Viewing Patterns of Naturalistic Scenes Differ Between Typically Developing Children and Those with Autism Spectrum Disorders in the Second Year of Life

Background: Previous research has shown that, compared to typically-developing peers, 2-year-olds with Autism Spectrum Disorders (ASD) fixate more on the mouth and less on the eyes when watching videos of infant-directed caregiver approaches.  These atypical patterns of looking indicate altered patterns of engagement with the social world: decreased fixation on the eyes is correlated with more severe social disability (as measured by the ADOS 1 Social Algorithm).  Similar results have been observed in adolescent and school-age children, demonstrating the extent to which patterns of visual fixation can serve as performance-based metrics of social functioning.  However, the extent to which these metrics quantify relevant behaviors in the second year of life is not yet known.

Objectives: This study will advance this line of research into the 2nd year of life, testing the extent to which (a) differential patterns of visual fixation are apparent in 12-24 month-old children with ASD, and (b) whether those patterns of visual fixation are related to social and communicative competence.  We hypothesize that like older cohorts, 12-24 month-olds with ASD will fixate less on the eyes and more on mouths, bodies, and objects; and that these patterns will be correlated with level of social disability.

Methods: 12-24 month-olds with ASD (ASD, N = 48), controls with developmental delays but without ASD (DD, N = 14), and typically-developing children (TD, N = 48), watched video clips of actresses engaged in child-directed caregiving activities.  Data were collected using eye-tracking, and visual fixation was quantified as the percentage of time spent fixated on each region of interest throughout all movies. Between-group comparisons measured level of fixation between children with ASD and TD and DD controls.  Within-group analyses tested for correlations between visual fixation and scores on the Mullen Scales of Early Learning, Vineland Adaptive Behavior Scales, and the Autism Diagnostic Observation Schedule (ADOS).

Results: In comparison with typically-developing controls, 12-24 month-old children with ASD show increased fixation on body and object areas.  Contrary to our initial hypothesis, mean level of ASD and TD eye fixation was not significantly different in this age group.  However, this similarity appears to be driven by a developmental change in TD behavior: relative to typically-developing 2-year-olds, 12-24 month-old TD children show increased fixation on the mouth.  TD fixation on mouths was highly correlated with verbal function: more mouth looking in this age group correlated with better verbal function.  In children with ASD, however, this was not the case: fixation on eyes and mouth was uncorrelated with verbal and nonverbal function, but was instead correlated with level of social disability; more mouth looking and less eye looking both predicted more severe impairment in social disability.

Conclusions: These results demonstrate one way in which social visual engagement relates to processes of normative socialization in typical children.  In contrast, for children with ASD, the data reveal that by 12-24 months, these children are already on an altered course of development, in which fixation on eyes and mouths does not fulfill its normative role in social adaptive action.