Sign language acquisition in a mute autistic boy.

A mute autistic boy learned to communicate extensively through American Sign Language. Over a six-month period he produced many spontaneous signs and sign combinations, and analyses of child's sign combinations indicated the presence of a full range of semantic relations. Further evidence of conceptual progress was provided by the child's increased score on the Peabody Picture Vocabulary Test. In addition, parents' and teacher's reports indicated that the child's social behavior improved. The extent of the boy's linguistic progress and associated improvement in social behavior markedly exceeds that usually reported for mute autistic children.