The Search for Biomarkers and Clinically Meaningful Subtypes of ASD Based on Eye Tracking Data
Objectives: As part of an education motivated panel, the primary objective is to discuss the ways in which such a large dataset could be examined. Topics relating to disentangling heterogeneity and the value of eye tracking indices as diagnostic and prognostic biomarkers will be considered. Other topics include examination of state and trait markers and stability of responding across time and different paradigm types to discover a true biotype.
Methods: Combining Samples 1-3, a total of 837 toddlers participated and included 242 ASD and 595 contrast toddlers (LD, DD, Typical, Typical Sibling and “Other”) ranging in age from 12-48 months. Using a Tobii wireless eye tracker, all toddlers participated in the “GeoPref Test”, a 1-minute movie containing both dynamic geometric and social images. Fixation duration within each area of interest and number of saccades were recorded. Toddlers were diagnostically and psychometrically evaluated at time points both proximal and distal to the eye tracking session. In order to examine stability of responding across paradigms, toddlers participated in several different eye tracking tests beyond the GeoPref Test, such as one containing complex social interactions.
Results: Data from the new unpublished sample (Sample 3), replicates the finding that overall ASD toddlers fixate more on geometric images than other diagnostic groups (e.g., ASD vs TD, t212 = 8.37, p<.0001, CI of the difference = 17.6%-28.5%). Other analyses will be performed to understand subtypes, examine visual attention across time and consider how a child’s visual fixation patterns at ages 1-2 years might predict his outcome at ages 3-4 years.
Conclusions: Eye tracking is a powerful tool for discovering subtypes of ASD and for understanding its early course.