Vincent Kaminski, a Rice University business school professor who once served as managing director of research for Enron, the company that famously filed for bankruptcy in 2001 as a result of reckless business practices, told the Washington Post a similar story of a business culture in which aggressive risk-takers enjoyed too high a status relative to cautious introverts. Kaminski, a soft-spoken and careful man, was one of the few heroes of the Enron scandal. He repeatedly tried to sound the alarm with senior management that the company had entered into business deals risky enough to threaten its survival. When the top bra.s.s wouldn't listen, he refused to sign off on these dangerous transactions and ordered his team not to work on them. The company stripped him of his power to review company-wide deals.

"There have been some complaints, Vince, that you're not helping people to do transactions," the president of Enron told him, according to Conspiracy of Fools, a book about the Enron scandal. "Instead, you're spending all your time acting like cops. We don't need cops, Vince."

But they did need them, and still do. When the credit crisis threatened the viability of some of Wall Street's biggest banks in 2007, Kaminski saw the same thing happening all over again. "Let's just say that all the demons of Enron have not been exorcised," he told the Post in November of that year. The problem, he explained, was not only that many had failed to understand the risks the banks were taking. It was also that those who did understand were consistently ignored-in part because they had the wrong personality style: "Many times I have been sitting across the table from an energy trader and I would say, 'Your portfolio will implode if this specific situation happens.' And the trader would start yelling at me and telling me I'm an idiot, that such a situation would never happen. The problem is that, on one side, you have a rainmaker who is making lots of money for the company and is treated like a superstar, and on the other side you have an introverted nerd. So who do you think wins?"

But what exactly is the mechanism by which buzz clouds good judgment? How did Janice Dorn's client, Alan, dismiss the danger signs screaming that he might lose 70 percent of his life savings? What prompts some people to act as if FUD doesn't exist?

One answer comes from an intriguing line of research conducted by the University of Wisconsin psychologist Joseph Newman. Imagine that you've been invited to Newman's lab to partic.i.p.ate in one of his studies. You're there to play a game: the more points you get, the more money you win. Twelve different numbers flash across a computer screen, one at a time, in no particular order. You're given a b.u.t.ton, as if you were a game-show contestant, which you can press or not as each number appears. If you press the b.u.t.ton for a "good" number, you win points; if you press for a "bad" number, you lose points; and if you don't press at all, nothing happens. Through trial and error you learn that four is a nice number and nine is not. So the next time the number nine flashes across your screen, you know not to press that b.u.t.ton.

Except that sometimes people press the b.u.t.ton for the bad numbers, even when they should know better. Extroverts, especially highly impulsive extroverts, are more likely than introverts to make this mistake. Why? Well, in the words of psychologists John Brebner and Chris Cooper, who have shown that extroverts think less and act faster on such tasks: introverts are "geared to inspect" and extroverts "geared to respond."

But the more interesting aspect of this puzzling behavior is not what the extroverts do before they've hit the wrong b.u.t.ton, but what they do after. When introverts. .h.i.t the number nine b.u.t.ton and find they've lost a point, they slow down before moving on to the next number, as if to reflect on what went wrong. But extroverts not only fail to slow down, they actually speed up.

This seems strange; why would anyone do this? Newman explains that it makes perfect sense. If you focus on achieving your goals, as reward-sensitive extroverts do, you don't want anything to get in your way-neither naysayers nor the number nine. You speed up in an attempt to knock these roadblocks down.

Yet this is a crucially important misstep, because the longer you pause to process surprising or negative feedback, the more likely you are to learn from it. If you force extroverts to pause, says Newman, they'll do just as well as introverts at the numbers game. But, left to their own devices, they don't stop. And so they don't learn to avoid the trouble staring them in the face. Newman says that this is exactly what might happen to extroverts like Ted Turner when bidding for a company on auction. "When a person bids up too high," he told me, "that's because they didn't inhibit a response they should have inhibited. They didn't consider information that should have been weighing on their decision."

Introverts, in contrast, are const.i.tutionally programmed to downplay reward-to kill their buzz, you might say-and scan for problems. "As soon they get excited," says Newman, "they'll put the brakes on and think about peripheral issues that may be more important. Introverts seem to be specifically wired or trained so when they catch themselves getting excited and focused on a goal, their vigilance increases."

Introverts also tend to compare new information with their expectations, he says. They ask themselves, "Is this what I thought would happen? Is it how it should be?" And when the situation falls short of expectations, they form a.s.sociations between the moment of disappointment (losing points) and whatever was going on in their environment at the time of the disappointment (hitting the number nine.) These a.s.sociations let them make accurate predictions about how to react to warning signals in the future.

Introverts' disinclination to charge ahead is not only a hedge against risk; it also pays off on intellectual tasks. Here are some of the things we know about the relative performance of introverts and extroverts at complex problem-solving. Extroverts get better grades than introverts during elementary school, but introverts outperform extroverts in high school and college. At the university level, introversion predicts academic performance better than cognitive ability. One study tested 141 college students' knowledge of twenty different subjects, from art to astronomy to statistics, and found that introverts knew more than the extroverts about every single one of them. Introverts receive disproportionate numbers of graduate degrees, National Merit Scholarship finalist positions, and Phi Beta Kappa keys. They outperform extroverts on the Watson-Glaser Critical Thinking Appraisal test, an a.s.sessment of critical thinking widely used by businesses for hiring and promotion. They've been shown to excel at something psychologists call "insightful problem solving."

The question is: Why?

Introverts are not smarter than extroverts. According to IQ scores, the two types are equally intelligent. And on many kinds of tasks, particularly those performed under time or social pressure or involving mult.i.tasking, extroverts do better. Extroverts are better than introverts at handling information overload. Introverts' reflectiveness uses up a lot of cognitive capacity, according to Joseph Newman. On any given task, he says, "if we have 100 percent cognitive capacity, an introvert may have only 75 percent on task and 25 percent off task, whereas an extrovert may have 90 percent on task." This is because most tasks are goal-directed. Extroverts appear to allocate most of their cognitive capacity to the goal at hand, while introverts use up capacity by monitoring how the task is going.

But introverts seem to think more carefully than extroverts, as the psychologist Gerald Matthews describes in his work. Extroverts are more likely to take a quick-and-dirty approach to problem-solving, trading accuracy for speed, making increasing numbers of mistakes as they go, and abandoning ship altogether when the problem seems too difficult or frustrating. Introverts think before they act, digest information thoroughly, stay on task longer, give up less easily, and work more accurately. Introverts and extroverts also direct their attention differently: if you leave them to their own devices, the introverts tend to sit around wondering about things, imagining things, recalling events from their past, and making plans for the future. The extroverts are more likely to focus on what's happening around them. It's as if extroverts are seeing "what is" while their introverted peers are asking "what if."

Introverts' and extroverts' contrasting problem-solving styles have been observed in many different contexts. In one experiment, psychologists gave fifty people a difficult jigsaw puzzle to solve, and found that the extroverts were more likely than the introverts to quit midway. In another, Professor Richard Howard gave introverts and extroverts a complicated series of printed mazes, and found not only that the introverts tended to solve more mazes correctly, but also that they spent a much greater percentage of their allotted time inspecting the maze before entering it. A similar thing happened when groups of introverts and extroverts were given the Raven Standard Progressive Matrices, an intelligence test that consists of five sets of problems of increasing difficulty. The extroverts tended to do better on the first two sets, presumably because of their ability to orient quickly to their goal. But on the three more difficult sets, where persistence pays, the introverts significantly outperformed them. By the final, most complicated set, the extroverts were much more likely than the introverts to abandon the task altogether.

Introverts sometimes outperform extroverts even on social tasks that require persistence. Wharton management professor Adam Grant (who conducted the leadership studies described in chapter 2) once studied the personality traits of effective call-center employees. Grant predicted that the extroverts would be better telemarketers, but it turned out that there was zero correlation between extroversion levels and cold-calling prowess.

"The extroverts would make these wonderful calls," Grant told me, "but then a shiny object of some kind would cross their paths and they'd lose focus." The introverts, in contrast, "would talk very quietly, but boom, boom, boom, they were making those calls. They were focused and determined." The only extroverts to outperform them were those who also happened to be unusually high scorers for a separate personality trait measuring conscientiousness. Introvert persistence was more than a match for extrovert buzz, in other words, even at a task where social skills might be considered at a premium.

Persistence isn't very glamorous. If genius is one percent inspiration and ninety-nine percent perspiration, then as a culture we tend to lionize the one percent. We love its flash and dazzle. But great power lies in the other ninety-nine percent.

"It's not that I'm so smart," said Einstein, who was a consummate introvert. "It's that I stay with problems longer."

None of this is to denigrate those who forge ahead quickly, or to blindly glorify the reflective and careful. The point is that we tend to overvalue buzz and discount the risks of reward-sensitivity: we need to find a balance between action and reflection.

For example, if you were staffing an investment bank, management professor Kuhnen told me, you'd want to hire not only reward-sensitive types, who are likely to profit from bull markets, but also those who remain emotionally more neutral. You'd want to make sure that important corporate decisions reflect the input of both kinds of people, not just one type. And you'd want to know that individuals on all points of the reward-sensitivity spectrum understand their own emotional preferences and can temper them to match market conditions.

But it's not just employers who benefit from taking a closer look at their employees. We also need to take a closer look at ourselves. Understanding where we fall on the reward-sensitivity spectrum gives us the power to live our lives well.

If you're a buzz-p.r.o.ne extrovert, then you're lucky to enjoy lots of invigorating emotions. Make the most of them: build things, inspire others, think big. Start a company, launch a website, build an elaborate tree house for your kids. But also know that you're operating with an Achilles' heel that you must learn to protect. Train yourself to spend energy on what's truly meaningful to you instead of on activities that look like they'll deliver a quick buzz of money or status or excitement. Teach yourself to pause and reflect when warning signs appear that things aren't working out as you'd hoped. Learn from your mistakes. Seek out counterparts (from spouses to friends to business partners) who can help rein you in and compensate for your blind spots.

And when it comes time to invest, or to do anything that involves a sage balance of risk and reward, keep yourself in check. One good way to do this is to make sure that you're not surrounding yourself with images of reward at the crucial moment of decision. Kuhnen and Brian Knutson have found that men who are shown erotic pictures just before they gamble take more risks than those shown neutral images like desks and chairs. This is because antic.i.p.ating rewards-any rewards, whether or not related to the subject at hand-excites our dopamine-driven reward networks and makes us act more rashly. (This may be the single best argument yet for banning p.o.r.nography from workplaces.)

And if you're an introvert who's relatively immune to the excesses of reward sensitivity? At first blush, the research on dopamine and buzz seems to imply that extroverts, and extroverts alone, are happily motivated to work hard by the excitement they get from pursuing their goals. As an introvert, I was puzzled by this idea when I first came across it. It didn't reflect my own experience. I'm in love with my work and always have been. I wake up in the morning excited to get started. So what drives people like me?

One answer is that even if the reward-sensitivity theory of extroversion turns out to be correct, we can't say that all extroverts are always more sensitive to rewards and blase about risk, or that all introverts are constantly unmoved by incentives and vigilant about threats. Since the days of Aristotle, philosophers have observed that these two modes-approaching things that appear to give pleasure and avoiding others that seem to cause pain-lie at the heart of all human activity. As a group, extroverts tend to be reward-seeking, but every human being has her own mix of approach and avoidance tendencies, and sometimes the combination differs depending on the situation. Indeed, many contemporary personality psychologists would say that threat-vigilance is more characteristic of a trait known as "neuroticism" than of introversion. The body's reward and threat systems also seem to work independently of each other, so that the same person can be generally sensitive, or insensitive, to both reward and threat.

If you want to determine whether you are reward-oriented, threat-oriented, or both, try asking yourself whether the following groups of statements are true of you.

If you are reward-oriented:

1. When I get something I want, I feel excited and energized.

2. When I want something, I usually go all out to get it.

3. When I see an opportunity for something I like, I get excited right away.

4. When good things happen to me, it affects me strongly.

5. I have very few fears compared to my friends.

If you are threat-oriented:

1. Criticism or scolding hurts me quite a bit.

2. I feel pretty worried or upset when I think or know somebody is angry at me.

3. If I think something unpleasant is going to happen, I usually get pretty "worked up."

4. I feel worried when I think I have done poorly at something important.

5. I worry about making mistakes.