Introverts & Extroverts: It’s Not as Simple as Shy or Outgoing - Part 1

Originally posted on Michigan Science Writers

Key words: neuroscience, neurology, introverts, extroverts, personality, dopamine, acetylcholine

Seemingly every Friday night, I'm curled up on my couch with a glass of wine and a good movie. Yet, it amazes me how many people scoff or flat-out laugh when I tell them that I'm an introvert. I am! In social situations, my mood can change very suddenly. It's as if my social batteries have run out—flipping my social switch from on to off. Such changes are confusing for my friends, which might be based on the big misconception surrounding introversion and extroversion in society.

How Do We Define Introversion & Extroversion?
Typically, introversion and extroversion are thought to relate to a person's social ability. Extroverts are often thought of as outgoing, while introverts are thought of as shy. This common misconception is what Susan Cain—a self-proclaimed introvert, and best-selling author of "QUIET: The Power of Introverts"—fought to challenge in her viral 2012 Ted Talk. In this talk, she described introversion and extroversion as the way a person responds to stimulation, such as social stimulation or adrenaline-inducing activities. Extroverts often crave situations with large amounts of stimulation, while introverts gravitate more toward low-key, mellow situations.

Figure 1. For all of those moments when the introverts among us want nothing more than silence and solace. Image Credit:

These classifications are supported by psychological definitions. Carl Jung, a renowned psychotherapist and founder of analytical psychology, defined the two opposing personality types by where a person focuses their energy. An extrovert’s energy moves "toward the outer world of people, places, and things," focusing more outside of themselves on the outside world. On the contrary, an introvert’s energy moves “toward the inner world of thoughts and ideas." They are often described as introspective, with a tendency to focus on their feelings, dreams, and their own internal world.

Nowhere in this definition of introversion do we see the word “shy.” In fact, these definitions make an important distinction: that extroversion and introversion have less to do with a person’s social ability and more to do with where they focus their thoughts and energy. Extroverts focus on what’s outside of their minds, whereas introverts focus on what’s inside. 

However, there do seem to be social differences between introverts and extroverts. Various groups have sought to address whether introversion/extroversion affect social engagement, how introverts and extroverts spend their free time, and how they manage stress. In one study, participants were classified as introverts and extroverts using a questionnaire called the Eysenck Personality Inventory. The results of this test were correlated with other self-assessments of the participant’s leisure activities, utilization of free time, social situation preferences, and inventory of stressful situations.

As would be expected, extroverts were shown to prefer social interactions, even seeking out and engaging in social activities, including “those which involve assertiveness, intimacy, and competition.” On the contrary, introverts did not seek out these situations, but it is unclear whether they actively avoided these situations or they simply had a tendency to be reserved and withdrawn.

What if I’m not an introvert or an extrovert?

Introversion and extroversion do not deal in absolutes, though. It is not uncommon for an introvert to desire a social environment on occasion, while an extrovert may desire some peace and quiet.

"There is no such thing as a pure introvert or a pure extrovert," Cain explained in her Ted Talk.

Some personalities fall right in the middle of the introvert-extrovert spectrum, and are often called “ambiverts,” but I personally prefer the phrases “outgoing introvert” and “shy extrovert” over “ambivert” because these terms distinguish between a person’s social preferences and their external or internal energy focus. I, myself, identify with the label of outgoing introvert. I enjoy socializing and engaging with people; however, I prefer to recharge my batteries in mellow environments and in solitude. On the contrary, shy extroverts are energized by stimulating environments, but are nonetheless shy in social situations. More often than not, introverts and extroverts gravitate toward situations that represent the degree of stimulation they prefer. 

These labels demonstrate the importance of distinguishing between a person’s social ability and their desired method of rejuvenation. This is an important distinction in accurately defining and introvert and an extrovert—not just based on whether someone is shy or outgoing.

The social and basic behavioral differences between introverts and extroverts are not difficult to observe. But is there a biological basis to the differences in these two personalities that we cannot see with our eyes? In my next post, I will discuss the known neurological differences between extroverts and introverts.

Click to continue reading Part 2!