Prevalence and functions of stereotyped behaviors in nonhandicapped children in residential care.

Caregivers in nine residential care institutions rated the occurrence of 15 stereotyped behaviors in 142 nonhandicapped children aged from 10 months to 11 years. The frequency and duration of each stereotypy as well as the typical situations in which it occurred were assessed. The most frequent stereotypies were thumbsucking, hair twisting, and body rocking in infants and young children; thumbsucking and making faces in preschool-age children; and nail biting/chewing in school-age children. Boys exhibited stereotypies more frequently than girls, and children with a suspected history of child abuse more frequently than other children. Typical situations for stereotypies could be classified to four types: concentration/demand, arousal/frustration, boredom/monotony, and stimulation/distraction. Nail biting/chewing and lip biting occurred predominantly in concentration/demand; thumbsucking and hair twisting in boredom/monotony; and pulling faces and scratching oneself in arousal/frustration and concentration/demand situations. These results provide preliminary indications regarding the different functions of individual stereotypies.