Save money: shop when you're happy!

Looking to avoid overpaying on trips to the mall? Don't shop when you're in a bad mood.

At least that's the conclusion of a study conducted by researchers at Harvard, Carnegie Mellon, Stanford, and Pittsburgh universities. In the study, participants who had just watched a sad movie clip were inclined to pay, on average, 4 times as much for an insulated water bottle as those who watched an emotionally neutral clip.

Harvard professor Jennifer Lerner told the Associated Press that "This is a phenomenon that occurs without awareness. This is really different from the idea of retail therapy, where people are feeling negative and want to cheer themselves up by shopping. People have no idea this is going on."

Interestingly, most participants insisted that they weren't basing their offer price on the movie clip they had just seen -- not surprising. Who in their right mind would pay more for a water bottle based on a video they just saw? But apparently that's exactly what they did.

I guess the lesson here is to avoid extravagant spending when you're in a bad mood. But if you're down in the dumps and a $3 water bottle might cheer you up, I say go for it.