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Answers Lie in the Science of the Introvert's Brain

Why Introverts Think, Plan, and Enjoy Quiet Time...

Oftentimes we wonder why introverts do what we do.

  • Why are we introspective?

  • Why do we tend to overthink things?

  • Why do we enjoy our solitude and our personal hobbies so much?

  • Why are big crowds of strangers too much?

  • Why do we tend to take more time to analyze situations and make decisions?

Is this how we were raised or is it just who we are - part of our DNA?

Recent research has revealed there is indeed a lot of science to our actions. Three primary areas help answer our questions.


Dopamine and acetylcholine have a significant impact on the different actions and behavior of introverts and extroverts. Everyone has the same amount of dopamine and acetylcholine in their bodies. Both provide a feeling of happiness to the individual. So why do introverts and extroverts have such different personalities then?


Extroverts have more dopamine receptors than introverts. They also have a high tolerance for dopamine, so they end up craving it in order to get enough to satiate the receptors. Dopamine is released into the brain from the expectation of, and actual activities with, external stimuli like socializing, talking, and adventure. Extroverts have a high tolerance for dopamine so they need more of these activities to quench their hunger for dopamine. They are driven to stay at the party later and engage with more people along the way. It truly makes them happier.

Introverts on the other hand have fewer dopamine receptors. They are not driven to crave it. They have a low tolerance for dopamine. Hence, too much socializing overstimulates introverts. So while many introverts do indeed enjoy socializing, extended periods of engagement become overwhelming. While extroverts need lots of dopamine to feel the rush, introverts get a rush from small, short exchanges, after which it is exhausting.


Introverts however crave acetylcholine. It's in our DNA. We crave this just as extroverts need dopamine. Acetylcholine is released when we are calm, quiet, and introspective in thought. So the more we engage in these traditionally introverted strong suits, the greater sense of contentment we receive. While an extrovert's dopamine high is spurred externally, an introvert's acetylcholine high is triggered internally.

Extroverts also have acetylcholine, but the high from solitary and calming activities is typically minimal, so extroverts remain drawn to dopamine-inducing activities.

DID YOU KNOW? Oftentimes people's cravings for the dopamine high result in abuse of drugs like opiates, alcohol, nicotine, amphetamines, and cocaine. Interestingly, I couldn't find research on illicit drugs that satisfy an introvert's craving for acetylcholine. Guess we'll just have to manufacture that ourselves with a nice book, some art, and calming reflection.
Alzheimer's disease is believed to occur, in part, when acetylcholine supply is stunted and thus those inflicted struggle with brain function in general and connection to memories in particular. Hence, introverts who feed their need are, theoretically, less susceptible to Alzheimer's.
Since there is no acetylcholine replacements, medicines focus on thwarting the breakdown of the body's natural acetylcholine supply.

Nervous System Highways

There are two primary pathways in the brain that carry neurotransmitters. Once chemicals are released due to the external or internal stimuli we covered above, the pulses travel along highways to certain parts of the brain.

Dopamine Pathway

When dopamine is released, it travels on the dopamine highway. It is a short highway that passes by sensors of taste, sight, hearing, and touch. So external events trigger these senses, they feel good, and the extrovert wants more. Also, because this highway is short, there is a short time span between stimulus and reward. This drives and satisfies their craving quicker.

Acetylcholine Pathway

When acetylcholine is released, it travels on a much longer acetylcholine highway. It travels toward the frontal lobes of the brain where empathy, self-reflection, emotions, planning, self-talk, and memories are stored. So introvert's craving for this chemical spurs these more introspective activities which, in turn, spark the introvert to do these activities more to continue to feel contentment. Because this highway is quite a bit longer, introverts tend to take more time to process, ponder, think, and act. That is why we are typically less spontaneous or comfortable in making rapid decisions.

Pre-Frontal Cortex Gray Matter

Everyone has a pre-frontal cortex that manages what is often termed Executive Function. Actions like planning, decision-making, abstract thought, resilience, and self-control are found in this lobe.

Thicker Gray Matter

Those with thicker gray matter appear to have greater strength in these areas. Many studies indicate introverts have noticeably thicker gray matter. Thus, introverts tend to excel in thinking, planning, and resilience. This may come as a shock to many, especially in the business world, but this is one reason why introverts are well suited for the rigors of business leadership.

Thinner Gray Matter

Extroverts tend to have thinner gray matter. Thus they tend to be less wrapped up in thinking and pondering and favor more rapid, seat-of-the-pants decision-making and living in the moment. This can lead to a very active and adventurous lifestyle but is not always well suited for evaluating problems and making thoroughly analyzed decisions.

Shedding Light on Our Personalities

When I researched this article, I must admit I felt a bit overwhelmed by the science. I've tried to highlight key takeaways from our discussions. But after reviewing the information and consistent interpretations, I feel a bit vindicated. I am very proud to be an introvert. I've had periods of my life when I've tried to put on an extrovert's façade, but I've experienced the pain and torment repeatedly, ultimately recognizing introversion is in my DNA. It is who we are at our core.

These studies confirm this.

While no two introverts are alike and some are more sociable than others, we all have a predisposition for calmer, more introspective activities. It's in our DNA. It's part of our chemical composition. It's who we are.

So while I am a big advocate of stretching ourselves, I suggest rather than expending our energy trying to become "more extroverted," we focus our stretching our own strengths. Revel in those strengths. Learn new hobbies. Meet more people in small groups for short durations. Enjoy our quiet time. Start a journal. Try meditation. These are the kinds of activities that feed our craving for acetylcholine and help us lead happier lives.

So when someone goads you to join a social, speak up, or make a quick decision, we can just explain, "I'm not wired that way. I'm an acetylcholine junkie with longer highways and thicker gray matter. I'll get back to you shortly with a thoughtful, balanced, circumspect response in due time."


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