May 12, 2011 5:41 PM
TUCSON - A new study by University of Arizona researchers used MRI imagery to prove what psychologists have been saying for years: people often cooperate out of guilt.
"One idea is that most people cooperate because it feels good to do it. And there is some brain imaging data that shows activity in reward-related regions of the brain when people are cooperating," says Luke Chang, a doctoral student at the UA psychology department. "But there is a whole other world of motivation to do good because you don't want to feel bad. That is the idea behind guilt aversion."
An unlikely team of cognitive neuroscientists, psychologists and economists devised a study in which 30 volunteers played a game where they were given money by an investor, and their brains were scanned as they decided how much money should be returned to their investors.
"The theory will then operate on the expectations the players have," said Martin Dufwenberg, a behavioral economist in the UA Eller College of Management. "I would feel guilt if I give you less than I believe that you expect that you will get. Then we measure expectations in the experimental situation. The theory predicts when people will experience guilt. Then we see how that correlates with brain activity."
Different areas of the brain became active during these decisions, on whether to cooperate or abuse the trust of their investor and maximize their own gain.
The results showed that there was a neural system that "plays a critical role is assessing moral sentiments that in turn can sustain human cooperation in the face of temptation."
The collaboration of economists, psychologists and neuroscientists was instrumental in understanding the biological drive behind complex social behavior, such as guilt, Chang says.
"In the end, it's a two-way exchange. Economists take inspiration from the richer concept of man usually considered in psychology, but at the same time they have something to offer psychologists through their analytical tools," says Dufenberg.
Pictured: The fMRI image above depicts areas of the brain associated with the competing motivations of minimizing guilt (yellow) and maximizing financial reward (blue) when participants decide whether or not they want to honor an investment partner's trust. The motivation to minimize guilt is associated with the insula, anterior cingulate cortex and supplementary motor area (yellow). The motivation to maximize financial reward is associated with the ventral striatum, ventromedial prefrontal cortex and dorsomedial prefrontal cortex. (Image courtesy Luke Chang/UA psychology department via UANews.org)