Reduced Hand Specialization and Idiosyncratic Visuomotor Strategies in Autism During Naturalistic Object Manipulation.

Autistic individuals exhibit altered perceptual and visuomotor behaviors, potentially due to reduced cortical specialization. The current study focuses on handedness, a robust marker of cerebral specialization, which is less right-biased in autism. Previous studies have typically assessed handedness via questionnaires or simple manual tasks that do not characterize the dynamic, on-going nature of real-life actions. To address this gap, autistic and non-autistic right-handed adults recreated LEGO models from blocks placed on a standardized tabletop, enabling analysis of dynamic, real-world visuomotor behaviors. Autistic participants displayed a lower proportion of right-hand grasps and fewer contralateral movements (i.e., crossing the body midline) with their right hand. Additionally, we observed differences in 3D space utilization, such that autistic participants exhibited a stronger preference for blocks placed closer to their hands. Finally, autistic participants were slower, and their movement trajectories were more idiosyncratic when compared with non-autistic participants. These results reveal reduced hand specialization and profound visuomotor control differences in autism, highlighting potential clinical utility for early, objective autism markers.