Why are some of the world's best athletes also some of the most superstitious? Because lucky charms actually do work, according to psychologists Lysann Damisch of the University of Cologne:
In one of the experiments, volunteers were told to bring a lucky charm with them. Then the researchers took it away to take a picture. People brought in all kinds of items, from old stuffed animals to wedding rings to lucky stones. Half of the volunteers were given their charm back before the test started; the other half were told there was a problem with the camera equipment and they would get it back later.
Volunteers who had their lucky charm did better at a memory game on the computer, and other tests showed that this difference was because they felt more confident. They also set higher goals for themselves. Just wishing someone good luck – with "I press the thumbs for you," the German version of crossing your fingers – improved volunteers' success at a task that required manual dexterity. The research is published in Psychological Science, a journal of the Association for Psychological Science
http://www.usnews.com/science/articles/2010/07/15/keep-your-fingers-crossed-how-superstition-improves-performance.html