Hundreds of customers at Walmart stores across the country took advantage of deals on top items, like televisions, video game consoles, and toys.

“Initially, we had Black Friday, which was the day after Thanksgiving when everybody did their shopping,” says Christopher Newman, an assistant professor of marketing at the University of Mississippi.

It’s known as goal contagion, says Art Markman, a professor of marketing and psychology at the University of Texas at Austin and author of “Brain Briefs.”

Yes, shoppers really do run through store doors at opening time, push their way through packed aisles and throw merchandise around in the process.

NerdWallet is a USA TODAY content partner providing general news, commentary and coverage from around the Web.