Kissing the mezuzah and cognitive performance: Is there an observable benefit?

A mezuzah is a small case affixed to the doorframe of each room in Jewish homes and workplaces which contains a tiny scroll of parchment inscribed with a prayer. It is customary for religious Jews to touch the mezuzah every time they pass through a door and kiss the fingers that touched it. However, kissing the mezuzah has also become customary for many secular Jews who think of the mezuzah as a good luck charm. In view of a recent revelation that kissing the mezuzah entails a health hazard, the present paper inquires whether it also has some observable benefit. In an experiment conducted among non-religious mezuzah-kissing economics and business students confronted with a logic-problem exam, some were allowed to kiss the mezuzah before taking the exam, whereas the others were asked not to do so or could not do so because it had been removed from the room doorframe. The experiment revealed that participants who did not kiss the mezuzah performed worse than those who kissed it, and that the stronger is one's belief in the mezuzah's luck-enhancing properties, the better he performs when he kisses it but the worse he performs when he does not.