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It is a somewhat unexpected conclusion. After all, you would thinkthat the more people are paid, the harder they will work, and thebetter they will do their jobs -- until they reach the limits oftheir skills. That notion tends to hold true when the stakes arelow, says Vikram Chib, a postdoctoral scholar at Caltech and leadauthor on a paper published in the May 10 issue of the journal Neuron . Previous research, however, has shown that if you pay people toomuch, their performance actually declines. Some experts have attributed this decline to too much motivation:they think that, faced with the prospect of earning an extra chunkof cash, you might get so excited that you will fail to do the taskproperly. But now, after looking at brain-scan data of volunteersperforming a specific motor task, the Caltech team says that whatactually happens is that you become worried about losing yourpotential prize. The researchers also found that the more someoneis afraid of loss, the worse they perform. In the study, each participant was asked to control a virtualobject on a screen by moving an index finger that had a trackingdevice attached to it. The virtual object consisted of two weightedballs connected by a spring. The task was to place the object,which stretched and contracted as a weighted spring would in reallife, into a square target within two seconds. The researchers controlled for individual skill levels bycustomizing the size of the target so that everyone would have thesame success rate. That way, people who happened to be really goodor bad at this task would not skew the data. After a training period, the subjects were asked to perform thetask while inside an fMRI machine, which measures blood flow in thebrain -- a proxy for brain activity, since wherever a brain isactive, it needs extra oxygen, and thus a larger volume of blood.By monitoring blood flow, the researchers can pinpoint areas of thebrain that turn on when a particular task is performed. The task began with the researchers offering the participants arandomized range of rewards -- from $0 to $100 -- if they couldsuccessfully place the object into the square within the timelimit. At the end of hundreds of trials -- each with varying rewardamounts -- the participant was given their reward, based on theresult of just one of the trials, picked at random. As expected, the team found that performance improved as theincentives increased -- but only when the cash reward amounts wereat the low end of the spectrum. Once the rewards passed a certainthreshold, which depended on the individual, performance began tofall off. Incentives are known to activate a part of your brain called theventral striatum, Chib says; the researchers thus expected to seethe ventral striatum become increasingly active as they bumped upthe prizes. And if the conventional thought were correct -- thatthe reason for the observed performance decline was over-motivation-- they would expect the striatum to continue showing a lot ofactivation when the incentives became high enough for performanceto suffer. What they found, instead, was that when the participants were showntheir potential rewards, activity in the striatum did indeedincrease with rising incentives. But once the volunteers starteddoing the task, striatal activity decreased with rising incentives. They also noticed that the less activitythey saw in a participant's striatum, the worse that personperformed on the task. Other studies have shown that decreasing striatal activity isrelated to fear or aversion to loss, Chib says. "When peoplesee the incentive that they're being offered, they initially encodeit as a gain," he explains. "But when they're actuallydoing the task, the thing that causes them to perform poorly isthat they worry about losing a potential incentive they haven'teven received yet." He adds, "We're showing loss aversioneven though there are no explicit losses anywhere in the task --that's very strange and something you really wouldn't expect." To further test their hypothesis, Chib and his colleagues decidedto measure how loss-averse each participant was. They had theparticipants play a coin-flip game in which there was an equalchance they could win or lose varying amounts of money. Each participant was offered varying potential win-loss amounts($20-$20, $20-$10, $20-$5, for example), and then given theopportunity to either accept each possible gamble or decline it.The win-loss ratio at which the subjects chose to take the gambleprovided a measure of how loss-averse each person was; someonewilling to gamble even when they might win or lose $20 is lessloss-averse than someone who is only willing to gamble if they canwin $20 but only lose $5. Once the numbers had been crunched and compared to the originalexperiment, it turned out that the more averse a participant was,the worse they did on the task when the stakes were high. And for aparticularly loss-aversive person, the threshold at which theirperformance started to decline did not have to be very high."If you're more loss-averse, it really hurts you," Chibsays. "You're going to reach peak performance at a lowerincentive level, and your performance is also going to be worse forhigher incentives." "Previously, it's been shown that the ventral striatum isinvolved in mediating performance increases in response to risingincentives," says John O'Doherty, professor of psychology andcoauthor of the paper. "But our study shows that changes inactivity in this same region can, under certain situations, alsolead to worsening performance." While this study only involved a specific motor task and financialincentives, these results may well be universal, says ShinsukeShimojo, the Gertrude Baltimore Professor of ExperimentalPsychology and another coauthor of the study. "Theimplications and applications can include any sort of decisionmaking that contains high stakes and uncertainties, such asbusiness and politics." These findings, the researchers say, might be used to develop newways to motivate people to perform better or to train them to beless loss-averse. "This loss aversion can be an important wayof deciding how to set up incentive mechanisms and how to figureout who's going to perform well and who isn't," Chib says."If you can train somebody to be less loss-averse, maybe youcan help them avoid performing poorly in stressfulsituations." The other author on the Neuron paper, "Neural mechanisms underlying paradoxical performancefor monetary incentives are driven by loss aversion," isformer Caltech postdoc Benedetto De Martino, who is now at theUniversity College of London. Funding was provided by the NationalScience Foundation, the Gordon and Betty Moore Foundation, theJapanese Science and Technology Agency's Exploratory Research forAdvanced Technology program, and the Caltech/Tamagawa UniversityGlobal Center of Excellence program. We are high quality suppliers, our products such as Hospital Furniture Chairs , China Homecare Hospital Bed for oversee buyer. To know more, please visits Medical Hospital Beds.
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