Early development of stereotyped and self-injurious behaviors: II. Age trends.

Thirty-nine infants who were served in early intervention programs and who engaged in stereotyped or self-injurious behaviors were studied weekly from the time they entered the school until they were 3 years old. The development of these behaviors increased and declined over age more slowly than in typical babies. A few children retained the behaviors for long periods, and some were still showing them when they left the program. The hypothesis that body-rocking promotes motor development was not supported. Indeed, body-rocking may be a consequence of motor development. Head-banging seemed to be related to tantrums, whereas eye-poking developed early and seemed to be self-stimulatory. Suggestions for early treatment are presented.