Motor Variability of Circular Movements Reveals Differences in Non-Dominant Hand and Foot Control in Autistic Adults

Autism spectrum disorder (ASD) is increasingly recognized to involve difficulties in sensorimotor control. This study aimed to evaluate whether motor variability during rhythmic circular movements could serve as a measure of movement coordination quality. Seventeen clinically diagnosed autistic adults and twenty age- and IQ-matched individuals each performed fifteen-second circular movements with their left and right hands and feet, paced by a metronome. Motor variability was quantified as the deviation in circular acceleration trajectories measured using a smartphone’s accelerometer sensor. Autistic adults showed greater motor variability in both lower limbs and their non-dominant hand compared to the comparison group. They also exhibited greater hand laterality than the comparison group. Individuals with greater foot variability also tended to show greater hand variability. This relationship was similar in the autistic and comparison groups. Quantifying the movement variability of circular movements made with the upper and lower limbs may provide a rapid, quantitative assessment of coordination difficulties in autistic adults.