Visual Illusion Susceptibility in Children with Autism Spectrum Disorder: Local Versus Global Processing

Background: Research by Happè (1996) showed that individuals with ASD demonstrated less susceptibility to visual illusions, which may suggest enhanced local processing abilities. However, subsequent studies have produced mixed results, and there is also debate as to whether superior local processing corresponds to difficulties in processing visual illusions at the gestalt level.

Objectives: The present study aimed to reconcile the discrepancy in results across studies by conducting a replication of Happè’s design and extending the measurement precision of previous research through the use of eye tracking instrumentation. Eye gaze data may help to reconcile contradictory findings by determining whether all children in the present sample demonstrate a local processing bias, and whether this local processing bias is the mechanism responsible for decreased illusion susceptibility.

Methods: Participants were 36 children (17 with ASD, 19 typically developing) ages 4-13 years matched on chronological age. Local global processing was measured using a visual illusion task conducted with eye tracking technology, as well as an existing measure of central coherence.

Results: In contrast to Happe (1996), analyses revealed no overall group differences in illusion susceptibility, but eye gaze data revealed that children with ASD attend to different areas of the visual scene depending on individual variability in illusion susceptibility.

Conclusions: These findings augment recent research on the nature of visual processing in ASD, specifically suggesting a local bias for some children with ASD rather than an overall deficit in the ability to process global information inherent to all ASD cases. For a subset of children with ASD that do demonstrate evidence of a local processing bias, this in part contributes to decreased susceptibility to visual illusions.