Impairment of interpersonal synchrony of head rotation movement and its association with autistic traits in childrenwith autism spectrum disorder

Abstract

<p indent="0mm">A noteworthy characteristic of most social interactions is the coordination of behaviours. One of these is interpersonal motor synchrony, which relates to various aspects of successful social interactions, such as feelings of rapport, formation of a social unity and the quality of relationships. The importance of interpersonal motor synchrony in social interactions makes it a pathway to understanding mental disorders with social deficits, such as autism spectrum disorders (ASD). Individuals with ASD have shown reduced interpersonal motor synchrony in structured interpersonal motor tasks or naturalistic conversations. Moreover, the degree of synchrony of individuals with ASD correlates to symptom severity, social cognition competence, attention problems and communication abilities. However, existing literature mainly focuses on movements of the entire body or limbs. In addition to these aspects, head movements convey communicative information in social interactions. To the best of our knowledge, only one study has examined the interpersonal synchrony of head movement for children with ASD, although the focus was the head displacement in space. Another aspect of head movement, which is rotation, has been overlooked. Therefore, the current study explores the characteristics of the interpersonal synchrony of head rotation movement for children with ASD and the associations between head rotation synchrony and autistic traits. Free play with teachers was selected as the scenario of social interactions. Autistic traits were quantified using the Chinese version of the Autism Spectrum Quotient: Children’s Version (AQ-Child). A manual coding method was used to distinguish the episodes of two-way social engagement and one-way adult social engagement, which may affect the interpretation of results. The extraction of head rotation measures was based on the head angles in the directions of yaw, pitch and roll, which were estimated with a deep learning-based algorithm automatically. After pre-processing the raw time series of head angles and segmentation according to social engagement states, angular displacement and velocity were computed in each segment. Windowed cross-correlation was used to compute the interpersonal synchrony. A surrogate analysis method was then used to generate the level of synchrony and thus confirmed the presence of significant synchrony. The coding of social interactions revealed deficits in social reciprocity of children with ASD. The analysis showed that both the children with and without ASD exhibited the interpersonal synchronies of head rotation, which were greater than chance. However, the degree of synchrony of the ASD group was reduced compared with the typically developing control group in the directions of yaw and roll. In addition, the synchrony of head angular displacement in the direction of yaw was negatively correlated with AQ sub-scores of attention switching. Results help to complete the depiction of characteristics of the interpersonal motor synchrony in individuals with ASD, and extend the impairments of the motor synchrony to head rotation movement. More importantly, in contrast to synchrony of entire body and limb movements that relate to a broader set of traits of ASD, synchrony of head rotation specifically relates to attention problems, at least in the areas included in AQ. The decreased synchrony of head rotation indicates that children with ASD may have difficulties in coordinating their attention to the object of their social partners’ attention during naturalistic social interactions, which may contribute to their deficits in social understanding and their odd and one-sided social behaviours.