PubMed1986
Mentally retarded children who can read aloud written words better than one would expect from their Mental Age are often called hyperlexic. The reading comprehension thought to be impaired in such children was investigated in four experiments. Mentally retarded advanced decoders, including autistic and nonautistic children, were compared with younger nonretarded children matched for Mental Age and Reading Age. Experiment 1 established that mildly mentally retarded readers could match sentences to pictures as well as could be expected from their verbal ability. This was the same whether they read the sentences or heard them. Experiment 2 demonstrated that only the more able retarded subjects, but not the less able ones, used sentence context in a normal way in order to pronounce homographs. Experiments 3 and 4 showed that these same more able children could extract meaning at both sentence and story level, and their performance was indistinguishable from that of normal controls. Hence, it is doubtful whether these advanced decoders should be called hyperlexic. In contrast, the readers of relatively low verbal ability performed much worse than their normal controls. Although they could be induced under certain conditions to read sentence-by-sentence rather than word-by-word, they did not do so spontaneously. Furthermore, they did not make use of already existing general knowledge in order to answer questions about the stories they had read. The ability to comprehend in terms of large units of meaning seems to be specifically impaired in these low verbal ability fluent readers. We suggest that it is this impairment that marks true hyperlexia. Since there were no differences between autistic and nonautistic readers on any of our tasks, we conclude that hyperlexia is not an autism-specific phenomenon.