Add more people to a tug-of-war team and each person quietly pulls less hard

In 1913, French engineer Max Ringelmann had men pull on a rope alone and in groups, measuring the rope's tension each time. Individual effort dropped steadily as group size grew, from imperfect coordination and from people coasting once no one could tell exactly how hard they personally were pulling. Decades later, researchers renamed the coasting part 'social loafing' and found it in tasks from clapping to brainstorming.

— Max Ringelmann, Ringelmann effect — Rope-pulling study, 1913