Auditory and reading comprehension in hyperlexia: Semantic and syntactic skills

In contrast to dyslexia, in hyperlexia, there is precocious development of reading in the absence of other precocious skills, thus reading is significantly above expectation on the basis of prediction from age and intelligence. A psycholinguistic investigation is reported, of a 10 year old, non-autistic hyperlexic, on tasks of both written and auditory presentation of single words, sentences and text. M.S. shows good development of both phonological and lexical reading mechanisms. He does not display a pattern of reading performance which resembles any selective reading disorder and there is no evidence that the nature of his reading development, in relation to accuracy, is abnormal in style. However, reading accuracy is significantly better than both reading comprehension and auditory comprehension. The comprehension deficit does not affect language in an undifferentiated way. Semantic comprehension is normal for age but syntactic comprehension is significantly impaired. Thus, although there are no unusual dissociations in relation to reading accuracy, there is a significant dissociation between reading accuracy and reading comprehension, and also between semantic and syntactic comprehension of both written and auditory material which argues for modularity in the development of these subsystems.