Postural control and use of eye movements differ during quiet standing in Autism Spectrum Disorder and Typical Development
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PURPOSE: Individuals with Autism Spectrum Disorder (ASD) have clinically-significant difficulty with postural stability and motor coordination. However, few studies quantitatively examine differences in postural stability and eye movement between ASD and typical development (TD). Individuals with ASD have atypical eye movements, and emerging evidence suggests that they also have difficulty using vision to support postural control. This study aimed to quantify differences in eye movement and postural stability between individuals with ASD and TD. METHODS: 18 individuals with ASD (Mage = 15.3) and 23 TD (Mage = 14.3) participated in this study. Participants stood on a force plate while wearing eye-tracking glasses. The force plate monitored their center of pressure, a common metric used to assess balance and stability. The eye-tracking glasses monitored their fixation and saccadic eye movements. Participants completed a quiet standing task with three conditions: eyes open (EO), eyes closed (EC), and EO while wearing a translucent dome on the head, obscuring visual context (Dome). Each condition lasted 30 seconds, and participants were monitored for compliance by a member of the research team. RESULTS: Participants in the ASD group had greater overall postural instability than the TD group across all conditions. Notable differences also occurred between the groups for anterior-posterior sway and sway in the EO condition. The two groups also differed in proportion of fixations versus saccadic eye movements used to support postural stability. CONCLUSIONS: These data suggest that the specific profile of postural instability and contributing eye movements differs between ASD and TD. The ASD group had markedly increased instability when visual context was eliminated (EC) or obscured (Dome), suggesting an important influence of visual information and potential failure to engage in sensory reweighting. Sensory reweighting is critical function, increasing flexibility in the strategies a person uses to maintain balance in situations where one dominant source of sensory input (e.g., vision) is unreliable or unavailable. Data collection is ongoing, and additional studies are necessary to investigate the mechanisms responsible for postural instability in ASD.