Psychol Res (1981) 43:193--199 (Developmental Dyslexia Issue)

Psychological Research © Springer-Verlag • 1981

Visual Memory and Phonological Skills in Reading and Spelling Backwardness

Lynette Bradley and Peter Bryant

Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX13UD, England

Summary. A large group backward readers remembered visually presented un- familiar written words as well as normal readers at the same reading level. This was in sharp contrast to the same group of backward readers' relative difficul- ties with a phonological task involving detection of rhyme and alliteration. Although the backward readers were as competent as normal readers in the visual memory task, there was a strong relationship between success in this task and reading/spelling skills in both groups.

Introduction

There is considerable evidence that linguistic problems of one sort or another play a large part in children's reading difficulties. It is a significant fact that the verbal IQ of other- wise normally intelligent children who are backward in reading tends to be compara- tively low (Rutter and Yule 1975). Moreover there have been several claims that these children have specific linguistic difficulties with, for example, breaking words into phonemes, or retrieving words from long term memory, or learning verbal associations (Vellutino 1979). It is easy to see why there might be a relationship between perfor- mance in such tasks and learning to read: there is every reason why a child's spoken language should be reflected in his attempts to learn a written language.

However, one cannot conclude that all reading difficulties must be explained in this way. There are at least two reasons for hesitating. The first is that much of the evidence for the language hypothesis is ambiguous. Its problems turn around the question of experimental design. Studies which attempt to show backward children's weaknesses in breaking words into phonemes (Liberman et al. 1977), in word finding (Denckla and Rudel 1976), in extracting phonemes, and in learning verbal associations (Vellutino 1979) have traditionally compared backward readers with normal children of the same age and mental age. The two groups had different reading ages, and this meant that the backward readers' consistent inferiority on such tasks could just as well be the result of their slower progress in reading as its cause. The solution is to compare backward readers with younger normal children at the same reading level.

0340--0727/81/0043/0193/~ 01.40

194 L. Bradley and P. Bryant

Any difference that then emerges between the two groups and in favour of the control group is unlikely to be determined by reading level since that is the same for both groups.

The second reason for hesitating is that linguistic and phonological processes do not account for the whole of reading which obviously demands considerable visual skills as well. This raises the possibility that for example failures in visual memory for written words might account for some reading difficulties. In fact the evidence on this question

is unsatisfactory as Vellutino has pointed out (Vellutino 1979) and again virtually all the relevant studies have stuck to the traditional design. Another problem is that there seems to have been no attempt to relate or connect backward readers' linguistic and

visual performance. Most studies keep to one type of task. We report here a study which tries to remedy some of these problems. It looks at the

performance of a large group of backward readers in a phonological and a visual memory task.

Method

Composition of Groups There were three groups of children. The first was a large group of 62 backward readers of normal intelligence but 18 months or more behind the average reading skill for their

age. The second group were 30 much younger children, who were reading normally

for their age and intelligence, and at the same level as the backward readers. All these

children were attending primary schools, and were assessed individually on the Wechsler Intelligence Scale for Children (WISC), the Neale Analysis of Reading Ability, and the

Schonell Graded Words Spelling Tests. A third group of children of the same age as the backward readers but reading nor-

mally for their age were also seen in this experiment. However, as none of these child- ren (with the exception of one child who made one acceptable error in one condition) made any errors in any of the conditions, this group will not be mentioned further until the discussion. Thc details of all three groups of children are presented in Table 1.

Table 1. Reading and spelling ages and IQs of children in this experiment

Number Chronological IQ Reading age a Spelling age b age (yrs. (WISC) (yrs. mths.) (yrs. mths.) mths.)

Backward readers 62 Mean 10:4 108:7 7:7 6:10 Range 8:4-13:5 93-137 6:0-9:4 5:0-8:9

Young 30 Mean 6:10 107.9 7:6 7:2 normal readers Range 5:8-8:7 93-119 6:0-9:2 5:1-10:2

Older 30 Mean 10:4 11:6 10:4 normal readers Range 8:6-12:4 8:9-12:10 7:11-13,4

a Neal Analysis of Reading b Schonell

All the children took part in the experiment on phonological skills and in the visual

memory experiment.

Visual Memory and Phonological Skills 195

Procedure - Phonological Experiment

This test is described in an earlier publication (Bradley an:i Bryant 1978).

It was a test of children's ability to detect alliteration and rhyme. In every trial four words were spoken by the experimenter, three of which had a phoneme in common; the fourth did not and the child's task was to spot the odd one out. There were three conditions, each with six trials. They were 1) First sound: example "sun sock see rag"; 2) Middle sound: example "nod red fed bed"; 3) Last sound: example "weed peel need deed." (There were also checks for memory and for understanding the oddity task in a visual analoque of our phonological task. All the backward and normal readers were

able to understand the oddity instructions, but we had to eliminate two backward readers because of their consistent memory failures, thus reducing that group to 60 in this

experiment.)

Procedure - Visual Memory Experiment (V-M)

There was one main condition - visual memory - and three others mainly devised as

controls. There were four trials in each condition.

A. Visual Memory Condition. The child was given letter cards ~(each with a single letter

on it). The experimenter showed him one word per trial (made up with letter cards)

and explained to him that he would have to reproduce it in letter cards. After a 5 s exposure the word was removed and the child was asked to reproduce it.

B. Visual-Auditory Condition - Reading (V-A). This was an analoque of reading. The child was shown a word made up with the letter cards and had to read it.

C. Auditory-Visual Condition - Spelling (A-V). This condition was put in as an analo- gue of spelling. The experimenter spoke a word to the child and the child then had to

reproduce it as a written word with the letter cards in the same way as in the visual memory condition.

D. Auditory-Memory Condition. This was to check that the child would remember the word when spoken. The child heard a word spoken and had to repeat it on each trial.

E. Material. Sixteen four-letter, phonetically regular but unfamiliar words were used. Each child was given four words - one per trial - i n each condition, and the alloca-

tion of words to conditions as well as their order was systematically varied. So was the order of the conditions. The words were: clam slob glen crop next limp rent grid twig plum flop snub clog grip drag flat.

Results

I. Phonological Experiment

There was a Striking difference between the two groups. The backward readers were

very much worse, as Table 2 shows, in all three conditions. The difference is particularly impressive when one recalls that the backward readers who did so badly were actually older and at a higher intellectual level than the normal group. Yet they made far more errors.

196

Table 2; Mean error scores (out of 6) in Experiment 1

L. Bradley and P. Bryant

Odd word Backward readers Normal readers (N - 60) (N - 30) Mean S .D. Mean S.D.

First sound 2.62 2.26 0.67 1.188

Middle sound 1.49 1.58 0.37 0.99 Last sound 1.15 1.43 0.17 1.11

The group differences was significant in Groups x Conditions analysis of variance (F 32.499 d.f. 1,88 P < 0.001). There was also a significant Groups × Conditions

interaction (F 4.28 d.f. 2,176 P < 0.05) which was due to the fact that the backward

readers were at a particular disadvantage in the first sound condition as Table 2 shows.

We have established a serious phonological problem among backward readers.

II. Visual Memory Experiment

Table 3 presents the mean scores in the four conditions. There were virtually no errors in the auditory memory condition which was dropped

from the analysis.

Table 3. Mean correct in 3 conditions in the Visual Memory Experiment

Backward readers Normal readers (N-62) (N-30) Mean S.D. Mean S.D.

Visual Memory (VM) 2.60 1.38 2.90 1.21

Visual-Auditory (VM) 2.34 1.40 2.80 1.54 Auditory-Visual (AV) 2.10 1.51 2.83 1.53

The control group did better than the backward readers in the other three conditions. However there was less difference between the two groups in the visual memory con-

ditions than in the remaining two conditions (V-A and A-V) which required phono- logical translation of visual into phonological information or vice versa. Thus the re- suits are consistent with the hypothesis that the major difficulties among backward readers are phonological ones.

This conclusion is supported by the results of a 2 × 3 (unequal numbers) analysis of variance in which the main terms were Groups and Conditions (V-M, V-A, A-V). It produced a significant Groups term (F 5.02: d.f. 1,90: P < 0.05) and also a significant interaction between Groups and Conditions (F 4.66: d.f 2,180: P < 0.05). The inter- action was post tested using the Tukey HSD which showed a significant difference be- tween the groups on V-A and A-V (P < 0.05) but not in the visual memory condition.

Visual Memory and Phonological Skills 197

We also conducted a qualitative analysis of errors in the visual memory condition, which we shall not report in any detail here. This seemed to show that backward read- ers got more letters incorrect than normal readers in the words that they did recall wrongly. However the overall shape of the words produced wrongly tended to be more similar to the correct response among backward readers than among normal readers. This suggested that the backward readers concentrated on the global properties of the words to be recalled and the normal readers on the details. However these differences did not reach significance.

One possible explanation for the lack of a difference between the two groups in the visual memory condition is that the scores in this condition might bear no relationship to success in reading and spelling. So we looked at the correlations between visual mem- ory scores and reading and spelling skills.

They were all high. In the backward reading group the corrdations between visual memory scores and Neale reading and Schonell spelling scores were respectively 0.538 and 0:733. In the normal reading group the equivalent correlations were 0.603 and 0.671. Thus visual memory scores are related to reading and spelling, and this suggests that visual memory might play a role in learning to read and to spell.

IlL Relations Between the Visual Memory and the Phonological Experiment

We correlated the performance of the two groups in the visual memory condition with their total scores for detecting rhyme and alliteration in the phonological exper- iment (Bradley and Bryant 1978). There was a significant (P < 0.05) and virtually iden- tical correlation in both cases. (r = 0.4381 with the backward readers and 0.4389 with the normal readers).

So the overall relationships between the two skills were the same for both groups. However the phonological scores of the backward readers were as we have noted consid- erably lower, which raises the possibility that normal readers may be able to compensate for an absence of one skill by the presence of another. In particular it would presumably be more likely that a normal reader with poor visual memory might make up for it by using intact phonological skiUs. The backward reader would be less likely to be able to do this. So we looked in particular at those children who did make errors in the visual memory task (41/62 backward readers and 18/30 normal readers). As expected many more o f the normal readers falling into this category (10/18) made no errors, or one error in 18 trials in the phonological experiment (which was our criterion for successful phonological performance). In contrast only 2 out of 41 backward readers in this cate- gory were successful in the phonological experiment. We reason that they may be less able to compensate for visual failures with the use of phonological skills. ~ Our tentative suggestion is that it may in some cases be the coincidence of visual and phonological difficulties which handicaps backward readers.

Discussion

Our experiments produce a number of conclusions and raise a number of questions. We have definite evidence of a serious phonological difficulty among backward

readers. There are obvious reasons why children who cannot judge properly when words

198 L. Bradley and P. Bryant

begin and end with the same sounds will be in difficulties with reading and writing. Not to be able to group words on the basis o f hearing sounds in common will prevent a child from seeing why they have spelling patterns in common as well. So our results accord with the now very common hypothesis o f a phonological difficulty among backward readers, and our evidence is compelling because we matched our two groups on reading level.

This matching on reading level raised something of a puzzle in the visual memory experiment, because the backward readers were worse than the control group in the visual-auditory and the auditory-visual conditions. These were respectively reading and spelling conditions and since the reading scores o f the two groups were the same one might have expected little difference. But this apparent anomaly can be explained as another example of a phonological difficulty. The words which we used in this experimen were unfamiliar and phonologically regular. The child could only read and spell them by using phonological translation rules. This is probably not true of the reading tests on which the groups were matched and which feature several familiar words like 'school' and 'table' which cannot be constructed on a letter by letter basis using phonological rules and which may be recognised as familiar patterns. Thus we argue that our reading and spelling conditions (V-A - A-V) rely more on phonological codes than the tradi- tional reading (and spelling) tests, and that is why they were relatively difficult for the backward readers.

Does this mean that visual memory failures play no part in backward readers' partic- ular difficulties? We certainly have produced no evidence that they do, and indeed our results could support the opposite hypothesis. The fact that phonological difficulties may cause reading difficulties and that there was a relationship between reading and spelling skills and visual memory, coupled with our findings of no great difference in visual mem- ory between the two groups, could suggest that performanee in the visual memory task is in part a product of the child's phonological skills. Our visual memory test after all did involve real words and letters, and a child's ability to handle this kind of material might be influenced by his phonological ability. It would be interesting to compare back- ward readers' memory for this material with their memory for visual patterns.

However there are three possible reasons for hesitation over the abandonment of the idea of visual memory failures. One is the good relationship between reading/spelling Skills and the visual memory scores in both groups: though the cause/effect relationships could go either way here these correlations are consistent with the possibility of visual memory playing a part in learning to read and to spell. The second is the notion of com- pensation which we put forward earlier: it may be that in some cases normal readers compensate for visual failures by using their higher phonological abilities, whieh would mean that backward readers might be more affected by forgetting their visual patterns. This idea, however, could only be tested with larger numbers of subjects than there were in our study. The third reason concerns the kind of comparison which we made. We matched the two groups on their reading skills, which meant that the age and intellectual level of the backward readers was considerably the higher of the two. The reason for this kind of comparison is simple. If reading age is controlled and it is found that backward and normal readers are still different along some dimensions, then it is unlikely that this difference is the result of their reading backwardness. Thus this kind of comparison is a better way of detecting causes of reading backwardness. However, we found no differ-

Visual Memory and Phonological Skills 199

ence on our measure of visual memory. On the other hand we did also test another normal control group whose age and mental age were the same as our backward readers (the traditional comparison), and they made no errors at all. Thus their visual memory was significantly better than that of the backward readers. So we can say that the visual memory scores of the backward readers were lower than would normally be expected for children of their age and intellectual level. Whether this was a cause or a result of their reading difficulties remains an open question.

Acknowledgements. We thank the Oxfordshire, Berkshire, and Buckinghamshire Education Authorities and Psychological Services for their co-operation, and the SSRC for support for this research.

References

Bradley L, Bryant PE (1978) Difficulties in auditory organisation as a possible cause of reading backwardness. Nature 271:746-747

Denckla MS, Rudel R (1976) Rapid 'Automatized' Naming (R.A.N.). Dyslexia differ- entiated from other learning disabilities. Neuropsychologia 14:471-479

Liberman IY, Shankweiler D, Liberman AM, Fowler C, Fischer FW (1977) Phonetic segmentation and recording in the beginning reader. In: Reber AS, Scarborough D (eds) Towards a psychology of reading. LEA, Hillsdale

Rutter M, Yule WC (1975) The concept of specific reading retardation. J Child Psychol Psych 16:181-197

Vellutino FR (1979) Dyslexia: theory and research. MIT Press, Cambridge, Mass