Keep Your Fingers Crossed!
How Superstition Improves Performance.
-- Damisch et. al., Psychological Science July 2010 vol. 21 no. 7 1014-1020.
Superstitions are typically seen as inconsequential creations of irrational minds. ... Experiments 1 through 4 show that activating good-luck-related superstitions via a common saying or action (e.g., “break a leg,” keeping one’s fingers crossed) or a lucky charm improves subsequent performance in golfing, motor dexterity, memory, and anagram games. Furthermore, Experiments 3 and 4 demonstrate that these performance benefits are produced by changes in perceived self-efficacy.