For years Little returned to lecture at the college, and for years, at lunchtime, he walked the banks of the Richelieu River indulging his imaginary hobby-until the day the college moved its campus to a landlocked location. Stripped of his cover story, Professor Little resorted to the only escape hatch he could find-the men's room. After each lecture, he would race to the restroom and hide inside a stall. One time, a military man spotted Little's shoes under the door and began a hearty conversation, so Little took to keeping his feet propped up on the bathroom walls, where they would be hidden from view. (Taking shelter in bathrooms is a surprisingly common phenomenon, as you probably know if you're an introvert. "After a talk, I'm in bathroom stall number nine," Little once told Peter Gzowski, one of Canada's most eminent talk-show hosts. "After a show, I'm in stall number eight," replied Gzowski, not missing a beat.)

You might wonder how a strong introvert like Professor Little manages to speak in public so effectively. The answer, he says, is simple, and it has to do with a new field of psychology that he created almost singlehandedly, called Free Trait Theory. Little believes that fixed traits and free traits coexist. According to Free Trait Theory, we are born and culturally endowed with certain personality traits-introversion, for example-but we can and do act out of character in the service of "core personal projects."

In other words, introverts are capable of acting like extroverts for the sake of work they consider important, people they love, or anything they value highly. Free Trait Theory explains why an introvert might throw his extroverted wife a surprise party or join the PTA at his daughter's school. It explains how it's possible for an extroverted scientist to behave with reserve in her laboratory, for an agreeable person to act hard-nosed during a business negotiation, and for a cantankerous uncle to treat his niece tenderly when he takes her out for ice cream. As these examples suggest, Free Trait Theory applies in many different contexts, but it's especially relevant for introverts living under the Extrovert Ideal.

According to Little, our lives are dramatically enhanced when we're involved in core personal projects that we consider meaningful, manageable, and not unduly stressful, and that are supported by others. When someone asks us "How are things?" we may give a throwaway answer, but our true response is a function of how well our core personal projects are going.

That's why Professor Little, the consummate introvert, lectures with such pa.s.sion. Like a modern-day Socrates, he loves his students deeply; opening their minds and attending to their well-being are two of his core personal projects. When Little held office hours at Harvard, the students lined up in the hallway as if he were giving out free tickets to a rock concert. For more than twenty years his students asked him to write several hundred letters of recommendation a year. "Brian Little is the most engaging, entertaining, and caring professor I have ever encountered," wrote one student about him. "I cannot even begin to explain the myriad ways in which he has positively affected my life." So, for Brian Little, the additional effort required to stretch his natural boundaries is justified by seeing his core personal project-igniting all those minds-come to fruition.

At first blush, Free Trait Theory seems to run counter to a cherished piece of our cultural heritage. Shakespeare's oft-quoted advice, "To thine own self be true," runs deep in our philosophical DNA. Many of us are uncomfortable with the idea of taking on a "false" persona for any length of time. And if we act out of character by convincing ourselves that our pseudo-self is real, we can eventually burn out without even knowing why. The genius of Little's theory is how neatly it resolves this discomfort. Yes, we are only pretending to be extroverts, and yes, such inauthenticity can be morally ambiguous (not to mention exhausting), but if it's in the service of love or a professional calling, then we're doing just as Shakespeare advised.

When people are skilled at adopting free traits, it can be hard to believe that they're acting out of character. Professor Little's students are usually incredulous when he claims to be an introvert. But Little is far from unique; many people, especially those in leadership roles, engage in a certain level of pretend-extroversion. Consider, for example, my friend Alex, the socially adept head of a financial services company, who agreed to give a candid interview on the condition of sealed-in-blood anonymity. Alex told me that pretend-extroversion was something he taught himself in the seventh grade, when he decided that other kids were taking advantage of him.

"I was the nicest person you'd ever want to know," Alex recalls, "but the world wasn't that way. The problem was that if you were just a nice person, you'd get crushed. I refused to live a life where people could do that stuff to me. I was like, OK, what's the policy prescription here? And there really was only one. I needed to have every person in my pocket. If I wanted to be a nice person, I needed to run the school."

But how to get from A to B? "I studied social dynamics, I guarantee more than anyone you've ever met," Alex told me. He observed the way people talked, the way they walked-especially male dominance poses. He adjusted his own persona, which allowed him to go on being a fundamentally shy, sweet kid, but without being taken advantage of. "Any hard thing where you can get crushed, I was like, 'I need to learn how to do this.' So by now I'm built for war. Because then people don't screw you."

Alex also took advantage of his natural strengths. "I learned that boys basically do only one thing: they chase girls. They get them, they lose them, they talk about them. I was like, 'That's completely circuitous. I really like girls.' That's where intimacy comes from. So rather than sitting around and talking about girls, I got to know them. I used having relationships with girls, plus being good at sports, to have the guys in my pocket. Oh, and every once in a while, you have to punch people. I did that, too."

Today Alex has a folksy, affable, whistle-while-you-work demeanor. I've never seen him in a bad mood. But you'll see his self-taught bellicose side if you ever try to cross him in a negotiation. And you'll see his introverted self if you ever try to make dinner plans with him.

"I could literally go years without having any friends except for my wife and kids," he says. "Look at you and me. You're one of my best friends, and how many times do we actually talk-when you call me! I don't like socializing. My dream is to live off the land on a thousand acres with my family. You never see a team of friends in that dream. So notwithstanding whatever you might see in my public persona, I am an introvert. I think that fundamentally I'm the same person I always was. Ma.s.sively shy, but I compensate for it."

But how many of us are really capable of acting out of character to this degree (putting aside, for the moment, the question of whether we want to)? Professor Little happens to be a great performer, and so are many CEOs. What about the rest of us?

Some years ago, a research psychologist named Richard Lippa set out to answer this question. He called a group of introverts to his lab and asked them to act like extroverts while pretending to teach a math cla.s.s. Then he and his team, video cameras in hand, measured the length of their strides, the amount of eye contact they made with their "students," the percentage of time they spent talking, the pace and volume of their speech, and the total length of each teaching session. They also rated how generally extroverted the subjects appeared, based on their recorded voices and body language.

Then Lippa did the same thing with actual extroverts and compared the results. He found that although the latter group came across as more extroverted, some of the pseudo-extroverts were surprisingly convincing. It seems that most of us know how to fake it to some extent. Whether or not we're aware that the length of our strides and the amount of time we spend talking and smiling mark us as introverts and extroverts, we know it unconsciously.

Still, there's a limit to how much we can control our self-presentation. This is partly because of a phenomenon called behavioral leakage, in which our true selves seep out via unconscious body language: a subtle look away at a moment when an extrovert would have made eye contact, or a skillful turn of the conversation by a lecturer that places the burden of talking on the audience when an extroverted speaker would have held the floor a little longer.

How was it that some of Lippa's pseudo-extroverts came so close to the scores of true extroverts? It turned out that the introverts who were especially good at acting like extroverts tended to score high for a trait that psychologists call "self-monitoring." Self-monitors are highly skilled at modifying their behavior to the social demands of a situation. They look for cues to tell them how to act. When in Rome, they do as the Romans do, according to the psychologist Mark Snyder, author of Public Appearances, Private Realities, and creator of the Self-Monitoring Scale.

One of the most effective self-monitors I've ever met is a man named Edgar, a well-known and much-beloved fixture on the New York social circuit. He and his wife host or attend fund-raisers and other social events seemingly every weeknight. He's the kind of enfant terrible whose latest antics are a favorite topic of conversation. But Edgar is an avowed introvert. "I'd much rather sit and read and think about things than talk to people," he says.

Yet talk to people he does. Edgar was raised in a highly social family that expected him to self-monitor, and he's motivated to do so. "I love politics," he says. "I love policy, I love making things happen, I want to change the world in my own way. So I do stuff that's artificial. I don't really like being the guest at someone else's party, because then I have to be entertaining. But I'll host parties because it puts you at the center of things without actually being a social person."

When he does find himself at other people's parties, Edgar goes to great lengths to play his role. "All through college, and recently even, before I ever went to a dinner or c.o.c.ktail party, I would have an index card with three to five relevant, amusing anecdotes. I'd come up with them during the day-if something struck me I'd jot it down. Then, at dinner, I'd wait for the right opening and launch in. Sometimes I'd have to go to the bathroom and pull out my cards to remember what my little stories were."

Over time, though, Edgar stopped bringing index cards to dinner parties. He still considers himself an introvert, but he grew so deeply into his extroverted role that telling anecdotes started to come naturally to him. Indeed, the highest self-monitors not only tend to be good at producing the desired effect and emotion in a given social situation-they also experience less stress while doing so.

In contrast to the Edgars of the world, low self-monitors base their behavior on their own internal compa.s.s. They have a smaller repertoire of social behaviors and masks at their disposal. They're less sensitive to situational cues, like how many anecdotes you're expected to share at a dinner party, and less interested in role-playing, even when they know what the cues are. It's as if low self-monitors (LSMs) and high self-monitors (HSMs) play to different audiences, Snyder has said: one inner, the other outer.

If you want to know how strong a self-monitor you are, here are a few questions from Snyder's Self-Monitoring Scale:

When you're uncertain how to act in a social situation, do you look to the behavior of others for cues?

Do you often seek the advice of your friends to choose movies, books, or music?

In different situations and with different people, do you often act like very different people?

Do you find it easy to imitate other people?

Can you look someone in the eye and tell a lie with a straight face if for a right end?

Do you ever deceive people by being friendly when really you dislike them?

Do you put on a show to impress or entertain people?

Do you sometimes appear to others to be experiencing deeper emotions than you actually are?

The more times you answered "yes" to these questions, the more of a high self-monitor you are.

Now ask yourself these questions:

Is your behavior usually an expression of your true inner feelings, att.i.tudes, and beliefs?

Do you find that you can only argue for ideas that you already believe?

Would you refuse to change your opinions, or the way you do things, in order to please someone else or win their favor?

Do you dislike games like charades or improvisational acting?

Do you have trouble changing your behavior to suit different people and different situations?

The more you tended to answer "yes" to this second set of questions, the more of a low self-monitor you are.

When Professor Little introduced the concept of self-monitoring to his personality psychology cla.s.ses, some students got very worked up about whether it was ethical to be a high self-monitor. A few "mixed" couples-HSMs and LSMs in love-even broke up over it, he was told. To high self-monitors, low self-monitors can seem rigid and socially awkward. To low self-monitors, high self-monitors can come across as conformist and deceptive-"more pragmatic than principled," in Mark Snyder's words. Indeed, HSMs have been found to be better liars than LSMs, which would seem to support the moralistic stance taken by low self-monitors.

But Little, an ethical and sympathetic man who happens to be an extremely high self-monitor, sees things differently. He views self-monitoring as an act of modesty. It's about accommodating oneself to situational norms, rather than "grinding down everything to one's own needs and concerns." Not all self-monitoring is based on acting, he says, or on working the room. A more introverted version may be less concerned with spotlight-seeking and more with the avoidance of social faux pas. When Professor Little makes a great speech, it's partly because he's self-monitoring every moment, continually checking his audience for subtle signs of pleasure or boredom and adjusting his presentation to meet its needs.

So if you can fake it, if you master the acting skills, the attention to social nuance, and the willingness to submit to social norms that self-monitoring requires, should you? The answer is that a Free Trait strategy can be effective when used judiciously, but disastrous if overdone.

Recently I spoke on a panel at Harvard Law School. The occasion was the fifty-fifth anniversary of women being admitted to the law school. Alumnae from all over the country gathered on campus to celebrate. The subject of the panel was "In a Different Voice: Strategies for Powerful Self-Presentation." There were four speakers: a trial lawyer, a judge, a public-speaking coach, and me. I'd prepared my remarks carefully; I knew the role I wanted to play.

The public-speaking coach went first. She talked about how to give a talk that knocks people's socks off. The judge, who happened to be Korean-American, spoke of how frustrating it is when people a.s.sume that all Asians are quiet and studious when in fact she's outgoing and a.s.sertive. The litigator, who was pet.i.te and blond and feisty as h.e.l.l, talked about the time she conducted a cross-examination only to be admonished by a judge to "Back down, tiger!"