Selective Impairments in Action Understanding and Movement Intentionality in Young Children with Autism When Compared to Williams Syndrome

Background: Although previous studies comparing Autism spectrum disorder (ASD) and Williams syndrome (WS) have focused on the social and motor domains separately, recent theoretical perspectives on “motor cognition” have proposed that the motor system is fundamentally intertwined with social functioning. Despite the simplistic view of opposing abnormalities in social behavior, with ASD characterized by hyposociability, and WS exhibiting hypersociability, there are striking similarities in motor dysfunction across these two syndromes. Yet, the extent to which ASD and WS share common deficits in the encoding of others’ motor intentions and movement interference, which are critical motor mechanisms impacting on social functioning, is as yet unexplored. Direct cross-syndrome comparisons of young children with ASD and WS provide a hitherto unprecedented opportunity to examine specificity of motor mechanisms impacting on cognitive and adaptive social functioning.

Objectives: Here we compare the ability to understand and predict others’ intentional actions and movement interference in preschoolers with ASD when compared to a matched sample of children with WS, and typically developing (TD) children. Specifically, we aimed to identify whether deficits in encoding motor intentions and movement execution during incongruent actions are specific to ASD, and explore the extent of association with cognitive and social functioning.

Methods: Using novel experimental behavioral and eye tracking tasks that were video-recorded, we examined childrens’ movement interference when observing a models’ incompatible actions and their understanding of the intended goal of reaching actions across the following conditions: 1) observation of a model performing either congruent or incongruent actions (e.g. placing coins in a moneybox, stacking rings in correct order), 2) coding of childrens’ movement efficiency (time and effective actions) during incongruent versus congruent conditions, and (3 patterns of anticipatory looking to a target during successful or failed attempts by a model to reach over a barrier to retrieve it.

Results: Preliminary findings suggest that children with ASD showed significantly reduced movement interference time during incongruent relative to congruent actions when compared to TD children. Interestingly, reduced movement interference during action observation correlated with greater severity of symptoms in social affect and restricted repetitive behavior in ASD. Although there were no group differences in anticipatory fixations or duration to goal-directed reaching actions, less anticipatory fixations to the target correlated with greater severity of autism symptoms in children with ASD.

Conclusions: Our findings add to the growing evidence base supporting a critical role for motor system dysfunction contributing to difficulties in the social domain in young children with ASD. Direct cross-syndrome comparisions will be important in revealing autism-specific impairments in motor cognition which may lead to new treatment targets for core ASD symptomatology.