A lot of factors contribute to who we may become一the culture we grow up in, how we’re socialized, and lessons we glean from our role models. Part of our personalities, however, may be predisposed by our brain chemistry. Recent science has highlighted neural differences that contribute to our tendencies towards either introversion or extroversion.
Carl Jung, the psychoanalyst who popularized these terms in the 1920s, described introverts as individuals who are more energized by their internal worlds. They recharge by spending time alone and enjoy turning inwards towards their thoughts and feelings. Extroverts, on the other hand, are more externally oriented; they seem to draw energy from interactions with others and are often focused on their surroundings. While no one complies completely with either extreme, most of us lean in one direction. Many scientists believe that this personality variation is tied to differences in our how our brains use chemicals like dopamine.
Think of the last time you accomplished something important to you一maybe you were selected for your dream internship, made a new friend, or discovered that the person you’ve been crushing on likes you back. The surge of happiness that likely followed is related to dopamine, a neurotransmitter that plays an integral role in our brains’ reward systems. It helps us not only recognize external goals, but also motivates us to work towards them and rewards us with pleasure and satisfaction when we do. When released, dopamine makes all of us more talkative, pro-risk, and attentive to our surroundings.
According to Scott Barry Kaufman, the Scientific Director of The Imaginative Institute, introverts and extroverts have equal amounts of dopamine available, but extroverts have more active reward networks. Consequently, higher doses of dopamine are released more frequently in their brains. This makes them more attuned to the potential external rewards present in social situations一recognition, for example, or making a new friend. At the thought of such opportunities, extroverts get a boost of positive feelings that motivate them to spend time with others, particularly in groups. Socializing is tiring for everyone一we all expend energy in each interaction一but the vitalizing dopamine surge that occurs in extroverted brains makes the experience less fatiguing. Introverts, on the other hand, are more likely to get worn out by socializing and are less drawn towards the possible rewards.
Not only do introverts have less active dopamine systems, but surges of this chemical can leave them feeling overwhelmed as well as excited. According to Dr. Marti Olsen, the author of The Introvert Advantage, extroverts have a higher tolerance for dopamine. They need a lot to fully feel its effects and thus seek out the adventure and excitement that produces it. Introverts, on the other hand, can easily become overstimulated by a dopamine rush and instead tend to rely on a different neurotransmitter called acetylcholine to produce pleasure.
Acetylcholine generates positive feelings while thinking and feeling. It supports introverts’ abilities to reflect introspectively and focus on one thing for an extended period. Many quieter people seek out calm environments because, without distractions or external stimuli, it’s easier to turn inward and therefore to produce acetylcholine.
Today, more and more people are aware of introversion, extroversion, and where they fit on the spectrum. Understanding the brain chemistry linked to these qualities can give us another piece of the puzzle of personality, cueing us in to how and why we function and perceive the world in different ways.