A Meta-Analysis of Gaze Differences to Social and Nonsocial Information Between Individuals With and Without Autism.

Objective: Numerous studies have identified abnormal gaze in individuals with autism. However, only some findings have been replicated, the magnitude of effects is unclear, and the pattern of gaze differences across stimuli remains poorly understood. To address these gaps, a comprehensive meta-analysis of autism eye-tracking studies was conducted.

Method: PubMed and a manual search of 1,132 publications were used to identify studies comparing looking behavior to social and/or nonsocial stimuli between individuals with autism and controls. Sample characteristics, eye-tracking methods, stimulus features, and regions of interest (ROIs) were coded for each comparison within each study. Multivariate mixed-effects meta-regression analyses examined the impact of study methodology, stimulus features, and ROI on effect sizes derived from comparisons using gaze-fixation metrics.

Results: The search yielded 122 independent studies with 1,155 comparisons. Estimated effect sizes tended to be small to medium but varied substantially across stimuli and ROIs. Overall, nonsocial ROIs yielded larger effect sizes than social ROIs; however, eye and whole-face regions from stimuli with human interaction produced the largest effects (Hedges g = 0.47 and 0.50, respectively). Studies with weaker study designs or reporting yielded larger effects, but key effects remained significant and medium in size, even for high-rigor designs.

Conclusion: Individuals with autism show a reliable pattern of gaze abnormalities that suggests a basic problem with selecting socially relevant versus irrelevant information for attention and that persists across ages and worsens during perception of human interactions. Aggregation of gaze abnormalities across stimuli and ROIs could yield clinically useful risk assessment and quantitative, objective outcome measurements.