Interpersonal autonomic nervous system synchrony and its association to relationship and performance - a systematic review and meta-analysis.

Interpersonal physiological synchrony is the spontaneous temporal coordination of physiological processes between several individuals. This type of synchrony is critical for human relationships, as it promotes two important outcomes: the quality of the relationships between synchronized individuals, and how well synchronized individuals perform together. Nonetheless a clear estimation of the size of the correlations between interpersonal physiological synchrony and relationship or performance outcomes is missing. To address this gap in knowledge was the main goal of the current meta-analysis. We focused on interpersonal physiological synchrony in measures of autonomic nervous system activity, and specifically we examined the distinct branches of the autonomic nervous system. We conducted two meta-analyses: (1) Estimating the association between interpersonal physiological synchrony and relationship outcomes (2) Estimating the association between interpersonal physiological synchrony and performance outcomes. In the first meta-analysis (i.e., relationships), the overall estimated correlation was small with a marginal significance (ES=0.09, p>.10) and high heterogeneity (I=76.0%). In further sub-group analysis, we discovered a positive relationship for measures of sympathetic synchrony (ES=0.19, p=.02), a negative relationship for measures of parasympathetic synchrony(ES=-0.21, p=.03), and a positive relationship for measures of combined sympathetic and parasympathetic synchrony (ES =0.16, p=.02). As for the second meta-analysis (i.e., performance), the overall effect size of correlation was small (ES=0.26, p<.01) and heterogeneous (I=52.7%). Our results emphasize the small effect sizes of the correlations between physiological synchrony and performance or relational outcomes, as well as the differential effects for synchrony in sympathetic versus parasympathetic activity. Combined with the high heterogeneity, our results point to the need for a rigorous a-priori scientific approach which distinguishes between different types of physiological synchrony.