Editors’ Note: Portions of this post appeared in similar form in an April, 2010, column by Jonah Lehrer for the Wall Street Journal and in a July, 2009, article for the Guardian, which was an excerpt of Lehrer’s book “How We Decide.” We regret the duplication of material.

Last Sunday, at the Memorial golf tournament in Dublin, Ohio, Rickie Fowler looked like the man to beat. He entered the tournament with momentum: Fowler had recently gained his first ever P.G.A. tour victory, and he had finished in the top ten in his last four starts. On the first hole of the final round, Fowler sank a fourteen-foot birdie putt, placing him within two shots of the lead.

And that’s when things fell apart. Fowler pulled a shot on the second hole and never recovered. On the next hole, he hit his approach into a greenside bunker and ended up three-putting for a double bogey. He finished with an eighty-four, his worst round on the tour by five shots. Although he began the day in third place, he finished in a tie for fifty-second, sixteen shots behind the winner, Tiger Woods.

In short, Fowler choked. Like LeBron James—who keeps on missing free throws when the game is on the line—he seems to have been undone by the pressure of the situation. And choking isn’t just a hazard for athletes: the condition also afflicts opera singers and actors, hedge-fund traders and chess grandmasters. All of sudden, just when these experts most need to perform, their expertise is lost. The grace of talent disappears.

As Malcolm Gladwell pointed out in his 2000 article on the psychology of choking, the phenomenon can seem like an amorphous category of failure. Nevertheless, choking is actually triggered by a specific mental mistake: thinking too much. The sequence of events typically goes like this: When people get anxious about performing, they naturally become particularly self-conscious; they begin scrutinizing actions that are best performed on autopilot. The expert golfer, for instance, begins contemplating the details of his swing, making sure that the elbows are tucked and his weight is properly shifted. This kind of deliberation can be lethal for a performer.

Sian Beilock, a professor of psychology at the University of Chicago, has documented the choking process in her lab. She uses putting on the golf green as her experimental paradigm. Not surprisingly, Beilock has shown that novice putters hit better shots when they consciously reflect on their actions. By concentrating on their golf game, they can avoid beginner’s mistakes.

A little experience, however, changes everything. After golfers have learned how to putt—once they have memorized the necessary movements—analyzing the stroke is a dangerous waste of time. And this is why, when experienced golfers are forced to think about their swing mechanics, they shank the ball. “We bring expert golfers into our lab, and we tell them to pay attention to a particular part of their swing, and they just screw up,” Beilock says. “When you are at a high level, your skills become somewhat automated. You don’t need to pay attention to every step in what you’re doing.”

But this only raises questions: What triggers all of these extra thoughts? And why does it only happen to some athletes, performers, and students? Everyone gets nervous; not everyone chokes.

A new study in Neuron, by a team of neuroscientists at Caltech and University College of London, begins to solve this mystery. The experiment featured a simple arcade game, in which subjects attempted to move a virtual ball into a square target within two seconds. To make the task more difficult, the ball appeared to be weighted and connected to a spring, which flexed and bent as if it were real.

After a short training period, the subjects were put into an fMRI machine and offered a range of rewards, from nothing to a hundred dollars, if they could successfully place the ball into the square. (The subjects were later given an actual reward based on their score.) At first, their performance steadily improved as the incentives increased; the extra money was motivating. However, this effect only lasted for a little while. Once the rewards passed a certain threshold—and the particular tipping point depended on the individual—the scientists observed a surprising decrease in success. The extra cash hurt performance; the subjects began to choke.

Because the game was unfolding inside a brain scanner—an admittedly imperfect tool, which uses changes in blood flow as a proxy for neural activity—the scientists could begin to decipher the mental mechanics behind this process. They quickly zeroed in on a subcortical region called the ventral striatum, which has been implicated in the processing of various pleasures, from taking cocaine to eating ice cream to receiving cash gifts. (The striatum is dense with dopamine neurons.) As expected, the striatum tracked the financial stakes of the game, so that telling subjects about a bigger payout led to increased activity in the brain area. So far, so obvious: the extra money led people to get more excited about the potential rewards, which led them to work harder. This is why businesses give people bonuses.

However, when the subjects actually began playing the video game, the striatum did something very peculiar. All of a sudden, the activity of the brain area became inversely related to the magnitude of the reward; bigger incentives led to less excitement. Furthermore, activity in the ventral striatum* was closely correlated with success, with decreased activity leading to decreased performance.

What explains this result? The researchers argue that the subjects were victims of loss aversion, the well-documented psychological phenomenon that losses make us feel bad more than gains make us feel good . (In other words, the pleasure of winning a hundred dollars is less intense than the pain of losing the same amount.)

At first glance, this hypothesis doesn’t make much sense, since there were no actual losses in the experiment; subjects were never punished for failure. According to the scientists, however, the act of playing the game leads people to “encode” the potential gain as an actual gain, which means they start worrying about losing it. They are counting chickens that haven’t hatched, contemplating payoffs that have yet to be paid, thinking about tournament wins they haven’t achieved.

And this is why the striatum, that bit of brain focussed on rewards, was going quiet. Instead of being excited by their future riches, the subjects were fretting over their possible failure. What’s more, the scientists demonstrated that the most loss-averse individuals showed the biggest drop-off in performance when the stakes were raised. In other words, the fear of failure was making them more likely to fail. They kept on losing because they hated losses.

Such results should probably make us rethink the role of incentives in the workplace. Although we assume that there’s a simple, linear relationship between financial rewards and productivity—that’s why Wall Street gives its best employees huge bonuses—such rewards can backfire, especially when the task is difficult, or requires expertise. Consider a classic study led by the psychologist Sam Glucksberg in the early nineteen-sixties. He gave subjects a standard test of creativity known as “Duncker’s candle problem.” A “high drive” group was told that the person solving the task in the shortest amount of time would receive twenty dollars. A “low drive” group, in contrast, was reassured that their speed didn’t matter. To Glucksberg’s surprise, the subjects with an incentive to think quickly took, on average, more than three minutes longer to find the answer.

There is something poignant about this deconstruction of choking. It suggests that the reason some performers fall apart on the back nine or at the free-throw line is because they care too much. They really want to win, and so they get unravelled by the pressure of the moment. The simple pleasures of the game have vanished; the fear of losing is what remains.

*Editor's Note: The activity correlated with success occurred in the ventral striatum, not the insula, as originally reported.

Photograph of LeBron James by Jim Rogash/Getty Images.