Reduced Dissociation between Perception and Action in Individuals with Autism

Changes in perceptual behaviors are commonly reported in individuals with Autism. Nevertheless, the mechanisms that mediate these alterations are yet to be determined. One hypothesis is that these changes are the result of reduced cortical specialization. In this study, we scrutinize this hypothesis utilizing the framework of the functional dissociation between perception and action. Past studies have demonstrated that unlike their robust effect on perception, altering the temporal or spatial size context of stimulus presentation have little effect on grasping. Therefore, we manipulated the temporal or spatial context of stimulus presentation, while both autistic and neurotypical participants completed grasping and estimation tasks. In Experiment 1 (spatial context), we used two objects that differ in size, and placed on an illusory Ponzo background such that they were perceived as “close” or “far” from the observer. The neurotypical individuals showed a perception-action dissociation with a robust effect of the illusion only during the estimation task, and no effect of the illusion during grasping. In contrast, autistic individuals were affected by the illusion under both conditions. In Experiment 2 (temporal context), we presented a standard stimulus (40mm) in two temporally distinct blocks. In one block (“wide”), the stimuli used as flanks for the standard stimuli encompassed a larger range (20-60mm). In the other block (“narrow”), the flanks encompassed a smaller range (35-45mm). The neurotypical individuals showed a perception-action dissociation with a robust effect of the experimental temporal context only during the perceptual task. In contrast, autistic individuals showed a consistent effect of the experimental temporal context under the perceptual and the visuomotor task, with larger JNDs for the standard stimulus presented during the “wide” block. Taken together, these results provide converging evidence for reduced functional dissociation between perception and action in autism, such that perceptual representations intrude and modulate visuomotor behaviors.