We buy a lot of stuff we don't really need. The average American spends over $5,000 a year on impulse buys. A new study may have figured out an easy trick to help you avoid that habit, and save some real money.

The next time you're tempted to buy something, take a few seconds to think about something you already own. Think about the last time you used it, and why you like it. It doesn't even have to be similar to what you're about to buy.

Researchers at Rice University did a study with about 150 people. They had some of them reflect on things they owned, and describe how they use them. For example, one woman talked about her Kindle Fire and how she loves using it to read in bed.

Then they showed everyone five products: a sweater, a watch, a chair, a box of chocolates, and a coffee maker. The researchers then asked how much they'd pay for them. People who'd just thought about something they already owned were 14% less willing to buy the stuff than people who didn't do the exercise.