Reduced Dissociation Between Perception and Action in Autistic Individuals.

PURPOSE: Changes in perceptual behaviors are a core phenotype of autism (in acknowledgment of the ongoing discourse regarding terminology about individuals diagnosed with autism, we use "autistic individuals" and “non-autistic individuals” in line with recent conventions), yet the underlying mechanisms remain unclear. In order to explore this, 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.

METHODS

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. In Experiment 2, we presented a standard stimulus (40 mm) in two blocks of stimuli: a “wide” range (20–60 mm) and a “narrow” range (35–45 mm).

RESULTS

In Experiment 1, non-autistic individuals showed a robust illusion effect only during perceptual estimation, while autistic individuals were affected during estimation and grasping. In Experiment 2, once again, non-autistic participants showed a strong contextual effect, but only during the estimation task, displaying reduced sensitivity (i.e., higher discrimination thresholds) when viewing objects in the “wide” contextual block. Autistic participants showed consistent effects of the experimental context for both the grasping and estimation tasks.

CONCLUSION

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.