RISKY RESEARCH: Damage to the amygdala encourages bad gambles, scientists say.
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Imagine you've lost your job. You have some money saved, and a chance to double it with a gamble. But if you lose the bet, you'll forfeit everything. What would you do?
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). But these two rare cases with damage to the very structure in question allowed De Martino to directly test his hypothesis. "In functional MRI, you never know if the response is reflecting something else. With the amygdala injury, you have an on "off" response," De Martino says.
Whereas healthy control subjects who stood to win $20 but lose $15 were less likely to gamble than if they stood to win $50 but lose only $10, the two patients with amygdala damage were much less affected by the disparity between potential gains and losses. In some cases, they chose to gamble even when the potential losses outweighed the potential gains.
The concept of loss-aversion can be applied to many things. Take, for example, someone considering elective surgery. The more serious the possible complications—not matter how unlikely—the less likely he or she is to proceed. But De Martino is especially interested in how loss-aversion applies to money. "My dream would be an economic theory that could capture the complexities of human behavior, based on real people and real brains rather than assumptions," he explains. De Martino's field of study is aptly named neuroeconomics. "It is a more biological view of social science," he says. "A lot of economic theorists think about humans as machines and forget about emotional processing."
In previous work, De Martino showed that amygdala damage makes people behave more like these theoretical machines. "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."
Interestingly, the older of the two women not only lacked loss-aversion, she was even loss-seeking. This difference between the two women was mirrored by differences between their age-matched controls. "As you get older, you get less loss-averse," De Martino says, explaining that even the older control subjects were less fearful of loss. "Your perspective on life changes because you have fewer years to live." This effect could stem from age-related reductions in the volume of the amygdala—as we age, our brains shrink. De Martino says in addition to age, other factors such as income and education are also at play.
The amygdala damage did not appear to affect risk-aversion—a similar behavior with an important difference. People who are risk-averse are less likely to take chances even when they have nothing to lose.
Whereas loss-aversion might sound abstract to an economist, De Martino says, it probably reflects a very ancient mechanism in the brain. "Think about an animal. It has to get food, but at the same time it has to protect itself from predators. It would be very wise for an animal to weigh gains and losses from an evolutionary perspective." Although a long time has passed since humans had to worry about predators, financial well-being is necessary for survival in the modern world, albeit more abstractly. 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.
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10 Comments
Add CommentAnd what causes such damage? A blow to the head? A high fever? A mind worm?
Reply | Report Abuse | Link to thisThe amygdala is part of the mood regulating system and when this system dysregulates parts of the brain are destroyed gradually by cortisols primarily. This might be thought of as a kind of autoimmune type activity where the body is attacking itself. Alternatively this is possible with MS or in cases of subsyndromal MS. If you are like this a gadolinium enhanced MRI study is in order. You also want white matter hyperintensities checked and signs of volume loss indicating atrophy in this and other brain regions. Alternatively the problem may be adrenal possibly Cushing's Disease
Reply | Report Abuse | Link to thisThe amygdala is part of the mood regulating system and when this system dysregulates parts of the brain are destroyed gradually by cortisols primarily. This might be thought of as a kind of autoimmune type activity where the body is attacking itself. Alternatively this is possible with MS or in cases of subsyndromal MS. If you are like this a gadolinium enhanced MRI study is in order. You also want white matter hyperintensities checked and signs of volume loss indicating atrophy in this and other brain regions. Alternatively the problem may be adrenal possibly Cushing's Disease
Reply | Report Abuse | Link to this"A lot of economic theorists think about humans as machines and forget about emotional processing."
Reply | Report Abuse | Link to thisUh, that would be almost ALL economists. Economics is based on an assumption that all participants in an economy are rational. Since very FEW people in any economy are rational, economics is flawed at its most basic level.
"Your perspective on life changes because you have fewer years to live." Bupkis. Life perspective changes because we have more experience to draw from and our perspective of reality is changed.
Reply | Report Abuse | Link to thisI didn't get the difference between risk-aversion and loss-aversion.
Reply | Report Abuse | Link to thisI didn't get the difference between risk-aversion and loss-aversion.
Reply | Report Abuse | Link to thisI agree the human body is mere a machine with brain activity regulated neurological inpulsen. Education, cause and effect awarnes and efficient moral dissapline is the degree of how we are in control of the neurological impulsen of the body and the living world around us.
Reply | Report Abuse | Link to thisWhat role, if any, does the amygdala play in social media risk taking? Is it as simple as the lack of sensory input?
Reply | Report Abuse | Link to thisthe part plays even without sensory input.
Reply | Report Abuse | Link to thisor does not.
if damage is loss, then it is nature over nurture.