Ouch, that’s expensive!

As well as hurting your wallet, your brain expects an expensive product to cause you pain too. Researchers have found that in terms of brain activity, whether or not we choose to make a purchase is reflected in a trade-off between regions of the brain involved in anticipating pain and pleasure.

Twenty-six participants’ brains were scanned while they decided whether or not to purchase a series of products, including a DVD, chocolates and a book. On each trial, the participants were first shown the product, then its price and finally they made their purchasing decision. After each decision the participants rated their preference for the product and how much they would have been willing to pay for it.

When looking at a product, activity in the nucleus accumbens, the brain’s reward centre, was associated with subsequent self-reported product preference and also predicted a purchase. Meanwhile, during presentation of the price, activity in the medial prefrontal cortex, an area involved in weighing up relative gains and losses, also predicted a subsequent purchase, and was related to how much smaller the actual price was than the price a participant reported being prepared to pay. Finally, also during the price presentation, increased activity in the insula, a region involved in anticipating physical pain, predicted a decision not to purchase the product.

This shows the decision to buy was the result of a “hedonic competition between the immediate pleasure of acquisition and the equally immediate pain of paying”, said Brian Knutson and colleagues who conducted the study. They added this could help explain why people over-spend on credit cards. “The abstract nature of credit coupled with deferred payment may ‘anaesthetise’ consumers against the pain of paying”, they said.

Knutson, B., Rick, S., Wimmer, E., Prelec, D. & Lowenstein, G. (2007). Neural predictors of purchases. Neuron, 53, 147-156.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.