Operationalizing atypical gaze in toddlers with autism spectrum disorders: a cohesion-based approach.

Background: Multiple eye-tracking studies have highlighted the "atypical" nature of social attention in autism. However, it is unclear how "atypical" or "typical" should be quantified.

Methods: We developed a method for identifying moments when members of a group looked at similar places (High-Cohesion Time Frames; HCTFs). We defined typicality as the proximity of gaze points to typically developing (TD) gaze points during TD HCTFs. Comparing toddlers with ASD ( n =  112) to developmentally delayed (DD, n =  36) and TD ( n =  163) toddlers during a video with Dyadic Bid, Sandwich-Making, Joint Attention, and Animated Toys conditions, we examined (a) individual typicality scores, (b) the relationship between typicality and symptom severity, and (c) HCTF distributions associated with each diagnostic group.

Results: The ASD group had lower gaze typicality scores compared to the TD and DD groups in the Dyadic Bid and Sandwich-Making conditions but not during Animated Toys. The DD and TD groups did not differ in any condition. Correlational analyses indicated that higher typicality scores were associated with increased looking at pre-planned locations of the scene indexed by each experimental condition. In the ASD group, lower gaze typicality was associated with more severe autism symptoms. Examining ASD HCTFs, the gaze of toddlers with ASD was least cohesive during Dyadic Bid and most cohesive during Animated Toys.

Conclusion: In contrast to non-ASD groups, toddlers with ASD show high cohesion during salient nonsocial events, suggesting that consistency in looking strategies may depend more on perceptual features. These findings are consequential for understanding individual differences in visual attention in ASD and for the design of more sensitive biomarker tasks for stratification, between-group differentiation, and measuring response to treatment.