Abstract:

Synchrony, a core element of collective rituals, is of great significance to the survival and development of groups. Interpersonal synchrony is a type of coordination behaviour that refers to the temporal overlap of the movements of two or more people, emphasising the coordinated consistency of movements among group members with the time- and phase-locked characteristics. Recent studies have found that synchrony can promote prosocial behaviours such as cooperation, and this promoting effect has been verified in two-person synchrony, three-person synchrony, and even group synchrony. Moreover, both cooperative behaviour in classical experimental paradigms of cooperation (e.g. prisoner’s dilemma and public goods game) and real-life cooperative activities (e.g. task cooperation) can be positively influenced by interpersonal synchrony. A review of previous studies suggests that the potential process mechanisms underlying this promoting effect involve the activation of neurophysiological systems, an enhanced sense of social connectedness, increased cognitive sensitivity, and evocation of positive emotions. These mechanisms may play different roles in the effect of interpersonal synchrony on cooperation, including providing a physiological and psychological bases as well as facilitating positive interpersonal interactions. Previous researches have also proposed three different models of this positive effect from different perspectives: (1) the self-other representational overlap model, which suggests that individuals promote cooperative behaviour by generating a sense of connectedness through perceived similarity between self and other representations and behaviours; (2) the reinforcement of cooperation model, which suggests that emphasising shared intentionality and increasing joint attention will enhance individuals’ expectations of partners’ cooperation and thus promote cooperative behaviour; and (3) the collective effervescence model, which suggests that synchrony with others creates a positive emotional climate in which individuals generate positive emotions and group-identity, thus enhancing cooperative behaviour. These three models have their own focuses in explaining the role of interpersonal synchrony in promoting cooperation, but they still have shortcomings and cannot fully explain how interpersonal synchrony affects cooperation. Therefore, this paper integrates previous researches and constructs a new psychological process model of synchrony for cooperation. This model provides a more comprehensive and clearer structure of the direct and indirect paths through which synchrony affects cooperation and identifies two important moderators (group size and identity/cultural background). According to this model, synchrony can directly generate cooperative motivation (concern for others’ well-being, liking, trust, and a sense of commitment to performing an action) and then promote cooperative behaviour. Moreover, the shared behaviours, shared intentionality, joint attention as well as positive emotion induced by interpersonal synchrony can promote group identification and, at the same time, synchrony conveys important cues representing the level of competence and the willingness to change for others of partners—namely individual idiosyncratic characteristics. This means that cooperation can also be enhanced by clarifying who is cooperating, thus enhancing the motivation to cooperate. This paper summarises the shortcomings of the existing researches and provides suggestions for future research. The small number and inconsistency of studies on interpersonal synchrony and cooperative behaviour suggest that the facilitative effect of synchrony on cooperative behaviour is susceptible to interference by other factors, and future research needs to further explore the moderating mechanisms of the synchrony effect and reveal the effects of various factors such as social identity, group size, type of cooperative behaviour, and cultural background. In addition, the temporality, specificity, and generalisability of this positive effect need further validation in order to effectively increase the prosocial function of synchrony and reduce its antisocial risk.

Key words: interpersonal synchrony, cooperation, perception of social bonding, group-identification, self-other representational overlap