Should you leave yourcomfortable job for one that pays better but is less secure? Should you have asurgery that is likely to extend your life but poses some risk that you willnot survive the operation? Should you invest in a risky startup company whose stockmay soar even though you could lose your entire investment? In the Jan. 26issue of the journal Science, UCLA psychologists present the first neuroscienceresearch comparing how our brains evaluate the possibility of gaining versuslosing when making risky decisions.
Participants in the study,mostly UCLA students in their 20s, were given $30 and then asked whether theywould agree to each of more than 250 gambles in which they had a 50-50 chanceof winning an amount of money or losing another amount of money. Would they,for example, agree to a coin toss in which they could win $30 but lose $20?While the 16 participants wereconsidering the possible wagers, they were in a functional magnetic resonanceimaging (fMRI) scanner at UCLA's
For each question, theparticipants answered whether they would strongly agree to the gamble, weaklyaccept it, weakly refuse it or strongly reject it. Participants were not toldwhether they had won or lost until after they left the scanner; afterwards, theresearchers randomly selected three of the gambles, and if the participants hadpreviously agreed to accept those, the researchers flipped a coin and theparticipants either won or lost the money. What interested the researchers,however, was the activity of the brain's regions during the decision-makingprocess, not the subject's reaction to winning or losing.
On average, participantsneeded to be offered a 50 percent chance of winning about $19 to risk losing$10, but that amount varied widely among the subjects. One subject, forexample, needed the chance to win $60 to risk losing $10, while another neededonly the chance to win $11 to risk losing $10. The researchers could predictpeople's tolerance to risk by analyzing their brain patterns.
"Looking at how your brainresponds to potential gains versus potential losses, we can predict howrisk-averse you are going to be in your choices," said study co-author Russell Poldrack, UCLAassociate professor of psychology, who holds UCLA's Wendell Jeffrey and Bernice Wenzel Term Chair in BehavioralNeuroscience. "Brain activity predicts behavior."
"Individual differences inbrain activity correspond very closely to individual differences inparticipants' actual choices," said co-author Craig Fox, an associate professorof policy at the UCLA Anderson School of Management and an associate professorof psychology. "The people who show much more neural sensitivity to lossesrelative to gains are the same people who are very reluctant to gamble unlessthey are offered extremely favorable gambles. The people who are about assensitive to losses as gains neurologically are the ones who are more willingto gamble."
Thinking about thepossibility of winning money turns on some of the same areas of the brain thatare activated when people take cocaine, eat chocolate or look at a beautifulface, Poldrack said.
The researchers studied whichparts of the brain became more active or less active as the amount of moneyparticipants could win or lose increased. Regions that become more active asthe amount increases are considered "reward centers" in the brain, such as theprefrontal cortex and the ventral striatum, Poldrack said.
The researchers also foundthat reward centers in the brain respond not only when we actually receiverewards but also when we make decisions about potential rewards, and that whenwe make decisions, the reward circuitry in the brain is more sensitive topossible losses than to possible gains.
The research is federallyfunded by the National Science Foundation's Human and Social Dynamics program (http://www.nsf.gov).
What happens in our brainwhen we think about potentially losing money? Some of the same areas that getturned on when we think about winning money get turned off when we think aboutlosing money.
A surprising finding is thatas the amount of a potential loss increases, the parts of the brain thatprocess fear or anxiety, such as the amygdala or the insula, are not activated.
"What we found instead," Poldrack said, "is you don't turn anything up. You turndown the reward areas of the brain, and you turn them down more strongly forlosses than you turn them up for gains. Just as people respond more strongly toa $100 potential loss than a $100 potential gain, the brain responds morestrongly to a $100 potential loss versus a $100 potential gain."
Fox, a behavioral decisiontheorist, said the study confirms previous research showing that people aremore turned off by losses than they are turned on by gains and it provides, forthe first time, neural evidence to support this pattern.
"We found for the first timethat the neural response to potential losses islarger than the neural response to potential gains," Fox said.
Poldrack and Fox said they are both comfortablewith risk in their lives, declining, for example, to buy insurance when theyrent cars and declining to buy extended warranties for products.
When Fox was anundergraduate at the
"In this new study, we found for the first time neurophysiologicalevidence for prospect theory, the most important behavioral model ofdecision-making to emerge in the past 50 years, whose components include theasymmetry between how losses and gains are valued," Fox said.
Sabrina Tom, a UCLA researchassistant in psychology and lead author of the study, said the people who havethe most deactivation in the reward pathways were also the most loss-averse.
A woman in a badmarriage, Tom said, is not likely to leave unless she has prospects that aremuch better than what she has.
"She's probablynot going to leave for something that's only moderately better," Tom said. "Sheneeds to know it's going to be a lot better before giving up what she alreadyhas."
The people whowere most willing to gamble were least turned on as the stakes got higher,while the people who were most averse to gambling were most turned on as gainsand losses increased, Poldrack said.
The biggestrisk-takers, who are willing to accept very risky gambles, have brains thatrespond less as the stakes increase, Poldrack said.