New approaches to the developmental dyslexias.
Although Hinshelwood (10-15), at the turn of the century, was interested in both analysis of individual cases and comparisons between acquired and developmental dyslexia, the most widespread approach to the developmental dyslexias has been the investigation of large groups of dyslexics in comparison to normal readers on a variety of tests. These studies ignore the heterogeneity of the disorder. In contrast, progress has been made in the investigation of acquired disorders of reading by conducting individual psycholinguistic analyses of reading difficulties and utilizing input from cognitive psychology to construct explanatory models and theories. Two of the disorders described and elucidated by this approach are acquired surface dyslexia, in which there is an impairment in whole word recognition and overreliance on sounding out words to obtain their pronunciation and meaning, and acquired phonological dyslexia, in which whole word recognition is good but sounding out of words and nonwords is poor. This approach has recently been used with cases of developmental dyslexia. This chapter compares and contrasts the pattern of performance of different dyslexic children when investigated in this way. Two of the children described are developmental phonological dyslexics; one is a developmental surface dyslexic. The developmental phonological dyslexics are poorer at reading words than non-words; the developmental surface dyslexic performs equally well on both. The developmental surface dyslexic is significantly influenced by spelling-to-sound regularity; the developmental phonological dyslexics are unaffected by this linguistic dimension. The developmental surface dyslexic makes more neologistic responses than the developmental phonological dyslexics, and also makes more valid errors. The developmental phonological dyslexics make derivational, pseudoderivational, and visuosemantic errors. Both groups make visual errors. The developmental phonological dyslexics are significantly impaired when stimuli are presented in a way that prohibits global analysis; the developmental surface dyslexic is unaffected by this manipulation. The developmental surface dyslexic makes homophone confusions, but these are not made by the developmental phonological dyslexics. (ABSTRACT TRUNCATED AT 400 WORDS)
D002648:Child; D004410:Dyslexia / Q000145:classification / Q000175:diagnosis*; D004411:Dyslexia, Acquired / Q000175:diagnosis; D006801:Humans; D007360:Intelligence; D010700:Phonetics; D011578:Psycholinguistics; D011932:Reading; D012660:Semantics; D014825:Vocabulary