Restricted Kinematics in Children With Autism in the Execution of Complex Oscillatory Arm Movements

Abstract

Restricted and repetitive behavior is a core symptom of autism spectrum disorder (ASD) characterized by features of restrictedness, repetition, rigidity, and invariance. Few studies have investigated how restrictedness is manifested in motor behavior. This study aimed to address this question by instructing participants to perform the utmost complex movement. Twenty children with ASD and 23 children with typical development (TD) performed one-dimensional, left-right arm oscillations by demonstrating varying amplitudes and frequencies. The entropy of amplitude and velocity was calculated as an index of kinematic complexity. Results showed that the velocity entropy, but not the amplitude entropy, was significantly lower in ASD than in TD (p < 0.01), suggesting restricted kinematics. Further analysis demonstrated that a significantly higher proportion of the velocity values was allocated at a low-speed level in the children with ASD (p < 0.01). A qualitative comparison of the complex movement with movement at preferred frequency suggested that the children with ASD might be less likely to shift away from the preferred movement. However, our study can be improved in terms of recruiting a larger sample of participants, measuring the level of motivation, and collecting both complex and preferred movements of the same participant.

Level of autistic traits in neurotypical adults predicts kinematic idiosyncrasies in their biological movements

“…Interestingly, these patterns of results resemble findings by Vabalas et al in which motion tracking of simple pointing and aiming movements of the hand in individuals with and without ASD revealed slower, more restricted, and accurate movements in ASD compared to typically developing individuals ( Vabalas et al, 2019 ). The notion of more restricted kinematics in the autism spectrum is also consistent with recent work by Zhao and colleagues (e.g., Zhao et al, 2021 , 2022 ) in which entropy and amplitude was measured during arm oscillations in children with ASD and typically developing controls. Children with ASD showed lower entropy values, indicating more restricted movements.…”

“…Children with ASD showed lower entropy values, indicating more restricted movements. One interpretation of Zhao et al’s finding is that children with ASD may deviate less from the preferred movement, resulting in less complexity over time ( Zhao et al, 2021 ). This reduction in the complexity of body movement also extends to face-to-face interactions with an experimenter ( Zhao et al, 2022 ).…”