Relative prevalence and relations among stereotyped and similar behaviors.

Relative prevalence and relations among stereotyped and similar behaviors were studied in 246 children and adults with developmental disabilities. For each subject, two staff members who knew the participant at least moderately well filled out a checklist of 54 items that sampled various forms of stereotyped behaviors, abnormal focused affections, compulsions, rigidity, savant skills, and defensiveness. Agreements between raters for individual participants were low to moderate. However, the item prevalence scores for the two groups of observers were stable. Correlations between several items were significant. Factor analyses produced weak evidence for a general Stereotypy factor and further evidence for 6 to 8 subfactors, some of which are generally consistent with accepted classification of the types of behaviors studied here.