Why do Black Friday shoppers throw punches over bargains?

  Black Friday, the most celebrated shopping day of the year, abounds with tales of fistfights over discounted televisions or even stampedes as consumers rush to get that low-priced sweater they saw in an ad.

  Many people chalk it up to bad behavior. But marketers like me have a term to describe one feeling that contributes to it: psychological ownership.

  Have you ever felt as if another driver stole your parking spot? Or were supremely miffed when someone else nabbed the last red sweater that you had your eye on? And isn’t it irritating when someone else receives credit for your idea? If so, you have experienced psychological ownership.