Maybe you have to tap the plane three times as you board. Maybe you can't watch your beloved Eagles play without wearing your lucky (and desperately in need of washing) green socks. Maybe you're stressing out because it's Friday the 13th and your neighbor's black cat just darted past your bedroom window. But what makes some people superstitious, while others can pay no mind to, say, being seated in row 13, or don't feel compelled to knock on wood after making a bold pronouncement?