Physiological Regulation in Young Children During Parent-Child Free Play: Attachment-Related Differences and RMSSD...

This study examined parent-child physiological synchrony within the context of interactions and attachment-related differences. Specifically, this study investigated physiological synchrony, as indexed by the association between parent and child root mean square of successive differences (RMSSD) during free-play interactions, and differences in children's mean heart rates according to attachment classification. The participants were 25 parent-child dyads (mean child age = 36.48 months). Physiological responses were assessed during free-play interactions using heart rate (HR) and heart rate variability (HRV). Children's attachment was classified as secure or resistant based on their behaviors observed during the separation-reunion procedure. The results showed a significant positive association between the parent and child RMSSD (ρ = 0.48, p < 0.05). Parental anxiety was positively associated with both parents' and children's physiological arousal. Attachment-related group differences were observed only in the mean heart rate, with children with resistant attachment showing a significantly higher HR than those with secure attachment (t = 2.69, p < 0.05). No significant group differences were observed in the RMSSD or HR/RMSSD ratios. Overall, these findings suggest that the parent-child RMSSD association, as a component of physiological synchrony, may reflect a normative feature of parent-child interaction that emerges across attachment classifications. In addition, attachment-related differences were primarily observed in physiological arousal.