For some reason, during the month of August introversion exploded on the internet, reaching meme status. I don’t know why, but I figured I’d chime in with some scientifically backed data on this interesting personality category.
But first. How do you spell it? In psychological research, extravert is preferred, while in popular writing extrovert is commonly used. Either is correct, although perhaps appropriate for different target audiences. Luckily, both researchers and laymen call the opposite end introverts (intraverts are not a thing).
So is extraversion a thing? Yes, very much so. The extraversion-introversion axis is one of the most robust dimensions in personality research. Scientists in the field more or less unanimously agree that whatever categories best describe personality, the major component of one of them is the degree of extraversion-introversion (extraversion for short, although this refers to the whole spectrum, not just the one end of it).
Is it a Western invention? Nope, it has been found in a sample spanning 40 different countries across the world, ranging from very individualistic to very collectivist cultures.
Exactly what is it? This one’s trickier. The simplest folk idea is that extraversion is simply the degree to which a person is sociable. Extraverted people are people who are outgoing and engage in a lot of social interaction. This is a broad oversimplification according to science. A slightly more complex folk psychology idea is that extraversion is simply the question of whether a person draws “mental energy” from social interaction or alone time. According to this idea, introverts may enjoy social interaction, but need to be alone to recharge, while extraverts may enjoy alone time, but need to spend time with others in order to recharge. Surprisingly, there is little scientific evidence for this idea either.
Scientists don’t agree exactly on what constitutes the core of extraversion. Here is a list of facets that have been included in models of extraversion (different authors will include different subsets of these):
These six facets are venturesome (feelings of excitement seeking and desire for change), affiliation (feelings of warmth and gregariousness), positive affectivity (feelings of joy and enthusiasm), energy (feeling lively and active), ascendance (feeling dominant or being an exhibitionist), and ambition (valuing achievement and endurance).
However, there seems to be broad agreement that there is some underlying principle that explains all or most of these and ties them together. Extremely robust evidence links positive affect and extraversion, both between subjects and within subjects (more on this later). Extraverts are happier than introverts.
Wait, what? Yes. This is undeniable. All the research agrees: positive emotions and extraversion are very strongly correlated. Extraverts are happier than introverts. This has led some to propose that the unifying theme underlying all or most of the extraversion facets is positive affect. In the aforementioned study spanning more than 6,000 subjects in 40 countries, the authors contrasted two hypotheses for explaining the link between extraversion and positive feelings. One says that sociability is the core trait of extraversion, and that the correlation between happiness and extraversion is indirect: either social interaction is highly pleasurable, and extraverts spend more time interacting, thus becoming happier; or extraverts and introverts spend equal time alone and together with others, but people on the extraverted end of the spectrum enjoy the together time more.
The other hypothesis is their novel reward-sensitivity model. According to this model, extraverted people are simply more sensitive to and prone to seek out rewarding stimuli. It just so happens that social interaction is especially rewarding for humans, and empirical studies show that both introverts and extraverts tend to report more positive affect in social situations; extraverts are also apparently happier than introverts even when alone. According to this hypothesis, extraverts should be more likely to seek out rewarding stimuli both in social and nonsocial situations, and their sociable behavior is simply an instance of a more general pattern of reward seeking. According to their statistical analysis, the other facets of extraversion correlated much more strongly with positive affect than with sociability. The statistical evidence suggests that the unifying phenomenon that underlies the complex set of behaviors and traits that make up extraversion is reward sensitivity.
How would this be expressed in the brain? Recent research has found connections between differences in the dopaminergic system and differences in extraversion. Dopamine is a neurotransmitter implicated in reward, motivation and reinforcing behavior. For example, one study published this year measured brain activity in people who scored very low or very high on a measure of extraversion, corresponding to extreme introverts and extreme extraverts. Subjects were given placebo or different doses of sulpiride, a drug that interacts in a dose-dependent manner with dopamine. At low doses, it is a partial agonist, meaning it slightly increases dopamine activity; at higher doses, it is an antagonist, meaning it decreases activity. At higher dosages, introverts’ brain scans shifted in the direction of extraverts’ baselines and beyond, while extraverts shifted in the opposite direction. The authors suggest that a difference in the density of dopamine receptors might best explain their results. Basically, the hypothesis goes, introverts have less of certain kinds of dopamine receptors and more of a different kind, resulting in an overall lower dopamine activity. Since dopamine is implicated in reward and motivation, this would lead them to be less reward seeking and to experiencing less rewarding, positive feelings in general.
Another 2013 study looked at this behaviorally. It administered methylphenidate (Ritalin), a dopamine reuptake inhibitor, to subjects in what could best be described as a recreational manner. The subjects were conditioned to associate the lab environment with reward by taking feel-good drugs while in the lab environment. But tests showed that this association between reward and the specific lab environment was only acquired by extraverts, not by introverts, nor by introverts/extraverts who had been conditioned to associate a different lab environment with the reward stimulus. This is further evidence that extraverts are more reward sensitive than introverts.
But wait, does this mean if I’m introverted I’m genetically doomed to unhappiness, or that I will never learn to associate social contexts with pleasure? Here’s the twist. All of the above rather robust evidence could be turned on its head by a different line of research. Because all the above data were gathered by comparing groups of individuals. On average, what are the differences between introverts and extraverts? But a separate line of investigation seeks to understand the relationship between extraversion and other traits within the same person.
A 2002 paper details experiments that probe the relationship between positive affect and extraversion within the same subject. In one experiment, subjects were asked to answer questions designed to assess their state extraversion (how extraverted they acted in the moment) within the previous hour and their state happiness (how happy they felt in the moment) during the same time period. This was done five times per day, using PDAs (this was before smartphones). In the second experiment, a single report was made for the previous week, for ten weeks. In the third, the findings from the first two experiments were tested in the lab. Subjects were randomly assigned to group discussions in groups of three. They participated in two group discussions, randomly assigned to act in an introverted manner in one discussion and in an extraverted manner in the other. Then they evaluated each other and themselves using the same metrics as in the other experiments.
Now, one might think that simply acting extraverted wouldn’t be as effective as being extraverted. But the experiments proved this wrong. The individuals who were trait introverts (tended to be introverted) had just as strong a correlation between positive emotions and extraversion as the extraverts. In fact, in the first trial, the one where emotional states were assessed 5 x day, the introverts had a stronger correlation between acting extraverted and happiness than the extraverts! In the third trial, the people who were told to act introverted or extraverted were consistently rated by others to be introverted or extraverted, respectively. And yet again, the more extraverted they acted, the more they enjoyed the discussion.
Faking it ‘till you make it, scientifically validated!
This suggests two things: first, the simple fact that acting extraverted appears to make you happier. And second, that all the neurological differences between extraverts and introverts may not actually explain much. After all, within subjects, most people had periods of very outgoing and very introverted behavior, and their mental state for the most part correlated exactly with the behavior. Your brain is malleable, but it doesn’t completely rewire itself multiple times every day. These results throw a wrench into the reward sensitivity / dopamine framework detailed above. If we can replicate and expand on these within-subject findings and reunite these results with the between-subject findings, we’ll have come a lot closer to understanding introversion and extraversion.
OK, I get it. There’s still much work to be done. But however it is, how come these two different temperaments evolved? Especially if one sort is much happier than the other, wouldn’t one die out under selective pressure?
Good question. First of all, extraversion is a complex phenomenon, controlled by many genes. It takes a long, long time for evolution to completely eliminate variation in all of these genes. Second of all, there is good reason to believe that introverts and extraverts evolved to fill different niches in human society. It has been empirically shown that extraverts have more mates, but also die younger than introverts. Perhaps extraverts’ social activity and prowess make them more attractive mates, or give them more opportunity to meet mates, or some combination, which raises their evolutionary fitness, but are also more prone to impulsitivity and reckless behavior in their search for excitement and reward, thus resulting in more premature deaths.
Whatever happened to introvert/extravert pride? A common trend in the latest popular culture writings on introverts and “extroverts” is that whichever end of the spectrum the author identifies with is presented in a broadly positive light. The author takes pride in their orientation, whichever way it goes, often extolling its virtues in opposition to some perceived or real prevailing cultural current.
But science doesn’t function this way. It does not say that one kind of person is more worth than any other kind of person. That is well outside science’s scope.
However, the fact remains that the scientific consensus is that extraverted people are happier. And acting in an extraverted manner makes introverts and extraverts alike happier. And being happy, aside from being the higher-order goal of every human being, will make you more successful in almost every area of life—from income and marriage to mental health and longevity. It seems that from nature’s side, introverts have been cursed. But hey, at least you’re less likely to die in a parachuting accident or hunting sharks or from some other dangerous, thrill-seeking behavior. Besides, chances are you can be instantly happier by acting more outgoing.
But I like being introverted!
That’s perfectly fine. There is still a lot of work to be done on this personality dimension. The last word has not been said. But the current data we have cannot be denied: the link between happiness and high extraversion is undeniable.
Ernst Schäfer was a good scientist and a good Nazi. In 1938-39 he led a German expedition to Tibet sponsored by SS leader Heinrich Himmler, who was fascinated by Aryan culture. Although Schäfer specialized in the study of birds, and indeed took many bird speciments with him back to Germany, the most extraordinary artifact turned out to be of extraterrestrial origin. When he or one of his expedition members discovered an ancient Buddhist statue with a swastika—the ancient Indian luck symbol adopted by the Nazis as their symbol and now tainted by their legacy—prominently displayed on the chest, they couldn’t help but bring it back. At least that is the most plausible explanation of how it came to Munich, where it was held in privately owned obscurity until it was auctioned off in 2009.
When scientists analyzed the statue last year, they found that it was carved from a meteoric fragment. The 10kg iron statue showed a composition indicating it came from an ataxite meteorite, the rarest kind of meteorite. It is believed to be 1,000 years old and depicts a Buddhist deity. It may have come from the Chinga meteorite, which fell near the border between Siberia and Mongolia ten to twenty thousand years ago.
I went outside for a minute before intending to head to bed. As my eyes adjusted to the darkness, I looked up and saw the entire sky bridged by an auroral arc reminiscent of the bridge to the stars from His Dark Materials. It’s kind of unusual for this latitude and time of year to see it this clearly. By the time I had my camera set up, the sky arc had dissipated in favor of a more subdued light show, and perhaps it’s not the greatest photograph ever made, but this was the sky above my house an hour ago. Just like the weather forecast, space weather forecasts exist, and they will tell you when and where conditions for viewing the northern lights will be optimal. Of course, the main rules are rather simple and obvious: as close to the magnetic pole as possible (so farther north is better), clear skies, and away from light pollution (I live in a small town, but if I’d been standing in the middle of the town center, I wouldn’t have been able to see anything due to the ambient lighting).
Let us clear up a few confusing things. When a Chinese philosopher talks about “chi,” which is often translated as “energy,” he is talking about something quite different from what a modern physicist is talking about when he talks about energy, as in, “energy can’t be created or destroyed.”
I just finished reading your answer to the “mind-body question”, and I have a question regarding your answer. You say there’s no way to scientifically prove consciousness surpasses us after death, but what about our energy? According to physics, energy can’t be created or destroyed. Could it be possible our consciousness is linked in with this energy (which some may call our soul)? This is actually an on-going debate I’ve had for quite some time and I would love to hear your thoughts :)
In physics, energy is roughly the capacity to do work. Not the mental energy to show up for another grueling day of 9-5 at the office, but the capacity to apply force over distance. To push a particle in a certain direction, say. The international standard unit for energy, the joule, is given by the equation J = kg × m2 / s2, where kg is the kilogram, m is the meter, s is the second, and J is the amount of energy measured in joules.
Energy persists. The matter and energy that make up you once made up stars. To call it “your” energy is a gross injustice to the universe. You are simply borrowing the energy. In fact, even that is misleading. You are the universe. Not all of it, of course, but you and I are as intrinsic and inextricable parts of the universe as stars and planetary systems. There’s nothing special about us, which is either beautiful or terrifying, depending on how you look at it. We are the same matter and energy that was once in stars and when we die, this matter and energy will simply go over to other forms, become other things.
But this continuity can hardly be appealed to for eternal life. When the atomic nuclei in your body were part of a star billions of years ago, were they conscious? Was the star conscious? When your body is dirt, will the dirt have thoughts? Will the dirt cry inwardly when its relatives, living humans, stand upon it and watch its grave? If energy and consciousness are equivalent, consciousness must be omnipresent. Some have argued for this position, but we shouldn’t take that very seriously, because philosophers are a crazy bunch who will argue for anything, sometimes just for sport, sometimes because they’re not right in the head. If you don’t believe soil is conscious, there is no reason to think that the conservation of energy means the conservation of the soul.
This is known as the fallacy of equivocation: of using the same word with different meanings, carelessly substituting one meaning for the other. It’s an honest mistake to make, but it’s a mistake nonetheless. Ancient philosophers thought that the thing they called variously by names like “chi,” the “life force,” and so on was interchangeable with other things which we today call “energy.” For this reason, modern spiritualists will often use the word energy to refer to such nebulous, spiritual concepts (for which there is little to no scientific support). The first law of thermodynamics is the one about conservation of energy. You know how it goes, at least in the layman’s version: “energy can be neither created nor destroyed, only converted from one form to another.” But the “energy” physicists talk about is the kind that is measured in joules. It has nothing to do with consciousness.
If, like most scientists now believe, consciousness arises out of a particular kind of arrangement of matter and energy in the brain, then obviously there is a connection between consciousness and energy. Obviously, if mind is physical, then it must be matter and energy. But the catch here is that this matter and energy must be arranged in a particular way. A rock, for instance, is not conscious. The matter and energy that make up the rock aren’t arranged in the appropriate pattern for consciousness to arise. And when humans die, the same happens to “our” energy. It gets converted into other forms, takes part in other configurations of matter. Perhaps in a billion years, the same molecules that once made up you or me will, through an endlessly complicated series of operations, again take part in a configuration of matter and energy sufficient for consciousness to arise. Does this mean your “soul” has reincarnated? I think not. Not in the sense that religious people mean when they talk about the soul surviving or reincarnation. But in a poetic sense, perhaps it has. That is a matter of interpretation, for you to decide.
(By request, since Tumblr doesn’t allow Q&A posts to be reblogged, I have made this answer into a text post that can be reblogged. The previous post has been deleted. Sorry for double-posting.)
What’s your opinion on the mind-body problem? Do you think the mind can survive after death and is a separate element?
It’s tempting to suggest that if science can’t explain the way consciousness arises from matter, then there might be something to the old myths about the afterlife and the survival of the soul or reincarnation anyway. But it’s very important to distinguish between these two questions: what is consciousness, and does consciousness continue after death?
There is no reason to suppose that the mind doesn’t die when the body does. Near-death experiences are just that: they’re not experiences of death, otherwise the person who had the experience couldn’t have lived to tell the tale. Furthermore, it isn’t implausible that we might sometimes enter an altered state of consciousness in extreme conditions that bring us to the brink of death—after all, everyone experiences the altered state of consciousness we call dreaming almost every night. That these experiences might resemble myths or narratives prevalent in your society is hardly surprising. If your subconscious is creating a story, surely it must take the raw material from somewhere, and if you live in a traditionally monotheistic society where life after death is a common notion known to everyone, believers or not, then tunnels of white light or talks with dead relatives during a hallucinatory near-death experience is almost to be expected. After all, people who ingest a lot of drugs or become psychotic also have similar experiences.
What other reasons might one have for believing in the continuation of consciousness after the brain is dead? Excluding theoretical future inventions that facilitate “brain uploading,” and excluding religious scripture, what more is there to say? How would we ever know? If the mind is intangible, unobservable, at best we could say that the mind might survive death, but without any good reason to believe so, why would you? The only mind we have direct access to is our own.
The famous philosophical question of other minds asks, how do you know your neighbor is conscious? How do you know your mailman isn’t an automaton, an assemblage of matter that behaves like a human but has no consciousness, for whom there is nothing to be like them? The answer, of course, is that we don’t, but they behave roughly like we do, they respond as if they are conscious, and besides it seems hard to imagine how a robot could accomplish what other people do without having sentience. Whether such automatons—identical molecule by molecule with humans, but lacking conscious experience—can exist is known as the philosophical zombie problem. Most of us who have common sense accept that other minds exist, that other people are conscious, because they appear to be. And we also accept that rocks and bacteria aren’t conscious, because they display no signs of being conscious. Of course, until we can prove definitely that the mind is purely physical, we can’t prove that rocks aren’t conscious, but not even the most hardcore treehugger argues that we shouldn’t tread on rocks for fear of hurting their feelings. The same argument can be applied to life after death: dead people don’t display any of the signs of being conscious. The most parsimonious explanation is that when the body dies, so does the mind. Even if dead people’s minds somehow were separated from the body, and remained in existence after physical death, we would never know.
There is a lot of things we don’t understand about the brain. But one thing we’re pretty sure: it isn’t breaking any of the laws of physics. Clearly mind and brain are intrinsically linked. If the mind were nonphysical but somehow capable of interacting with the physical brain in the way that a dualist account of consciousness requires, we would expect to see energy spontaneously come into existence as the non-physical self pulls the strings. But we don’t. The second law of thermodynamics holds as well for the brain as it does for everything else in the universe.
I believe the mind isn’t nonphysical. Exactly what that entails is a matter of both philosophy and science. The philosophical zombie thought experiment is troubling; not so troubling that I believe it proves the mind can’t be physical, for reasons explained above, but troubling in a more fundamental sense. The fundamental question is: why does a certain configuration of physical, objective matter translate into subjective consciousness? It seems entirely conceivable that it wouldn’t. Biology reduces to chemistry which reduces to physics, and it would be logically contradictory for biological mechanisms to violate the laws of chemistry, or for chemistry to violate the laws of physics. And it works the other way around: physics necessarily gives rise to chemistry, which necessarily gives rise to biology. But with psychology, the same seems not to be true. We have yet to find the piece of the puzzle that guarantees that physics gives rise to consciousness. It seems entirely conceivable that it wouldn’t, in ways it’s inconceivable that physics wouldn’t give rise to chemistry.
I believe the mind-body problem is the hardest one in science, in part because the brain is so complicated, and in part because it is a problem that is both philosophical, linguistic, and scientific all at once, and which discipline which aspect belongs to is hard to determine. Combining quantum mechanics and general relativity? I think we’ll do that long before we solve the mind-body problem. Perhaps, in the end, we must simply accept that there is no explanation. For no good reason, certain configurations of matter give rise to subjective experience, just like there is no reason for the other fundamental constants of physics to be what they are. They just are. But this seems hard to accept because the fundamental forces of nature are so elementary, and the mind so complex, and it seems hard to believe that elementary facts can be true for no good reason, but that they still can’t explain more complicated facts which are entirely supervenient on them. (That, I’m afraid, is philosopher-speak. I have been damaged by reading too many philosophy papers, and this is a very complicated subject, and it’s very hard to write about without using technical language, even though I try and explain technical terms the average reader would not be familiar with as much as possible on this blog.)
Because it is so complicated—perhaps the hardest nut to crack in science—and because it is so essential to our lives—by definition, all our experience is, well, conscious experience—the study of mind and brain is probably my favorite part of science. You may have noticed there’s a lot of pharmacology and psychology on here. But it’s very hard to give a straightforward answer to a question like, “What’s your opinion on the mind-body problem?” Life after death though? Nah, old fairy tale.
Gone are the days when we could comfortably assume that a single gene or hormone is responsible for a complex disease or behavior. As new data roll in, previously clear-cut cases turn out to be more complex. One such case is oxytocin, a neurohormone closely related to prosocial, bonding behavior in decades of research. This strong association has given oxytocin the nickname “the love hormone,” and oxytocin nasal spray—currently used primarily for its effects on lactation in nursing women—has been proposed as a novel treatment for autism and social anxiety. But new data suggests that oxytocin also plays a role in human ethnocentrism, and in strengthening negative memories in mice.
Researchers at the University of Amsterdam investigated the effects of oxytocin on in-group v. out-group bias in a series of trials. Ethnically Dutch males self-administered either oxytocin or placebo and then completed a series of double-blind computer tasks designed to measure implicit bias towards a perceived in-group or against two perceived out-groups, represented by ethnically Dutch people and by Germans or people of Middle Eastern descent, respectively. The tasks included trolley problems, empathy exercises, and tasks where the participants had to group positive words together with names from either in- or out-group and negative words with the other, or vice versa (the speed with which this grouping takes place being a measure of implicit bias). The researchers found a significant incrase in bias towards the in-group as compared to either out-group (the Germans or the Middle Easterners) with oxytocin as compared to placebo. They also found limited out-group derogation, but the good news is that it appears oxytocin more strongly increases favoritism towards the in-group than hate towards the out-group. Still, this research suggests the “love hormone” is implicated in ethnocentrism and xenophobia.
This, however, contrasts with previous research which has showed that oxytocin leads to prosocial behavior and decreases our aversion towards the unknown, and increases trust in economic games. Previous studies, however, may not have controlled properly for in- versus out-group bias. For example, one study measured the brain activity of fathers as they looked at pictures of their own child, a familiar child, or an entirely unknown child, and found that oxytocin lead to decreased activity in areas of the brain implicated in critical social evaluation. That study, however, did not control for ethnicity of the children and fathers or other factors that may create an in- versus out-group dynamic, only for gender and whether the child was known to the father or not.
A recent study in mice found that oxytocin strengthens negatively charged memories. Rather than reducing future anxiety, it strengthened it. In one experiment, three groups of mice (without oxytocin receptors, with normal densities and with increased densities of receptors) were exposed to aggressive mice in a cage, a stressful experience. When later reintroduced to the cage, the mice without oxytocin receptors didn’t appear to remember the aggressive mice, and did not exhibit fear responses. The mice with normal and high densities of receptors, however, exhibited typical and above average fear responses, respectively. These effects were not limited to socially salient negative memories. In another experiment, the aggressive mice were replaced by startling, but not painful electric shocks. When reintroduced to the box, the oxytocin-deficient mice did not show any particular fear while in the box where they had received shocks, while the oxytocin-boosted mice showed enhanced fear responses.
This new data certainly complicates the picture of oxytocin as a cuddly hormone involved with all that is good in human nature. Despite this, research into the possible therapeutic benefits of oxytocin remains promising, although perhaps not as unanimously cheery as it may once have looked.