How Credit Cards Affect Our Brains

It’s been known for decades that credit cards encourage spending. But why that happens still isn’t entirely clear. New research offers some fresh insight into the causes—and how consumers might be manipulated in an increasingly cashless society.

Research on credit-card spending has tended toward the explanation that delaying payment removes a barrier to purchases in shoppers’ minds. A study published in February in Scientific Reports found evidence of another kind of trigger. Differences it found in brain activity between shoppers planning to use a credit card and those planning to buy with cash indicate that buying on credit doesn’t just ease shoppers’ inhibitions, it actively encourages purchases, the researchers say.

The upshot: When people are shopping with credit cards and see a product they like, the neural network in the brain that produces a sensation of reward perks up, which seems to create a craving to spend, says Sachin Banker, assistant professor at the University of Utah, who worked on the study as a Ph.D. student at the MIT Sloan School of Management.

“You’re basically feeling more reward when you shop with credit cards,” he says. “We don’t see that with cash. It was actually a very stark difference.”

Researchers used a form of magnetic resonance imaging to measure the brain activity of the study subjects as they participated in a shopping exercise. Each participant was shown a total of 84 everyday products over the course of three sessions and was asked whether they would buy each product at the stated price. Half the products were offered for purchase by credit card and half for purchase with cash. None of the products cost more than $50.

The differences in the shoppers’ brain activity support the hypothesis that after repeated credit-card purchases over time the brain learns to anticipate the rewards of credit-card shopping, according to the report. And that suggests that consumers could be conditioned to spend through the use of various sensory rewards in new payment systems, Dr. Banker says. For instance, with digital payments the use of particular sounds or vibrations on your smartphone when you make certain purchases but not others could, over time, teach your brain to anticipate rewards for buying specific products while you’re shopping.

Dr. Banker adds that further research could be done to see if the study’s theories hold true at higher prices. It also could study consumers who tend to overuse or misuse credit cards, to understand further why they act as they do. This study focused on people who mostly paid on time and used credit cards appropriately. Understanding brain patterns for other types of consumers could help lead to solutions that attempt to pre-empt harmful spending behaviour, Dr. Banker says.

The hottest crypto trade has turned cold. Some investors are saying “told you so,” while others are doubling down.

It was the move to make for much of the year: Sell shares or borrow money, then plough the cash into bitcoin, ether and other cryptocurrencies. Investors bid up shares of these “crypto-treasury” companies, seeing them as a way to turbocharge wagers on the volatile crypto market.

Michael Saylor pioneered the move in 2020 when he transformed a tiny software company, then called MicroStrategy , into a bitcoin whale now known as Strategy. But with bitcoin and ether prices now tumbling, so are shares in Strategy and its copycats. Strategy was worth around $128 billion at its peak in July; it is now worth about $70 billion.

The selloff is hitting big-name investors, including Peter Thiel, the famed venture capitalist who has backed multiple crypto-treasury companies, as well as individuals who followed evangelists into these stocks.

Saylor, for his part, has remained characteristically bullish, taking to social media to declare that bitcoin is on sale. Sceptics have been anticipating the pullback, given that crypto treasuries often trade at a premium to the underlying value of the tokens they hold.

“The whole concept makes no sense to me. You are just paying $2 for a one-dollar bill,” said Brent Donnelly, president of Spectra Markets. “Eventually those premiums will compress.”

When they first appeared, crypto-treasury companies also gave institutional investors who previously couldn’t easily access crypto a way to invest. Crypto exchange-traded funds that became available over the past two years now offer the same solution.

BitMine Immersion Technologies , a big ether-treasury company backed by Thiel and run by veteran Wall Street strategist Tom Lee , is down more than 30% over the past month.

ETHZilla , which transformed itself from a biotech company to an ether treasury and counts Thiel as an investor, is down 23% in a month.

Crypto prices rallied for much of the year, driven by the crypto-friendly Trump administration. The frenzy around crypto treasuries further boosted token prices. But the bullish run abruptly ended on Oct. 10, when President Trump’s surprise tariff announcement against China triggered a selloff.

A record-long government shutdown and uncertainty surrounding Federal Reserve monetary policy also have weighed on prices.

Bitcoin prices have fallen 15% in the past month. Strategy is off 26% over that same period, while Matthew Tuttle’s related ETF—MSTU—which aims for a return that is twice that of Strategy, has fallen 50%.

“Digital asset treasury companies are basically leveraged crypto assets, so when crypto falls, they will fall more,” Tuttle said. “Bitcoin has shown that it’s not going anywhere and that you get rewarded for buying the dips.”

At least one big-name investor is adjusting his portfolio after the tumble of these shares. Jim Chanos , who closed his hedge funds in 2023 but still trades his own money and advises clients, had been shorting Strategy and buying bitcoin, arguing that it made little sense for investors to pay up for Saylor’s company when they can buy bitcoin on their own. On Friday, he told clients it was time to unwind that trade.

Crypto-treasury stocks remain overpriced, he said in an interview on Sunday, partly because their shares retain a higher value than the crypto these companies hold, but the levels are no longer exorbitant. “The thesis has largely played out,” he wrote to clients.

Many of the companies that raised cash to buy cryptocurrencies are unlikely to face short-term crises as long as their crypto holdings retain value. Some have raised so much money that they are still sitting on a lot of cash they can use to buy crypto at lower prices or even acquire rivals.

But companies facing losses will find it challenging to sell new shares to buy more cryptocurrencies, analysts say, potentially putting pressure on crypto prices while raising questions about the business models of these companies.

“A lot of them are stuck,” said Matt Cole, the chief executive officer of Strive, a bitcoin-treasury company. Strive raised money earlier this year to buy bitcoin at an average price more than 10% above its current level.

Strive’s shares have tumbled 28% in the past month. He said Strive is well-positioned to “ride out the volatility” because it recently raised money with preferred shares instead of debt.

Cole Grinde, a 29-year-old investor in Seattle, purchased about $100,000 worth of BitMine at about $45 a share when it started stockpiling ether earlier this year. He has lost about $10,000 on the investment so far.

Nonetheless, Grinde, a beverage-industry salesman, says he’s increasing his stake. He sells BitMine options to help offset losses. He attributes his conviction in the company to the growing popularity of the Ethereum blockchain—the network that issues the ether token—and Lee’s influence.

“I think his network and his pizzazz have helped the stock skyrocket since he took over,” he said of Lee, who spent 15 years at JPMorgan Chase, is a managing partner at Fundstrat Global Advisors and a frequent business-television commentator.

How Credit Cards Affect Our Brains

Buying with plastic doesn’t just eliminate a barrier to buying. It actively encourages purchases.

Selloff in bitcoin and other digital tokens hits crypto-treasury companies.