Interpersonal synchrony increases prosocial behavior in infants

Abstract

Adults who move together to a shared musical beat synchronously as opposed to asynchronously are subsequently more likely to display prosocial behaviors toward each other. The development of musical behaviors during infancy has been described previously, but the social implications of such behaviors in infancy have been little studied. In Experiment 1, each of 48 14-month-old infants was held by an assistant and gently bounced to music while facing the experimenter, who bounced either in-synchrony or out-of-synchrony with the way the infant was bounced. The infants were then placed in a situation in which they had the opportunity to help the experimenter by handing objects to her that she had ‘accidently’ dropped. We found that 14-month-old infants were more likely to engage in altruistic behavior and help the experimenter after having been bounced to music in synchrony with her, compared to infants who were bounced to music asynchronously with her. The results of Experiment 2, using anti-phase bouncing, suggest that this is due to the contingency of the synchronous movements as opposed to movement symmetry. These findings support the hypothesis that interpersonal motor synchrony might be one key component of musical engagement that encourages social bonds among group members, and suggest that this motor synchrony to music may promote the very early development of altruistic behavior.

Effects of Interpersonal Movement Synchrony on Infant Helping Behaviors

“…These rates of bouncing match those used in our previous experiments (Cirelli, Wan, & Trainor, 2014. Our original experiment (Cirelli, Einarson, & Trainor, 2014) used both faster and slower bouncing for different infants in the asynchrony condition. Since no differences were found between infants bounced faster versus slower, in the present experiment we used only faster bouncing by the experimenter in the asynchronous condition.…”

“…During the remaining 20 s, the experimenter involved the infant in the problem by alternating her gaze between the infant and object, and eventually naming the object. Infants who had been bounced synchronously handed back significantly more dropped objects than infants who had been bounced asynchronously (Cirelli, Einarson, & Trainor, 2014). Furthermore, infants who had been bounced synchronously helped more than asynchronously bounced infants particularly during the first 10 s of the 30 s response window in each trial.…”

“…For example, 12-month-old infants are more likely to show a social preference for a synchronously over an asynchronously rocking animate toy in a nonmusical context (Tunçgenç, Cohen, & Fawcett, 2015). Furthermore, work in our laboratory has shown that interpersonal synchrony in a musical context actually encourages directed prosociality in 14-month-old infants (Cirelli, Einarson, & Trainor, 2014;Cirelli, Wan, & Trainor, 2014Trainor & Cirelli, 2015). In these studies, infants were held in a baby carrier worn by an assistant, facing an experimenter.…”

“…After the first 10 s, the infant is given social cues (e.g., the experimenter looks at the infant and the object) so helping during this period may reflect compliance as well as prosociality. An increase in spontaneous helping is interpreted as increased altruistic helping rather than compliance (Carpenter, Uebel, & Tomasello, 2013;Cirelli, Einarson, & Trainor, 2014).…”

“…The procedure and participant sample closely matches those used by Cirelli and colleagues (Cirelli, Einarson, & Trainor, 2014;Cirelli, Wan, & Trainor, 2014. The critical difference is that instead of listening to music during the interpersonal movement phase, infants listened to nonrhythmic nature sounds (such as rushing water, windrustled leaves).…”