Today is July 13. It's the third Friday the 13th of 2012. Are you scared?

Having three occurrences of Friday the 13th in one year is unique, especially when the three dates fall exactly 13 weeks apart, like they do this year. That hasn't happened since 1984.

So why does the Friday the 13th superstition stick so firmly in our minds? According to Thomas Gilovich, who chairs the department of psychology at Cornell University, our brains are almost too good at making associations:

"If anything bad happens to you on Friday the 13th, the two will be forever associated in your mind, and all those uneventful days in which the 13th fell on a Friday will be ignored."

The next year in which we'll have three Friday the 13ths is 2015. They'll fall in February, March and November.