Varieties of repetitive behavior in autism: Comparisons to mental retardation

Systematic study of abnormal repetitive behaviors in autism has been lackin g despite the diagnostic significance of such behavior. The occurrence of s pecific topographies of repetitive behaviors as well as their severity was assessed in individuals with mental retardation with and without autism. Th e occurrence of each behavior category, except dyskinesias, was higher in t he autism group and autistic subjects exhibited a significantly greater num ber of topographies of stereotypy and compulsions. Both groups had signific ant patterns of repetitive behavior cooccurrence. Autistic subjects had sig nificantly greater severity ratings for compulsions, stereotypy, and self-i njury. Repetitive behavior severity also predicted severity of autism. Alth ough abnormal repetition is not specific to autism, an elevated pattern of occurrence and severity appears to characterize the disorder.