Trick-or-treaters stole far more candy once their costumes hid who they were
In a 1976 field experiment, researchers greeted Halloween trick-or-treaters at homes around Seattle, told them to take only one candy each, then left the room with a large bowl. Children left anonymous by masks or large groups took extra candy far more often than children asked their name first or trick-or-treating alone. The study became a classic, concrete demonstration that anonymity measurably loosens people's normal self-restraint.