The Moment an Autistic Child Adapts to a Task: Analysis of Multiple Time Scales as an Index of Movement Variability

Objectives This study observes the trajectory of the motor development of a child with autism spectrum disorder (ASD) from the perspective of multiple time scales and elucidates how the movement of the child changed through interaction with tasks and the environment. Methods To analyze the trajectory of motor development in more detail, the present study focused on the case of one child with ASD in a motor development clinic, specifically examining the variability of the ball-throwing motion throughout 11 months and analyzing the interaction between the trajectory of the motion variability and the task. Results Throughout the observation period, two different tasks were performed, and a total of 135 ball-throwing motions were observed. These motions repeatedly varied between large and small, indicating that the constraints of the tasks strongly impacted him. In the phase of rapid movement variation, his psychological situation when faced with the task influenced how he directed his attention during the performance, which affected the final expression of ball-throwing motions. This indicates that one’s psychological situation of adapting to changes in the task influences the fluctuation of large and small movements. Conclusions This trajectory of motor development was considered to be a process of “adaptive variation,” in which the subject searches for a strategy adapted to them in response to the task encountered, which is an important factor in motor development.