Obviously, crossing your fingers, knocking on wood, stockpiling four-leaf clovers, and avoiding ladders and/or black cats has no effect on the world, tangible or otherwise. But if superstitions are all in our heads, then how do superstitions affect our minds?
You could quite easily build a convincing case for or against the psychological effects of superstitious beliefs and whether those beliefs provide any benefits. On the one hand, superstitions are fundamentally irrational and require turning over some control of our lives over to unseen forces – it's not particularly hard to see how that mindset might translate to reduced performance of tasks and activities.
Then again, you could just as easily argue that believing you've successfully navigated these superstitious influences can provide tremendous confidence. What's more, a belief that you're not totally in control could serve to take the pressure off and relax you, which means you end up performing better than you otherwise would have.
They're both plausible enough hypotheses, as these things go, but they're both pretty much worthless without some evidence to back them up. For that we turn to an intriguing study performed last year by psychologists at the University of Cologne in Germany. At the risk of giving out spoilers for the next sentence, superstitious people are going to like what the researchers found:
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.
So what's behind the performance enhancing power of superstitious beliefs? The researchers found that is indeed all about confidence:
Furthermore, Experiments 3 and 4 demonstrate that these performance benefits are produced by changes in perceived self-efficacy. Activating a superstition boosts participants' confidence in mastering upcoming tasks, which in turn improves performance. Finally, Experiment 4 shows that increased task persistence constitutes one means by which self-efficacy, enhanced by superstition, improves performance.