Restricted and repetitive behaviors in young children with autism spectrum disorders.

Restricted and repetitive behaviors (RRBs) on the Autism Diagnostic Interview- Revised (ADI-R: Lord, Rutter, & Le Couteur (1994) were examined in 165 children with Autism Spectrum Disorders (ASD), 49 children with non-spectrum developmental disorders (DD), and 65 children with typical development (TD) at approximately 2 years of age. A factor analysis found evidence for a repetitive sensorimotor (RSM) factor and an insistence on sameness (IS) factor. Behaviors that loaded on the RSM factor were prevalent in children with ASD and significantly more common and severe than in children with DD or TD. On average, children with ASD had more RSM behaviors. Behaviors that loaded on the IS factor were relatively uncommon and did not differ in prevalence or severity across groups.