Abstract
Motor functioning and social interactions are dynamically linked in children with Autism Spectrum Disorders (ASD), such that children with more severe social impairments also exhibit more severe motor atypicalities. Deficits in motor functioning, such as head movement atypicalities, may contribute to the perceptual and social impairments that characterize individuals with ASD. To date, deficits in motor movement in children with ASD have been characterized descriptively by human observers; however, automated measurement can provide objective, continuous measurement of head position and head movement. The objective of this study is to quantify differences in pitch, yaw, and roll in children with (n=21) and without ASD (n=33). Children without ASD were classified as low risk (n=21) or high risk dependent on having an older sibling with ASD (n=12) to investigate differences in at-risk children. Children were video recorded while watching a 16-minute video containing different blocks of social and nonsocial stimuli. Three dimensions of rigid head movement—pitch (nodding), yaw (head turns), and roll (lateral head inclinations) were tracked using an automatic person-independent tracker. Compared to low- and high-risk children without ASD, children with ASD inclined their heads (roll) with more variable speeds. As indexed by larger angular displacement of yaw and angular velocity of yaw and roll, children with ASD turned their heads to more variable positions and turned and inclined their heads with more variable speeds than low-risk children. These group differences were specific to the social condition. By turning their heads with greater positional variability and more variable speeds, children with ASD may be regulating the amount of incoming social stimuli, perhaps in the service of enhancing their perceptual processing.