Comparison of Applied Behavioral Analysis (ABA) Versus ABA and Risperidone

Hypotheses: 1. Preschool children with autism spectrum disorders (ASDs) who undergo ABA treatment only will demonstrate significantly better outcomes compared to an age and severity matched control group without ABA treatment. 2. Preschool children with ASDs who undergo ABA in combination with risperidone will demonstrate significantly better outcomes compared to age and severity matched children who are receiving ABA alone. 3. Young age, cognitive development and attentional abilities at baseline will be predictive of good socio-emotional and neuropsychological outcomes after ABA treatment. 4. At baseline, children with ASDs will show significantly lower performances on measures of cognitive, neuropsychological, and socio-emotional functioning than age-matched typically developing controls.