Reduced Dissociation between Perception and Action in Autistic Individuals

Changes in perceptual behaviors are a core phenotype of autism, yet the underlying mechanisms remain unclear. We tested the hypothesis that these changes arise from reduced cortical specialization by examining the well-established functional dissociation between visual processing for perception and action. Specifically, we examined the effects of spatial context (Experiment 1) and stimulus history (Experiment 2), both of which typically influence perception but not grasping in non-autistic individuals. In each experiment, autistic and non-autistic participants completed grasping and estimation tasks. In Experiment 1, we used two objects of different sizes, placed on an illusory Ponzo background, making them appear “close” or “far” from the observer. Non-autistic individuals showed a robust illusion effect only during perceptual estimation, while autistic individuals were affected during estimation and grasping. In Experiment 2, we presented a standard stimulus (40mm) in two blocks of stimuli: a “wide” range (20-60mm) and a “narrow” range (35-45mm). Again, non-autistic participants showed a strong effect of context on their sensitivity, but only for the estimation task, exhibiting higher thresholds in the “wide” block. Autistic participants showed consistent effects of the experimental context for both tasks. Together, these results provide novel evidence for a reduced functional dissociation between perception and action in autistic people, supporting the reduced specialization account as a possible underlying mechanism mediating perceptual alterations in autism.