Imagine you're about to make a big purchase like this car.

You've negotiated a great deal and you're ready to pull out your check book when your cell phone rings.

Well according to one study, when you come back to the table there's a good chance you'll be adding some upgrades, like the heated seats and leather interior.

Researchers found that when we buy a big-ticket item, our decision-making process initially tends to focus on details like price, and whether we can afford it.

But when that process gets interrupted--even by a quick phone call--we have time to start focusing on what we really want.

In other words, the decision switches from a rational one--to an emotional one.

And considering how many distractions we face every day, making a big purchase could cost you--big time.

So the next time you're buying something expensive, like a car or vacation, stay focused--and turn off that cell phone.