Tap out 'Happy Birthday' on a table — listeners guess the tune about once in 40 tries
Elizabeth Newton had 'tappers' drum out well-known songs on a tabletop while 'listeners' tried to name the tune. Tappers predicted listeners would succeed half the time; the real rate was about 2.5%. Once you already know a tune, you can't help hearing it in your own taps — a vivid demonstration of the curse of knowledge.