Moving, singing or chanting in time with others raises felt closeness and willingness to cooperate with them afterwards.
Wiltermuth and Heath had participants walk in step, sing together or move in time, and found greater cooperation in subsequent economic games than matched groups doing the same activity out of step. The manipulation carries no information and produces the effect anyway, which is why marching, drill, hymn-singing and terrace chanting recur across societies that share nothing else.
In practice
- A team that spends the first ten minutes doing something in unison argues more productively for the next hour.
- A congregation that sings together leaves more willing to lend each other money than one that listened.