Developmental Changes in Pretend Play from 22- to 34-Months in Younger Siblings of Children with Autism Spectrum Disorder.

Developmental trajectories of children's pretend play and social engagement, as well as parent sensitivity and stimulation, were examined in toddlers with an older sibling with autism spectrum disorder (ASD, high risk; HR) and toddlers with typically-developing older siblings (low risk; LR). Children (N = 168, 97 boys, 71 girls) were observed at 22, 28, and 34 months during free play with a parent and elicited pretend play with an examiner. At 28 and 34 months, children were asked to imagine the consequences of actions pantomimed by the examiner on a pretend transformation task. At 36 months children were assessed for ASD, yielding 3 groups for comparison: HR children with ASD, HR children without ASD (HR-noASD), and LR children. Children in all 3 groups showed developmental changes, engaging in more bouts of pretend play and obtaining higher scores on the elicited pretend and transformation tasks with age, but children with ASD lagged behind the other 2 groups on most measures. Children with ASD were also less engaged with their parents or the examiner during play interactions than either LR or HR-noASD children, with minimal developmental change evident. Parents, regardless of group, were highly engaged with their children, but parents of HR-noASD children received somewhat higher ratings on stimulation than parents of LR children. Most group differences were not accounted for by cognitive functioning. Instead, lower social engagement appears to be an important correlate of less advanced pretend skills, with implications for understanding the early development of children with ASD and for early intervention.