A context‐dependent perspective to understand the relation between parent–child physiological synchrony and child socioemotional adjustment

= 8.64 years, 63 girls) and their primary caregivers participated in this study. After attaching electrocardiogram (ECG) electrodes, parent-child dyads were instructed to complete a 4-minute conflict discussion task. Parent-child physiological synchrony was calculated based on the within-dyad association between parents' and children's respiratory sinus arrhythmia (RSA) levels across eight 30-second epochs. Parental emotional support, child relationship quality with parents, and child emotion regulation during the discussion task were coded by trained research assistants. Supporting our hypotheses, parental emotional support moderated the relations of parent-child RSA synchrony with both child relationship quality with parents and child emotion regulation. Furthermore, the Johnson-Neyman technique of moderation indicated that the associations between parent and child RSA synchrony and child socioemotional adjustment indicators shifted from negative to positive as the parental emotional support became increasingly high. Our findings suggest that parent-child physiological synchrony may not be inherently adaptive or maladaptive, highlighting the importance of understanding the function of parent-child physiological synchrony under specific contexts. RESEARCH HIGHLIGHTS: Physiological synchrony may not be inherently adaptive or maladaptive, and the meanings of parent-child physiological synchrony might be contingent on contextual factors. Parental emotional support moderated the relations between parent-child respiratory sinus arrhythmia (RSA) synchrony and child socioemotional adjustment indicators (i.e., child relationship quality with parents and child emotion regulation). More positive/less negative parent-child RSA synchrony was associated with better child socioemotional adjustment under a supportive emotional context, whereas with poorer child socioemotional adjustment under an unsupportive emotional context. These findings highlight the significance of considering the emotional context in physiological synchrony studies.