Unveiling Distinctive Eye Tracking Markers to Distinguish Toddlers with High-Risk Autism as Indicated by ADOS Within...

Eye tracking technology can be utilized to identify early markers of autism. Several neurodivergent features of social attention have been revealed by eye tracking studies in ASD toddlers. Our aim was to develop stimulus material that elicits highly distinctive gaze patterns in toddlers at low and high risk for autism as indicated by ADOS (i.e., scoring below and above the ADOS cut-off point). Additionally, we sought to identify the variables most effective in differentiating between these groups.

In our research, we analyzed the data of 74 toddlers between 12 and 30 months. Children were divided into two groups based on their ADOS scores: the lower ADOS (lrADOS) group included those scoring below the ADOS cut-off point (n = 42; mean age = 22.5 ± 5.0 months), while the higher ADOS (hrADOS) group comprised children scoring above the cut-off (n = 32; mean age = 23.3 ± 4.8 months). We recorded eye gaze data during the presentation of dynamic social attention stimuli with a self-developed eye tracking device. We used two types of social attention stimuli: joint attention (ostensive) and preferential looking paradigm. We analyzed the area of interest based on the gaze-time ratio. To ensure sufficient robustness, we selected gaze retention interval (GRI) variables characterized by broader spatial and temporal parameters compared to traditional fixation-based measures.

As anticipated, we observed significant differences between the two groups across most variables. Typically, within the preferential paradigm, the distinct indicators of the social domain were higher on average in the lrADOS group compared to the hrADOS group, while the non-social domain exhibited the opposite trend. The results of correlations with ADOS scores indicated that the social ratio in the preferential paradigm exhibited the strongest negative correlation. Notably, there were higher effect sizes within the hrADOS group in comparison to the lrADOS group when correlation with ADOS scores was tested separately for each group.

We developed stimulus materials and eye tracking variables that, thanks to their robustness, appear promising even when dealing with noisy eye tracking data typical of young children. In the preferential paradigm, beyond AOI ratio measures, GRI variables show promise in distinguishing between toddler groups with higher vs. lower ADOS scores. Furthermore, they may be related to severity based on their marked and significant correlations with ADOS scores. Especially when used in combination, these variables appear well-suited to capturing characteristics indicative of an elevated likelihood of autism.