Hemispheric lateralization of language in autistic and aphasic children.

The profound language deficit in early infantile autism has led to speculation about the similarities between autistic and language-impaired children. Since aphasia in adults and many children is typically the result of left cerebral hemisphere damage, some researchers have suggested that autistic children also suffer from left hemisphere damage. So far, only indirect or unreliable evidence has been offered in support of this hypothesis. In the present experiment, autistic, language-impaired, and non-language-impaired children were compared on a dichotic listening task designed to overcome some of the deficiencies of earlier research. Language-impaired children were found to exhibit a left ear bias for language material (indicating right hemisphere lateralization for language), whereas the autistic and non-language-impaired children showed the opposite, right ear bias. As the autistic children showed a pattern similar to that of normal children, the present experiment found no evidence for either left hemisphere damage or aphasiclike performance among autistic children. The implications of these findings for understanding the autistic language deficit are explored.