If you've ever come out of a supermarket with a cart-load of unhealthy foods, which you later regret buying (and eating), it might not just be a lack of willpower. According to a study published this month in the Journal of Consumer Research (subscription required), researchers suggest that credit cards mediate the pain of parting with hard-earned cash, making it easier to load up on Oreos, coffee cakes, and Cokes when you pay with plastic.
On the flip side, our intuitive feelings about spending cash could help control that impulsive behavior.
Manoj Thomas, one of the study’s authors and a marketing professor at Cornell University, examined the habits of 1,000 shoppers at one chain grocery store. After looking over their receipts for a six-month period, he crunched the data and found that credit or debit cards contributed to impulsive purchases of "vice products." The reason: paying with plastic is "emotionally more inert" and "abstract." Cold hard cash, on the other hand, is concrete. You can see it.
"Normally paying by cash is no different than paying by debit card, but psychologically, paying by cash feels different," Thomas told me. "It becomes more difficult to justify. Why am I spending three dollars on a slice of cheesecake when I know cheesecake is unhealthy?"
Because it's less pleasurable to think about parting with a paper Jackson than charging twenty dollars on your Visa, cash can act as an aversive "visceral regulator"—one that could be more effective than our willpower alone to cut out the desire to buy that cheesecake now.
The implications of the research are certainly worth adding to our arsenal of obesity-fighting techniques. But given the proliferation of automated checkouts and a half-century's worth of automated supermarket technologies, cash-only supermarkets, or even cash-only candy stores, are probably out of the question.
So perhaps there's another way to integrate the research into our lives. In Predictably Irrational, Dan Ariely suggests "self-control credit cards" that come with a $50 limit on chocolate purchases. Thomas has another solution that doesn't sound all that far-fetched: a credit card that shows your debt as soon as you swipe it. Who knows? Seeing those numbers might not be as painful as paying cash, but could be an emotional nudge away from unwanted consumption.