The understanding and use of interpersonal gestures by autistic and Down's syndrome children.

Autistic adolescents with mild, moderate, and severe degrees of mental retardation, Down's syndrome adolescents, and clinically normal 4-, 5-, and 6-year-old children were compared in their ability to understand a set of simple instrumental gestures. Almost all gestures were perfectly understood, that is, correctly responded to, by normal children from age 5 onwards, and by all the handicapped groups, regardless of diagnosis or degree of retardation. However, the ability to initiate such gestures on verbal request was generally less good, especially in the less able autistic groups. The same subjects were unobtrusively observed in the playground and during mealtime at their schools. Peer interactions were least frequent in the autistic subjects, regardless of degree of mental retardation. However, relative to interaction frequency, the autistic group used nonverbal instrumental gestures as a means of communication to the same extent as the other groups. Unlike Down's syndrome adolescents, or normal preschool children, no autistic adolescent ever used expressive gestures.