In addition to testing the primary effects of this early intervention on the developmental outcomes of children with signs of autism, we will examine whether this method is superior to an early intervention focused on global infant development. Because brain development occurs rapidly in infants and toddlers, we will use high density EEG to investigate (1) biomarkers of change in these infants as a result of intervention and (2) biomarkers predicting response to treatment, with focus on the neural correlates of social attention and learning from joint engagement.