STORY BYAn admitted shopoholic, I will budget $20 a month for groceries and the rest for shopping. My new purchases make me happy, unlike groceries, which make my pants shrink. Needless to say, this financial behavior is less than optimal.
So, why does my brain continue to let me buy instead of pulling me up by my purse straps?
A new study at Stanford University examines brain areas involved in financial decisions, a new branch of study known as neuroeconomics. “It’s an important part of human behavior,” states Michael S. Beauchamp, assistant professor in the Department of Neurobiology and Anatomy at The University of Texas Medical School at Houston. “Everyone likes to shop.”
Neuroeconomists are interested in how people make financial decisions and how the brain participates in the process—valuable information for consumers, advertisers, store architects and hopeless shopoholics.
The study ultimately tests a current theory of shopping behavior: that purchasing decisions are the result of a tug-of-war between the pleasure of purchasing and the pain of paying.
Shoppers “virtually” purchased items (simulated on a computer) while being monitored by functional magnetic resonance imaging (fMRI). This machine provides an indirect measure of brain activity via the blood oxygen level dependent (BOLD) signal. The brain is constantly consuming oxygen from the blood, which means there is a baseline BOLD signal when a person is just sitting in the MRI machine.
“The fMRI is the only way in which you can non-invasively measure brain activity with high spatial resolution in normal human subjects,” Beauchamp explains. “What happens is the brain sends more blood to regions that are more active, resulting in an increase in the BOLD signal.”
Research subjects performing a virtual shopping task were shown a product for a period of time, then shown the price, and finally asked to decide whether or not they would purchase the product. Researchers found that the three distinct stages of the purchasing task resulted in activation of distinct areas of the brain.
In the first stage of the task, subjects viewed a product and reported if they would consider purchasing it. A positive preference correlated with a small increase in activation of the nucleus accumbens (NAcc), a part of the brain’s striatum, known as the “reward center.”
“The nucleus accumbens is a key reward center, but it is a very small part of the human brain. Small structures are hard to study with fMRI,” Beauchamp says. Increased activity in the NAcc is associated with conversion of motivation into action, explaining its role in item preference, an evaluation of the desirability of an object based on the reward of ownership.
The second stage of the task was the presentation of the price. Most of us shoppers agree that we have an idea of the approximate amount of money we’re willing to part with for an item. The difference between this amount and the ugly price reality is called the price differential.
Presentation of the price of the item correlated with increased bilateral (both sides of the brain) activation of the medial prefrontal cortex (MPFC), an area at the front of the brain responsible for decision making and planning. Greatest activation of the MPFC occurred when the actual price was lower than anticipated. (In shopping parlance, this is known as “a great deal.”)
The final step was purchasing, which correlated with deactivation of the right insula. This area, which activates with anticipation of pain and negative arousal, is your brain’s detector for all things nasty. Deactivation of the insula means that the shopper had reduced negative feelings toward the purchase, thus driving the final decision.
On average, subjects purchased 30 percent of the total 80 items. Why the restraint? Perhaps it’s because with this task, shoppers did not actually purchase the products. They may have been shopping and thinking in a manner different from what happens out of the laboratory—in a mall or online. There is no way to reproduce the total shopping experience—sights, sounds and triggers we shoppers absorb subconsciously. Thus the activation profiles also may not accurately reflect what is happening during actual shopping.
“For example, if you see an avocado at the supermarket, then you think about whether you feel like eating guacamole or not, and that’s how you’re making your buying decision,” Beauchamp says.
“We can never completely reflect a natural situation in the MR scanner. Brain activity may be similar, but not exactly the same,” Beauchamp says. “Appetitive circuits may not be fully represented.”
The Stanford study group found that they only needed activity profiles of the three brain areas during the appropriate steps to predict purchasing with 60 percent accuracy. Although other brain areas were activated in the distinct stages of the task, NAcc, MPFC and right insula activity profiles alone predicted purchasing more accurately than self-reported measures.
“The question is, are those three areas more critical than all the other brain areas?” Beauchamp asks. “The other regions may be just as important. With a complex cognitive task, there are dozens of brain areas that are likely to be involved.”
Financial behavior in this virtual shopping task resulted from changes in activity from the brain’s resident hedonist, penny pincher and nasty detector. Scientists may refer to them as the nucleus accumbens, medial prefrontal cortex, and insula, respectively. One could speculate that, for shopoholics, the hedonist may rule the land.
“Even if there are 20 brain areas involved, some will be more important and some less important predictors,” states Beauchamp.
More research is required to understand what happens to the brain on retail, but for rational shoppers, the take-home message is: Purchasing is a pleasure if the price is right.
UPDATED: 3-06-2007
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Dr. Michael S. Beauchamp is an assistant professor in the Department of Neurobiology and Anatomy at the UT Medical School.
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