Identity fusion with proximal but not distal social groups rises after mastering a coordinated marching routine

Humans coordinate their movements during collective rituals that celebrate their social groups. Participation in such rituals increases identity fusion with fellow participants. However, it is unclear whether increased fusion extends to the symbolic groups they are celebrating. We tracked a university marching band as members (n = 267) practised coordinated marching for a new halftime show. At the beginning and end of a week of practise, we measured identity fusion between band members and their proximal social groups—instrument rank and the full band, and a distal symbolic group—the university, as well as band members’ feelings of connection to every other band member. By matching digitally created drill videos of perfect coordination to drone footage of live practises, we showed that marching became more coordinated after a week of practise. Band members also felt more fused with their instrument rank and the full band after a week of practise, and marchers felt most fused to these groups when they were more coordinated. Network density—the number of band members’ close connections—also increased. However, marching was not associated with fusion with the university, suggesting that coordination fuses individuals to proximal groups participating in the ritual, but not necessarily distal, symbolic groups.