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Brain’s “shopping circuitry” mapped

Jan. 3, 2007
Courtesy Cell Press
and World Science staff

Sci­en­tists say they’ve mapped the brain ar­eas ac­ti­vat­ed when shop­pers judge how much they want a prod­uct, ver­sus feel­ing the pain of pay­ing. 

The re­search­ers iden­ti­fied those re­gions so pre­cise­ly, they said, that they could pre­dict wheth­er some­one would buy a prod­uct or not, just by watch­ing the brain ac­tiv­i­ty dur­ing the de­ci­sion.

A weak­ness for cred­it card shop­ping sprees may be root­ed in your brain, re­search­ers say.

The find­ings could help economists for­mu­late poli­cies to en­cour­age sav­ing and to pro­tect con­su­mers against cred­it card over­spend­ing—a re­gret­ta­bly “pain­less” way of pay­ing, to many, the re­search­ers said.

Bri­an Knut­son of Stan­ford Uni­ver­si­ty in Stan­ford, Ca­lif., and col­leagues pub­lished their find­ings in the Jan. 4 is­sue of the re­search jour­nal Neu­ron.

The scientists asked vol­un­teers to make rap­id-fire shop­ping de­ci­sions. The part­i­ci­pants viewed pro­d­ucts on a com­pu­ter screen, along with pric­es, and were asked to choose wheth­er to “buy” the prod­uct or not. To main­tain shop­pers’ in­ter­est, prices were kept low. 

Although most of the pur­chases were vir­tu­al, the sci­en­tists ran­dom­ly des­ig­nat­ed a real pur­chase among the items shop­pers “bought.” The re­search­ers de­duct­ed the cost from a $20 ac­count giv­en to sub­jects for the ex­per­i­ment, and de­liv­ered the prod­uct.

As the vol­un­teers went through the shop­ping pro­cess, the re­search­ers scanned their brains us­ing func­tion­al mag­net­ic res­o­nance im­ag­ing. This wide­ly used im­ag­ing tech­nique in­volves us­ing mag­net­ic fields and ra­di­o waves to de­ter­mine blood flow in brain re­gions, which re­flects brain ac­tiv­i­ty.

After the shop­ping phase, the sub­jects were asked to rate the prod­ucts’ de­sir­a­bi­lity and what per­cent­age of the re­tail price they would be will­ing to pay for it.

The re­search­ers found that spe­cif­ic re­gions of the brain’s cor­tex, the out­er lay­er of the brain deal­ing with more com­plex thought, were ac­tive in dif­fer­ent com­po­nents of the shop­ping pro­cess. The nu­cle­us ac­cum­bens, part of the brain’s re­ward cen­ter, ac­ti­vat­ed when the sub­jects were judg­ing how de­sir­a­ble the prod­uct was. Ex­ces­sive prices ac­ti­vat­ed the in­su­la and deac­ti­vat­ed the me­di­al pre­fron­tal cor­tex, both in the cor­tex.

“This find­ing has im­pli­ca­tions for un­der­stand­ing be­hav­ior­al anoma­lies, such as con­sumers’ grow­ing ten­den­cy to over­spend and un­der­save when pur­chas­ing with cred­it cards rath­er than cash,” they wrote. “The ab­stract na­ture of cred­it cou­pled with de­ferred pay­ments may ‘anes­thetize’ con­sumers against the pain of pay­ing.”

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Scientists say they’ve outlined the brain areas activated when shoppers judge how much they want a product, versus feeling the pain of paying. The researchers identified those regions so precisely, they said, that they could predict whether someone would buy a product, just by looking at the brain activity during the decision whether to buy. The findings could help economists formulate policies to encourage saving and to protect consumers against credit card overspending—a regrettably “painless” way of paying to many, the researchers said. Brian Knutson of Stanford University in Stanford, Calif., and colleagues published their findings in an article in the Jan. 4, issue of the research journal Neuron. The researchers subjected volunteers to rounds of rapid-fire shopping decisions, in which they were presented products, given the products’ prices, and asked to decide whether to “buy” the product or not. To keep the shoppers’ interest, the products were presented at bargain-basement prices. Also, while most of the purchases were mostly virtual, the scientists randomly designated a purchase among the series that the shoppers actually bought, deducting the cost from a $20 account given them for the experiment, and actually delivering the product. As the volunteers went through the shopping process, the researchers scanned their brains using functional magnetic resonance imaging. This widely used imaging technique involves using magnetic fields and radio waves to determine blood flow in brain regions, which reflects brain activity. Following the shopping phase, the subjects were asked to rate the products’ desirability and what percentage of the retail price they would be willing to pay for it. The researchers found that specific regions of the brain’s cortex, the outer layer of the brain dealing with more complex thought, were active in different components of the shopping process. The nucleus accumbens, part of the brain’s reward center, activated when the subjects were judging how desirable the product was. Excessive prices activated the insula and deactivated the medial prefrontal cortex, both in the cortex. “This finding has implications for understanding behavioral anomalies, such as consumers’ growing tendency to overspend and undersave when purchasing with credit cards rather than cash. Specifically, the abstract nature of credit coupled with deferred payments may “anesthetize” consumers against the pain of paying. Neuroeconomic findings might eventually suggest methods of restructuring institutional incentives to facilitate increased saving,” they wrote.