Date of Award


Document Type

Open Access Dissertation




School Psychology

First Advisor

Jane E. Roberts


Characterizing early predictors of autism facilitates earlier identification, diagnosis and treatment. Although aberrant visual attention is one of the earliest identified predictors of autism and may play an integral role in developmental cascades that contribute to associated impairments, the emergence of atypical attention in infancy is poorly understood. The present dissertation includes three related manuscripts examining early patterns of visual attention in two infant samples at elevated risk for autism: infant siblings of children with autism (ASIBs) and infants with fragile X syndrome (FXS). Together, these manuscripts identify patterns of abnormal heart defined attention among ASIBs (Study 1), investigate the association between abnormal heart defined attention and attention orienting in ASIBs (Study 2), and examine the generalizability of these patterns to infants with FXS (Study 3). Together, findings provide novel evidence of atypical heart-defined and associated behavioral attention in ASIBs and FXS, with abnormalities emerging as early as 6 months of age in ASIBs. Importantly, Study 3 revealed diverging patterns of attention-arousal relationships in infants with FXS, suggesting potentially unique biological pathways subserving similar patterns of abnormal behavior across two infant samples at high risk for autism. These findings provide evidence of both shared and diverging endophenotypic features of autism in infants at high genetic risk, potentially informing early detection and interventions that target mechanisms, rather than symptoms, of impairment.