Date of Award

Spring 2019

Degree Type


Director of Thesis

Jane Roberts

Second Reader

Kelly Caravella


Autism spectrum disorder (ASD) is distinguished by deficits in social communication and the presence of restricted, repetitive, and stereotypic behavior. Research into familial patterns of ASD has indicated there is a behavioral phenotype in relatives, including siblings, that is milder but qualitatively similar to behaviors within ASD. This broader ASD phenotype (BAP) is characterized by sub-clinical impairments in cognition, language, and social communication, but more research is required to understand the developmental trajectory of these high-risk siblings (ASIBs). Thus, this study utilizes the Brief Observation of Social Communication Change (BOSCC), a behavioral coding assessment intended to track subtle change in social communication behaviors within ASD, to measure the developmental trajectory of ASIBs compared to that of typically developing (TD) children, hypothesizing that ASIBs would show more deficits over time compared to TD children. BOSCC assessments were completed at two time points for 16 ASIB and 15 TD participants; change scores were determined by subtracting the assessment 1 score from the assessment 2 score. ASIBs showed a decrease in BOSCC scores over time, while TD participants showed little change over time. However, there was no significant difference in assessment scores at either time point between ASIBs and TD children; yet, there was a significant difference between the change scores of these groups. This indicated that, while ASIBs may show more social communication impairment at a younger age, they may grow out of these deficits as they develop. Thus, the developmental trajectory of ASIBs appears unstable when compared to TD children.

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