What Happens in the Amygdala
Damage to Brain's Decision-Making Area May Encourage Dicey Gambles Individuals with amygdala damage are more likely to lay a risky bet. Most people would not gamble their savings, according to Benedetto De Martino of California Institute of Technology, author of a study published February 8 in Proceedings of the National Academy of Science. People tend to choose avoiding losses over acquiring gains—a behavior known as loss-aversion.
But people with damage to the amygdala—an almond-shaped part of the brain involved in emotion and decision-making—are more likely to take bigger risks with smaller potential gains, De Martino's study found. Two women with bilateral amygdala damage showed a dramatic reduction in loss aversion compared with age-matched control subjects on a series of experimental gambles, despite understanding full well the values and risks involved.
De Martino already suspected that the amygdala was crucial for loss-aversion based on earlier studies using functional magnetic resonance imaging (fMRI). In some cases, they chose to gamble even when the potential losses outweighed the potential gains. "Strangely enough, people with damage to the emotional system are, paradoxically, more rational in making certain types of decisions. Their decisions don't take into account any emotional processing." Whereas loss-aversion might sound abstract to an economist, De Martino says, it probably reflects a very ancient mechanism in the brain. De Martino's study suggests that the amygdala—known to be involved in processing fear—may make us afraid to risk losing money. "It may be that the amygdala controls a very general biological mechanism for inhibiting risky behavior when outcomes are potentially negative," De Martino says.