Stone, Wendy LHarker, Colleen Mary2014-10-132014-10-132014-10-132014Harker_washington_0250O_13386.pdfhttp://hdl.handle.net/1773/26355Thesis (Master's)--University of Washington, 2014Infant siblings of children diagnosed with autism spectrum disorder (ASD; High-Risk, HR-infants) are at an increased risk of developing ASD compared to infant siblings of typically developing children (Low-Risk, LR-infants; Messinger et al., 2013; Ozonoff et al., 2011). Limited social smiling has been identified as an early behavioral risk marker of ASD (e.g. Ozonoff et al., 2010). Recent theories propose that maternal behaviors that promote engagement and reciprocity during parent-child interactions may attenuate ASD symptom development over time for infants at high risk for developing ASD (Dawson, 2008). This study examined maternal and infant behaviors in HR- and LR-infants during free play sessions. Maternal responsiveness and directiveness at 9 months were examined as predictors of growth in infant social smiling between 9 and 18 months. Both maternal responsiveness and directiveness predicted growth in infant social smiling. Higher levels of responsiveness were associated with increased growth in social smiling for HR- and LR-infants. Conversely, higher levels of maternal directiveness were associated with slower growth in infant social smiling for both groups. Mothers of HR-infants displayed higher levels of maternal directiveness, but not responsiveness, relative to mothers of LR-infants. No group differences were found for trajectory of growth in infant social smiling. These findings provide further evidence that early maternal behaviors may play an important role in the social development of infants at high and low risk for ASD.application/pdfen-USCopyright is held by the individual authors.PsychologypsychologyThesis