Newswise — Spend $200 on a great Christmas gift at the big box store and get a $50 gift card. Sounds like a great offer. It may, in fact, entice you to spend more than you normally would, warned a marketing expert at Washington University in St. Louis.

“Price promotions that feel too good to be true are always an opportunity for consumers to take an extra moment for reflection,” said Cynthia Cryder, associate professor of marketing at Olin Business School. “Instead of thinking about how much money they are ‘saving,’ consumers might want to stop to ask themselves: How much am I actually paying for this product, and am I willing to pay that much?”

Cryder and co-author Andong Cheng, of the University of Delaware, examined the phenomenon of this “mental discounting” in a new paper, “Double Mental Discounting: When a Single Price Promotion Feels Twice as Nice,” accepted in the Journal of Marketing Research.

With certain price promotions, such as a receiving a gift card to spend in the future, consumers mentally deduct the gift card’s value from the initial purchase as well as from the second purchase when they use the gift card. Multiple mental deductions based on a single price promotion result in consumers’ perceptions that their costs feel lower than they actually are, and can increase spending, Cryder said.

“Consider a situation in which a college student purchases a $900 Macbook and receives a $100 gift card to spend in an Apple store in the future,” Cryder and Cheng wrote in the paper. “Feeling confident that she will use the gift card, the student may mentally reduce the laptop cost and think: ‘I am spending only $800 (instead of $900) on this laptop because I am receiving $100 worth of credit back in my pocket.’

“Now imagine that later, the student is back in the store purchasing a $300 iPad. At this point, she applies the $100 gift card, resulting in a final $200 charge for the iPad,” they wrote. “She may think: ‘I am spending only $200 (instead of $300) for this tablet, because my gift card covers some of the cost.’ In total, this consumer has paid $1100 for the laptop and tablet, yet, because she mentally applied the price promotion to both purchases, she may feel as if she paid substantially less.”

According to industry research, Cryder said, businesses will load $14.5 billion onto promotional credit offers in 2017, triple the amount from 10 years ago.

“These promotions create opportunities for retailers, and consumers should carefully consider these offers before taking advantage of them,” Cryder said. “Although consumers might feel like they are spending less, these offers can sometimes encourage them to spend more.”

Journal Link: Journal of Marketing Research (forthcoming)