Feed pigeons on a fixed timer, and they invent rituals to explain the food

In 1948, B. F. Skinner fed hungry pigeons at fixed time intervals no matter what they did. Most birds developed repeated, ritual-like behaviours, head-bobbing, turning, swinging, as if their own actions had caused the food to appear. Skinner used the result as a working model for how human superstition can form from pure coincidence.

— B. F. Skinner, 'Superstition' in the Pigeon — Journal of Experimental Psychology, Vol. 38, No. 2 (1948)