Fig. 4

Enhanced motor noise specific to the poor motor skill autism subtype. Panel A shows the reach-to-drop task, segmented into reach and drop actions, and with the reach action split into feedforward and feedback phases according to the deceleration peak. The velocity plot represents the instantaneous velocity of the medial wrist marker of a random participant. Panel B shows group differences (TD, yellow-orange; Autism High, light blue; Autism Low, dark blue) when motor noise is measured across the entire reach and drop actions. Panel C shows group differences when the task is split into reach and drop actions and with the reach action split into feedforward and feedback phases. Panels D and E show the variability across trials for a randomly selected participant. Trajectories for one body part (lateral wrist) are displayed in their native 3D space (x, y, z). Panel D displays one example subject from the 'High' subtype, whereas Panel E displays an example subject from the 'Low subtype'. Each colored line indicates one trial. Asterisks indicate p < 0.05