acquired bilingual, the results of testing do support the usefulness of the basic

model. The basic model was sufficient to account for the data of the remaining

participants, without needing to expand the model by dividing the lexicons into input and

output lexicons. Furthermore, the results of the six participants could not have been

interpreted more clearly within the context of any other model.

For the purpose of research, and in striving towards a more complete understanding of

language processes, cognitive models have become increasingly sophisticated, and will

continue to do so. However, with increased sophistication comes an equivalent increase in

complexity, and many of these models can be quite difficult to apply in clinical settings,

particularly in view of limited time and resources. A simpler model, such as the basic

model applied to this case series, could better enable clinicians to generate and test

hypotheses, and design more appropriate therapeutic intervention, with a smaller battery of

tests selected on the basis of individualised hypotheses.

The following sections elaborate on some of the issues that were raised by the case series,

including the process of reading aloud, the production of semantic naming errors, and

several methodological issues.

Reading aloud

The evidence from this case series supports the inclusion of the lexical non-semantic route

over other accounts of reading, including the summation hypothesis, other dual route

models, and the hypothesis proposed by Orpwood and Warrington (1995). This was best

demonstrated by the results for DHT, whose grapheme-phoneme conversion was

completely non-functional and who showed signs of a semantic deficit, yet read words

aloud without making a single semantic error, a pattern which cannot be explained by the

summation hypothesis, or any other dual route model. While DHT’s results could also be

accounted for by Orpwood and Warrington, the patterns of results for MWN and RPD are

best explained by the lexical non-semantic route.

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However, the results did not reveal any definitive evidence to either support or refute the

hypothesis proposed initially by Orpwood and Warrington (1995). The reason for this lack

of evidence is twofold. Firstly, reading performances for most of the aphasic participants

was too close to ceiling. Secondly, for the aphasic participants that were assessed, the

evidence that was found could easily be argued to support either position. In fact, it seems

a rare event for convincing evidence to surface that can distinguish any one cognitive

model of language from another. The conclusive argument for or against most models is

based largely on the anticipation of identifying an ideal aphasic participant that has exactly

the right pattern of deficits and intact components.

For the Orpwood and Warrington hypothesis, clear support would be in the form of a

participant for whom word reading is more severely impaired than oral naming for the

same set of items (with intact lexical decision to confirm that orthographic input is intact).

Alternatively, a participant would need to be identified as having intact reading yet

sustained damage to the lexical representations for oral naming. To demonstrate that

representations in the phonological (output) lexicon were impaired, repeat administration

of the oral naming test plus complex calculations for item consistency would need to

demonstrate that the representations are consistently unavailable and that the consistency

demonstrated cannot be ascribed to the effects of linguistic complexity, word frequency or

imageability. Intact exception word reading would then support the hypothesis, though if

grapheme-phoneme conversion was at least partly functional, the summation hypothesis

would also be adequate. On the other hand, impaired reading of exception words with

consistency of oral naming errors, and consistency between reading of exception words

and oral naming of the pictures representing these words, would strongly refute the

hypothesis.

Semantic errors on oral naming

For three participants, MWN, RPD and DHT, evidence was found for the concept that

semantic errors in naming can result from damage to post-semantic processing. This

contrasts with some models of processing, such as discrete models (e.g. Levelt et al.,

1991), which assume that the information flow in the lexical-semantic system is serial (i.e.

there is no feedback) and discrete (i.e. at the semantic stage of processing there is only

semantic activity; during phonological encoding there is only phonological activity).

Therefore, the model does not have the capacity to explain semantic errors (beyond

chance) that are caused by post-semantic lesions. However, there is a substantial number of

authors who have claimed that their participants provide clear evidence against this

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position (e.g. Antonucci, 2006; Beaton et al., 1997; Caramazza & Hillis, 1990; Gainotti,

Silveri, Villa, & Miceli, 1986; Laine & Martin, 1996; Laine, Niemi, Niemi, & Koivuselka-

Sallinen, 1990; Lambon Ralph, 1998; Lambon Ralph et al., 2000; Miceli et al., 1996;

Miceli et al., 1994; Miceli et al., 1991; Raymer et al., 2000).

For example, Caramazza and Hillis (1990) present RGB and HW, who produce semantic

errors on all tasks involving oral output except for repetition. However, they produce no

semantic errors in comprehension or in written output. In arguing their case for post-

semantic damage, they discuss the logogen theory, which holds that the target semantic

representation will activate all entries in the phonological (output) lexicon that are

semantically related to it, with varying degrees of activation depending on the degree of

relatedness.

In presenting case IL, Laine and Martin (1996) argue that her anomia is the result of

reduced activation of the phonological lexicon from the semantic system, which can be

accounted for by an interactive activation model (a non-discrete model). Within this model,

all semantically related words activate their relevant phonological representations to some

extent. However, with weakened connections between semantics and phonology, the

phonological nodes can only be activated to a limited degree. Representations are not lost

from the phonological lexicon, but instead have a reduced probability of accurate retrieval

and phonological activation becomes more vulnerable to the effects of random variation.

It should be pointed out that there is no suggestion that semantic errors are only caused by

post-semantic impairments. Indeed, poor performance on the comprehension test was

strongly associated with increased semantic errors on oral naming for the aphasic

participants (r(4) = 0.74, p < 0.05). This is in accordance with Gainotti, Silveri, Villa and

Miceli (1986) who found that participants with greater comprehension deficits produce

more semantic errors in naming. However, they also found that in their group of five

participants without comprehension deficits, all but one still produced semantic errors. In

fact, it is quite possible that the increase of semantic errors associated with more severe

comprehension deficits is simply an artefact of the increase in total errors on oral naming.

In fact, there was a significant correlation between comprehension test errors and total

errors on oral naming, (r(4) = 0.85, p = 0.02). Furthermore, controlling for this variable by

considering semantic errors on oral naming as a proportion of total errors reduces the

correlation between comprehension test errors and semantic errors to almost zero (r(4) =

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0.09, p = 0.43). This suggests that although semantic errors are positively associated with

semantic deficits, it is perhaps only because increased semantic deficits lead to an increase

of all errors, in keeping with previous views that an increase in semantic errors should, in

many cases, be considered the result of chance (Caramazza & Hillis, 1990; Ellis &

Marshall, 1978).

In addition to cases for which obvious semantic impairments are identified, it is also

common for semantic errors on oral naming to reflect mild damage to the semantic system,

in cases in which the comprehension tests employed are not sensitive enough to detect

these mild impairments. Lambon Ralph and colleagues (2000) argue that receptive

comprehension tasks are less sensitive to semantic defects than are expressive tasks. One

explanation for this phenomenon is that degraded semantic representations might be

sufficiently activated to respond to word-picture matching tasks but not sufficient to

activate the entire vocabulary (Lambon Ralph et al., 1999). For example, Laine and

colleagues (1992) investigated the comprehension deficits of two brain injured

participants. Although they both achieved ceiling on word-picture matching and

classification tasks, they were outside the normal range when asked to indicate a semantic

feature for pictures they had been unable to name. Others have made similar claims that

accurate performance on word-picture matching tasks does not require a fully intact

semantic system (e.g. Howard, Patterson, Franklin, Orchard-Lisle, & Morton, 1985).

According to Lambon Ralph and colleagues, assessment of the semantic system should

include a broad range of comprehension tasks that demand precise understanding of

infrequent concrete and abstract words (2000).

If the method of eliminating semantic deficits as cause of deficits is inadequate, then it may

be possible that the semantic errors are in fact caused by a semantic impairment that is too

subtle to detect on testing. In response to this argument, some authors report participants

who demonstrated intact comprehension even on sensitive measures of the semantic

system. For example, Orpwood and Warrington’s (1995) examination of MRF involved

presenting him with a written word and asking him to define or describe the word, which

could be done through verbalisation, drawing and/or mime. He was found to be very

successful at this task, with a naïve examiner correctly identifying 59/60 of the nouns and

57/60 of the verbs. The authors claim that semantic errors produced by MRF were

therefore the result of damage to output word forms. In situations where the target word

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form is inaccessible, the intact semantic entry might maximally activate a semantically

related word form.

Other aphasic individuals, such as GM and JS (Lambon Ralph et al., 2000), also made

semantic errors on oral naming despite an extensive semantic examination. Another case is

MOS (Lambon Ralph et al., 1999), who was not found to have a measurable deficit on

either comprehension or reading despite a detailed assessment using concrete and abstract

words, yet still produced errors of which more than 25% were semantic relatives. For all

three cases, the authors conclude a breakdown between semantics and phonological

representations (both of which were themselves intact).

Results for MWN, RPD and DHT all provide support for the concept that semantic errors

can occur on oral naming following post-semantic lesions, though in each case it was clear

that this argument could be refuted. For all three participants a semantic impairment is

likely. For RPD and DHT, the claim is also supported by the higher rate of semantic errors

on oral naming than on written naming, though it is quite possible that semantic

impairments are simply expressed differently in each naming task.

Therefore, the overall pattern of these cases might be more in keeping with the view that

semantic errors usually represent mild semantic deficits that are undetected by standard

semantic testing due to the lack of sensitivity of receptive tests. In hindsight, it seems

apparent that a greater depth of semantic testing would have alleviated this problem,

perhaps by replacing PPT with semantic tests of varying difficulty and including a timed

component and both receptive and expressive tasks.

Comments on methodological issues

Results of the unimpaired control group raised concerns about the interpretation of certain

tests in clinical practice. First, the average result of PPT was lower than that originally

reported for English controls (Howard & Patterson, 1992). The authors of the test indicate

that their original sample of controls made no more than three errors on either occasion

that they were tested. From this perspective, one in four of the Australian-educated

controls who took part in this project would have been classified as borderline impaired or

worse. This is of some concern, and suggests the need for a more comprehensive sample of

controls for use in clinical settings in Australia, and perhaps exploring the possibility that

9:114

patients from other cultural backgrounds are even more disadvantaged by this possible

cultural bias.

Second, use of the BORB object recognition test revealed what should be considered an

unacceptably wide range and high standard deviation. Observations of testing, including

comments from the control participants, leads to the suggestion that practice and coaching

on this test could reduce the wide performance variability of this test, thereby improving

reliability and, hopefully, sensitivity.

It also became clear that nonword repetition is extremely sensitive to mild hearing loss, an

observation which must be taken into account when working with older individuals that

may have an unidentified impairment. Audiological examination would be extremely

helpful, both clinically and in research, though patterns of cases presented in this report

were mostly interpreted on the basis of the relationship between word and nonword

repetition. Written naming was also lacking sensitivity, though this is an inevitable effect

of the difficulties that many normal individuals have with spelling.

In hindsight, writing words and nonwords to dictation could have provided valuable

(though not really vital) information for some of the cases. However, dictation was not

included because it did not in any way relate to the original research question, and was

considered superfluous in an already lengthy battery of tests. Another methodological

decision made on the basis of time constraints was to administer word repetition shortly

after written naming, which might have boosted results on the repetition test. Admittedly,

some of the published tests could have been used to separate these tests, though it was

thought that the time taken for written naming meant that this final session was already

quite long. Also, repeat administration of certain tests could have provided valuable

information about a) items consistency, and whether impaired performances reflected

damage to representations or impaired access to those representations, and b) test-retest

consistency to examine fluctuations in test results. Finally, since semantic impairments for

several of the participants were ascribed to slowed semantic processing, additional testing

of processing speed, attention and concentration, and working memory might have

contributed by establishing whether their slowed processing was a problem specific to the

semantic system or a more global pattern of impairment. Better control over temporal

effects (both response time and time between items) could also have provided valuable

information.

9:115

Finally, it has already been established that the items used for the unpublished tests were

probably too familiar and linguistically simple. The items were chosen with the intention

that if unimpaired controls could perform with a high level of accuracy (e.g. upwards of

95%) then even a few errors by aphasic participants would indicate impairment. However,

the stimuli chosen were so easily named and read that most of the aphasic participants also

performed quite well, particularly on the reading test, reducing any regularity effects that

might have been demonstrated on more difficult reading tests. Therefore, hypotheses about

reading patterns and other contrasts could not be properly examined (e.g. Orpwood and

Warrington’s hypothesis). Furthermore, having control scores that were so close to ceiling

reduced the ability to test significant differences between tests relative to the control group

due to the extremely small standard deviations. Therefore, it became clear in hindsight that

word-picture items selected to distinguish between different models and hypotheses

probably need to be chosen on the basis that few unimpaired participants will actually

reach ceiling. This would also enable better discrimination between tests by validating use

of more appropriate statistical measures, such as the Bayesian approach (Crawford &

Garthwaite, 2007). On the other hand, this would perhaps further reduce the sensitivity of

written naming by increasing the level of difficulty for some control participants more than

others, and this would obviously need to be taken into consideration.

In sum, a number of methodological issues became apparent during the course of this

research, most of which related to the design of test materials and to problems with certain

published tests. However, most of these would have been difficult to predict and, even if

they were expected, equally difficult to control. Furthermore, it is argued that the results

gleaned from this research have provided valuable insights into the cognitive architecture

of language processing, and that resolution of some or all of these methodological issues

would further aid our ability to represent language using cognitive models.

116

117

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123

Appendices

Appendix 1. Materials

Appendix 1:a. Full list of test items including details of matching. ........................... 124

Appendix 1:b. Results of item matching..................................................................... 126

Appendix 1:c. Classification of items: Natural vs manmade. .................................... 127

Appendix 1:d. Classification for natural, manmade or 'unclear.' ............................. 127

Appendix 1:e. Design of the comprehension test. ....................................................... 128

Appendix 1:f. Matching of regular/exception groups for semantic test. ................... 129

Appendix 1:g. Comprehension test - distractors and relatedness figures. ................ 130

Appendix 2. Analyses

Appendix 2:a. Calculation of chance overlap in item consistency. ............................ 132

Appendix 2:b. Examples of overlap calculation and interpretation.......................... 132

Appendix 3. Control group results

Appendix 3:a. Acceptable variations and queried responses..................................... 133

Appendix 3:b. Control group performance on lexical decision ................................. 133

Appendix 3:c. Control group performance on BORP ............................................... 133

Appendix 3:d. Control group performance on homophone decision ........................ 134

Appendix 3:e. Controls: Natural/manmade contrast on oral naming....................... 134

Appendix 4. Nonword reading

Appendix 4:a. Nonword reading stimuli and participant responses. ........................ 135

Appendix 5. Error analysis for aphasic participants

Appendix 5:a. MWN: Full list of errors on unpublished tests................................... 137

Appendix 5:b. RPD: Full list of errors on unpublished tests. .................................... 139

Appendix 5:c. DHT: Full list of errors on unpublished tests. .................................... 141

Appendix 5:d. DPC: Full list of errors on unpublished tests. .................................... 143

Appendix 5:e. JWS: Full list of errors on unpublished tests. .................................... 145

Appendix 5:f. SJS: Full list of errors on unpublished tests....................................... 147

Appendix 5:g. Lexical decision – aphasic errors. ....................................................... 149

Appendix 5:h. Homophone decision – aphasic errors................................................ 149

Appendix 5:i. Object decision – aphasic errors.......................................................... 149

124

Appendix 1. Materials

Appendix 1:a. Full list of test items including details of matching.

Animate = natural (1), manmade (2) or unclear (3)

Regular words Exception words

ITEM

Lett

ers

Ph

on

em

es

Sp

ok

en

fr

eq

ue

nc

y

Wri

tten

fr

eq

ue

nc

y

An

ima

te

ITEM

Lett

ers

Ph

on

em

es

Sp

ok

en

fr

eq

ue

nc

y

Wri

tten

fr

eq

ue

nc

y

An

ima

te

bee 3 2 117 1 1 axe 3 3 120 7 3

beer 4 2 657 175 2 ball 4 3 1610 54 3

belt 4 4 375 5 3 bath 4 3 751 65 3

bib 3 3 30 2 3 bear 4 2 1100 12 1

bone 4 3 451 27 2 blinds 6 6 64 3 3

brain 5 4 1174 40 2 book 4 3 4256 676 3

brick 5 4 483 15 3 bowl 4 3 498 27 3

cake 4 3 367 16 2 bread 5 4 1215 112 2

cat 3 3 707 32 1 chalk 5 3 167 8 3

cloud 5 4 503 57 2 cheese 6 3 488 9 2

clown 5 4 56 2 2 chef 4 3 47 1 2

cork 4 3 67 3 3 comb 4 3 99 1 3

crab 4 4 79 2 1 crow 4 3 52 2 1

desk 4 4 1438 35 3 eye 3 1 2184 100 2

dice 4 3 42 0 3 flask 5 5 75 1 3

dog 3 3 1229 56 1 foot 4 3 1704 93 2

door 4 2 5780 111 3 ghost 5 4 327 24 2

drum 4 4 141 9 2 glass 5 4 2192 54 3

duck 4 3 168 6 1 glove 5 4 80 2 3

egg 3 2 633 28 2 hook 4 3 549 2 3

125

Test items continued

Regular words Exception words

ITEM

Lett

ers

Ph

on

em

es

Sp

ok

en

fr

eq

uen

cy

Wri

tten

fr

eq

uen

cy

An

imate

ITEM

Lett

ers

Ph

on

em

es

Sp

ok

en

fr

eq

uen

cy

Wri

tten

fr

eq

uen

cy

An

imate

flag 4 4 326 30 3 hose 4 3 65 1 3

fork 4 3 243 0 3 key 3 2 1250 31 3

frog 4 4 68 6 1 mast 4 4 45 1 3

gate 4 3 856 22 3 nose 4 3 1266 41 2

goat 4 3 199 10 1 pear 4 2 44 0 1

ice 3 2 914 20 2 salt 4 4 709 33 2

kite 4 3 52 2 3 screw 5 4 224 2 3

noose 5 3 26 0 3 scroll 6 5 54 2 3

plane 5 4 774 41 3 shield 6 4 151 6 3

plug 4 4 129 3 3 shoe 4 2 249 4 3

prawn 5 4 18 2 1 ski 3 3 106 4 3

road 4 3 3537 254 2 soup 4 3 344 18 2

shell 5 3 500 18 2 steak 5 4 145 1 2

shorts 6 4 187 8 3 sword 5 3 223 14 3

skull 5 4 304 1 2 tongue 6 3 556 46 2

snail 5 4 45 1 1 vase 4 3 69 2 3

sock 4 3 52 1 3 wasp 4 4 43 0 1

tent 4 4 657 0 3 watch 5 3 1851 99 3

tooth 5 3 223 10 2 wolf 4 4 117 2 1

witch 5 3 274 5 2 worm 4 3 126 7 1

M 4.20 3.30 597.03 26.40 2.20 M 4.40 3.30 630.38 39.18 2.43

SD 0.72 0.69 1041.81 49.64 0.79 SD 0.84 0.91 866.66 107.99 0.75

Items with * were included in the reduced list for written naming.

126

Appendix 1:b. Results of item matching.

Full list Reduced list (written naming)

Reg

ula

r

597

.03

1041.8

1

Reg

ula

r

646

.30

1080.3

4

Sp

oke

n f

req

uen

cy

Ex

cep

tio

n

630.3

8

866.6

6

78

0.6

8

0.5

0

Sp

oke

n f

req

uen

cy

Ex

cep

tio

n

905.1

0

1360

.40 1

8

0.4

7

0.4

3

Re

gu

lar

26.4

0

49.6

4

Re

gu

lar

33.7

0

79.2

1

Wri

tten

fre

qu

en

cy

Ex

cep

tio

n

39

.18

107.9

9 7

8

0.1

6

0.8

8

Wri

tten

fre

qu

en

cy

Ex

cep

tio

n

90

.40

209.2

4 1

8

0.8

0

0.6

4

Reg

ula

r

3.3

0

0.6

9

Reg

ula

r

3.5

0

0.5

3

Nu

mb

er

of

ph

on

em

es

Exc

ep

tio

n

3.3

0

0.9

1

78

0.0

0

1.0

0

Nu

mb

er

of

ph

on

em

es

Exc

ep

tio

n

3.3

0

0.6

7

18

0.7

4

0.4

7

Reg

ula

r

4.2

0

0.7

2

Reg

ula

r

4.5

0

0.8

5

Nu

mb

er

of

lett

ers

Ex

cep

tio

n

4.4

0

0.8

4

78

1.1

4

0.2

6

Nu

mb

er

of

lett

ers

Ex

cep

tio

n

4.5

0

0.8

5

18

0.0

0

1.0

0

Re

gu

lar

9.8

3

0.3

8

Re

gu

lar

9.5

0.5

3

Va

lid

ati

on

su

cces

s

Ex

cep

tio

n

9.7

5

0.4

4

78

0.8

1

0.4

2

Va

lid

ati

on

su

cces

s

Ex

cep

tio

n

9.8

0.4

2

18

1.4

1

0.1

8

Co

mp

ari

so

n

Ca

teg

ory

Me

an

StD

ev

DF

T-t

est

p

Co

mp

ari

so

n

Ca

teg

ory

Me

an

StD

ev

DF

T-t

est

p

127

Appendix 1:c. Classification of items: Natural vs manmade.

FULL SET REDUCED SET

Comparison NATURAL/MANMADE Comparison NATURAL/MANMADE

Category Regular Exception Category Regular Exception

Natural 9 6 Natural 1.00 0.00

Manmade 17 23 Manmade 5.00 2.00

Unclear 14 11 Unclear 4.00 8.00

DF 4 DF 2

W2� 5.72 W2� 3.75

p 0.22 p 0.15

Appendix 1:d. Classification for natural, manmade or 'unclear.'

CLASSIFICATION NATURAL MANMADE UNCLEAR

fruit tools homewares manmade

foods mythical

hardware clothing anatomy occupations CATEGORIES

animals weapons transport musical instruments

bear axe glove beer ghost

bee ball hook bone ice

cat bath hose brain nose

crab belt key bread road

crow bib kite cake shell

dog blinds mast cheese skull

duck book noose chef soup

frog bowl plane cloud steak

goat brick plug clown tongue

pear chalk screw drum tooth

prawn comb scroll egg witch

snail cork shield eye

wasp desk shoe foot

salt (salt shaker)

wolf dice shorts 25

ITE

MS

worm door ski

15 flag sock

flask sword

fork tent

gate vase

glass watch

40

128

Appendix 1:e. Design of the comprehension test.

The semantic distance norms were taken from WordNet (Maki et al., 2004). The norms are

based on computational measures devised by Jiang and Conrath (Jiang & Conrath, 1997),

who combined two previous approaches, the edge-based and node-based approaches, both

of which are concerned with the relationships between nodes in a semantic taxonomy.

According to Maki and colleagues, the Jiang and Conrath method is well supported by

evidence such as semantic similarity ratings from human observers and computational

measures.

Of the 80 word/picture items used as the materials, eight could not be matched with

picturable semantic relatives (four from each of the regular and exception word groups). In

a few cases, one member of the relationship (either the target or the distractor) appeared

with its American name (e.g. prawn � shrimp; duster � eraser). The semantic distance in

these cases was assumed to be equivalent. The only additional caveat was that the distance

norms apply to the words, not the concepts. Therefore, there was a potential for figures to

suggest stronger relationships because of differences between spoken and written

frequency and, perhaps more significantly, relationships between nouns that are also verbs,

and could perhaps be semantically closer that way (e.g. comb/brush). In cases in which one

or both members of a word-pair did not seem to represent the pictured object, a different

relative was sought (the pairing of comb and brush was probably the most ‘verb-like;’ any

pairing that seemed less likely to represent objects for both members was changed for more

obvious object-object relationship.

Phonemic distractors were selected on the bases of phoneme overlap, which was calculated

from the number of shared phonemes (in a reasonably similar position) and number of

unshared phonemes (including same phoneme but in a different word position e.g. brick

and crib share the middle two phonemes but not the first and the last). For the latter,

number of unshared phonemes in each member of the pair was determined and the higher

of the two recorded. The table below also shows the number of shared phonemes divided

by the number not shared, which was the primary basis for matching the regular and

exception word groups.

Several of the semantic distractors shared a single phoneme with the target, which was

only considered reasonable in cases where such a relationship was considerably stronger

than the next best target/distractor relationship. Conversely, some phonological distractors

were also semantically related to the target – this was unavoidable in these instances (e.g.

the only picturable item phonologically similar to shorts is shirts). Although it could

perhaps be argued that items for which semantic and phonological distractors were difficult

to find should have been excluded from the set, this would have further reduced a set of

items that was already quite limited in number, as well as affecting the matching described

in Appendix 1. In total, five semantic distractors shared a single phoneme with the target,

while four phonological distractors could be argued to have a clear semantic link to the

target (this is obviously much more subjective and was not measured in any way). Note

that other complicating factors were not taken into account, such as visual similarity

between distractors. Also, many items also had to be repeated, including some targets that

were used as distractors.

The full list of distractors appears in below, along with individual figures of phoneme

overlap and semantic distance. Unrelated distractors were chosen on the basis that they

were easily picturable and not semantically or phonologically related to the target or to

either of the other two distractors.

129

Appendix 1:f. Matching of regular/exception groups for semantic test.

PHONEME OVERLAP Comparison

SEMANTIC DISTANCE Same phoneme Different phoneme Overlap

Category Regular Exception Regular Exception Regular Exception Regular Exception

Mean 8.53 9.03 2.08 2.13 1.28 1.38 0.68 0.71

StDev 5.46 5.44 0.57 0.76 0.45 0.49 0.34 0.34

DF 70* 78 78 78

T-test -0.39 -0.33 0.19 0.34

p 0.70 0.74 0.85 0.74

*Each group had 4 missing values. Matching of semantic association.

Regular Exception

Within group 22 27

Associated 18 13

Fisher exact p = 0.359

130

Appendix 1:g. Comprehension test - distractors and relatedness figures.

PHONEMIC SEMANTIC TARGET

Distractor S D S/D Distractor Cx Relationship JCN UNRELATED

axe ox 1 1 1.00 saw w tools/woodcutting 6.34 mug

ball bell 2 1 0.50 bat a use together 9.41 drill

bath bark 2 1 0.50 towel a use together 17.70 drill

bear beer 1 1 1.00 tiger w animals 6.77 vice

bee bear 1 1 1.00 wasp w animals/stinging insects 2.51 flute

beer bee 1 1 1.00 wine w drinks 4.00 clock

belt bolt 3 1 0.33 tie w clothing/accessories 6.24 fish

bib bin 2 1 0.50 dummy w baby things scales

blinds blenders 5 2 0.40 curtains w window covers peas

bone phone 2 1 0.50 skull w anatomy/internal 4.17 mouse

book bark 2 1 0.50 pen a b used for a skates

bowl bell 2 2 1.00 spoon a a goes with b 7.28 trike

brain train 3 1 0.33 skull w anatomy/internal 14.24 snake

bread bride 3 1 0.33 meat w food 3.54 crown

brick crib 2 2 1.00 rock a natural vs manmade 16.27 spoon

cake rake 2 1 0.50 pie w food/sweets 3.86 bag

cat hat 2 1 0.50 mouse w animals 8.46 hearse

chalk fork 2 1 0.50 duster (eraser)

w stationary 12.71 barn

cheese peas 2 1 0.50 bread w food 7.87 buoy

chef shed 2 1 0.50 waiter w occupation 13.60 safe

cloud clown 3 1 0.33 moon a in the sky moth

clown crown 3 1 0.33 juggler w occupation/circus folk truck

comb coat 2 1 0.50 brush w hair styling 2.00 tap

cork chalk 2 1 0.50 bottle a wine bottle plugs? 15.41 vice

crab crib 3 1 0.33 lobster w animals/crustaceans 2.22 suit

crow rope 2 2 1.00 bird a sub/super 5.99 bag

desk disk 1 1 1.00 chair w furniture 5.81 shears

dice rice 2 1 0.50 cards w games 18.20 leaf

dog log 2 1 0.50 cat w animals/pets 2.24 tie

door deer 1 1 1.00 hinge a part-whole 16.76 bowl

drum plum 2 2 1.00 guitar w musical instruments 7.05 scarf

duck truck 2 2 1.00 swan w animals/water birds 3.81 stamp

egg peg 2 1 0.50 chicken a a comes from b 15.68 scythe

eye tie 1 1 1.00 ear w anatomy/face 2.62 trowel

flag bag 2 1 0.50 shield a representations couch

flask mask 3 2 0.67 bottle w drink containers 2.33 whip

foot flute 2 2 1.00 shoe a b goes on a 11.57 boat

fork cork 2 1 0.50 knife w cutlery 8.24 whip

frog log 2 2 1.00 rabbit w animals 11.44 anvil

gate plate 2 2 1.00 door a function 2.93 wheel

S = shared phonemes

D = different phonemes

S/D = number of shared phonemes divided by number of different phonemes

Cx = criteria for semantic relationship (w = within the same category; a = associated by function)

JCN = Jiang & Conrath number

131

PHONEMIC SEMANTIC TARGET

Distractor S D S/D Distractor Cx Relationship JCN UNRELATED

ghost toast 3 1 0.33 witch w mythical monsters 12.43 chair

glass grass 3 1 0.33 mug w kitchen/drinking 10.19 bike

glove glass 2 2 1.00 hat a a goes on b 8.12 mace

goat boat 2 1 0.50 cow w animals/farm 4.44 easle

hook book 2 1 0.50 nail w hardware 7.00 trowel

hose rose 2 1 0.50 tap a a goes on b 17.77 deer

ice rice 2 1 0.50 glass a a goes in b 5.99 safe

key cow 1 1 1.00 lock a a goes in b 9.61 net

kite cat 2 1 0.50 bird a function 5.99 mallet

mast mask 3 1 0.33 wheel a boat parts biscuit

noose goose 2 1 0.50 rope a part-whole 10.86 bolt

nose rose 2 1 0.50 ear w anatomy/face 3.97 bowl

pear bear 1 1 1.00 apple w food/fruit 2.07 sink

plane plate 2 2 1.00 car w vehicles 4.53 monk

plug plum 3 1 0.33 sink a a goes in b 16.22 raft

prawn (shrimp)

corn 2 2 1.00 lobster w animals/crustaceans? 3.42 rope

road rose 2 1 0.50 car a b uses a 10.02 lamp

salt bolt 3 1 0.33 pepper w food/spices 4.67 bike

screw scroll 3 2 0.67 nail w hardware 5.31 bed

scroll screw 3 2 0.67 pen a b used for a 20.91 lock

shell shed 2 1 0.50 fish a beach 6.65 ruler

shield shed 2 2 1.00 armour a function 1.59 sunglasses

shoe shark 1 2 2.00 sock w clothing 10.75 couch

shorts shirts 3 1 0.33 pants w clothing/legs 1.79 rock

ski key 2 1 0.50 sled w snow flute

skull skunk 3 2 0.67 brain w anatomy/internal 14.24 house

snail whale 2 2 1.00 slug w animals/slimy invertebrates 2.76 bandage

sock rock 2 1 0.50 foot a a goes on b 15.64 bed

soup suit 2 1 0.50 bowl a part-whole 17.80 ox

steak rake 2 2 1.00 potato a a goes with b 10.41 flowers

sword saw 2 1 0.50 shield w medieval weapons 14.00 pretzel

tent pen 2 2 1.00 house w forms of shelter 8.13 onion

tongue tongs 2 2 1.00 tooth w anatomy/mouth 16.65 cards

tooth roof 1 2 2.00 mouth a part-whole 6.96 sai

vase jars 2 1 0.50 flowers a b goes in a 17.39 horse

wasp watch 2 2 1.00 fly w animals/stinging insects 7.40 phone

watch witch 2 1 0.50 clock w function 1.73 shark

witch watch 2 1 0.50 broom a a uses b 19.92 tongs

wolf bull 2 2 1.00 dog w animals/canines 3.55 throne

worm world 2 2 1.00 caterpillar w animals/invertebrates 12.09 camera

2.13 1.40 0.73 9.29

0.68 0.48 0.34 5.36

S = shared phonemes

D = different phonemes

S/D = number of shared phonemes divided by number of different phonemes

Cx = criteria for semantic relationship (w = within the same category; a = associated by function)

JCN = Jiang & Conrath number

132

Appendix 2. Analyses

Appendix 2:a. Calculation of chance overlap in item consistency.

The calculation of chance overlap is the prediction of overlap between two tests that would

result from chance alone. This calculation generates exactly the same figures as would be

produced by Cohen’s Kappa. Which of the two tests is ‘Test 1’ and which is ‘Test 2’ in the

following equation makes no difference to the result. The equation for chance error

overlap is:

(number of errors Test 1 ÷ number of items test 1) x number of errors test 2

The equation for chance overlap for correct items is:

(number correct Test 1 ÷ number of items test 1) x number correct test 2

The total chance overlap is found by adding these two scores, and this figure can then be

compared to the actual overlap to gauge whether or not the ‘consistency’ between the two

tests is authentic or just due to chance.

Appendix 2:b. Examples of overlap calculation and interpretation.

Example 1

Reading test is 70/80 while repetition is 60/80, with 8 of the errors overlapping (and

therefore 58 correct overlapping, with a total of 66 overlapping items). The calculation

would be:

Errors: 10/80 x 20 = 2.5

Correct: 70/80 x 60 = 52.5

Total chance overlap = 55

Maximum overlap = 70

When the actual overlap of 66 is compared with the chance overlap of 55 (with a

maximum overlap of 70) it can be seen that this overlap is reasonably high.

Example 2

Consider another example with a larger difference between the scores, but the same

overlap of errors. In this example, the reading test is again 70/80 while oral naming is

20/40, with 8 errors again overlapping (and this time 18 correct overlapping, for a total of

26 items overlapping). This time the calculation would be:

Errors: 10/80 x 60 = 7.5

Correct: 70/80 x 20 = 17.5

Total chance overlap = 25

Maximum overlap = 30

In this case, comparing the actual overlap of 26 with the chance overlap of 25 (with a

maximum overlap of 30) is less impressive – the overlap would need to be closer to the

maximum of 30 to suggest consistency between the tests (an overlap of 28 or 30 might be

more convincing, though in this case the gap between chance and maximum overlap is

probably too small to be meaningful).

133

Appendix 3. Control group results

Appendix 3:a. Acceptable variations and queried responses.

Acceptable variations are based on control group responses, and do not include common responses

that included the correct response (e.g. t-bone steak).

Item Acceptable response

Prompted for desired response

bath tub

beer drink/glass etc

blinds blind

chalk blackboard*

crow bird

gate gates

glass cup

road highway

soup bowl

steak t-bone

*To give the chalk context, it was pictured with a blackboard, which was named occasionally.

Appendix 3:b. Control group performance on lexical decision

LEXICAL DECISION n=60

CORRECT

Range 53-60

Mean 58.33

StDev 2.38

REAL WORDS NONWORDS n=30

Range 29-30 24-30

Mean 29.73 28.60

StDev 0.46 2.16

Regular Excep-

tion Pseudo-

homophones Nonhomo-

phonic n=15

Range 14-15 14-15 9-15 12-15

Mean 14.87 14.87 13.87 14.73

StDev 0.35 0.35 2.00 0.80

Appendix 3:c. Control group performance on BORP

BORB

CORRECT n=32

Range 20-29

Mean 25.93

StDev 2.66

Real Unreal n=16

Range 14-16 6-13

Mean 15.27 10.67

StDev 0.80 2.13

134

Appendix 3:d. Control group performance on homophone decision

HOMOPHONE DECISION n=60

TOTAL CORRECT

Range 50-60

Mean 55.65

StDev 3.46

TOTAL YES TOTAL NO n=30

Range 22-30 22-30

Mean 27.35 27.94

StDev 2.55 2.68

REAL WORDS n=40

Range 32-40

Mean 37.60

StDev 2.20

REGULAR EXCEPTION NONWORDS n=20

Range 15-20 15-20 16-20

Mean 18.60 19.00 18.13

StDev 1.30 1.51 1.60

Yes No Yes No Yes No n=10

Range 9-10 5-10 5-10 8-10 6-10 7-10

Mean 9.27 9.33 9.33 9.67 8.93 9.20

StDev 0.46 1.35 1.35 0.62 1.16 0.94

Appendix 3:e. Controls: Natural/manmade contrast on oral naming

NATURAL MANMADE UNCLEAR

n 15 40 25

Mean 14.73 39.33 24.93

StDev 0.59 0.98 0.26

-

135

Appendix 4. Nonword reading

Appendix 4:a. Nonword reading stimuli and participant responses.

Lexicalisations are italicised.

Item

n

um

ber

Sti

mu

lus

item

No

rmal

pro

nu

n-

cia

tio

n

Nu

mb

er

of

lett

ers

Nu

mb

er

of

ph

on

em

es

RPD DPC DHT JWS SJS

1 ked /ked/ 3 3 √ cooked reed kade bed

2 bem /bem/ 3 3 beam tem beam beam bath

3 nar /na:/ 3 2 √ √ \ washing

4 cug /kUg/ 3 3 could ked cugs cup

5 fon /fPn/ 3 3 fond √ fond font tent

6 lat /lzt/ 3 3 nat /lət/ late tent

7 shid .Rhc.� 4 3 sheared shell jabu ship \

8 boak /boTk/ 4 3 boat book book boo-ak bath

9 doop /dup/ 4 3 she-opt dop drom new

10 birl /b2l/ 4 3 birled bird bill bird

11 dusp /dUsp/ 4 4 dust dus ship brush

12 soaf /soTf/ 4 3 soak √ \ soup

13 snite /snaHt/ 5 4 √ snike snipe slug

14 hance /hzns/ 5 4 √ √ hence hant door

15 hoach /hnTsR. 5 3 hoached hot drum hoe-ak pain

16 smode /smoTd/ 5 4 mode s..m..dee \ plaine

17 glope /gloTp/ 5 4 √ goes drom gud

18 grest /grest/ 5 5 √ √ trashed flowers

19 dringe .cYqHmcY.� 6 5 gringle drink \ ring

20 squate .rjvdHs.� 6 4 she-ote see…tee square go-ate oysters

21 churse .sR2r.� 6 3 church church church church church

22 thease .Shr.� 6 3 √ /tisis/ \ flowers

23 shoave .RnTu.� 6 3 shove shell \ sho-ave wood

24 pretch .oqdsR.� 6 4 preach perch scred prench flowers

Mean 4.5 3.417

Standard deviation 1.142 0.717

Total correct 7 5 0 13 0

Percent overlap 71 59 31 83 20

Number of lexicalisations 12 5 10 5 5

136

Appendix 5. Error analysis for aphasic participants

Legend for following pages:

Comp = Comprehension test

ON = Oral naming

WN = Written naming

Read = Reading test

Rep = Repetition test

Sem = semantic error

Ph = phonological error

Mor = morphological error (error indicated -s or –ed)

Un = unrelated error

NR = no response

Delayed = delayed error

Q = Participant cued following an acceptable (non-target) response

(e.g. ‘bird’ Q ‘crow’).

(g) = gestured as part of response

Shading indicates that the item was responded to correctly on all occasions.

137

Appendix 5:a. MWN: Full list of errors on unpublished tests.

Correct (ticked) or error type and response

Target Comp ON WN Read Rep

AXE √ √ √ √ √

BALL √ √ √ √ √

BATH √ Ph /braS/ √ √ √

BEAR √ √ √ √ √

BEE √ √ √ √ √

BEER √ Ph breer √ √ √

BELT √ √ √ √ √

BIB √ √ √ √ √

BLINDS √ √ √ √ √

BONE √ √ √ √ √

BOOK √ √ √ √ √

BOWL √ √ √ √ √

BRAIN √ √ √ √ √

BREAD √ Ph /br2d/ √ √ √

BRICK √ √ √ √ √

CAKE √ √ √ √ √

CAT √ √ √ √ √

CHALK √ √ √ √ √

CHEESE √ √ √ √ √

CHEF √ √ √ √ √

CLOUD √ √ √ √ √

CLOWN √ √ √ √ √

COMB √ √ √ √ √

CORK √ √ √ √ √

CRAB √ √ √ √ √

CROW √ Sem bird Q currawong Sem bird Q ? √ √

DESK √ Delayed √ √ √

DICE √ √ √ √ √

DOG √ √ √ √ √

DOOR √ √ √ √ √

DRUM √ Mor drummed √ √ √

DUCK √ √ √ √ √

EGG √ √ √ √ √

EYE √ √ √ √ √

FLAG √ √ √ √ √

FLASK √ Sem cigarette lighter Sem* cig. lighter √ √

FOOT √ √ √ √ √

FORK √ √ √ √ √

FROG √ √ √ √ √

138

MWN’s errors (continued).



GATE √ Ph /dYeIts/ √ √ √

GHOST √ √ √ √ √

GLASS √ Ph grass √ √ √

GLOVE √ √ √ √ √

GOAT √ √ √ √ √

HOOK √ √ √ √ √

HOSE √ √ √ √ √

ICE √ NR - NR - √ √

KEY √ √ √ √ √

KITE √ √ √ √ √

MAST √ √ √ Ph mask √

NOOSE √ Sem rope Sem rope √ √

NOSE √ √ √ √ √

PEAR √ √ √ √ √

PLANE √ Ph prane √ √ √

PLUG √ √ √ √ √

PRAWN √ √ √ √ √

ROAD √ √ √ √ √

SALT √ √ √ √ √

SCREW √ Delayed √ √ √

SCROLL √ √ √ √ √

SHELL √ √ √ √ √

SHIELD √ √ NR - √ √

SHOE √ √ √ √ √

SHORTS √ √ √ √ √

SKI √ NR - √ √ √

SKULL √ Sem skeleton √ √ √

SNAIL √ √ √ √ √

SOCK √ √ Sp sox √ √

SOUP √ √ √ √ √

STEAK √ √ √ √ √

SWORD √ √ √ √ √

TENT √ √ √ √ √

TONGUE √ √ √ √ √

TOOTH √ √ √ √ √

VASE √ √ √ √ √

WASP √ √ √ √ √

WATCH √ √ √ √ √

WITCH √ NR - NR - √ √

WOLF √ √ √ √ √

WORM √ √ √ √ √

Correct 80 64 73 79 80

139

Appendix 5:b. RPD: Full list of errors on unpublished tests.



axe √ Sem tomahawk NR - √ √

ball √ √ √ √ √

bath √ √ √ √ √

bear √ √ √ √ √

bee √ √ √ √ √

beer √ Sem drink (q) (√ o/t) √ √ √

belt √ √ √ √ √

bib √ Sem baby √ √ √

blinds √ √ √ √ √

bone √ √ √ √ √

book √ √ √ √ √

bowl √ Sem dish NR - √ √

brain √ √ √ √ √

bread √ √ √ √ √

brick √ √ √ √ √

cake √ √ √ √ √

cat √ √ √ √ √

chalk √ Sem crayon Sem blackboard √ √

cheese √ √ √ √ √

chef √ √ Sem cook √ √

cloud √ Mor -s √ √ √

clown Sem juggler √ √ √ √

comb √ √ √ √ √

cork √ √ √ √ √

crab Sem lobster Mor √ √ √

crow √ Sem bird (q) magpie √ √ √

desk √ √ √ Ph des √

dice √ √ √ √ √

dog √ √ Sem puppy √ √

door √ √ √ √ √

drum √ √ √ √ √

duck √ Sem dove (√ o/t) √ √ √

egg √ √ √ √ √

eye √ Mor eyed √ √ √

flag √ √ √ √ √

flask √ √ √ √ √

foot √ √ √ √ √

fork Sem knife Sem fork, no knife √ √ √

frog √ √ √ √ √

gate √ √ √ √ √

140

RPD’s errors (continued).



ghost √ √ √ √ √

glass √ Sem beaker…(√ o/t) √ √ √

glove √ √ √ √ √

goat √ √ √ √ √

hook √ √ NR - √ √

hose √ √ √ √ √

ice √ √ √ √ √

key √ √ √ √ √

kite √ √ √ √ √

mast √ Sem flagship, no, stern √ Ph /mastk/ √

noose √ Mor -s Sem rope √ √

nose √ √ √ √ √

pear √ √ √ √ √

plane √ √ √ √ √

plug √ √ √ √ √

prawn √ √ √ √ √

road √ √ Sem bitumen √ √

salt √ √ √ √ √

screw √ √ √ √ √

scroll √ Sem Magna Carta Sem 0 √ √

shell √ √ Sem 0 √ √

shield √ √ Sp sheild √ √

shoe √ √ √ √ √

shorts √ √ √ √ Ph shore

ski √ √ √ √ √

skull √ Sem skeleton Sem skellton √ √

snail √ Mor -s √ √ √

sock √ Mor -s √ √ √

soup √ Delayed √ √ √

steak √ √ √ √ √

sword √ √ √ √ √

tent √ √ √ √ √

tongue √ √ √ √ √

tooth √ √ √ √ √

vase √ Delayed √ √ √

wasp √ Sem mosquito Sem bee √ √

watch √ √ √ √ √

witch √ √ Sp which √ √

wolf √ √ √ √ √

worm √ √ √ √ √

Correct 77 59 67 78 79

141

Appendix 5:c. DHT: Full list of errors on unpublished tests.



AXE √ Ph atches √ Ph ashed √

BALL √ Delayed NR - √ √

BATH √ √ √ √ √

BEAR √ √ √ √ √

BEE √ √ √ √ √

BEER √ √ √ √ √

BELT √ Ph belk √ √ √

BIB √ √ √ Ph big, no √

BLINDS √ √ √ Ph blounds √

BONE √ √ √ √ √

BOOK √ Sem bible Sem bible √ √

BOWL √ √ √ NR - Mor bowled

BRAIN √ √ √ √ √

BREAD √ Ph bled √ √ √

BRICK √ √ √ √ √

CAKE √ √ Sem icing √ √

CAT √ √ √ √ √

CHALK √ NR - √ Ph core Ph shal

CHEESE √ NR - √ √ √

CHEF √ √ √ √ √

CLOUD √ √ √ NR - √

CLOWN Sem juggler √ √ √ Mor -s

COMB √ √ √ √ √

CORK √ Sem bottle opener √ Ph cort √

CRAB √ √ √ Ph scrub √

CROW √ Sem bird (q) evil √ √ √

DESK √ Ph dest √ NR - Ph guest

DICE √ √ √ √ √

DOG √ √ √ √ √

DOOR √ √ √ √ √

DRUM √ Ph grum √ Ph grum Ph grum

DUCK Sem swan √ √ Ph duts √

EGG √ √ √ √ √

EYE √ √ √ √ √

FLAG √ Ph flad √ √ √

FLASK √ Sem whiskey √ Ph flast Ph glass

FOOT √ √ √ √ Ph /f�k/

FORK √ √ √ √ √

FROG √ √ √ √ √

GATE √ NR - √ NR - Ph gaik

142

DHT’s errors (continued).



GHOST √ NR - √ √ √

GLASS √ NR cup of, no √ √ √

GLOVE √ NR - √ √ √

GOAT √ Delayed √ √ √

HOOK √ NR - NR - √ √

HOSE √ NR - √ √ √

ICE √ Sem rain √ √ √

KEY √ √ √ √ √

KITE Sem bird NR - √ √ √

MAST √ NR - NR - √ Ph mask

NOOSE √ NR - √ NR - √

NOSE √ √ √ √ √

PEAR √ Sem apple √ √ √

PLANE √ √ √ √ √

PLUG √ Ph glug √ √ √

PRAWN √ √ √ √ √

ROAD √ √ √ √ √

SALT √ √ √ √ √

SCREW √ √ √ √ √

SCROLL √ √ √ √ √

SHELL √ NR - √ √ √

SHIELD √ Ph seal √ NR - √

SHOE √ Mor -s √ √ √

SHORTS √ Mor -s √ Mor -s Mor -s

SKI √ √ √ √ √

SKULL √ √ √ √ √

SNAIL √ √ √ √ √

SOCK √ Mor -s √ √ Ph shock

SOUP √ √ √ √ √

STEAK √ Ph scray √ Ph snake Ph skake

SWORD √ √ √ √ √

TENT √ Delayed √ √ √

TONGUE √ Ph tun √ √ Ph kung

TOOTH √ Mor teeth √ NR - √

VASE √ Sem bowl √ Ph vaze UR glue

WASP √ Sem bee √ Ph wost √

WATCH √ √ √ √ √

WITCH √ √ √ √ √

WOLF √ √ √ √ √

WORM √ √ √ √ √

Correct 77 42 75 61 66

143

Appendix 5:d. DPC: Full list of errors on unpublished tests.


Target Comp ON Read Rep WN

axe √ √ √ √ √

ball √ √ √ Ph fall

bath √ √ √ √

bear √ √ √ √

bee √ √ √ NR -

beer √ √ √ Ph fear

belt √ √ √ √

bib √ Circ baby stuff √ √

blinds √ NR - √ Ph

bone √ √ √ √

book √ √ √ √ √

bowl √ √ √ Ph

brain √ √ √ √

bread √ √ √ √

brick √ Ph brook Ph bock √

cake √ Delayed √ √

cat √ √ √ √

chalk Sem duster Ph chorch √ √ Sp calb

cheese √ √ √ √

chef √ cough, C.H., kef NR f… √ NR c

cloud √ Delayed √ Ph ploughed

clown √ √ √ √ NR c

comb √ √ √ √

cork √ Ph qwark √ √

crab √ NR - √ √

crow √ Ph bird (q) NR √ √

desk √ √ √ √

dice √ Ph spelled out (L.I.C.E.) √ NR -

dog √ √ √ √ √

door √ √ √ √

drum √ √ √ √ Sp dume

duck √ √ √ √

egg √ √ √ √

eye √ Delayed √ Ph ice

flag √ √ √ √

flask √ √ √ √

foot √ √ √ √ Sp foo

fork √ √ √ √

frog √ √ √ √

gate √ Un glass √ √

144

DPC’S errors (continued).



ghost √ √ √ √

glass Ph grass Delayed √ √

glove √ Mor -s √ √ NR c

goat √ √ √ √

hook √ NR - √ √ NR -

hose √ NR - √ √

ice √ NR - √ √

key √ √ √ √

kite √ Ph skite √ √ Sp kile

mast √ Ph mask Ph mask Ph nast

noose NR - Sem rope Ph nose √ NR -

nose √ √ √ √

pear √ Delayed √ Ph hair

plane √ √ √ Ph play

plug √ √ √ √

prawn √ Mor -s √ √

road √ Delayed √ √ Sp ro

salt √ √ √ √

screw √ Delayed √ √

scroll √ Circ chinese thing √ √ NR -

shell √ √ √ √

shield √ NR - √ Ph sheel

shoe √ √ √ √

shorts √ Mor -s √ Mor -s Sp shorh

ski √ √ √ √

skull √ √ √ √ Sp scal

snail √ √ √ √

sock √ √ √ √

soup √ √ √ √

steak √ √ √ √

sword √ √ √ √ Un sko

tent √ √ √ √ NR c-

tongue √ NR - √ √

tooth √ NR - √ √

vase √ √ √ √

wasp √ NR - √ √

watch NR - √ √ √ Sp whc

witch √ √ √ √ Sp wick

wolf Sem dog Sem vox NR - Ph woof

worm √ √ √ √

Correct 75 48 75 66 3/20

145

Appendix 5:e. JWS: Full list of errors on unpublished tests.



axe √ √ √ Ph act Sp ars

ball √ √ √ √

bath √ Circ washing √ √

bear √ √ Ph beer √

bee √ Sem fly √ √

beer √ Sem drink √ √

belt √ Delayed √ √

bib √ Delayed √ Ph bid

blinds √ Sem drapes √ Ph line

bone √ √ √ √

book √ √ √ √ √

bowl √ Sem toilet √ √

brain √ Delayed √ √

bread Delayed √ √ √

brick √ √ √ √

cake Sem pie Circ happy bday √ √

cat √ Delayed √ √

chalk √ Circ to write √ √ Sp calk

cheese √ √ √ √

chef √ √ √ √ Un kook (cook)

cloud √ √ √ √

clown √ √ √ √ √

comb √ Delayed √ √

cork √ Sem √ √

crab √ Sem √ Un fred

crow √ √ √ √

desk √ √ √ √

dice √ Sem marbles √ √

dog √ Delayed √ √ √

door √ √ √ √

drum √ NR - √ √ Sp dump

duck √ Delayed √ √

egg √ √ √ √

eye √ √ √ √

flag √ √ √ √

flask √ Sem bottle √ √

foot Sem shoe Sem toes √ √ Sem feet

fork √ Sem knife √ √

frog √ √ √ √

gate √ √ √ √

146

JWS’ errors (continued).



ghost √ Sem spook √ √

glass Ph grass √ √ √

glove √ √ √ √ Un ?craif

goat √ Delayed √ √

hook √ √ √ √ NR -

hose √ √ √ √

ice √ Delayed √ √

key √ √ √ √

kite √ √ √ √ Sp kert

mast √ Ph mask Ph mask Ph mask

noose Sem rope √ Ph nose √ Un ?lassa (lassoo)

nose Sem ear √ √ Ph no

pear √ √ √ Ph bear

plane √ √ √ √

plug √ Sem sink √ √

prawn √ NR - √ √

road √ Delayed √ √ Un ?garda

salt √ √ √ √

screw √ √ √ √

scroll √ Ph stroll √ √ NR -

shell √ NR - √ √

shield √ √ √ √

shoe √ √ √ Mor -s

shorts √ √ √ √ Sem pant?

ski √ Delayed √ √

skull √ Sem hat √ √ NR -

snail √ Sem horse √ √

sock √ √ √ √

soup √ √ √ √

steak √ Sem beef √ √

sword Sem shield √ √ √ Sp sord

tent √ Delayed √ √ √

tongue √ √ √ √

tooth Sem mouth √ √ √

vase √ Delayed √ √

wasp √ Sem fly √ Ph wops

watch √ √ √ √ Sp wath

witch √ NR - √ √ NR -

wolf √ Sem dog √ √

worm √ √ √ √

Correct 75 41 77 71 4/20

147

Appendix 5:f. SJS: Full list of errors on unpublished tests.



axe √ √ Un key √ √

ball Sem bat Ph bowl Un cab √ √

bath √ √ √ √ √

bear √ Un yuck √ Un jam √

bee √ Sem fly Sp eeb √ √

beer √ Sem glass Un chare √ √

belt √ NR - Un check NR - √

bib √ Sem baby,pram NR - NR - √

blinds √ Circ open,doors Un kike √ √

bone √ √ Sem dag NR - √

book √ √ √ √ √

bowl √ √ Sem cup Sem soup √

brain √ √ Un chart √ √

bread √ Sem toast Un cuk √ √

brick √ Un foot Sp breed Sem book s/c wood √

cake √ Un nice Un cubam √ √

cat √ √ √ √ √

chalk √ Sem pencil Sp chair Sem drawing √

cheese √ √ √ √ √

chef √ Circ chinese Un chark NR - √

cloud √ Circ sky,rain Sp cud Sem rain √

clown √ Circ rodeo(g) NR - Circ easter show √

comb Sem brush √ Un door √ √

cork √ √ Un edde √ √

crab √ √ Sem claw √ √

crow √ √ NR - Un flower √

desk √ √ Un key √ √

dice Sem cards √ Un rarrd Ph ice √

dog √ Sem cat √ √ √

door √ √ Un teet Circ (g) √

drum Sem guitar √ Un door √ √

duck √ √ Un raddon √ √

egg √ √ Un eye Mor -s √

eye √ √ √ √ √

flag √ √ Un teet √ √

flask Ph mask Sem wine Un done Sem vase √

foot √ √ Un door √ √

fork √ √ Un teeth Un wine √

frog √ √ Un rared √ √

gate √ Sem door Un bickle Circ lock,up there(g) √

148

SJS’ errors (continued).



ghost √ Circ halloween NR - Sem halloween √

glass √ NR - Un tub Sem drink √

glove Ph glass √ Un dick Un linning √

goat √ NR - NR - Sem bull √

hook √ Sem paint Un start Un loe-en √

hose √ Circ grass(g) NR \ √ √

ice √ √ Un ith √ √

key Sem lock Ph chee √ √ √

kite √ Circ fly, sails Un key √ √

mast √ Sem flag Un teet NR - √

noose √ Sem rope Un role Un duck √

nose √ Sem eye Un good Ph hose √

pear √ Sem apple Un parth Circ fridge(g) √

plane √ √ Sp plain NR - √

plug Ph plum Circ bath,drains Un teeth √ √

prawn √ NR - Sp prane Mor -s √

road √ Circ drive Un door √ √

salt √ Sem pepper NR teeth Sem pepper √

screw √ Circ roof(g) NR tart Sem cork √

scroll √ Circ old,long time NR - NR - √

shell √ Circ listen(g) NR - NR - √

shield √ Sem iron Un plant Un lawn √

shoe √ Sem foot Un chart Mor -s √

shorts √ √ Un saw NR - √

ski √ √ Un kid Sem ice √

skull √ √ Un stuke NR - √

snail √ Sem slug Un dekeey Sem worms √

sock √ NR - NR - Sem shoes √

soup √ Circ bowl,yummie Un cad √ √

steak √ Un yuck √ √ √

sword √ √ Un stew Un hose √

tent √ √ Sp tant √ √

tongue √ Sem arm Sem eye Sem camp √

tooth √ Mor teeth Sem eye Sem thumb √

vase √ √ Un reeth √ √

wasp √ Circ up there,yuck NR - Sem fly √

watch √ NR - Sp swith √ √

witch Sem broom Circ h'ween,flys NR - NR - √

wolf √ Un yuck Un clart Sem tiger √

worm √ Mor -s Un ebe √ √

Correct 71 32 9 35 80

149

Appendix 5:g. Lexical decision – aphasic errors.

Cor R E Real PH NH Non

MWN 60 15 15 30 15 15 30

RPD 52 15 15 30 10 12 22

DHT 59 15 15 30 15 14 29

DPC 55 13 14 27 13 15 28

JWS 35 13 13 26 3 6 9

SJS 55 14 13 27 15 13 28

Mean 52.67 14.17 14.17 28.33 11.83 12.50 24.33

SD 9.14 0.98 0.98 1.86 4.75 3.39 8.02

Cor = total correct; R = regular words; E = exception words; Real = total for real words (R + E); PH =

pseudo-hompophonic nonwords; NH = non-homophonic nonwords; Non = total for nonwords (PH +

NH).

Appendix 5:h. Homophone decision – aphasic errors

Cor Y(t) N(t) R(Y) R(N) R(t) E(Y) E(N) E(t) Real N(Y) N(N) N(t)

MWN 57 29 28 10 9 19 10 10 20 32 9 9 18

RPD 41 27 14 10 7 17 8 4 12 28 9 3 12

DHT 44 27 17 9 8 17 9 6 15 29 9 3 12

DPC 28 16 12 8 4 12 4 3 7 19 4 5 9

JWS 36 17 19 6 8 14 8 7 15 25 3 4 7

SJS 32 19 13 8 4 12 9 4 13 24 2 5 7

Mean 39.67 22.50 17.17 8.50 6.67 15.17 8.00 5.67 13.67 26.17 6.00 4.83 10.83

SD 10.29 5.79 5.91 1.52 2.16 2.93 2.10 2.58 4.27 4.54 3.35 2.23 4.17

Cor = total correct; (t) = total; Y = homophonic pairs; N = non-homophonic pairs; R = regular word

pairs; E = exception word pairs; Real = total for real word pairs; N = nonword pairs.

Appendix 5:i. Object decision – aphasic errors.

C R UR

MWN 26 16 10

RPD 29 16 13

DHT 27 15 12

DPC 26 15 11

JWS 29 16 13

SJS 29 14 15

Mean 27.67 15.33 12.33

SD 1.51 0.82 1.75

Cor = total correct; R =real objects; UR = unreal objects.

Documents

Patterns of Reading Impairments in Cases of Anomia - Dr Christopher Williams