In all cultures around the world and far back into human history, people have come together to sing and dance. Why do humans perform such behaviour? One popular explanation is that collective music and dance bonds people together and increases cooperation. Such an important function in human sociality could explain music and dance’s ubiquity and its selection and retention. Observations from ethnographies, historical analysis, and experimental research support this social bonding hypothesis. However, it is not yet clear through what mechanism music and dance might produce this effect.
Despite variance in expressions and contexts of collective music and dance performances, one common underlying factor found in most forms of collective music and dance is the matching of rhythmic behaviours amongst performers. Performers move their bodies or produce sound at the same frequency (frequency-locked synchrony) or phase (phase-locked synchrony). Behavioural synchrony has been linked with greater social bonding and cooperation suggesting that such synchrony could be one of the key mechanism behind collective music and dance’s prosocial effect.
Previous research on synchrony has predominantly been conducted on pairs (dyads), modeling the spontaneous and automatic synchrony that often occurs when two people interact. However, the synchrony that occurs in music and dance is not accidental, but rather a deliberate communal practice. In collective music and dance, performers intentionally modify the timing of their rhythmic movement to entrain to the behaviour of others with the knowledge that others also share the goal of entrainment. This sharing of psychological states enabling collaborative behaviours is termed shared intentionality. Kirschner and Tomasello proposed that it is shared intentionality that is essential in creating the cooperative effects of collective music and dance, “getting people to experience each other as co-active, similar and cooperative members of a group”.
“Getting people to experience each other as co-active, similar and cooperative members of a group”.
To further understanding of how collective music and dance influences cooperation, we conducted three studies designed to disentangle the social effects of synchrony and shared intentionality. In Experiment 1, we compared a condition in which shared intentionality was used to create synchrony with conditions in which synchrony and asynchrony were created as a by-product of hearing the same or different rhythmic beats. Our results from Experiment 1 helped to clarify whether shared intentionality is an important factor in producing cooperative effects from group synchrony. In Experiment 2, we measured cooperation after varying intentional synchrony with intentional asynchrony. This helped us to understand whether synchrony matters to cooperation. In Experiment 3 we manipulated both shared intentionality and synchrony to examine how their interaction affected cooperation.
The results of the three experiments reported above indicate that synchrony promotes cooperation more powerfully when it is framed as a collective goal. We found that synchrony combined with shared intentionality leads to greater cooperation than synchrony without shared intentionality or shared intentionality combined with asynchronous movement or vocalising. Our study offers the first demonstration that synchrony interacts with explicitly shared goals to support cooperative interactions. Additionally, we present and empirically assess a plausible psychological model for the proximate cognitive processes that underpin heightened prosociality, when synchrony and collective goals combine.
Reddish P, Fischer R, Bulbulia J (2013) Let’s Dance Together: Synchrony, Shared Intentionality and Cooperation. PLoS ONE 8(8): e71182. https://doi.org/10.1371/journal.pone.0071182