Are the Brains of Introverts and Extroverts Actually Different?

By Guest Blogger | August 27, 2013 10:21 am

By Ben Thomas

introvert extrovert

Introversion, it seems, is the Internet’s current meme du jour. Articles on introverts are nothing new, of course—The Atlantic’s 2003 classic “Caring for Your Introvert” still gets passed around Facebook on a regular basis—but the topic has gained some sort of strange critical mass in the past few weeks, and has been popping up everywhere from Gawker to Forbes.

This latest swarm of articles ranges from glorified personality quizzes (31 Unmistakable Signs That You’re An Introvert”) to history lessons (“16 Outrageously Successful Introverts”) to business essays (“Why Introverts Can Make Excellent Executives”) to silly, self-aware send-ups of the trend itself (“15 Unmistakable, Outrageously Secret Signs You’re an Extrovert”). The vast majority of them also come packaged with the assumption the reader understands the basic concept of introversion, and already has a pretty clear idea of whether he or she is an introvert or an extrovert.

Scroll through the comments sections, though, and you’ll find that quite a few readers—even introverted ones—don’t appreciate being put in a labeled box. For every grateful response from a self-professed introvert, you’ll find several responses along the lines of, “No one is always extroverted and no one is always introverted,” and, “I consider myself an extrovert but a lot of these introvert traits apply to me.”

What does neuroscience have to say about all this? Do the brains of introverted people really look and behave differently from those of extroverts? And if so, what might those differences mean?

Introvert v. Extrovert

Before we go any further, it’s important to point out a significant distinction. When Carl Jung coined the terms “extrovert” and “introvert” in the early twentieth century, he emphasized that introverts aren’t necessarily shy or insecure—nor are extroverts necessarily empathic or loving. The distinction between the two, Jung wrote, lies mainly in the fact that introverts get exhausted by social interaction, while extroverts get anxious when left alone. Introverts need solitude in order to recharge, while extroverts draw energy from socializing.

Modern psychologists have added a third category, the ambivert, a personality that combines both introverted and extroverted traits—for example, a ruthless lawyer or CEO who loves to lead but doesn’t crave peer approval. And the Russian Hungarian psychologist Mihaly Csikszentmihalyi reports that his most artistic patients tended to drift between introversion and extroversion throughout their lives. “[They’re] usually one or the other,” he wrote, “either preferring to be in the thick of crowds or sitting on the sidelines and observing the passing show.”

And there’s evidence that artists and execs aren’t alone in this mutability. Psychologists today generally think of introversion and extroversion as labels for areas of a continuous personality spectrum, just as words like “red” and yellow” are labels for certain areas of the light spectrum. We all draw energy from others at times, just as we all need to recharge with some alone time every now and then. Still, says Jason Castro, an assistant professor of neuroscience at Bates College in Maine, “We know there are a few structural features in the brain that correlate with whether a person is relatively introverted, versus extroverted.”

Neural Clues

For one thing, a 2012 study by Harvard psychologist Randy Buckner found that people who identify as introverts tend to have larger and thicker gray matter in certain areas of the prefrontal cortex, a highly complex brain region associated with abstract thought and decision-making. People who identify as strongly extroverted, on the other hand, tend to have thinner gray matter in those same prefrontal areas—which hints that introverts tend to devote more neural resources to abstract pondering, while extroverts tend to live in the moment.

A 2013 study by Cornell University scientists Richard A. Depue and Yu Fu supports this idea. This team of investigators gathered a mixed sample of introverts and extroverts, then randomly split these volunteers into two groups. The first group took the stimulant Ritalin, while the second group took a placebo. The researchers then showed the participants a series of videos such as random landscape shots and forest scenes.

After three days of video-watching, the researchers took away the drugs and showed the films again, and then measured the subjects’ alertness and demeanor. Extroverts who’d taken Ritalin were excited by the films even in the absence of the drug; extroverts who hadn’t showed no change in their reaction to the films. These people had instinctively associated exciting feelings, if they had them, with the videos they’d watched.

But introverts weren’t happier or more alert post-video, regardless of whether they’d taken Ritalin or not. The Cornell researchers think this finding is rooted in a crucial difference between the ways introverts and extroverts process feelings of excitement. Extroverts, the researchers believe, tend to associate feelings of reward with their immediate environment, whereas introverts tend to associate them with their inner thoughts—or perhaps interpret them as anxiety rather than excitement.

Intriguing Hints

Other studies have found that the right-hemisphere amygdala tends to be larger in extroverts than in introverts, as does the anterior cingulate cortex—except in female extroverts, whose anterior cingulate cortices are apparently smaller than those of female introverts. Since other studies have implicated the anterior cingulate in social error detection, this may point to some underlying (but still incompletely understood) differences in the ways introverts and extroverts process social missteps.

Personality differences may have physical effects. Though no one’s been able to measure a difference in reaction time between extroverts and introverts, researchers have found that an introvert’s premotor cortex tends to process stimuli more quickly than that of an extrovert.

Still other studies have found that cortical neurons of introverts and extroverts may respond differently to the neurotransmitter chemicals gamma-aminobutyric acid (GABA) and N-methyl D-aspartate (NMDA)—an intriguing finding since both GABA and NMDA have both been implicated in anxiety disorders

The Science of Personality

In short, although the science of personality is still in the relative Dark Ages, researchers have begun to draw links between what these structural and functional brain differences between personality types might mean in terms of their respective peccadilloes.

But brain differences that correlate with introversion or extroversion don’t necessarily show which of these differences—if any—cause introversion or extroversion. “We don’t have experiments that really address whether those brain differences play a causal role,” Castro says. “We’re still pretty far from having … a scientific description of personality differences at the level of cells and synapses.”

And it’s important to keep in mind that our brain structures vary from person to person along all sorts of axes that inform our personalities—not just introversion and extroversion. As the science of brain mapping develops, maybe we’ll have a myriad of new spectrums we can use to describe our personalities in terms of our gray matter.

Just wait for the listicles that’ll produce.

Ben Thomas is an author, journalist, inventor and independent researcher who studies consciousness and the brain. A lifelong lover of all things mysterious and unexplained, he weaves tales from the frontiers of science into videos, podcasts and unique multimedia events. Lots more of his work is available at http://the-connectome.com.

Image by Creativemarc / Shutterstock

CATEGORIZED UNDER: Mind & Brain, Top Posts
MORE ABOUT: extrovert, introvert
  • riverc

    Typo: “researchers have found that an introvert’s premotor cortex tends to process stimuli more quickly than that of an introvert.”

    Which is which?

    • The Connectome

      It should be, “researchers have found that an introvert’s premotor cortex tends to process stimuli more quickly than that of an extrovert.” Good catch!

      • Beatle_Rick

        Just as I guessed, but then, I’m an introvert and could process the item toot sweet.

        Cordially…

  • saymwah

    Mihaly Csikszentmihalyi is Hungarian.

    • The Connectome

      You’re absolutely right; it even says so at the top of his Wikipedia entry. That was my mistake.

      • keyne

        And he’s Hungarian only by origin. He’s been in the United States for six and a half decades; he was certainly a well-known professor at the University of Chicago long before I arrived there in 1982.

  • http://www.alenmajer.com Alen Mayer

    Interesting article, thanks! What is on your take on ambiverts?

    • m12345

      Schizophrenics will enjoy the crowd instead of complaining of voices.

  • Emma

    I do not think so that the extrovert and introvert has difference with being socialization. Both could be socialize with their own environment. Environment make you socialize, how you like it rather being a extrovert or introvert. I feel I can be introvert and extrovert. I am very socialized, whereas I am also do my job by myself.

  • lrhodgin

    Bottom line analogy-extroverts recharge their batteries by being with others, introverts need alone time to recharge their batteries. Both types can be alone or interact with others-that is being a social person. I taught in secondary schools for 34 years and I guarantee people like me, an introvert, were tired and sometimes overstimulated by the end of the day and ready to have down time. While I watched my extroverted peers finish the school day and go work a second job or go out for a night out half the time without a hitch. I needed to recharge by being home and reading, cooking or gardening or being with my family-all calming activities for me. If my extroverted friends tried to live my life they would feel so depleted and unfulfilled because they need to be out there doing whatever float their boats. In American society only 25% of the people are introverts (Meyers/Briggs). I wish more introvert kids could know about this so they would understand their life style is just as valid as an extroverts.

  • John

    “researchers have found that an introvert’s premotor cortex tends to process stimuli more quickly than that of an introvert.”
    You might want to fix this. >__>

  • SixSixSix

    ‘except in female extroverts, whose anterior cingulate cortices are apparently smaller than those of female introverts.’

    Does anybody edit this copy before it gets posted? “Except in female extroverts” is a wonderful phrase given that the majority of people on this planet are female. So what is the stupid assertion about “extroverts”? It really means that male and female extroverts have opposite tendencies with females have smaller than average ones, so to speak.

  • David

    “…extroverts who hadn’t showed no change in their reaction…” Shouldn’t this read “…extroverts showed no change in their reaction…”?

    Also, I am surprised that any discussion of introversion and extroversion would fail to mention the work of Hans Eysecnk and others (including myself) working from his theoretical model. In his model, I/E is viewed as a biologically based temperament trait related to the basal arousal level in the CNS. Briefly, those with higher than normal arousal level are stimulus avoiders and introverts, while those with lower than normal arousal levels are stimulus seekers and extroverts. Eysenck was talking about I/E as a dimensional construct 50 years ago. Those who fall into the normal range (the majority of people) might be thought of as what is called an ambivert in this post. He and others developed a great deal of data supporting this model, including finding differences in reaction to stimulants that conformed to predictions from Eysenck’s theory. In short, anatomical brain differences may be part of the story but there are other important considerations.

  • Kata

    Mihaly Csikszentmihalyi is HUNGARIAN, not Russian.

    • Lisa Raffensperger

      Thanks for pointing out the error, Kata. It’s now been fixed.

  • Lori Hogenkamp

    Really the reason you think personality research is in the dark ages is because conventional or mainstream (linear) science chose to ignore and dismiss it. So it’s not so much Personality research but mainstream in the dark ages because theignored personality research.

  • John

    This article hits the hot spot in the few first sentences. Being an introvert has become popular, while being an extrovert has become undesired. The bottom line is, introverts are self-centered, it is a bad trait, it can be seen in the hundreds of popular articles and quizzes popping up everywhere, introverts want to think about themselves, they want to be seen as different, but yet all these tests and articles are proving that there are actually lots of introverts, we aren’t special guys, there are lots of us. As an introvert I am tired of learning about me, I want to learn about extroverts, I want to learn about what they have that I don’t, they interest me. I want more so called introverts to realize that they are actually extroverts who just want to be part of a fad. Being an introvert is not better than being an extrovert, there are pros and cons for each side. I want to see more extrovert articles no more of these “living with your little introvert” articles like it is harder to raise an introvert than an extrovert, hello, they are kids, it is hard period. the parents of extroverts have their own parental struggles, remember that. There is another side to this coin, don’t just polish your own.

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