Introvert / Extrovert: the difference is in your brain

Some time ago, I posted my thoughts on the misunderstood introvert. It seems to be a topic of widespread interest, since that post frequently shows up in my tracker stats.

This week I got a belated comment on the post from Nicole, who is studying clinical psychology at the graduate level in the midwestern USA. She added this insight to our earlier dialogue:

There is a theory that introversion/extroversion can be detected even before birth. Introverts tend to have a higher baseline state of arousal, therefore, it takes less to stimulate them.

Extroverts, conversely, have a lower baseline rate of arousal. Therefore, it takes more interaction to receive the same chemical/emotional feedback.

So, babies that are more active in the womb are correlated to extroversion.

And then Nicole returned with an update. Coincidentally, she had just discovered a newspaper article on this very topic. ("We all control the news, evidently", she commented.)

The article was originally published in USA Today. Here's an excerpt:

The attitude that there's something wrong with introverted people is widely shared in society, where fast talk and snap decisions are often valued over listening, deliberation and careful planning. Extroverts seem to rule the world or, at least, the USA, which hasn't elected an introverted president for three decades, since Jimmy Carter.

"The signals we get from the world agree that extroversion is valued," says Sanford Cohn, an associate professor in curriculum and instruction at Arizona State University.

I note, in passing, that I took the same position in my post: Western society rewards extroverts over introverts virtually every time. People respond to extroversion as a great virtue even if they haven't explicitly thought of it in those terms.

But let's move on and explore the new insight. It turns out that the distinction between introversion and extroversion is all in your head — but I mean this quite literally!

Introverted children enjoy the internal world of thoughts, feelings and fantasies, and there's a physiological reason for this. Researchers using brain scans have found introverts have more brain activity in general, and specifically in the frontal lobes. When these areas are activated, introverts are energized by retrieving long-term memories, problem solving, introspection, complex thinking and planning.

Extroverts enjoy the external world of things, people and activities. They have more activity in brain areas involved in processing the sensory information we're bombarded with daily. Because extroverts have less internally generated brain activity, they search for more external stimuli to energize them. [emphasis added]

How counterintuitive:  the flamboyant extrovert has lower levels of electrical activity in the brain; the quiet introvert has more!

The information explains why it is so difficult simply to will yourself to behave more like an extrovert (or more like an introvert), contrary to your innate tendency. It also confirms Nicole's observation: if the distinction is rooted in electrical activity in the brain, you are an introvert (or an extrovert) even while you are still in utero.

Fascinating!