Introvert or Extrovert? Most People Land Somewhere in the Middle

In January 2012, Susan Cain published Quiet: The Power of Introverts in a World That Can't Stop Talking. Her publisher's summary says Cain "argues that we dramatically undervalue introverts" and "charts the rise of the Extrovert Ideal throughout the twentieth century." About a month later she gave a talk on the same theme at TED2012; TED's page for that talk counted more than 36 million plays when it was checked in October 2026.

The popular version of the idea sorts everyone into two camps, introverts on one side and extroverts on the other. Measurement doesn't. When researchers score the trait, most people land between the poles, and some things that sound like introversion, such as shyness or feeling worn out after a long social day, turn out to be separate questions. (A note on spelling: the research papers linked here write "extravert" and "extraversion." This article uses the everyday "extrovert" except when describing that research.)

Two camps, or one scale?

The Myers-Briggs system treats Extraversion and Introversion as a pair of opposite preferences and assigns each person one letter of the pair. The Myers & Briggs Foundation describes the pair as "opposite ways to direct and receive energy" and frames it as a choice between focusing on the outer world or your own inner world. It also says "we use all the preferences," with most people preferring one side of each pair more than the other.

Whether that preference comes in two distinct kinds is where research pushes back. In a 1989 study of 468 adults, Robert McCrae and Paul Costa found "no support for the view that the MBTI measures truly dichotomous preferences or qualitatively distinct types"; the questionnaire behaved like four relatively independent dimensions. Earlier reports that MBTI scores pile up in two humps rather than one had been cited as support for types. In 2002, Tammy Bess and Robert Harvey scored the answers of about 12,000 people in leadership development programs and found those humps were an artifact of the scoring program's default settings. With the setting changed, the score distributions on all four dimensions became "strongly center-weighted." On a questionnaire built to sort people into either-or types, in other words, scores bunch toward the middle.

That's one reason the framework's scientific standing is contested, despite its popularity. A 2019 paper by Randy Stein and Alexander Swan concluded that the theory behind the types "falters on rigorous theoretical criteria": it "lacks agreement with known facts and data, lacks testability, and possesses internal contradictions." The site's longer look at the science behind MBTI covers the rest.

"Ambivert" is the everyday word for the middle. It isn't a third type, just the stretch of the scale where most scores fall. The word does have some research behind it: in a 2013 study of 340 call center sales representatives, Adam Grant found that sales revenue peaked in the middle of the extraversion scale, rather than at either end. That's one study in one kind of job, but it's a useful answer to the idea that the middle is a non-answer.

What the trait covers depends on who's measuring

Describing introversion as a matter of where you direct your energy and attention is the Myers-Briggs framing. Trait researchers measure something broader. In the Big Five model of personality, extraversion is one of five broad traits, and the BFI-2, a research questionnaire by Christopher Soto and Oliver John, splits it into three facets: sociability, assertiveness and energy level. The extraversion items on its short form include "Tends to be quiet" (scored in reverse), "Is dominant, acts as a leader" and "Is full of energy." So whether being quiet counts depends on which definition you use.

Whichever one you use, shyness is a separate question. Susan Cain draws the line in her talk:

Shyness is about fear of social judgment. Introversion is more about, how do you respond to stimulation, including social stimulation.

Acting out of character, and what it costs

Acting against your own disposition has a name in the work of the personality psychologist Brian Little. He argues for what he calls "free traits," which Harvard Magazine summarized as "tendencies expressed by individual choice," put to work for "core projects," the endeavors linked to a person's deepest values. He has used himself as the example, a "classic introvert" who performs "with great passion" when he lectures. As he put it to Harvard Magazine in 2003:

Introverts, when they are 'on,' become pseudo-extraverts. Can you tell the difference between a born extravert and a pseudo-extravert? Usually you cannot.

If Little is right, watching someone in a setting they care about says little about their usual leanings. Little is just as clear that the performance has a price. Overriding your temperament for long stretches "exacts a price in health, and can cause burnout," he told the magazine, unless you have a "restorative niche where you can indulge your first nature." His own, after an hour or two in front of a class, was "a quiet break in the washroom, or stepping outside for a breath of fresh air."

What the research found

Psychologists have also tested what happens when people are asked to act more outgoing than usual, and tracked how sociable behavior in everyday life relates to mood and tiredness. The results are more mixed than either label suggests.

• It usually feels better than expected. In a 2012 paper reporting two studies, John Zelenski and colleagues randomly assigned people to act introverted or extraverted. Acting extraverted raised positive mood regardless of disposition, and negative mood didn't rise, even for introverts acting out of character. A 2013 follow-up from the same lab found that introverts underpredicted how good acting extraverted would feel, particularly by overestimating the negative feelings and self-consciousness it would bring.
• The tiredness comes later, and not only for introverts. In a 12-day study that tracked 48 people's everyday behavior, mood and fatigue five times a day, Sointu Leikas and Ville-Juhani Ilmarinen found that extraverted behavior went with better mood and less fatigue in the moment, but more fatigue three hours later. That pattern didn't depend on personality traits, and the link ran through how many people someone had encountered. A 2020 study of 74 people by Leikas found the same delayed tiredness, two to three hours on. Both samples are small, but the finding cuts against an easy assumption: feeling worn out after a busy social stretch doesn't, on its own, make you an introvert.
• Kept up for a week, it costs introverts more. In a 2019 randomized trial, Rowan Jacques-Hamilton, Jessie Sun and Luke Smillie assigned 147 people to act extraverted for a week of everyday life or to follow a comparison exercise. On average, acting extraverted lifted positive mood. But the more introverted participants got a smaller lift and reported more negative mood and more tiredness.

Taken together, the studies line up with Little's account. Stepping outside your usual range can feel good while you're doing it and still cost something afterward, and in the week-long trial that cost was larger for the more introverted participants.

Questions worth asking yourself

None of this tells you what you are. It does suggest a few questions that get closer to it than choosing a label.

• Do plans you dreaded usually go better than you expected? If so, the forecasting gap in Zelenski's studies may be part of your picture, and the label may be talking you out of things you'd enjoy.
• Is it people that tire you, or how many of them? In Leikas and Ilmarinen's study, the later fatigue ran through how many people someone had encountered. A long dinner with one friend and a party of forty are not the same test.
• Is it preference or fear? Wanting a quiet evening is a preference. Dreading other people's judgment, and avoiding things because of it, is closer to what Cain calls shyness, and at its strongest it may be something else again (see the next section).
• What would someone who knows you say? In a 2010 study by Simine Vazire, 165 people rated themselves, were rated by four friends and up to four strangers, and then took a battery of behavioral tests. For extraversion-related traits, self, friends and strangers were equally good judges. The self did best on traits related to neuroticism, and friends on traits related to intellect. On this trait, then, your own view has no special authority, and a friend's is worth hearing.

Shyness, social anxiety and introversion

According to the U.S. National Institute of Mental Health, social anxiety disorder is a common anxiety disorder in which a person feels anxiety or fear in situations where they may be scrutinized, evaluated or judged by others, such as speaking in public, meeting new people or a job interview. It usually starts in childhood or adolescence and, in NIMH's words, "may resemble extreme shyness or avoidance of public situations or social interactions."

Shyness on its own isn't the disorder. In a national survey of more than 10,000 U.S. teenagers, analyzed by NIMH researchers and reported in 2011, about half described themselves as shy, but only 12 percent of the shy teens had met the criteria for social phobia, another name for social anxiety disorder, at some point in their lives. Among teens who didn't call themselves shy, about 5 percent had.

Introversion and social anxiety are different things, but they aren't unrelated. A 2010 meta-analysis by Roman Kotov and colleagues, covering 175 studies, found that social phobia went with markedly low extraversion; of the anxiety, depressive and substance use disorders it reviewed, only dysthymic disorder showed a larger effect. Every diagnostic group in the review also scored high on neuroticism. So the two can show up together, even though they're different questions.

The difference matters most for what helps. A preference for quiet calls for arranging your week around it: protecting recovery time and choosing the kinds of plans that suit you. Social anxiety disorder is a different matter. NIMH says that with the right treatment and support, people with it can manage their anxiety and improve their quality of life. It says cognitive behavioral therapy is commonly used to treat the disorder and calls CBT the "gold standard" choice for psychotherapy. That includes exposure therapy, a CBT method that focuses on "progressively confronting the fears underlying an anxiety disorder," and NIMH lists other therapies and medication as options too. If fear of being judged is what keeps you home, a doctor or a licensed mental health professional is the right person to talk to. A personality label isn't a substitute.

Practical notes for either end

If you lean introverted: plan recovery time before a heavy day rather than after you've run out, which is Little's restorative niche put on a calendar. Watch the headcount as well as the hours, given the fatigue findings above. And if you tend to turn things down in advance, the forecasting research is a reason to say yes now and then and see how it actually goes.

If you lean extroverted: the same logic runs the other way. In Zelenski's 2012 studies, the cognitive cost the researchers looked for showed up only in extraverts asked to act introverted, who did worse on a test called the Stroop task. The authors suggest that extraverts may want to adopt introverted behavior "strategically." Quiet time you plan, at moments you choose, fits that advice better than long stretches of it you didn't choose.

And for everyone in the middle, which on the evidence above is most people: notice which settings leave you better off a few hours later, not only in the moment. That's a more useful answer than a letter.

If you'd like a structured read on where you sit, the personality type quiz asks about this pair and the other three, then shows how your answers split on each one, and it flags a close split instead of hiding it behind a letter. It isn't the official MBTI, and like any quiz it reflects how you describe yourself; how the quizzes are built explains the scoring.

Correction, October 8, 2026: an earlier version of this article said that extraversion scores form a bell curve with most people in the middle, so most readers are probably ambiverts, and that people are better at predicting other people's extraversion than their own. Neither claim had a source. The first now has one: Tammy Bess and Robert Harvey's 2002 finding, linked above, that MBTI score distributions are center-weighted. The second is replaced by Simine Vazire's 2010 finding that self, friends and strangers were equally good judges of extraversion-related traits.