Nruropsycholoyw Vol. 23. No. 4, pp. 571 574. 1985. Pnnted in Great Entam

0028.3932!85 $3.00+000 d‘ 1985 Pergamon Press I.td.

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PARALEXIC ERRORS IN BROCA’S AND WERNICKE’S APHASIA

MELANIE PAYNE and WILLIAM E. COOPER*

Department of Psychology, University of Iowa, Iowa City, IA 52242, U.S.A

(Accepted 17 Januarv 1985)

Abstract-Paralexic speech errors were examined during the oral reading of sentences for 12 right- handed adults, including four Broca’s aphasics, four Wernicke’s aphasics and four patients with unilateral right-hemisphere lesions. A category system of error types was developed, and 129 errors were analyzed in terms of identifiable linguistic components, operating in isolation as well as interactively. The two aphasic groups produced a variety of errors, whereas the right-hemisphere group produced very few in number and type. Broca’s aphasics committed more morphological errors than did Wernicke’s aphasics, whereas Wernicke’s aphasics committed more graphophonemic-neologistic errors than did Broca’s.

INTRODUCTION

THE LANGUAGE deficits that distinguish Broca’s and Wernicke’s aphasia have recently been characterized in terms of various linguistic components, including articulatory, phonological, morphological/syntactic and lexical/semantic. It has been suggested, for example, that the language deficits observed for Broca’s aphasia arise more from a morphological/syntactic impairment than from a lexical/semantic one, whereas the language deficits observed for Wernicke’s aphasia are more likely attributed to the latter component [2]. Investigators have also begun to examine the extent to which impairments in each of the linguistic subsystems might interact. For example, BAKER it ul. [l] manipulated both phonological and semantic factors in picture-word matching tests with Wernicke’s aphasics and found that such aphasics exhibit a phoneme discrimination deficit that is exacerbated by semantic processing demands.

Since the study by Baker et al. and much of the literature on this topic is based on comprehension tests, we decided to test whether similar conclusions apply to the realm of oral reading. In this study, deficits in the linguistic components are examined in the patterns of paralexic speech errors observed for Broca’s and Wernicke’s aphasics within the same task.

METHODS

Subjects

Eleven right-handed adult males and one right-handed adult female participated in this study. All of the patients were native speakers of English. Of the subjects, four were classified as Broca’s aphasics and four were classified as Wernicke’s aphasics, based on both CT-scan data and the Boston Diagnostic Aphasia Examination [S], administered prior to the beginning of this study. The remaining four subjects, including the female subject, had sustained unilateral brain damage to the right cerebral hemisphere, also confirmed by CT scan. All subjects were prescreened for ability in oral reading. Thus, the aphasic subjects were generally mildly impaired in comparison to many other aphasic patients.

Procedures

Paralexic errors were transcribed from tape recordings of a test of oral reading originally designed to study acoustical aspects of intonation in these patient groups. Each subject read 14 sentences, each varying from five to 13 words in length and containing nouns, verbs, adjectives and grammatical functors. Representative sentences

*To whom requests for reprints should be addressed.

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included “The cat was asleep in the tree” and “The students on the bus threw gum at the teacher”. Each subject was instructed to first read the sentence silently and then to read it aloud. If the subject did not complete the sentence, he/she was instructed to reread the sentence. For purposes of this error analysis, the first complete reading of each bentence (i.e. in which the number ofcontent words in the utterance matched the number in the target) was used. This restrIctIon. combined with the prescreening for oral reading ability mentioned above, provides a conservative test of error production.

A categorical system of classifying errors was developed for the analysis. The system was roughly based on a classitication system for paralexias used by COLTHEART et al. [4], with the addition of several new categories. The first category of errors involves semmtic errors (SE), in which the substituted word is related in meaning to the target word. An example would be the production of “window” for the target word “door”. A second error type is a qrnfnrlluri~,aIfirncror .suhitutim error (GFS). An example of this type of error would be “to” for “by”.

A third error type is the morphologicul error (ME), where a grammatical transformation of the target word IS substituted, as when theword”branches”is substituted for”branch”.Thefourth typeoferror is a rtrndom error (RE). where no connection between the target word and substituted word can be made. An example of this type of error IS the substitution of the word “much” for “car”. The fifth type of error is a nrokoyistic, error (NE), involving a suhstltution that is not a real word.

The sixth category is the yrccphophonemic error (GPH). In these errors, the substituted word shares letters and phonemes with the target word but is unrelated in meaning. An example is the substitution of the word “oriental” for “original” or “baste” for “taste”.

The seventh type of error is a gruphop~lo,lrmic~nrologisli~ error (GPN), similar to the graphophonemic error except that it does not involve substitution of a real word. The eighth category is the phonemic error (PH). In this case the substituted word contains no letter or letter strings which are present in a comparable positIon in the target word, hut the word when spoken aloud sounds like the target word. An example of a phonemic error is the substitution of “stew” for “through”.

‘The ninth error type is the gruphrc error (GE). In this case a subject responds primarily to the letters of the word while giving a different phonemic pronunciation. For example, the word “either” would be substituted for the word “eight”. The tenth type oferror is the ambiguous error (AE). In this case the error could be Included in two or more of the above categories. An example is the substitution of “could” for “would”. This error can be viewed as a grammatical functor substitution error, a graphophonemic error, or as a combination of both.

RESULTS AND DISCUSSION

The subjects committed a total of 129 errors. Table 1 below shows the number oferrors In each category for the various groups.

Despite the small number of errors in this corpus. a number of distinctive results emerged Right-hemisphere- !esioned patients committed only four errors, consistent with their relatively intact linguistic capabilities. A x2 analysis revealed that. although the number of errors committed by the Wernicke’s and Broca’s aphasics was not significantly different (x’= 1. 2. df= l), the distribution of the errors between the two groups was significantI> different (x’ -49.92, Q= 16. P<O.O01). The categories of errors most relevant to differentiating Wernicke’s and Broca’s aphasics include ambiguous errors. graphophonemlc errors, graphophonemic neologistic errors, and morphological crl-ors. Subjects in the Broca’s group and Wermcke’s group differed not only in the number of errors in these categories but in the subtype of error they committed within each.

Broca’s aphasics committed far more ambiguous and morphological errors than did Wermcke’s, and Wernickc’s committed far more graphophonemic neologistic errors than did Broca‘s. In comparing graphophonemic errors and graphophonemic~ neologistic errors, the errors in Wernicke’s aphasics were almost evenly divided between those that were neologistic and those that were not. However, few graphophonemic-neologistic errors were committed by Broca’s aphasics.

Table I. Number of errors for each group

Error type Group SE GFS ME RE NE GPH GPN PI-I GE AE Total

Broca 1 II 14 1 1 12 3 0 0 12 55 Wernicke 2 II 6 4 5 21 17 2 0 2 70 RT HEMS 0 0 2 0 0 0 0 0 0 2 4

NOTE 573

Graphophonemic errors were more often characterized in the Broca’s aphasics by the substitution of one phoneme for another (for example “coast” for “host”). This type of error occurred in 75% of the Broca’s aphasics’ graphophonemic errors but in less than 25% of the graphophonemic errors of Wernicke’s aphasics. The Wernicke’s aphasics most often produced substitutions of a number of phonemes in a word, transposing syllables and extracting graphic elements to form a word that was related more graphically than phonemically to the target. Such errors have also been observed in French-speaking Wernicke’s aphasics [6]. In our study, an example of this type of error occurred when a Wernicke’s aphasic substituted the word “theater” for “teacher”. However, none ofthese errors was purely graphic, with at least some phonemic elements of the target word retained.

In graphophonemic errors, the errors of Broca’s and Wernicke’s aphasics also differed in their location within the word, Initial position errors (e.g. “stage” for “cage”) outnumbered final position errors (e.g. “part” for “park”) 3 : 1 in Broca’s aphasics, while for Wernicke’s aphasics final position errors outnumbered initial position errors by more than 4: 1. These results concur with those of a study by BURKS and CANTER 131, in which Wernicke’s aphasics and conduction aphasics produced errors in confrontation naming and repetition tasks. Burns and Canter found that final position errors were more frequent than initial position errors and that complex rather than simple phonemic errors were observed in their patients. Wernicke’s aphasics in the present study committed errors such as “campaign” for “canyon” (which may be a semantic-phonemic confusion) and “assembling” for “asleep”. Although these are graphophonemic errors, they do not exhibit the simple phonemic substitution quality found in the same category of errors produced by Broca’s aphasics.

The Broca’s aphasics exhibited substantially more ambiguous errors than did Wernick’s aphasics. These errors always involved functor words and the substitution of a grammatically and phonemically related word for one that was semantically similar. For example, one Broca’s aphasic read the sentence “the deer would (could) be seen from the window of the car”. This error can be viewed as a graphophonemic error, a grammatical functor substitution error, or a combination of both error types.

The data in Table 1 reveal very few semantic paralexias for all groups. This finding stands in contrast to a recently published study of single word reading by LANDIS et al. [7], in which 20 left-hemisphere patients, characterized according to the size of lesion, produced a fairly substantial percentage of semantic paralexias. Perhaps the greater severity of impairment of the patients in the Landis et al. study may be a factor in explaining this discrepancy. In a reply to Landis et al., MARSHALL and PATTERSON [8] assert that in their experience the incidence of semantic paralexias is lower than reported by Landis et al. The BAKER et al. [l] finding of a mixed phonemic/semantic impairment for Wernicke’s aphasics is paralleled in this production study by the finding of a similar mixed impairment, as evidenced by numerous paralexias that combine phonemic with semantic departures from the target word (see also [3]).

In this task the phonemic deficit of Broca’s aphasics was equal to their morphological deficit. Morphological errors in this study consisted of omissions, additions, and conversions, as described below. An example of an omission error is “student” for “students”. Four of the 13 morphological errors were of this type. Addition errors, such as “branches” for “branch”, were present also in four of 13 morphological errors. Conversion errors, which accounted for five of the 13 morphological errors, are typified by the substitution of “sleeping” for “asleep”. Wernicke’s aphasics and Broca’s aphasics both exhibited this type of error, although Broca’s aphasics committed nearly twice as many. The findings for Broca’s aphasics attest to a phonemic deficit and a morphological deficit of relatively equal proportion. The morphological deficit in Broca’s aphasics reflects their general agrammatism.

CONCLUSION

This study indicates that a system ofclassifying paralexic errors can be used to differentiate oral reading errors in Broca’s and Wernicke’s aphasics. The Broca’s aphasics’ errors were more evenly distributed across error type than were Wernicke’s errors, and the Broca’s errors often reflected articulatory and morphological aspects of the words. Wernicke’s aphasics’ errors most often involved the graphophonemic and graphophonemic-neologistic categories. The subtypes of errors within these categories were different for the two patient groups. The Wernicke’s graphophonemic errors were more “graphic”, and the Broca’s errors were more “phonemic”.

Acknowledyements-This research was supported by NIH Grants NS 11408 and NS 20071. The authors thank Barbara Shapiro for testing patients and Edgar B. Zurif for his support and cooperation.

REFERENCES

1. BAKER, E., BLUMSTEIN, S. E. and GOODGLASS, H. Interaction between phonological and semantic factors in auditory comprehension. Neuropsycholo,qia 19, I-15, 1981.

2. BERNDT. R. S. and CARAMAZZA. A. Syntactic aspects of aphasia. In Acquired Aphasia, M. T. SARNO (Editor), pp. 157-182. Academic Press. New York, 1981.

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BURNS, M. S. and CANTER, G. J. Phonemic behavior of aphasic patients with posterior lesions. Brain Larzy. 4, 492 -507. 1977. COLTHEART. M., PATTERSON, K. E. and MARSHALL, J. C. Deep Dyslexia. Routledge & Kegan Paul, London, 1980. G~MIDGLASS. H. and KAPLAN, E. The Asse.wnen~ of Aphasia and Related Disorders. Lea & Febiger, Philadephia, 1972. GUYARD, H., SABOURAUD, 0. and GAGNEPAIN, J. A procedure to differentiate phonological disturbances in Broca’s aphasia and Wernicke’s aphasia. Brain Lang. 13, 19 -30, 1981. LAWIS, T., REGARD, M., GKAVES, R. and GOODGLASS, H. Semantic paralexia: A release of right hemisphere function from left hemisphere control? Neuropsychologia 21, 359-364, 1983. MARSHALL, J. C. and PATTERSON, K. E. Semantic paralexia and the wrong hemisphere: A note on Landis, Regard, Graves and Goodglass. Neuropq~choloyia 21, 425427, 1983.