Younger siblings of children with autism are at higher risk for developing autism, and although they may not meet the diagnostic criteria for autism sometimes display subtle variants of the social, emotional, and cognitive deficits seen in autism. These children are therefore a valuable population in the study of the mechanisms of atypical development and behavior in autism. This study is designed to examine the associations between early cognitive and attentional processes and socialization skills among preschool-aged younger siblings of children with autism. The neural mechanisms of attentional control are especially important to understand, as it appears that these skills can be changed through behavioral training. Working with siblings of autistic children, these experiments will test the hypothesis that the greater amount of cognitive control and attention exhibited by a child, the more self-regulatory and prosocial behaviors the child will exhibit when they are socially engaged. To measure attention and cognitive control (the effort it takes to inhibit a response), the predoctoral fellow will use EEG/ERP to measure brain activity in regions known to be involved in these processes. The children will also be tested for various behavioral aspects of social engagement in order to determine whether there is an association between these behaviors and the degree of cognitive and attention control. Understanding the relationship between attention control and social behaviors may help in our ability to improve interventions directed at these processes.