Toddlers with Autism Observe the World in a More Variable Manner Exhibiting Large Intra-Individual Variability

Background: Previous eye-tracking studies have reported that children with autism do not fixate on social stimuli in the same manner as neurotypical children, perhaps interfering with their ability to learn social interactions. For example, children with autism exhibit reduced preference for social stimuli including faces, eyes, and biological motion. A lack of social preference may lead to idiosyncratic gaze preferences, large between-subject variability, and low inter-subject correlations. In the current study, toddlers with autism and matched controls observed several movies containing social stimuli twice. This design enabled us to determine whether between-subject variability was driven by reduced preference for social stimuli and quantify within-subject variability across the two presentations of each movie. All participating children were part of the regional autism database initiative at the Negev Autism Center in Israel (www.negevautism.org).

Objectives: To compare social preference, between-subject variability, and within-subject variability across autism and control children presented with naturalistic and animated movies containing social stimuli.

Methods: We recorded eye tracking data from 68 toddlers with autism and 29 control toddlers while freely viewing two animated movies and one naturalistic movie containing social interactions. Each of the movies was presented twice during the experiment. We then computed inter-subject correlations across individuals and intra-subject correlations across presentations from each group of subjects.

Results: Toddlers with autism exhibited significantly smaller inter-subject correlations (i.e. larger between-subject variability) in comparison to controls. Furthermore, toddlers with autism exhibited significantly smaller intra-subject correlations (i.e. larger within-subject variability) in comparison to controls.

Conclusions: Neurotypical children exhibit strong inter-subject correlations in gaze patterns, likely due to their preference for social stimuli. Children with autism, on the other hand, are not only different from each other, they also exhibit weak intra-subject correlations across presentations of the same movie. This indicates that their idiosyncratic gaze patterns are also less stable across repeated presentations of the same structured stimulus. Hence, toddlers with autism view the world in a more variable less consistent manner. This variability may have important implications for their ability to learn and explore the visual world.