Young Children with Autism Spectrum Disorder Exhibit Shorter Average Look Duration to Social As Compared to Nonsocial Stimuli

Background: When viewing complex dynamic stimuli, children with autism spectrum disorder (ASD) spend a lower proportion of time looking at the social as compared to the nonsocial elements (reduced social attention) of those stimuli. In this analysis, we evaluate a different measure related to social attention, namely, the average look duration to a social vs nonsocial stimulus. We were also interested in whether individual differences in average look duration to a social stimulus are correlated with social communication abilities and autism symptom severity.

Objectives: Our objectives were to 1) determine the average look duration of children with ASD to social versus nonsocial elements of a complex dynamic stimulus, and 2) examine the relationships between two measures of social attention, namely, the proportion of time spent looking at social elements and the average look duration to social elements, and measures of social communication abilities and autism symptoms. We hypothesized that children with ASD would exhibit shorter average look duration to social as compared to nonsocial elements, and that shorter look duration to social elements would be associated with lower social communication abilities and more severe autism symptoms.

Methods: One hundred seventy-six participants 2-8 years meeting criteria for ASD based on the Autism Diagnostic Observation Schedule-2 (ADOS) and Autism Diagnostic Interview-R, participated in a clinical trial. An eye-tracking task, administered at baseline, consisted of a 3-minute video that included an episode involving a social bid by an actress (social condition) and an episode when toys were activated (nonsocial condition). Sixteen subjects were excluded due to non-compliance and calibration failures (n=160, M age=65.3 months, M FSIQ=70.6). To measure average look duration, we divided total viewing time by the total number of looks to both stimulus conditions. We also measured the proportion of time spent looking at the actor and her face during the social condition. Correlations with Vineland Adaptive Behavior Scales-3, Pervasive Developmental Disorder Behavior Inventory (PDDB-I), and ADOS severity score were examined using multivariable linear regression controlling for age and FSIQ with α=0.05.

Results: As predicted, average look duration during the social condition was significantly shorter than during the nonsocial condition (M=3.11 (±1.10) and 3.89 (±1.63) respectively, p<0.001). Lower proportion of time spent looking at the actor was correlated with more severe symptoms, based on ADOS severity score (p=0.04). Shorter look duration during the social condition was associated with more severe symptoms (PDDB-I Receptive/Expressive Social Communication Abilities (p=0.004), PDDB-I Social Approach Behaviors (p= 0.03), and PDDB-I Autism Composite (p=0.05)). Look duration during the nonsocial condition was not correlated with symptom severity.

Conclusions: Young children with ASD exhibit shorter average look durations when viewing social stimuli, as compared to nonsocial stimuli. Furthermore, longer average look durations to social, but not nonsocial, stimuli were associated with reduced autism symptoms. The ability to look at a complex social stimulus for longer periods may reflect more advanced self-regulatory skills and lead to enhanced engagement with and comprehension of complex, dynamic social stimuli.