Acquired and developmental spelling dyslexia

BRAIN

AND

LANGUAGE

20, 263-285 (1983)

Acquired and Developmental Spelling Dyslexia MARGOT PRIOR AND MARY MCCORRISTON La Trobe University Two cases of acquired spelling dyslexia and one case of developmental spelling dyslexia are described along with accounts of their performance on various psycholinguistic tasks. It is argued that there is some evidence that spelling dyslexia may exist in developmental form but that parallels are difficult to draw because of the very different histories of child and adult cases. It is also suggested that features of surface dyslexia exist in at least a proportion of spelling dyslexic cases and that this may be influenced by level of premorbid reading skill.

The neurological syndrome involving the inability to read adequately without spelling each letter of a word has been called variously: alexia without agraphia, pure alexia, spelling dyslexia, word form dyslexia, word blindness, and letter by letter reading. According to Shallice and Warrington (1980), this particular syndrome is one of the peripheral (as opposed to central) dyslexias. Individuals who have acquired this form of reading disability usually do so as a consequence of reasonably well specified lesion sites (Patterson & Kay, 1982). Although not all cases of alexia without agraphia read by spelling, in those cases who do so some words can be read promptly, but for much of the time reading is dependent on consecutively identifying each letter of a word. Consequently reading is slow and laborious with frequent inability to satisfactorily read passages of discourse because the time taken to identify each word means that the memory for the sequential message is lost. A defining feature of the syndrome is that latency of word identification is directly proportional to word length (Patterson, 1981). It has been shown that some spelling dyslexic cases are additionally handicapped by impaired letter identification ability. The word identification accuracy in spelling dyslexic cases is also affected by the quality of the letter and word display; Warrington and We thank Professor Max Coltheart for comments on an earlier version of this paper. We also thank Dr. Kevin Walsh for referral and assessment of patient A.C. This research was supported by a grant from the Australian Research Grants Commission. Send requests for reprints to Dr. Margot Prior, Psychology Department, LaTrobe University, Bundoora, Victoria, Australia. 263 00!43-934x/83 $3.00 Copyright 0 1983 by Academic Press, Inc. All rights of reproduction in any form reserved.

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Shallice’s (1980) patient read words printed in script much more slowly than words printed in normal type. Similarly a brief exposure duration in tachistoscopic presentation of words is very disruptive of oral reading (Patterson & Kay, 1982, Warrington & Shallice, 1980). To what extent spelling dyslexics are affected by other properties of words has yet to be established since little detailed information on the syndrome from the point of view of cognitive psychology has been available. Spelling dyslexic cases are often reported as having a right homonymous hemianopia as a result of a lesion in the left occipital cortex. However this is not a necessary accompaniment of the syndrome. Speech is frequently not impaired although some anomia may be present. Neuropsychological testing often reveals problems in color naming and object naming. A major feature of the syndrome is the marked contrast between reading and writing performance. Writing is usually normal in fluency and content, however the patient is unable to read back his own written material except in the laborious style which characterizes his reading of print and indeed may not be able to read it back accurately especially if the script is somewhat degraded. One of our cases to be described shortly had adopted a strategy of printing because of his difficulties with reading his own writing. Spelling dyslexia has not to date received the detailed investigation which is available for other syndromes, for example “deep dyslexia” (see Coltheart, Patterson, & Marshall, 1980) but for further recent descriptive material the reader is referred to Patterson and Kay (1982); Warrington and Shallice, (1980); and Shallice and Warrington (1980). The neurological basis for spelling dyslexia is considered to be a disconnection between the left hemisphere angular gyrus and bilateral visual input (Dejerine, 1982, Geshwind, 1965). A left occipital lesion prevents the transmission of visual information to the left hemisphere and although the right hemisphere is undamaged allowing normal visual reception by the right occipital cortex, a lesion in the splenum of the corpus callosum prevents transfer from the right hemisphere to the left angular gyrus. However this pattern of damage is not the only one to produce spelling dyslexia since patients have been reported with lesions in other left hemisphere areas which however did disconnect the angular gyrus from both left and right visual cortex (e.g., Greenblatt, 1976; Staller, Buchanan, Singer, Lappin, 8z Webb, 1978; Vincent, Sadowsky, Saunders, & Reeves, 1977). DEVELOPMENTAL

PARALLELS

A question of interest in reading research is whether those dyslexic syndromes identified in adult acquired cases exist in similar forms in developmental cases. Coltheart, Masterson, Byng, Prior, and Riddock (1982) have described a case of developmental surface dyslexia, and there are documented examples of semantic errors made by reading-

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265

disabled children with single words suggesting that at least some of the features of deep dyslexia may be found in developmental forms (Baron & Treiman, 1980; Liberman, Liberman, Mattingly, & Shankweiler, 1980). However Baddeley, Ellis, Miles, and Lewis (1982) have reported preliminary evidence which indicates little experimental support for “developmental deep dyslexia,” at least as proposed by Jorm (1979) (see also Ellis, 1979). It appears that spelling dyslexia can also occur in a developmental form, i.e., in children with no known brain lesions who are unable to learn to read normally despite normal intelligence and no known biological or environmental handicaps. Farnham-Diggory has described one such case (1978) taken from Hinshelwood’s book “Congenital Work-Blindness.” He could rarely read by sight more than two or three words, but came to a standstill every second or third word, and was unable to proceed unless he were able to spell out the word aloud, thus appealing to his auditory memory, or to spell it silently with his lips thus appealing to his memory of speech movements. . . The words he struck at were chiefly polysyllables, but this was not always the case, as he often failed to recognize by sight even simple monosyllable words. He spelt very well, and when asked to spell the words he had failed to recognize by sight, he nearly always did so without difficulty. . . He was strong in arithmetic, good at spelling and average in other subjects, including geography and history. Farnham-Diggory, 1978, pp. 34-36)

Farnham-Diggory goes on to claim that such a case represents the quintessential dyslexic child; however in terms of his method of reading, i.e., spelling out unknown words it is doubtful whether this is nearly as common in reading-disabled children as are the strategies commonly ascribed to cases of surface dyslexia. Here there is some sounding out but it is in phonemes and makes much use of the regularities of English words. In addition it it not stated whether this boy used letter names or sounds. The report that his auditory memory and his spelling were both very good makes him very unlike usually reported developmental dyslexic cases and rather more like acquired spelling dyslexic patients. In this paper we report on three cases, two acquired dyslexics whose reading behavior is consonant with the characteristics of spelling dyslexia, and one developmental case, whom we will argue may also be described as a spelling dyslexic. In addition we shall report data which bears on the relationship between this syndrome and another identified syndrome, surface dyslexia. Our aims are first to provide more psychological data on acquired cases and second, to consider the possibility of the existence of the syndrome in a reading-disabled child. CASE REPORTS Case 1

A.C. is a 66-year-old man who underwent an endarterectomy (excision of thickened areas of the innermost coat of an artery) at the end of 1980.

266

PRIOR AND

MC CORRISTON

Immediately post operatively he suffered from a word finding difficulty, poor recent memory, and a reading difficulty. A CAT scan showed abnormality in the left occipital area. The neuropsychological examination carried out in March, 1981, produced the following summarized results. The memory examination revealed an amnesic syndrome of the type seen with bilateral posterior lesions, with a principle feature of marked difficulty in learning new information. Although the patient complained of calculation difficulties, his mental arithmetic on the NHAIS, an Australian adaption of the WAIS, yielded a Scaled Score of 13. He was able to name colors. General measures of intellectual abilities dependent on well established memories appeared to be unimpaired but he showed marked difficulty with all forms of visual analysis on tasks dependent on this function. Writing to dictation showed no evidence of difficulty apart from somewhat spidery writing. He appeared to be a case of “alexia without agraphia” and the neuropsychologist’s assessment concluded that there was residual loss of function in both posterior regions of the brain with marked emphasis on the left occipital region. The CAT scan was considered to fit well with neuropsychological testing results. There was no hemianopia but A.C. was ambliopic in the right eye and had a slight convergent squint. Despite the occipital damage he was not considered to have any central visual problems. AC had been a highly successful operator of his own business and available evidence suggests his premorbid functioning was excellent. His memory and word finding problems have induced him to relinquish control of his business. Speech was quite normal and A.C. was talkative, very friendly and cooperative, exhibiting a keen sense of humor with frequent jokes and blandishments. Testing on the NHAIS 2 months postoperatively elicited a Verbal IQ of 107, a Performance score of 85 and a Full Scale score of 98. Retesting with the WAIS 2 months later produced IQ scores of 110, 105, and 108 respectively. Wechsler Memory Scale quotients on test and retest were 99 and 100, respectively. A.C. is a letter by letter reader; only short familiar words can be named immediately on sight, mostly he is obliged to spell out each letter of a word before it becomes available to him. Consequently reading of sentences is tedious and frustrating for him. Sometimes it seems to be sufficient for him to identify the first two or three letters of a word to be able to name it. Reading of randomly presented single letters in upper and lower case was essentially normal with two errors only, q read as g in the lower case, and x read as y in the upper case. Experimental Tasks A.C. was given a number of reading tasks designed to give an overall picture of his reading skills and to provide data as a basis for comparison with other types of dyslexic cases reported in the literature. On the Schonell Graded Word Reading Test, Rl, he obtained a reading age of

SPELLING

DYSLEXIA

267

12 years. Apart from a few short high frequency words such as sit, clock, and train, he spelled out each word. Often he did not complete all the letters (at least aloud) before reporting the word. When his 27 reading errors were spelled aloud to him he correctly identified 20 of the words. His reading errors often appeared to arise from misidentification of some of the constituent letters. There was no effect of regularity on his reading of a list of 39 regular and 39 irregular words taken from Coltheart, Besner, Jonasson, and Davelaar (1979) (37 correct of each type), nor on sorting pairs of regular, irregular, and nonwords in a homophone matching task-41/50, 39/50, 40/50 correct, respectively (see Coltheart, 1980). The effect of imageability or abstractness on word naming was also explored by having A.C. first sort pairs of words of either high or low imageability (Coltheart, 1980) into synonymous and nonsynonymous categories and second having him read aloud these same words. Sorting of the words was extremely slow and labored but performance was essentially parallel for the two classes of words with a minimal error rate: high imageability, 36/38 correctly sorted; low imageability, 33/38 correct. Effect of Word Length The experimental evidence for letter by letter reading rests heavily on the finding that the time taken to name a word is proportionate to its length. This was investigated with A.C. in several ways. It was already apparent in untimed tasks that A.C. needed to spell out each word or part thereof, prior to identification and that his performance was dependent on word length. We tested this more systematically in two ways. First, in a lexical decision task with words varying in numbers of letters from four to six and matched for frequency and regularity, five-letter words elicited a higher proportion of errors (.3) than did four-letter words (.02). The mean latency to correct responses was also greater for five- (1024 msec) than for four- (894 msec) letter words. This effect of word length did not, however, extend to six-letter words for which mean latency was 858 msec and the proportion of responses in error .15. The complete results for this task are presented in Table 1. It will be noted that reaction time was much slower for nonword decisions than for word decisions. Second, using a tachistoscope we presented three-, four-, and fiveletter words to be named. The proportions of erroneous responses are presented in Table 2. While only partial support for the word length hypotheses was obtained in the lexical decision task it was clearly supported by the results of the tachistoscopic presentation. Comprehension Prior to Spelling It was also necessary to consider whether any comprehension of a word was possible before spelling occurred. Patterson & Kay (1982)

268 ACCURACYAND

PRIOR AND MC CORRISTON

REACTION

TIME

DATA

TABLE 1 AC. AND H.L.

FOR

ON THE LEXICAL

DECISION TASK

FPs

A.C. Words Nonwords H.L. Words Nonwords

4 Letter

5 Letter

.98 .76

.7 .72

.95 .71

.80 .79

6 Letter

4

5

6

.84 .89

.02 .24

.3 .28

.16 .I1

1 .73

.05 .29

.2 .21

0 .27

Reaction time (in msec) Errors A.C. Words Nonwords

4 894 1072

5 1024 1132

6 858 1403

997 1200

988 1017

991 825

H.L. Words Nonwords

2386 3542

2626 5035

3698 5064

2222 2832

4221 5308

5234

reported that there was no evidence for comprehension prior to spelling in any of their four cases. We asked A.C. to tell us what a presented word meant, or anything he could about its meaning before spelling it out for identification. He was able to successfully carry out this task with short high frequency words from the Easy Lexical Decision’ list of Coltheart (1980) even when words were presented very briefly via flash cards (approximately 400 msec). However with longer words from Coltheart’s (1980) Difficult Lexical Decision task,’ which he had previously been able to read successfully with unlimited time, A.C. could identify only the first few letters and was not able to give any information about the word. He appeared totally dependent on sequential letter identification for any kind of access to these words. While A.C. could define short high frequency words without spelling them, we have no firm evidence that subvocal spelling did not occur. It was our impression however that he recognized and identified these words immediately upon presentation. ’ The Easy Lexical Decision Task uses 25 short, frequently used English nouns and 25 nonwords generated by altering one letter of each of the 25 words. These 50 items are presented in random order on cards and the patients are asked to sort the cards into those which present real words and those which do not. In the Difficult Lexical Decision Task the same procedure is followed. However, the 40 items are derived from 20 abstract words of more than 11 letters, and 5 syllables with a frequency of 1 in the Kucera-Francis Word Frequency norms, and 20 nonwords generated by interchanging 2 syllables (e.g., gracontulation from congratulation).

SPELLING

269

DYSLEXIA

TABLE 2 PROPORTIONOF ERRONEOUSRESPONSESMADE BY A.C. TO TACHISTOSCOPICPRESENTATIONOF WORDS OF VARYING LENGTH AT THREE EXFQSURE TIMES Exposure Letters

time (msec)

per word

400

300

200

3 4 5 6

0.00 0.00 0.00 0.25

0.25 0.71 0.60 0.50

0.50 0.57 1.00 1.00

This was supported by his spontaneous reporting that while he needed to spell most words, he could read some very familiar short words without doing so. It seemed then, that while the need to spell out words was dependent on their length, it was also influenced by frequency. We asked A.C. to read a list of 49 short rare words such as saga, weir, silt, etc. (Masterson, Note 1.). On this task he spelled even these three-and four-letter words and scored only 36 correct. A number of his errors resulted from the misreading of letters, e.g., d3311for jowl, dgIrJk for kink, ever for ewer, and wait for waif. A.C. was also given a piece of discourse reading taken from Holmes (1978a). Here he made 13 errors which were for the most part word substitutions arising from incorrect letter identification or incorrect letter order. A number of words were simply left out. When questioned about the content of the exerpt after reading, A.C. had only a vague idea that the piece was about football and could give no details. This illustrated his main complaint about his reading, that while he could identify most words given time, it was so slow and interrupted by spelling that comprehension was was impossible. Degrading the quality of the letters was also influential in A.C.‘s reading performance. He reported great difficulty reading his own handwriting and he had resorted to lettering. He was given a passage of simple prose to read, some paragraphs in Prestige Elite 12-point type and others in script. The print type was read at a mean rate of 602 msec per syllable whereas the script required 625 msecs per syllable. Spelling

On the Schonell Graded Word Spelling Test Form B, A.C. achieved a Spelling Age of 12$years. Of his 26 errors 10 were phonetically acceptable, the remaining included letter substitutions which were most likely to occur when the names of the letters were confusable, e.g., d-t, n-m, a-e, e-i. Three contained letter insertions; there were two word sub-

270

PRIOR AND MC CORRISTON

stitutions, one homophonic substitution and one visually similar substitution. Spelling errors are listed in Table 3. When his 26 incorrectly spelled words were spelled aloud to him A.C. was able to correctly name and then write 13 of them. Those which were still incorrectly spelled included examples of letter omissions, substitutions and additions very similar to those shown in the original test. (See Table 3.) Many of A.C.‘s errors in word identification appeared to suggest the influence of surface errors of the kind said to characterize cases of surface dyslexia (Coltheart et al., 1982; Marshall & Newcombe, 1973). Thus although we are convinced that A.C. is a letter by letter reader there is some overlap here, with characteristics of another syndrome evident in his reading. This has also been observed by Patterson and Kay (1982) in two of four cases they have described. A.C. had difficulty with reading words involving use of the “rule of e” and pronunciation of vowel digraphs. However as noted earlier no regularity effect was shown on any tasks and it is this effect which has TABLE 3 A.C.‘s SPELLING ERRORS Stimulus word

A.C.‘s spelling

dad bed pen call dream mistake pair safely institution similar generous equally individual immediate breathe permanent sufficient customary leisure accredited subterranean

dat bid new cell driem mistage pear sofoly instatution simily generious ezually indevidual immiadiate bring permanint sufficiant custamery leasure accrediated subteranium portmanto miscellanius exueped exagerate commetee

equipped exaggerate committee

SPELLING

DYSLEXIA

271

been claimed to be a major feature of surface dyslexia (see Patterson, 1981). We will take up this point again in discussion. Case 2 H.L. is a 60-year-old man who had aortic valve replacement surgery and triple vessel bypass grafts in April, 1981. The postoperative course was complicated by a right-sided weakness which has gradually improved. His recent memory capacity and new learning were shown to be poor post operatively and were easily disrupted by interference. His thinking was described as rather concrete, he had difficulty shifting concepts and planning and organization were fairly poor. His specific reading difficulty was also reported postoperatively. The CAT scan however showed no lesion. He has a history of heavy drinking but this is reported to have ceased about 4 years before his operation. He described himself as an avid reader prior to the operation. He has worn reading glasses for some years but his long vision is excellent and he does not appear to have any other visual problems. Neuropsychological assessment suggested general lowering of abilities dependent on frontal lobe functioning probably related to overindulgence in alcohol. The specific reading problem together with right-sided weakness and reported paraesthesiae were considered to indicate a lesion in the parietal region. Testing with the WAIS 2 months postoperatively placed him in the borderline retarded range of functioning; however retesting 3 months later produced a full scale IQ of 99 with only a 2-point discrepancy between verbal and performance scores. In the testing sessions H.L. was clearly functioning at a lower level than A.C. and his conversation was a little slow and dull by comparison. Although he left school at 12 he claims that he was good at reading and spelling and was considered “bright.” He was in the army for many years and has also been a butcher. Like A.C. he reads by spelling out each letter of a word and is extremely slow and labored On the letter identification task described for A.C., he made four errors in identifying lower case letters, b was read as d, q as g, 1 as i, and p as g. Only one error was made with upper case, V being read as Y. Experimental

Tasks

H.L. was tested for the most part with the same tasks as A.C. His Schonell reading age was 8-6. He was observed to either move his lips silently when reading or to spell aloud most words (after the first four lines of short easy words in this test). His errors were reminiscent of those made by young disabled readers on this task, e.g., angel for angle, activity for attractive and suited for situated. When his 23 errors from the Schonell test were spelled back to him, he correctly identified 13 words. It was noteworthy that when the words were spelled to him he

272

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MC CORRISTON

persisted in repeating the letters aloud to himself before producing a word. It was as though he required the motor feedback as well as the auditory representation for word identification. He also misspelled words which had been spelled correctly to him and then gave the word corresponding to the incorrect or partial spelling. On the Coltheart et al. (1979) list of regular and irregular words H.L. read 33/39 regular and 31/39 irregular words correctly. This minimal effect of regularity was a little more substantial in the homophone matching task-where he scored 44/50 for regular word pairs and 36/50 for irregular word pairs. There was a small effect of imageability in the sorting of synonymous pairs task (37/39 and 29139,high and low imageable synonyms, respectively). Effect of Word Length The same procedures for estimating this effect on reading as were used for A.C. were applied to H.L. In the lexical decision task, as with A.C. five-letter words elicited a higher proportion of errors (.2) than did fourletter words (.05). No errors were made with six-letter words. Latency increased with word length and was much longer than for A.C. Latency for four-letter words was 2386 msec, for five-letter words 2626 msec, and for six-letter words 3698 msec. The results of this procedure are shown in Table 1. With tachistoscopic presentation H.L. was more proficient than A.C. All words of more than three letters had to be spelled aloud at least partially for identification at exposure durations of less than 400 msec. Comprehension Prior to Spelling Evidence for comprehension without spelling was sought with H.L. as for A.C. Although H.L. was capable of giving definitions of words he could do this only if presentation time was long enough for him to TABLE 4 PROPORTIONOF ERRONEOUSRESPONSESFROM H.L. TO TACHISTOSCOPICPRESENTATIONOF WORDS OF VARYING LENGTH AT THREE EXPOSUREDURATIONS Exposure duration (msec) Letters

per word

400

300

200

3 4 5 6

0.00 0.00 0.00 0.00

0.00 0.14 0.40 0.50

0.00 0.57 0.60 0.50

SPELLING

DYSLEXIA

273

spell them first. When the stimuli were presented very rapidly across the desk he was unable to do more than provide a few remembered letters and no information about the meaning or class of the word. H.L. was also presented with the list of 49 short rare words and was only able to correctly identify 2.5of these. Like A.C., he spelled almost every word despite the fact that they were short. This supports our claim that frequency as well as length is a significant factor. Errors in reading this list were almost all due to letter additions and substitutions. H.L. also showed an effect of degradation on print, taking 540 msec per syllable for printed discourse reading and 562 msec per syllable for discourse reading presented in script lettering. This was similar to but faster than A.C. on the same task. In both cases, the difference in difficulty was noticeable to the subject. H.L. was loath to attempt the script segment and commented “I can’t read this, I can’t see the words.” We did not ask H.L. to read the Holmes (1978a) discourse passage because it was considered too difficult for him and that failure would adversely affect his motivation on succeeding testing. Spelling

On the Schonell Spelling Test, H.L. achieved a spelling age of 9.9 years. Most of his errors were phonetic approximations to the required word such as elce, serch, and receant and there were also some errors best described as arising from letter problems such as accordiance and toppic. Spelling errors are presented in Table 5. Spontaneous prose writing also contained some spelling errors similar in kind to those seen with the Schonell, e.g., popalation, agow, and bein (for been). Thus H.L.‘s reading and spelling contained many of the surface errors observed for A.C. Similarly he showed problems with surface rules in reading words involving the vowel digraphs and the rule of “e.” Most of his errors in reading, whether he spelled or did not, could most parsimoniously be classed as letter errors of the kinds mentioned above. We have here then another case of the kind described by Patterson and Kay (1982)-a letter by letter reader who also makes numerous errors in letter identification and whose reading shows many of the features of surface dyslexia. Since a large proportion of developmental dyslexic children are also characterized by such errors one might propose that in addition to the letter by letter reading strategy, consequent to H.L.‘s brain damage, this reading shows many regressive features not unlike those observed in the cases described by Holmes (1978a). Case 3 N.M. is an 113 year-old boy who has been seen in the La Trobe Psychology Clinic regularly over the past 2 years. He was originally

274

PRIOR AND MC CORRISTON TABLE 5 H.L.‘s SPELLING ERRORS Word

Spelled

talk

taulk sun seamed rite annount elce enterid caught doughter serch toppic meathoid receant licord gees atindiance discicption welfaire viarious genwian inteigair accordiance

SOII

seem write amount else entered cough daughter search topic method recent liquid guess attendance description welfare various genuine interfere accordance

referred for aggressive and disruptive behaviour at school but it was discovered that he was severely reading disabled. His mother suffered from toxemia at the time of birth which was induced; there were no other reported problems. Early development was within normal range except for a severe bout of gastroenteritis at the age of 11 months. N.M. appears to have had multiple behavior problems from an early age and has been described as “hyperactive.” His father is Italian and little is known of his family background. His mother reports that some of the Italian relatives do not read but this may be because of lack of opportunity to learn. There are no reading problems on the maternal side of the family. The family is bilingual but in practice mostly English is spoken at home. N.M. appears to have only rudimentary expressive Italian. His speech production and comprehension appear absolutely normal although he has the impoverished vocabulary (WISC Vocab. Scaled Score = 7) so often observed in reading disabled children. On the Australian WISC N.M. achieved a Performance IQ of 95 and a Verbal IQ of 82, with a Full Scale score of 85, placing him in the low average range of intelligence. Only on Block Design and Object Assembly was N.M. above average with Scaled Scores of 12 and 13. He had also

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DYSLEXIA

275

been tested with the Illinois Test of Psycholinguistic Abilities where overall he was 2 years below his age in achievement. Auditory Memory (digit span) and Auditory Closure were particularly weak as was Verbal Expression, where N.M. was 3 years below age level. Overall he was especially weak in auditory channel tests. Based on his WISC scores and his chronological age, on the Neale Analysis of Reading Ability he was 2 years behind his expected level (Yule, 1967) on accuracy and rate of reading and 3 years behind on comprehension. On the Schonell Graded Work Reading Test Rl , his reading age was 6 years 8 months, well below that obtained on the Neale. His spelling age using the Schonell Graded Word Spelling Test A, was also 6 years 8 months. He is right handed and on a dichotic monitoring task he shows a clear right ear advantage. N.M.‘s reading is at an extremely low level making it quite difficult to test him using the kinds of tasks currently favored by workers in this area with acquired dyslexic cases (see, e.g., Shallice & Warrington, 1980; Coltheart et al., 1983; Patterson & Kay, 1982). His attitude to reading is also very poor, he is bored and extremely distractible when confronted by any language based tasks. N.M. appears to be a letter by letter reader. The only method which is available to this boy to access a printed word string is to spell out every letter. He uses a mixture of letter names and sounds for this purpose and only rarely employs phonemes of more than one letter. An example illustrating the effects of this strategy is in his reading of the word spare which he pronounced spari. There is a similarity in his reading and spelling strategies in that he also spells each word in a whisper before writing it. His spelling is predominantly phonetic. Some rules are contravened, e.g., talk was spelled as torck, and some are applied inconsistently, e.g., he spelled tree correctly but spelled seem as sem and the doubling of the final 1 occurred with ill but not with doll and ball. The effect of his letter naming strategy was also evident, e.g., egg was spelled eeg, brain as bran, and remain as reman. N.M. appears to have virtually no sight vocabulary except for some three-letter words such as dog and cat and very familiar words such as school and book. Examples of his versions of the words he attempted are given in Table 6. His reading was characterized by numerous letter errors including b/d reversals, letter omissions, and alterations and letter order errors, i.e., the kinds of errors which also characterize cases of surface dyslexia. Similarly he was more likely to get regular than irregular words correct, scoring 11/39 on regular and 3/39 on irregular words. On this task he produced two morphemic errors, came for come, and lost for lose, and some regularizations, glnvi for glove, flud for flood, and 13lind for island. N.M.‘s reading strategy was to spell out each letter to himself (this was usually accurate); if it sounded like a word he knew, he would offer that, if not, he would either refuse or guess.

276

PRIOR AND MC CORRISTON

EXAMPLES

Stimulus word horse sign cough rub bowl bury dance strewn lose break thorough dream something beginning shepherd sure mile barge

OF

TABLE 6 N.M.‘s READING

ERRORS

Response h, o, r, s, e, horsey, horse sIggan strAg rr\d doll bray daenk spring lost bmk strog brem sunnythings digging sheep head s,4rI mrlr bcgrr

He read 10 of 30, three-letter nonwords by correctly spelling each one letter by letter. If he was asked not to spell he was literally incapable of producing any word presented to him. Sometimes he added phonemes, e.g., hezi for hoz and then perseverated with the addition (hzi for uze, nAzi for nue). N.M. was given a variety of lexical tasks over a 2-year period, during which his reading improved minimally if at all. We report here those tasks which specifically bear on the hypothesis that N.M. is a developmental case of spelling dyslexia. Experimental Tasks N.M. was asked to read all the letters of the alphabet presented in random order and in both upper and lower case type. He failed to recognize y or j in lower case but apart from that was completely accurate. His adequate ability to discriminate letters was additionally demonstrated in a cross case word matching task taken from Coltheart(l980) where he was required to make same/different judgements on pairs of fourletter nonwords, in upper and lower case, which were either the same or differed by one letter. He made one error of sorting only. The regularity effect previously reported for his oral reading was also evident in the word sorting task. When given the regular, irregular, and nonword homophone matching task he correctly sorted 35 of 50 regular word pairs, 26 of 50 irregular word pairs, and 27 of 50 nonword pairs. Thus he was more accurate with regular words and was no better with

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277

irregular words than he was with nonwords. He appeared to sort words as “same” on the basis of their visual features such as letters in common. This was particularly likely if the beginnings of the words were the same. Effect of Word Length

The effect of word length was investigated by presenting him with a series of three-, four-, five-, and six-letter words and nonwords via a tachistoscope with an exposure time of 500 msec per word. We had tried an exposure time of 400 msec but in this condition he could access only very familiar three letter words. With the 500-msec exposure N.M. could read some familiar three- and four-letter words but his strategy was to spell them to himself and the 500 msec gave him sufficient time to memorize the letters to be able to do this, thus capitalizing on his visual memory. However, in fact, this attempt to measure the effect of word length was unsuccessful since N.M.‘s performance was so poor. He was as likely to report presented nonwords as he was the real words, and always did this by memorizing and repeating the letters to himself. For the most part he recalled only the first two or three letters and then had to guess. Not enough data was generated to compare with similar investigations of acquired cases. However it was clearly established that with short exposure times and words of more than three letters N.M. could not read. Comprehension

Prior to Spelling

An attempt was made to ascertain if N.M. could comprehend words without his spelling out strategy. He was given lists of words and instructed to first define the word, then read it and then spell out the letters. Two sources of stimuli were used for this task. The first was a list of words used by Doctor and Coltheart (1980) in a reading task with primary school children. The second was Coltheart’s lists of regular and irregular homophones which were devised for use with surface dyslexic cases (Coltheart et al., 1982). On the Doctor and Coltheart list (1980), N.M. was able to read 10 familiar words-friend, school, funny, father, run, want, mascot, mother, good, and wood. He was quite incapable of defining a word until he had spelled out each letter despite our exhortations to define first and his genuine but unsuccessful attempt to do so. If he could not spell out he could not produce any representation of the word at all. Examples of his errors on this task are presented in Table 7. Errors from the Coltheart lists of 27 regular and 27 irregular homophones are also presented in Table 6. His score correct was 10 for each type of homophone. Spelling the letters after reading was always accurate. It will be noted than in many, but not all cases his definition corresponded to the incorrect reading. Seven of the regular homophones were given irregular translations and one irregular homophone was given its regular definition.

278

PRIOR AND MC CORRISTON TABLE 7 ERRORSMADE BY N.M. IN THE READ, DEFINE,AND SPELLTASK

Source Doctor and Coltheart (1980) list

Coltheart (1980) irregular

regular

Stimulus word

Defined

barge take dread driven stroke mansion gross gone bury eight ceiling colonel mown none piece son sew dough seize sword sure war route suite chord rows bare sawed brake shore stake cord sealing grate moan pain doe peace seas paw sole sum so

insect tack drag carport don’t know jungle grass don’t know brewery don’t know don’t know don’t know don’t know no-one perish sown so so scissors sweat don’t know were don’t know city child row don’t know sour break sure steak card sale greater morning don’t know dough don’t know says pain soul some sew

Read

bug tack drag drive in strake mhnsan, amazon grass gun brewery WJ curling col-one mouan no-one perish sown so dug scissors sweat sail were rota city child row bay, bray sour

break sure steak card sale greater morning payer dough paink says pair soul some sow

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SPELLING DYSLEXIA

It is worth noting however that his ability to read simple stories in a “Breakthrough to Literacy” reader is better than would be expected given his inaccuracy in word recognition tasks, that is, he does seem to use context profitably although reading only at a Grade 2 level (i.e., four grades behind). Thus far it seems that N.M. is like A.C. and H.L. a letter by letter reader and we have no evidence that he can access a word in any way other than by spelling it out. There are however some other characteristics of the letter by letter reader which require investigation if we are to pursue the claim that N.M. is a developmental case of this particular syndrome. Neuropsychological approaches to letter by letter reading have used the term “alexia without agraphia.” Letter by letter readers of the acquired dyslexic variety are apparently not handicapped in writing either spontaneously or to dictation although they will have difficulty reading back what they have written. This was characteristic of both A.C. and H.L. To examine this characteristic N.M. was asked to write a short piece of prose on a subject of his own choosing and was also given a short piece of dictation from a Grade Two Reading Comprehension test published by the Australian Council for Educational Research. His efforts on these two tasks are shown in Table 8. His writing was labored and he had difficulty reading back his own prose even a few minutes after its production. He was much more successful with reading back the dictation (which of course had been recently read to him). Given N.M.‘s extremely poor reading skills it might be claimed that his writing skills were better than would be expected. Indeed his teachers report this opinion, However since his reading disability is likely to have hindered his acquisition of written language, whereas in the acquired case writing skills have been acquired normally, there seems little profit in speculating about the relationship between writing and reading in the developmental case. Alexia without agraphia is not an appropriate description for cases like N.M. TABLE 8 SPONTANEOUS

WRITING

AND WRITING

TO DICTATION

BY

N.M.

(a) Spontaneous writing I have frends a school We have fun to getha sum tim we get in trudel I haf to go to seter (sister) BuBea (Barbara) and sho sox me weth the cain a then I go and play with my frends and play for scre (four square) and then the Ball ring a we go in and ta ts the end of my steri. (b) Dictation Soon hem-i and his muther droow up by the sied of the old whinmild. as cwick as a flat hem-i had climd down from the lory’ diapid throow the opend dore of the windmirl and was soon up the sters and at on to the bawcunl with ran or a rond it come down very inst cord his muther but just the as+ of whind bloow a cros the flat filds, and ron went the sails of the windmill, with henry cling to won of then.

280

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This comparison highlights one of the many difficulties in comparing the developmental and acquired case especially when the dyslexia is as severe as it is with N.M. and is compounded with many negative attitudes and behaviors toward reading and writing skill acquisition. In a recent paper Patterson and Kay (1982) have reported on differences within a group of letter by letter readers where two cases showed the usually reported ability to accurately identify letters and to use the letter by letter technique to read correctly for the most part, and where the reading of two other cases contained numerous letter errors which are characteristic of “surface dyslexia.” Examination of N.M.‘s performance indicates that his reading is similar to that of patients T.P. and K.S. of the Patterson and Kay study, in that whilst he usually identifies letters correctly he then often produces an incorrect word and makes numerous surface errors. DISCUSSION In the presentation of these three case histories we have been interested in two issues. First, we have shown that there is good evidence for the existence of spelling dyslexia in a young boy who has never learned to read adequately but in whom there is no evidence of brain damage and no history to suggest the source of his particular disability. Whilst we have demonstrated the parallels between N.M. and the adult acquired cases there are two factors which were restricting in this regard. Inevitable differences exist between the developmental and acquired forms of this syndrome. N.M.‘s poor spelling ability and writing skills are in direct contrast to those of A.C. and H.L., although this is not surprising given the existence of his severe reading disability from an early age. Not only is the development of these related skills likely to have been limited by his concommitant behavioral and attitudinal problems in any learning milieu but they could also be expected to be deficient as a direct result of reading disability. It was shown by Frith (1980) that children who spell poorly, despite their competence in silent reading comprehension, read differently from other good readers and are deficient in any reading task where it is necessary to convert print to sound. It was proposed that the reading strategies employed by these children disadvantaged them in acquisition of spelling knowledge. If this is so and spelling retardation of more than a year can result from a deviant reading strategy then inability to read, as gross as that exhibited by N.M., and present from the beginning stages of reading, would of necessity seriously impede the acquisition of spelling skills. The resultant minimal output of written language would in turn prejudice the development of competence in writing. The fact that he is currently maintained in a normal eighth grade classroom and that his teachers, particularly in the Science and Mathematics areas vouch for his interest and achievement despite his handicap, suggest

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DYSLEXIA

281

that he is finding ways of absorbing and displaying knowledge. We were further restricted in the parallels we could demonstrate since N.M.‘s very low level of reading skill limited the range of tasks we could give him. It is worth noting that there have been numerous attempts over the years to remediate N.M.‘s reading. None of these, as far as we can establish, have encouraged letter naming or letter by letter reading and none have been able to alter his fixed strategy of naming or sounding each letter in a word. It remains to be seen whether it will be possible to modify this approach. We suspect that it will not, since past attempts to prevent spelling have produced a complete breakdown in the ability to read. Many young readers, of course, spell out words sometimes but we have met no others who do it all of the time. Accepting the very different histories of the child and adult cases we make the claim for developmental spelling dyslexia albeit with some caution. Confirmation of the existence of a developmental form of spelling dyslexia must await further detailed child case reports. Because of the severity of N.M.‘s handicap restricting our ability to obtain much comparative data and the limited available data in the Hinselwood case (Farnham-Diggory, 1978) we are unable to extract commonalities between these two cases. The second issue of interest concerns the characteristics of spelling dyslexia as a syndrome and the effects on reading of various lexical parameters. It seems clear that visual problems or visual/perceptual processing impairments are not a significant feature in spelling dyslexia (Patterson & Kay, 1982). Although they may be present in some cases they have little specific heuristic import. Evidence from our cases, those of Patterson and Kay (1982) and of Warrington and Shallice (1980) suggests that in this syndrome unless a word can be read letter by letter it cannot be comprehended or named. This applies in varying degrees in varying cases since there are some occasions where short familiar words can be assessed directly, but overall, spelling out is the major reading strategy used. How the auditory and/or motor feedback gained from spelling leads to word identification remains a matter for speculation. In the case of H.L. it seemed that motor feedback was important since he insisted on repeating for himself our spelling of a word before he could name it. Alternatively it could be suggested that this was necessary for him to remember the letters long enough to access the word. It is also open to speculation whether the phonological representation is converted directly to a word or whether it is converted to a visual word form and thence to a lexical representation. One way in which the letter representations are used by such patients may be examined by considering the effect on word naming accuracy of varying degrees of letter naming accuracy. Our two acquired cases

282

PRIOR AND

MC CORRISTON

differed in this respect. A.C. almost always gave the correct word if he got all the letters correct. Further, he always knew if, under these conditions, the word he offered was wrong and insisted we correct him. H.L. by contrast, especially in early sessions, sometimes gave incorrect names for words spelled clearly and correctly aloud, e.g., barn -i, born, knob --, know, knots --, notes, moan + moon. It is easy to see in these examples how reliance on partial auditory clues could produce these errors. On the other hand if letters were incorrectly spelled by H.L. (an infrequent occurrence) the response was usually appropriate to the incorrect spelling. This was most likely to occur with nonwords. It is also the case that some patients at least, need to spell only the first few letters in many words before achieving lexical access. This was particularly so with A.C. but also with H.L. It could be that a kind of dictionary look-up strategy is used until enough letters have been processed to make a word candidate available (e.g., Marslen-Wilson’s cohort model, 1978). This proposal could be tested since it would typically result in errors which were higher in frequency than the target word. We could not directly test this hypothesis since it was most often the case that the response was correct, thus insufficient data was generated. An alternative explanation however could be that while only some letters were vocalized the final ones were visually processed and perhaps subvocally spelled. Out finding that with brief presentations which permitted memorization of the first few letters but which rarely permitted word identification supports the latter suggestion that all letters need to be processed. Patterson and Kay (1982) have raised the question of whether spelling dyslexics search for a word or a pronunciation, and have suggested that two of their cases T.P. and K.C. who showed many of the characteristics of surface dyslexia, were searching for pronunciations. Our cases also showed characteristics of surface dyslexia; in two out of three some advantage of regular over irregular words, and in all cases poor knowledge of surface rules. Despite this commonality, we believe that they differed from each other in their search strategies but that this may have been a function of their premorbid reading skill level and to some extent their current level of functioning. A.C. (who did not show a regularity effect) almost invariably appeared to search for words and only when this strategy failed did he try a pronunciation just as any normal reader would do. H.L. however seemed to be both pre- and postmorbidly a less able reader than A.C. Unlike A.C. he was not very concerned with whether he was correct or not and rarely corrected himself even in discourse reading. It was difficult to tell whether he was searching for a word or a pronunciation. As we have noted his rule knowledge was particularly poor as was his nonword reading and it seems likely that the “regression” in reading skills which is observed in surface dyslexic cases (Holmes, 1978b) was a strong influence on his reading. A.C. on the other hand showed

SPELLING

DYSLEXIA

283

this influence much more mildly if at all, his phonological skills were good and he appeared to be a “purer” case of spelling dyslexia. Our developmental case N.M. was extremely accurate in identifying letters and appeared to be searching for a pronunciation, but he seemed to lack an adequate word store to which he could relate the sounds. The experimental tasks presented to these cases included a number of measures of lexical effects considered pertinent to the study of syndromes of dyslexia. In summary the results of the investigations are: (a) The regularity effect was minimal for A.C., but a little more in evidence for H.L. probably reflecting his poorer premorbid reading and/ or his greater regression. There was no regularity effect in the define and read homophone task but both cases were almost at ceiling on this task and had to spell before any knowledge of words was available to them. As an interesting aside, one of A.C.‘s few errors was that he spelled “wore” correctly and then defined it as “a naughty lady who satisfies the men.” (b) A.C. was also better with nonwords than H.L. despite the fact that he had a set against producing nonsense words and had to be continually reassured that we knew these were not proper words. His phonological skills like his reading level were superior to those of H.L. and N.M. (c) There was no effect of imageability in sorting pairs of synonymous and nonsynonymous pairs of words for either H.L. or A.C. (d) Whilst both acquired cases were poor in knowledge of phonetic rules, A.C. was less disabled than H.L. Because of N.M.‘s low level of reading it was not possible to obtain enough data from him to permit extensive assessment of the above factors. Thus although features of surface dyslexia were observable in all cases, they were most apparent in H.L. We believe this to be due to the level of his reading ability both pre- and postmorbidly. We have claimed also that frequency as well as word length is a significant influence on the need to read letter by letter. This factor has not always been controlled in previous investigations. The question remains, how do these cases get to the word from the auditory and motor processes involved in naming each of the letters. Whilst one might postulate some auditory memory process for short words whose spelling sounds much like the whole word, this clearly will not explain the accessing of such words as “idiosyncrasy.” In the latter case perhaps one could speculate that a spelling memory permits recognition of this series of letters. However it is far from clear what a spelling memory involves although in the case of these older men it may be influenced by ways of teaching reading and spelling some 50 years ago, particularly the practice of repeated oral spelling of difficult words. As Frith explains, “In the past, teachers only taught spelling, and assumed that their pupils would automatically acquire the ability to read” (Frith,

284

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1980, p. 497). Further construction and testing of models of this atypical method of reading on a larger sample of cases is necessary to take us beyond the speculations offered in previous research (e.g., Patterson & Kay, 1982; Shallice & Warrington, 1980). In conclusion it seems that whilst description of spelling dyslexic cases is leading to a clearer picture of the ways in which such cases read, we seem no closer to an understanding of either why recourse to such a strategy is necesssary, nor in what way the word representation is achieved. It is also apparent that features of surface dyslexia are not uncommon in such cases. Whether this is significant in the clinical picture is a further question for exploration. REFERENCES Baddeley, A., Ellis, N., Miles, T., & Lewis, V. 1982.Developmental and acquired dyslexia: A comparison. Cognition, 11, 185-199. Baron, J., & Treiman, R. 1980. Use of orthography in reading and learning to read. In J. F. Kavanagh & R. L. Venezky (Eds.), Orthography, reading and dyslexia. Baltimore: Univ. Park Press. Coltheart, M. 1980. Analysing acquired disorders of reading. Unpublished manuscript. Department of Psychology, Birbeck College, University of London. Coltheart, M. Besner, D., Jonasson, J. T., & Davelaar, E. 1979. Phonological encoding in the lexical decision task. Quarterly Journal of Experimental Psychology, 31, 489507. Coltheart, M., Patterson, K. E., & Marshall, J. C. (Eds.) 1980. Deep Dyslexia. London: Routledge & Kegan Paul. Coltheart, M., Masterson, J., Byng, S., Prior, M., & Riddock, J. 1983. Surface dyslexia. Quarterly Journal of Experimental Psychology, in press. Dejtrine, J. 1982. Contribution a l’etude anatomo-pathologique et clinique des differentes varidtts de &cite verbale. Compte Rendu Hebdomaire des Sceances et Memoires de la Societe de Biologie, 4, 61-90. Doctor, E. A., & Coltheart, M. 1980. Children’s use of phonological encoding when reading for meaning. Memory & Cognition, 8, 195-209. Famham-Diggory, S. 1978. Learning disabilities. Fontana Open Books. Frith, U. 1980. Unexpected spelling problems. In U. Frith (Ed.), Cognitive processes in spelling. London: Academic Press. Pp. 495-516. Geschwind, N. 1965. Disconnection syndromes in animals and man, Part II. Brain, 88, 585-644. Greenblatt, S. H. 1976. Subangular alexia without agraphia or hemi-anopsia. Brain and Language,

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Holmes, J. M. 1978. Dyslexia: A neurolinguistic study of traumatic and developmental disorders of reading. Unpublished Ph.D. thesis, University of Edinburgh. (a) Holmes, J. M. 1978. “Regression” and reading breakdown. In A. Caramazza & E. B. Zurif (Eds.) Language acquisition and language breakdown: Parallels and divergencies. Baltimore: John Hopkins Press. (b) Jorm, A. F. 1979. The cognitive and neurological basis of developmental dyslexia: A theoretical framework and review. Cognition, 7, 19-33. Liberman, I., Liberman, A. M., Mattingly, I., & Shankweiler, D. 1980. Orthography and the beginning reader. In J. F. Kavanagh & R. L. Venezky, (Eds.), Orthography, reading and dyslexia, Baltimore: Univ. Park Press. Pp. 137-153. Marshall, J. C., & Newcombe, F. 1973. Patterns of paralexia: A psycholinguistic approach. Journal of Psycholinguistic Research, 2, 175-199.

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Marslen-Wilson, W. D., & Welsh, A. 1978. Processing interactions and lexical access during word recognition in continuous speech. Cognitive Psychology, 10, 29-63. Patterson, K. E. 1981. Neurological approaches to the study of reading. British Journal ofPsychology, 72, 151-174. Patterson, K. E., & Kay, J. 1982. Letter-by-letter reading: Psychological descriptions of a neurological syndrome. Quarterly Journal of Experimental Psychology. Prior, M. R., & McCorriston, M. 1982. Dyslexia in twins. Submitted for publication. Shallice, T., & Warrington, E. K. 1980. Single and multiple component central dyslexic syndromes. In M. Coltheart, K. E. Paterson, & J. C. Marshall (Eds.), Deep dyslexia. London: Routledge & Kegan Paul. Staller, J., Buchanan, D., Singer, M., Lappin, J., & Webb, W. 1978. Alexia without agraphia: An experimental case study. Brain and Language, 5, 378-387. Vincent, F. M., Sadowsky, C. H., Saunders, R. L., & Reeves, A. G. 1977. Alexia without agraphia, hemianopia, or color-naming defect: A disconnection syndrome. Neurology, 27, 689-691. Warrington, E. K., & Shallice, T. 1980. Word-form dyslexia. Brain, 103, 99-112. Yule, W. 1967. Predicting reading ages on Neale’s Analysis of Reading Ability. British Journal

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REFERENCE NOTE 1. Masterson, J. Department of Psychology, Birbeck College, University of London. Masterson constructed this list which was made up of three- and four-letter words with a Thorndike-Lorge frequency of less than three per million.