Revisiting the Prosocial Effect of Interpersonal Synchrony in Infants: A Study Under a Pre-Post Manipulation During the COVID-19 Pandemic

Abstract

Helping behavior emerges reliably in the second year of life. Recent evidence suggests that the experience of interpersonal synchrony may facilitate this behavior in infants. However, whether and how infants’ helping behavior changes after experiencing interpersonal synchrony remain largely unexplored. To replicate and extend previous findings, the current study employed a pre-post manipulation design to examine the effect of interpersonal movement on infants’ helping behavior. Fifteen-month-old infants participated in a helping tasks phase twice: once before and once after the manipulation of interpersonal movement (synchronous or asynchronous). Our primary analysis revealed no statistical significance in the prosocial effect of interpersonal synchrony. Methodological constraints and socio-environmental factors are discussed as potential possibilities for the current null finding. A preliminary analysis focusing on individual differences did reveal a significant relationship between infants’ temperament traits of Negative Affectivity and the effect of interpersonal synchrony. Based on these findings, we discussed necessary methodological adjustments for future study and evolutionary implications of the prosocial effect of interpersonal movement in humans.