Today is One year ago was July 7, 2007, and Time magazine has declared it "the most popular wedding day ever." After all, the date 7-7-07 "carries some serious cosmic cachet," according to the Pittsburgh Times-Review.

Wait, wasn't I just writing about superstition just the other day?

I have been thinking about magical thinking all weekend, and my thoroughly non-scientific conclusion is that it seems to be the "default" way of thinking for human beings.

The behavioral psychologist B. F. Skinner believed that superstitions arise from coincidence combined with reinforcement. When a person experiences a fortuitous (or unfortuitous) event associated with something unrelated, posits Skinner, she may come to associate the unrelated thing with the stroke of fate. Then, whenever she experiences that unrelated thing, she will look specifically for the event she believes is connected to it. If the event doesn't happen, her thinking is not affected much, but if it does, the superstition is reinforced.

But that does not explain why superstitions become embedded in cultures. Everyone in the English-speaking world knows that the number 7 is good luck (hence the popularity of the 7-7-07 wedding) and 13 is bad luck. (Good thing 13-13-13 will never appear on the calendar.) In Chinese-related cultures, 4 is unlucky. Specific colors, animals, objects, and behaviors (like knocking on wood) are frequently co-opted into superstitions.

I think the popularity of superstitions stems from the natural human tendency toward magical thinking. It's probably an adaptive way to think, since in the nitty-gritty of daily life, magical thinking will usually do a person more good than harm. It's like the way the smarter animals think. In humans, the ability to reason seems to be appended to it.

Do you have any superstitions? What are some weird superstitions you have heard of?