Unveiling Distinctive Eye-Tracking Markers to Distinguish Toddlers with High-Risk Autism Spectrum Disorder within an Elevated Risk Toddler Population

Abstract Background Eye-tracking technology can be utilized to identify early markers of autism. Several atypical features of social attention has been revealed by eye-tracking studies in ASD toddlers. Our objective was to investigate novel eye-tracking variables aimed at distinguishing the ASD group from a population at elevated risk. Methods 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. In our research, we analyzed the data of 74 toddlers between 12–30 months (42 nonASD, mean age:22.5 ± 5,0 month; 32 with high-risk ASD (hrASD), mean age 23.3 ± 4,8 month). To examine group differences, we utilized both traditional and innovative eye movement variables, including those based on areas of interest (AOI), Markov variables and gaze retention interval variables (GRI). Results 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 non-ASD group compared to the hrASD group, while the non-social domain exhibited the opposite trend. In the joint attention paradigm, group differences appeared to be associated with the prompting and ostensive aspects of interpersonal engagement. The hrASD group consistently displayed a lower level of social attention towards individuals, albeit with a smaller effect size compared to the preferential paradigm. 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 hrASD group in comparison to the non-ASD group when correlation with ADOS scores was tested separately for each group. Conclusions We have developed variables (Markov and GRI) that are robust enough to use even in the noisy eye movement recordings typical of early childhood. In the preferential paradigm, besides the AOI ratio measures, the Markov and GRI variables show promise in distinguishing ASD toddlers. Furthermore, they exhibit potential for predicting the severity level and the likelihood of autism by correlating with the ADOS score. It is conceivable that, when utilized in conjunction, these variables capture characteristics indicative of early signs of autism.