The effect of different phases of synchrony on the synchrony effect

Synchronization of behaviour between individuals has been found to result in a variety of prosocial outcomes. The role of endorphins in vigorous synchronous activities (Cohen, Ejsmond-Frey, Knight, & Dunbar, 2010) may underlie these effects as endorphins have been implicated in social bonding (Dunbar & Shultz, 2010). Although research on synchronous behaviour has noted that there are two dominant phases of synchrony: in-phase and anti-phase (Marsh, Richardson, Baron, & Schmidt, 2006), research on the effect of synchrony on endorphins has only incorporated in-phase synchrony. The current study examined whether both phases of synchrony would generate the synchrony effect. Twenty-two participants rowed under three counterbalanced conditions - alone, in-phase synchrony and anti-phase synchrony. Endorphin release, as measured via pain threshold, was assessed before and after each session. Change in pain threshold during the in-phase synchrony session was significantly higher than either of the other two conditions. These results suggest that the synchrony effect may be specific to just in-phase synchrony, and that social presence is not a viable explanation for the effect of synchrony on pain threshold