Compelling Reasons Why Introverts and Extroverts Are Different

Ever asked yourself why introverts and extroverts are so different? It has to do with the wiring of their brains. Read on to learn much more.

Reviewed and approved by the psychologist Valeria Sabater.

Written by Valeria Sabater

Last update: 08 November, 2022

Introverts and extroverts are very different. But why? I’m standing in the crowd in front of the stage at the small gritty music club. My two extroverted friends are on either side of me. They sway along with the crooning Indie singer and smiling. Believe it or not, I was having fun for a while. However, now I’m ready to head home and find my bed. The loud music and the dense crowd of strangers are bothering me. 

Most importantly, the small talk I made all night left me feeling drained. It’s just too much, for too long, for an introvert like me. I’d rather be in the peaceful solitude of my apartment. Just me, no noise, maybe a great book . Likewise, the Internet helps me turn inward and recharge after this much socializing. But my extroverted friends could probably stay at the concert, chatting long past the encore. 

They’ll actually feel energized when they leave and won’t need any recovery time. But why do I react so differently than my extroverted friends to the same situation? It has to do with some key differences in the wiring of introverts’ brains.

Here’s a quick guide to some key differences between introverts and extroverts.

-Jane Austen-

Carl Jung’s studies

Carl Jung came up with the terms introvert and extrovert in the 1920s. He also founded analytical psychology. He did so to describe contrasting personality types. Likewise, to explain why distinct ways energized different people. So, he hypothesized that extroverts gained their energy from their social interactions and external environments. 

In addition, they felt uncomfortable and anxious when they found themselves alone. On the other hand, introverts, Jung further explained , replenish their energy levels when they’re in quiet environments. Unlike extroverts, they find socializing and busy environments overstimulating and too demanding. 

Therefore, introversion and extroversion are at the opposite ends of the same spectrum. Everybody moves up and down the spectrum depending on external and internal factors. However, a person tends to prefer one personality type over the other.

The dopamine difference

A difference between the brains of introverts and extroverts is the way they react to the neurotransmitter dopamine . Dopamine is a chemical that the brain releases. It gives a person their motivation to achieve external goals and receive external rewards. For example, dopamine motivates a person to earn more money and increase their circle of friends. 

Most importantly, thanks to dopamine, all of us become more alert to our surroundings and more talkative. We’re also more motivated to undertake activities we perceive as highly risky. Introverts and extroverts have equal amounts of dopamine in their brains. However, the major difference between both categories is the activity of the dopamine reward network. 

In other words, “the dopamine reward network’s more active and dynamic in introverted brains, ” says Kaufman. Scott Barry Kaufman is the Director of The Imagination Institute. When an extrovert anticipates a social event, they feel good and energized. On the other hand, an introvert will feel overstimulated. 

It’s no surprise for my extroverted friends, as the noise and the crowd at the concert were fun. This intensity of stimulation acted as a cue. In other words, they felt they were achieving their goal. For instance, the reward of socializing and a fun night out. But, for me, as the night wore on, the hubbub was bothersome and tiring, as the noise overstimulated me.

For introverts, acetylcholine is where it’s at

Did you know that introverts prefer to rely on a different neurotransmitter called acetylcholine? Believe it or not, author Christine Fonseca wrote it in her brilliant book. In fact, she published Quiet Kids: Help Your Introverted Child Succeed in an Extroverted World in 2013. Like dopamine, they also link acetylcholine to pleasure. But the difference is that acetylcholine makes us feel good when we turn inward. 

Likewise, it powers our abilities to think deeply, reflect, and think about one thing for a long period of time. It also helps explain why introverts like calm environments. After all, it’s easier to turn inward when we’re not attending to external stimulation. When I lounge at home in quiet solitude, whether lost in a book or watching Netflix, I’m basking in the pleasant acetylcholine effects.

Nervous system differences

The nervous system is divided into two distinct parts. For example, the sympathetic side and the parasympathetic side. Firstly, the sympathetic side relates to the “fight, fright, or flight.” But the parasympathetic side allows us to rest and digest. This is another piece of the introvert-extrovert puzzle. In fact, Dr. Laney discussed it in her book The Introvert Advantage: Thriving in an Extrovert World . 

Acetylcholine links to the parasympathetic side of the nervous system. People name it the “throttle down” or “rest-and-digest” side. But when we engage the parasympathetic side, our body conserves energy. So we withdraw from the outer environment. Our muscles relax, we store energy, and we metabolize food. In other words, pupils constrict to limit incoming light. 

Our heart rate and blood pressure lower. Basically, our body gets ready for hibernation and contemplation. Of course, these are two of the things introverts like the most. Both introverts and extroverts use both sides of their nervous systems. Therefore, just like they use both neurotransmitters.

Extroverts tend to favor the opposite side of the nervous system, the sympathetic side, a.k.a. “full-throttle” or “fight, flight”. This side mobilizes us to discover. For instance, new things and being active, daring, and inquisitive. Therefore, the brain’s alert, while focusing on its surroundings. Blood sugar and free fatty acids elevate to give us more energy. 

Secondly, it slows digestion and reduces thinking. We prepare ourselves to make snap decisions. Lastly, extroverts obviously thrive on the good feelings charged by dopamine. The charged good feelings they created when they engage the sympathetic side. However, it’s way too much for us introverts.

Why introverts tend to overthink

This is another major difference between introverts and extroverts. When an extrovert’s brain receives information from the external world, it travels via a short pathway. In other words, it goes through different areas of the brain where it processes four senses: touch, taste, sound, and sight.

On the other hand, when an introvert’s brain receives stimulus from the outside world, it’s a different situation. Therefore, the pathway that the information travels through is much longer. In fact, the information goes through many areas of the brain, including:

• Firstly, the right front insular. 
• Secondly, the Broca’s area.
• Thirdly, the right and left frontal lobes.
• Lastly, the left hippocampus.

The right front insular is an area involving empathy, emotional thought, and self-reflection. But the Broca’s area activates self-talk and plans speech. Likewise, the right and left frontal lobes plan and select ideas and actions. The left hippocampus decides what things are personal and places them in long-term memories.

There’s a long journey that the information takes when an introvert receives stimulus from the external world. Therefore, this is the reason that introverts take longer to speak, react, and make decisions.

Introverts have more gray matter in the front of their brains

Did you know that the prefrontal cortex is the part of your brain that regulates personality? Most importantly, it also regulates decision-making and social behavior, among other things. According to a genius study published in the Journal of Neuroscience, introverts have larger, thicker gray matter. It’s a type of tissue in the brain where most of its activity happens.

Likewise, according to the discovery, it locates in the prefrontal cortex. The prefrontal cortex is the place in the brain linked to abstract thought and decision-making. On the other hand, extroverts have thinner gray matter in the same area. What exactly does this mean? It means that introverts devote more of their energy and resources to abstract thought. But extroverts have the propensity to live in the moment.

Last thoughts

In short, there are many differences between introverts and extroverts. Do introverts dislike people?  Often people don’t truly understand introversion. Therefore, they might get the mistaken idea that introverts are shy, antisocial, reclusive, or rude. At the concert, I bolted for the door the first chance I got, leaving my extroverted friends. I imagined they would only reluctantly leave after the last song. 

For instance, when the lights came on. Or a security guard brusquely ushered them toward the door. Yet, given how my introverted brain works, it makes sense. After a few hours of stimulation and socializing, I had to get out of there. In other words, it’s not that I dislike people. But socializing is more tiring for me than it is for extroverts. For example, I love resting at home, curled up on the couch. 

In other words, I need a calm, familiar environment, where I unwind and relax. I’ll surely go to another concert and hang out with the extroverts again. But only after some soothing alone time. Not a moment sooner. Are you an introvert? I hope this helped. Sadly, the world can be confusing and extroverts don’t always get us. But I do. It’s okay to be quiet and a thinker.