Knocking on wood is a common superstition in Western culture, mostly used to prevent bad luck after talking about good fortune, but sometimes to reverse bad fortune or undo a "jinx."
Other cultures maintain similar practices, like spitting or throwing salt, after someone has tempted fate. Even people who aren't superstitious often participate in these practices. And since this baseball playoffs start today, don't even get one of them going about their crazy superstitions and rituals.
A recent paper contends that these superstitions actually do "reverse" perceived bad fortune. Invoking a kind of sympathetic/Reiki magical belief that many of the most common rituals for undoing bad luck – knocking on wood, spitting, and throwing salt – all seem to involve movements that exert force away from a person, they set out to test whether the avoidant nature of the action is key for reducing the negative expectations and heightened concern generated by tempting fate.
In five separate experiments, researchers had participants either tempt fate or not and then engage in an action that was either avoidant or not. The avoidant actions included those that were superstitious – like knocking on wood – or non-superstitious – like throwing a ball.
They found that those who knocked down (away from themselves) or threw a ball believed that a jinxed negative outcome was less likely than participants who knocked up (toward themselves) or held a ball. In addition, the researchers found that engaging in an avoidant action had its effect by leading people to have a less vivid mental image of the negative event.
"Our findings suggest that not all actions to undo a jinx are equally effective. Instead, we find that avoidant actions that exert force away from one's representation of self are especially effective for reducing the anticipated negative consequences following a jinx" says Jane Risen, associate professor of behavioral science at the University of Chicago Booth School of Business. "Engaging in an avoidant action seems to create the sense that the bad luck is being pushed away."
Citation: Zhang, Yan, Risen, Jane L., Hosey, Christine, 'Reversing One’s Fortune by Pushing Away Bad Luck', Journal of Experimental Psychology: General, Aug 12 , 2013, doi: 10.1037/a0034023