The hidden thrill of paying with a card

It might seem like a small choice: handing over cash or tapping a credit card. Yet, researchers have found that this decision can change not only how much we spend, but also how our brains respond. Paying with a card does more than make transactions easier — it appears to make spending itself more enjoyable.

In a study published two decades ago, MIT professor Drazen Prelec and his colleagues sought to understand why people often spend more with credit cards than with cash. Previous theories suggested two possibilities. One idea is that cards reduce the "pain" of paying — the discomfort of parting with money. 

To test these ideas, the researchers invited 28 participants to a lab. Each person brought a credit card and at least $50 in cash. Inside an fMRI scanner, participants were shown 84 products tailored to their interests and offered at significant discounts. Some items could only be bought with cash, while others required a credit card. Participants could add items to a virtual shopping cart, and at the end of the study, one item was randomly chosen and they paid for it with the indicated method. A few days later, the product was delivered to them.

The researchers focused on three areas of the brain. Two were linked to reward and pleasure, and one was associated with negative feelings such as pain and rejection. The results were striking. When participants had the option to pay with a credit card, the brain regions tied to reward and anticipation lit up far more than when using cash. These areas are the same regions that respond to addictive substances such as cocaine or amphetamines, although the researchers emphasised this does not mean people are addicted to credit cards in the same way.

Prelec described the effect as "putting a foot on the gas," making people more eager to spend. Sachin Banker, the lead author of the study, explained that cards appear to encourage people to act on their desire to buy, rather than simply dulling the discomfort of payment. He added that some individuals who are naturally more prone to addictive behaviours might be at greater risk of overusing credit cards.

Of course, the study had its limitations. It involved a small sample of participants, and all products in the test cost under $20, so it is not clear whether the same brain effects occur with larger purchases. 

The findings have wider implications for a world moving rapidly toward cashless payments. Credit cards are now the default payment method in the United States, and digital wallets are growing even faster. Prelec noted that economists often assume people already know what they want to buy and that the act of payment is neutral. But these results suggest the payment method itself can shape behaviour. By removing the friction of handing over cash, swiping or tapping may make people spend more than they intend.

This raises important questions for consumers, policymakers, and economists. If the act of payment triggers reward circuits in the brain, it could influence financial habits and budgeting decisions. It may also explain why overspending and credit card debt are common, even among otherwise careful consumers. Understanding the subtle ways technology interacts with human psychology is increasingly important in a cashless world.

In short, paying with a card is not just a convenience; it is an experience that engages our brains in a very particular way. The thrill of swiping may be small, but for many, it can quietly encourage spending.