Reading with partial phonology: Developmental phonological dyslexia

Recent psycholinguistic investigations have advanced our understanding of the acquired dyslexias. Developmental analogues have been described to some of these disorders. A new case of developmental phonological dyslexia is described here. A.H. is an intelligent 10-year-old boy with no neurological abnormality. Reading and spelling are below age level. A.H. is poorer at reading words than nonwords. The majority of his errors are paralexias: visual, derivations, or visuosemantic. Spelling-to-sound regularity does not affect the ability to read aloud. A.H.'s reading performance is significantly impaired when words are presented typed in reverse order, thereby prohibiting global strategies. Spelling of nonwords is no better than reading of nonwords. Only one-fifth of spelling errors are phonologically valid. A.H. has imperfect development of both the phonological route to reading and the phonological route to spelling.A shortened version of this paper was presented at the European meeting of the International Neuropsychological Society, Lisbon, Portugal, June 1983.     

Linguistic semantic agraphia: A dissociation of the lexical spelling system from semantics

Two spelling systems have been described. The phonological system transcodes speech sounds to letters and is thought to be useful for spelling regular words and pronounceable nonwords. Although the second system, the lexical-semantic system, is thought to use visual word images and meaning to spell irregular words, it is not known if this system is dependent on semantic knowledge. We used a homophone spelling test to examine the lexical-semantic system in five patients. The patients were asked to spell individual homophones (doe or dough) using the context of a sentence. Semantically incorrect and correct homophones were spelled equally well, whether they were regular or irregular. These results demonstrate that an irregular word may be spelled without knowledge of the word's meaning. Therefore, the lexical system can be dissociated from semantic influence.     

Mechanisms for accessing lexical representations for output: evidence from a category-specific semantic deficit

We report the performance of a neurologically impaired patient, JJ, whose oral reading of words exceeded his naming and comprehension performance for the same words--a pattern of performance that has been previously presented as evidence for "direct, nonsemantic, lexical" routes to output in reading. However, detailed analyses of JJ's reading and comprehension revealed two results that do not follow directly from the "direct route" hypothesis: (1) He accurately read aloud all orthophonologically regular words and just those irregular words for which he demonstrated some comprehension (as indicated by correct responses or within-category semantic errors in naming and comprehension tasks); and (2) his reading errors on words that were not comprehended at all (but were recognized as words) were phonologically plausible (e.g., soot read as "suit"). We account for these results by proposing that preserved sublexical mechanisms for converting print to sound, together with partially preserved semantic information, serve to mediate the activation of representations in the phonological output lexicon in the task of reading aloud. We present similar arguments for postulating an interaction between sublexical mechanisms and lexical output components of the spelling process.     

Phonological spelling

A case study is presented of phonological spelling, an acquired spelling disorder in which the primary symptom is the occurrence of phonologically plausible errors (e.g. "flood" → flud). Not all of the patient's spelling errors are as phonologically "perfect" as this example; but it is arguable that the errors primarily derive from a routine which segments a phonological code and assigns orthographic representations to these individual segments. This account of errors in phonological spelling is contrasted with an interpretation of oral reading errors in surface dyslexia. We conclude that errors in the two disorders do not reveal a precise parallel, and that the contrast is partly attributable to the differential role of comprehension in reading and spelling.     

Developmental surface dyslexia and dysgraphia: An orthographic processing impairment

This study presents a detailed investigation of a young man in his early twenties who has suffered from a severe spelling impairment since childhood, and currently has a spelling age of only 9 years and 2 months. In contrast with the developmental phonological dyslexics reported by Campbell and Butterworth (1985) and Funnell and Davison (1989), his performance on tests of phonological awareness is good. In addition, he can read and spell non-words competently and, unlike normal 9-year-old children, virtually all of his spelling errors are phonologically appropriate. Further analysis of these errors reveals that he has knowledge of many of the different ways in which a given phoneme can be written, and that he uses phoneme-to-grapheme correspondences at the end of a word that are different from those he uses earlier in a word. However, he finds it difficult to spell words that contain uncommon phoneme-to-grapheme correspondences, which is compatible with the view that he has not developed an orthographic spelling lexicon. Although his oral reading of words is prompt and generally accurate, analysis of his lexical decision performance and the way that he defines homophones indicate that he does not have fully specified lexical entries available for reading either. We suggest that he suffers from a general orthographic processing deficit, and relies instead upon the combination of sub-lexical phonology and a lexicon that contains only partial information about way in which words are spelt. This leads to reasonably competent reading, even of many irregular words, but produces very poor spelling. It is argued that qualitatively different types of developmental dyslexia do genuinely exist, but that reading impairments are likely to be much more pronounced in children who have a phonological rather than an orthographic processing deficit.     

Word regularity affects orthographic learning

Share's self-teaching hypothesis proposes that orthographic representations are acquired via phonological decoding. A key, yet untested, prediction of this theory is that there should be an effect of word regularity on the number and quality of word-specific orthographic representations that children acquire. Thirty-four Grade 2 children were exposed to the sound and meaning of eight novel words and were then presented with those words in written form in short stories. Half the words were assigned regular pronunciations and half irregular pronunciations. Lexical decision and spelling tasks conducted 10 days later revealed that the children's orthographic representations of the regular words appeared to be stronger and more extensive than those of the irregular words.     

Phonology acquired through the eyes and spelling in deaf children

Hearing and deaf children, ranging in age from 6 years 8 months to 14 years 4 months, and matched for general spelling level, were required to spell high-frequency and low-frequency words. Of interest was performance in relation to degree of exposure to Cued Speech (CS), which is a system delivering phonetically augmented speechreading through the visual modality. Groups were (a) hearing children, (b) deaf children exposed early and intensively to CS at home (CS-Home), and (c) deaf children exposed to CS later and at school only (CS-School). Most of the spelling productions of hearing children as well as of CS-Home children were phonologically accurate for high-frequency as well as for low-frequency words. CS-School children, who had less specified phonological representations, made a lower proportion of phonologically accurate spellings. These findings indicate that the accuracy of phonological representations, independent of the modality (acoustic versus visual) through which spoken language is perceived, determines the acquisition of phonology-to-orthography mappings. Analyses of the spelling productions indicate that the acquisition of orthographic representations of high precision depends on fully specified phonological representations.     

The role of left perisylvian cortical regions in spelling

In order to examine the role of left perisylvian cortex in spelling, 13 individuals with lesions in this area were administered a comprehensive spelling battery. Their spelling of regular words, irregular words, and nonwords was compared with that of individuals with extrasylvian damage involving left inferior temporo-occipital cortex and normal controls. Perisylvian patients demonstrated a lexicality effect, with nonwords spelled worse than real words. This pattern contrasts with the deficit in irregular word spelling, or regularity effect, observed in extrasylvian patients. These findings confirm that damage to left perisylvian cortex results in impaired phonological processing required for sublexical spelling. Further, degraded phonological input to orthographic selection typically results in additional deficits in real word spelling.     

Comparison between Oral and Written Spelling in Alzheimer's Disease

Written and oral spelling were compared in 33 patients with Alzheimer's disease (AD) and 25 control subjects. AD patients had poorer spelling results which were influenced by orthographic difficulty and word frequency, but not by grammatical word class. Lexical spelling was also more deteriorated than phonological spelling. Moreover, oral spelling was more impaired than written spelling in AD patients, whereas no difference was present between oral and written spelling of controls. Analysis of spelling errors showed that, for controls, errors were predominantly phonologically accurate in both spelling tasks. Significantly, AD patients produced more phonologically accurate than inaccurate errors in written spelling, whereas these errors did not differ in oral spelling. In contrast to controls who produced more constant than variable responses in oral and written spelling, AD patients made more variable responses (words correctly spelled in one task but incorrectly in the other) and they showed many instances of variable errors (different misspellings from one spelling task to the other). Two stepwise regression procedures showed that written misspellings were specifically correlated with language impairment, whereas oral spelling errors were correlated with attentional and language disorders. These results suggest that AD increases the attentional demands of oral spelling process as compared to written spelling. This dissociation argues, either for a unique Graphemic Buffer in which oral spelling requires more attentional resources than written spelling or for the hypothesis of separate buffers for oral and written spelling.     

The relationship between phonological and morphological deficits in Broca's aphasia: further evidence from errors in verb inflection

A previous study of 10 patients with Broca's aphasia demonstrated that the advantage for producing the past tense of irregular over regular verbs exhibited by these patients was eliminated when the two sets of past-tense forms were matched for phonological complexity (Bird, Lambon Ralph, Seidenberg, McClelland, & Patterson, 2003). The interpretation given was that a generalised phonological impairment was central to the patients' language deficits, including their poor performance on regular past tense verbs. The current paper provides further evidence in favour of this hypothesis, on the basis of a detailed analysis of the errors produced by these same 10 patients in reading, repetition, and sentence completion for a large number of regular, irregular, and nonce verbs. The patients' predominant error types in all tasks and for all verb types were close and distant phonologically related responses. The balance between close and distant errors varied along three continua: the severity of the patient (more distant errors produced by the more severely impaired patients); the difficulty of the task (more distant errors in sentence completion>reading>repetition); the difficulty of the item (more distant errors for novel word forms than real verbs). A position analysis for these phonologically related errors revealed that vowels were most likely to be preserved and that consonant onsets and offsets were equally likely to be incorrect. Critically, the patients' errors exhibited a strong tendency to simplify the phonological form of the target. These results are consistent with the notion that the patients' relatively greater difficulty with regular past tenses reflects a phonological impairment that is sensitive to the complexity of spoken forms.     

Spelling in Adults: The Combined Influences of Language Skills and Reading Experience

One hundred and twelve university students completed 7 tests assessing word-reading accuracy, print exposure, phonological sensitivity, phonological coding and knowledge of English morphology as predictors of spelling accuracy. Together the tests accounted for 71% of the variance in spelling, with phonological skills and morphological knowledge emerging as strong predictors of spelling accuracy for words with both regular and irregular sound-spelling correspondences. The pattern of relationships was consistent with a model in which, as a function of the learning opportunities that are provided by reading experience, phonological skills promote the learning of individual word orthographies and structural relationships among words.     

Recognizing orally spelled words: an analysis of procedures shared with reading and spelling

Some investigators have suggested that recognizing orally spelled words is dependent on the same procedures ordinarily used in spelling, whereas others have viewed it either as dependent on reading procedures or as an independent ability. In the present study, a single subject with dyslexia and dysgraphia was examined on parallel tests of recognizing orally spelled words, reading, and spelling (writing), and a comparison was made of his performance on the three tasks. On both words and nonwords, the patient's errors in recognizing orally spelled words and in reading were alike, whereas his spelling errors were often different. The distinction between recognizing orally spelled words and spelling was further shown by his inability to recognize a set of orally spelled words that he could write correctly to dictation or on the basis of word meaning. These findings suggest that the procedures normally used for reading can accept sequences of letter identities as input when orally spelled words must be recognized.     

Deaf and hearing children's plural noun spelling

The present study examines deaf and hearing children's spelling of plural nouns. Severe literacy impairments are well documented in the deaf, which are believed to be a consequence of phonological awareness limitations. Fifty deaf (mean chronological age 13;10 years, mean reading age 7;5 years) and 50 reading-age-matched hearing children produced spellings of regular, semiregular, and irregular plural nouns in Experiment 1 and nonword plurals in Experiment 2. Deaf children performed reading-age appropriately on rule-based (regular and semiregular) plurals but were significantly less accurate at spelling irregular plurals. Spelling of plural nonwords and spelling error analyses revealed clear evidence for use of morphology. Deaf children used morphological generalization to a greater degree than their reading-age-matched hearing counterparts. Also, hearing children combined use of phonology and morphology to guide spelling, whereas deaf children appeared to use morphology without phonological mediation. Therefore, use of morphology in spelling can be independent of phonology and is available to the deaf despite limited experience with spoken language. Indeed, deaf children appear to be learning about morphology from the orthography. Education on more complex morphological generalization and exceptions may be highly beneficial not only for the deaf but also for other populations with phonological awareness limitations.     

Semantic dementia without surface dyslexia in Spanish: unimpaired reading with impaired semantics

Surface dyslexia has been attributed to an overreliance on the sub-lexical route for reading. Typically, surface dyslexic patients commit regularisation errors when reading irregular words. Also, semantic dementia has often been associated with surface dyslexia, leading to some explanations of the reading impairment that stress the role of semantics in irregular word reading. Nevertheless, some patients have been reported with unimpaired ability to read irregular words, even though they show severe comprehension impairment. We present the case of M.B., the first Spanish-speaking semantic dementia patient to be reported who shows unimpaired reading of non-words, regular words, and - most strikingly - irregular loan words. M.B. has severely impaired comprehension of the same words he reads correctly (whether regular or irregular). We argue that M.B.'s pattern of performance shows that irregular words can be correctly read even with impaired semantic knowledge corresponding to those words.     

Writing with the right hemisphere

We studied writing abilities in a strongly right-handed man following a massive stroke that resulted in virtually complete destruction of the language-dominant left hemisphere. Writing was characterized by sensitivity to lexical-semantic variables (i.e., word frequency, imageability, and part of speech), semantic errors in writing to dictation and written naming, total inability to use the nonlexical phonological spelling route, and agrammatism in spontaneous writing. The reliance on a lexical-semantic strategy in spelling, semantic errors, and impaired phonology and syntax were all highly consistent with the general characteristics of right hemisphere language, as revealed by studies of split-brain patients and adults with dominant hemispherectomy. In addition, this pattern of writing closely resembled the syndrome of deep agraphia. These observations provide strong support for the hypothesis that deep agraphia reflects right hemisphere writing.     

Articulatory suppression and phonological codes in reading for meaning

The aim of this study was to investigate whether the phonological code that causes errors in printed sentence comprehension is affected by concurrent articulation. Forty adult subjects made speeded judgements of the acceptability of printed sentences. The critical sentences were foils that were (1) orthographi-cally unacceptable but phonologically acceptable (e.g. The palace had a thrown room), and (2) spelling controls that were orthographically and phonologically unacceptable (The palace had a thorns room). Half the subjects performed this task in silence (without concurrently articulating) and showed a marked phonological effect such that false alarms to phonologically acceptable foils were more frequent than false alarms to their spelling controls. The remaining subjects who performed this task with concurrent articulatory suppression showed an increase in false alarm rates, but no effect of phonology. In a control experiment using the same subjects, memory span for visually presented long and short words was measured under conditions of silence or concurrent articulation. The word length effect (Baddeley, Thomson, & Buchanan, 1975) disappeared under suppression, indicating that the suppression manipulation was highly effective. Thus the phonological codes that are used both in sentence comprehension and memory span are highly susceptible to articulatory suppression. We discuss possible relationships between phonological codes that mediate lexical access and those that support short-term verbal memory.     

Reading without semantics

Analysis of the reading of a neurological patient (HTR) indicates that it is based on the operation of a relatively unimpaired phonological route. Quantitative investigations of type of error, reading speed and the effects of lexicality and spelling-to-sound regularity all support this conclusion. Spelling-to-sound regularity is shown to influence reading not only through regular words being better read than irregular, but also through mildly irregular words being better read than very irregular ones. A model is presented of the operation of the phonological route and of its progressive impairment in certain types of neurological disease.     

Orthographic vs. phonological irregularity in lexical decision

This experiment investigates whether the influence of spelling-to-sound correspondence on lexical decision may be due to the visual characteristics of irregular words rather than to irregularities in their phonological correspondence. Lexical decision times to three types of word were measured: words with both irregular orthography and spelling-to-sound correspondence (e.g., GHOUL, CHAOS), words with regular orthography but irregular spelling-to-sound correspondence (e.g., GROSS, LEVER), and words regular in both respects (e.g., SHACK, PLUG). Items were presented in upper- and lowercase in order to examine the influence of “word shape” on any irregularity effects obtained. The results showed that irregular words with regular orthographies were identified more slowly than regular words in both upper- and lowercase. Words that are both orthographically and phonologically irregular were identified much more slowly with lowercase presentation. However, with uppercase, the lexical decision time for these items did not differ significantly from those of regular words. These data indicate that previous demonstrations of the regularity effect in lexical decision were not due to the unusual visual characteristics of some of the words sampled. In addition, the data emphasize the role of word shape in word recognition and also suggest that words with unique orthographies may be processed differently from those whose orthography is similar to other words.     

Acquisition and use of spelling-sound correspondences in reading

The acquisition and use of knowledge concerning the spelling-sound correspondences of English were evaluated by having children read words and nonwords that contained regular and homographic spelling patterns. Regular spelling patterns are associated with a single pronunciation (e.g., -UST as in MUST); homographic patterns have multiple pronunciations (e.g., -OSE as in HOSE, DOSE, LOSE). Analyses of errors, latencies, and pronunciations provided evidence for two complementary developmental processes: good beginning readers rapidly learn to recognize high-frequency words from visual input alone, while at the same time they are expanding and consolidating their knowledge of spelling-sound correspondences. Younger and poor readers rely more on phonological information in word decoding, as evidenced by their particular difficulty reading homographic spelling patterns. Poor readers do not appear to use a radically different strategy for reading words: their perfomance is similar to that of younger, good readers.     

Is surface dysgraphia tied to semantic impairment? Evidence from a case of semantic dementia

Recent models of lexical processing suggest that written spelling partly depends upon the semantic system. According to these models, a deterioration in word meanings would necessarily lead to a spelling impairment, especially for low-frequency and orthographically irregular words. We report a case study of a patient (MK) with semantic dementia who presents impairments in knowledge of word meanings and surface dysgraphia. By specifically identifying concepts that are still known or that are partially or completely deteriorated, we show that the patient's spelling deficit is highly correlated with word comprehension. These data confirm that surface dysgraphia is directly linked to the breakdown in semantic memory.