# Mother–Child Biobehavioral Synchrony and Its Association With Social Functioning in Autistic School‐Aged Children

## TL;DR

This study explores how heart activity and behavior patterns between autistic children and their mothers relate to social skills and language development.

## Contribution

The study is the first to investigate biobehavioral synchrony in autistic children and its link to social functioning.

## Key findings

- Mothers and autistic children showed negative RSA synchrony, with opposite heart activity patterns.
- High behavioral synchrony paired with negative physiological synchrony was linked to better pragmatic language skills in autistic children.
- Friendship quality was not associated with either type of synchrony.

## Abstract

Parent–child biobehavioral synchrony, or the concordance of behavior and physiological indicators between individuals, is theorized to support children's social development; however, this relationship has yet to be investigated in autistic children. This study examined whether moment‐to‐moment physiological synchrony—indexed via respiratory sinus arrhythmia (RSA)—and its interface with global levels of behavioral synchrony was associated with the pragmatic language skills and friendship quality of school‐aged autistic children in 40 mother–child dyads. Mother–child dyads participated in a collaborative task, from which RSA synchrony and behavioral synchrony were assessed. Mothers and their autistic children demonstrated negative RSA synchrony, such that when one partner displayed an increase in RSA, the other partner showed a decrease in RSA. The extent of behavioral synchrony between mothers and their children did not moderate the strength of concordance between mother and child RSA. Negative RSA synchrony was associated with better pragmatic language skills in autistic children from mother–child dyads who displayed high levels of behavioral synchrony. These findings highlight the complexity of dyadic synchrony, suggesting that the coordination of mother–child RSA, in conjunction with behavioral synchrony, may aid in the development of social skills in autistic children that extend beyond the immediate caregiver context. However, larger longitudinal studies are needed to confirm this.

This study examined whether mothers and their school‐aged autistic children have consistent heart activity patterns when interacting with each other, which is called physiological synchrony. We also explored whether physiological synchrony was linked to how closely their behaviors aligned, which is called behavioral synchrony. We found that mothers and their autistic children did match their heart activity but in the opposite direction—when one partner had an increase in heart activity, the other partner had a decrease. This is called negative physiological synchrony. In this study, we did not find a link between behavioral synchrony and physiological synchrony. We also explored whether physiological synchrony and behavioral synchrony are related to pragmatic language, or the social use of language, and friendship quality in autistic children. Friendship quality was not related to physiological or behavioral synchrony, but for mothers and children who displayed high levels of behavioral synchrony, more negative physiological synchrony was related to better pragmatic language skills for autistic children.