Thursday, January 11, 2007
Shoes and the dark secrets of the prefrontal cortex
Consumer preference and price are the two main components of Micro-economic Theory which has been accepted as a credible explanation for what drives what we buy, including shoes. Now scientists at Stanford University have demonstrated definite cerebral activity using event-related efMRI . This is a technique for detecting the brain’s response to brief stimuli or “events”. efMRI allows detection of the Blood Oxygenation Level Dependent (BOLD) haemodynamic response to neural activity, with a spatial resolution of millimeters and a temporal resolution of hundreds of milliseconds.
The nucleus accumbens (NAcc) is activated with product preference and excessive prices activated the insular cortex and deactivated the mesial prefrontal cortex (MPFC) prior to the purchase decision. Activity from each of these regions independently predicted immediately subsequent purchases above and beyond self-report variables. These findings suggest that activation of distinct neural circuits related to anticipatory affect precedes and supports consumers' purchasing decisions. Simply put when people see shoes they want to purchase, the nucleus accumbens is stimulated. When the price tag is considered too high, the insular complex becomes activate and the mesial prefrontal cortex (MPFC) is deactivated. Scientist were able to predict the purchase behaviours of consumers before they were conscience of making a decision using the scanning technique.
Researchers at University of Iowa have previously shown compulsive hoarders may have a problem in their right mesial prefrontal cortex, after studying pathological collectors. They found that damage to the frontal lobes of the brain impaired judgement and caused emotional disturbances. But only when the injury extended to the right mesial prefrontal cortex, did the subjects develop a serious collecting habit. Other studies in humans with bilateral damage of the ventromedial (VM) prefrontal cortex show that VM subjects develop severe impairments in decision making.
Research has also linked abnormality in the right mesial prefrontal cortex with paraphilia. The Prefrontal systems have been associated with several aspects of sexual behavior and human neuroimaging in normal individuals found activation of right prefrontal cortex during both sexual arousal and orgasm. Neuroanatomical differences have been found in the prefrontal cortex of individuals with antisocial personality disorder. Thus, it is possible that neurological deficits relate to sex offenses, possibly violent and nonviolent. The Stanford University researchers are planning to investigate brain activity in people with a more "pathological" relationship to shopping and hope future findings can help explain why it feels easier for many people to buy with a credit card than to spend cash.
Knutson B, Rick S. Wimmer SE, Prelec D, and Loewenstein G. 2006 Neural Predictors of Purchases
Knutson B. Wimmer GE, Rick S, Hollon NG, Prelec D, and Loewenstein G 2008 Neural predictors of the Endowment Effect Neurone 58, 814-822