wallet(Photo: Jonathan Kitchen; Getty Images)

According to researchers at the University of Winnipeg, you spend less when you use crisp cash than old, dirty bills.

Researchers gave college students $20 and told them they could buy as much as they wanted from a mock store. Half of the students were given new bills, while the other half were given old, crinkled cash. After rating how clean each bill appeared, the students spent the fake money, and kept whatever they bought along with the leftover cash. The results: Students carrying a crisp $20 bill spent $3.86 on average, while the dirty money students spent $8.35.

Researchers believe it's a matter of pride. You resist selling your Hank Aaron autographed baseball because you're proud of it, and it makes you feel more significant. It's the same with money: Crisp bills make you feel proud and powerful, so you're less willing to give them up. On the flip side, worn bills bring up feelings of dirtiness and contamination, thereby devaluing them, the researchers say. (Learn about 6 tricky money talks every man must have.)

Your money move: Save your credit card for big purchases, and bring on the Benjamins for smaller stocking stuffers. Researchers at the University of California found that you spend less with the big bucks--i.e. $100 bills--because you realize just how much you're spending when you're break down one large bill instead of paying with smaller ones.

Plus, you make fewer impulse buys with cash than credit, because pain centers in your brain actually activate when you hand over the bills, according to researchers at MIT.