Is introversion or extroversion nature or nurture? The Science behind it.
In the grand tapestry of human nature, the spectrum of introversion and extroversion paints a fascinating portrait. Are these traits etched in our genes or molded by our experiences? Let's delve into the science behind it.
Let’s begin with the 2 chemicals in our brains (or neurotransmitters) that guide messages from cell to cell and direct our brain functions and behavior. There is firstly Dopamine, a chemical that is released in the brain that provides motivation to seek external rewards, gets us to act quickly, take risks, makes us feel the intense zaps of happiness. https://mhanational.org/what-dopamine There is also Acetylcholine, which also rewards us but in a more subtle manner which makes us alert, relaxed and content. Acetylcholine plays a vital role in mental processes and human behaviours such as memory and cognition, by triggering a process that reduces or blocks background noise and enhance learning.
1. Different sensitivity to Dopamine
Extroverts have a low sensitivity to dopamine, so they require large amounts of it. The more they talk, move, and socialize, the more they feel dopamine’s pleasant effects. While introverts are highly sensitive to dopamine. Too much of dopamine will make them feel overstimulated. This explains why extroverts prefer action, movement and frequent social engagements for the brain to receive the reward feedback whereas the introverts’ brain, if exposed to the same amount of stimuli as the extroverts will feel overwhelmed. It also explains why Introverts are more sensitive than extroverts to various kinds of stimulation, from coffee to a loud bang to the dull roar of a networking event – and that introverts and extroverts often need very different levels of stimulation to function at their best.
2. Different usage preference in the nervous system
All humans have 2 sides to their nervous systems. The “Fight, Flight or fright” mode (Sympathetic) and the “ rest and digest” mode (parasympathetic) – likened to the brakes and the accelerator pedal in the car. When we engage the parasympathetic side of the nervous system, our body conserves energy, we withdraw from the outer environment, our body relaxes and calms down. The parasympathetic mode is activated by Acetylcholine. On the other hand, when we engage the sympathetic side of the nervous system, which is activated by Dopamine, the body goes into action, alert, ready to take-off. This is when the body is mobilized to be active, to discover new things, be daring and take risks.
Both extroverts and introverts use both sides of their nervous systems at different times. But it's no surprise that introverts generally engage their parasympathetic side more – the calmer and slower side while extroverts often hit the gas, yearning for adventure and embracing risks, propelled by the fiery Dopamine.
3. Different pathways through the nervous system
Dr Marti Olsen Laney in her book “The Introvert Advantage” states that when information is received from the outside world and enters an extrovert’s brain, it travels a shorter pathway. Dr Laney posits that this shorter pathway goes through areas of the brain where taste, touch, sight and sound are processed. For the introverts, the pathway is longer, travelling through many areas of the brain, which includes the area associated with empathy, self-reflection, and emotional meaning. It also goes through the area which plans speech and activates self-talk, and the area which select, plan, and choose ideas or actions. No wonder introverts are more prone to overthinking!
4. Different sensitivity of the Amygdala
The amygdala is the part of our brain that acts as the emotional switchboard, receiving information from the senses and then telling the rest of the brain and nervous system how to respond. In Susan Cain’s book “Quiet”, it reported the findings from Jerome Kagan, an American psychologist, who hypothesized that infants born with an especially excitable amygdala grow up to be children who were more likely to feel vigilant when meeting new people. The more reactive the amygdala, when confronted with something new and stimulating, displays more of the fight, flight or fright response. This hypothesis posits that the reactivity of our amygdala has a link to the temperament of introversion. Kagan discovered that the more reactive a child’s amygdala, the more physiological effects such as higher heart rate, widely eye dilation happens. Kagan’s research also uncovered that high reactive children (of their amygdala) tend to think and feel deeply, use more eye movements than others to compare choices before making decisions. Kagan’s research highlights that introversion does begin from infancy!
What does this all mean?
If your personality traits align more with that of an introvert (if you’re still unclear, take the quiz here!), is that the result of “nurture” –because your parents are both soft-spoken and reflective types or is that a result of “nature” – that it’s a part of your genetic make-up?
While none of the studies is perfect, but the results have consistently suggested that introversion and extroversion have a biological explanation and is probably heritable. So your preference for curling up with a book in hand in your cozy corner at home as opposed to partying it out after work is most likely your brain and nervous system at play.
“To be yourself in a world that is constantly trying to make you something else is the greatest accomplishment.” - Ralph Waldo Emerson
So, why do we need to know the science behind it all? If you don’t understand introversion, you might get the mistaken idea that introverts are antisocial, reclusive, or rude. Knowing that our temperament is largely a result of biological make-up helps introverts and extroverts accept themselves as they are. It validates their preferences and tendencies (A big yes to quiet time alone) which can lead to increased self-esteem and confidence! It also helps leaders in the marketplace and parents understand the diversity of personalities to find better ways to support their child’s personal or staff member’s professional development.
Ultimately, understanding the science behind introversion is crucial for promoting inclusivity, empathy, and personal growth. It helps create environments where all personality types can thrive and contribute their unique strengths. And as an introvert, it makes me glad to know that I’m uniquely created the way I am and you’re uniquely made the way you are!
Remember, your temperament shapes your journey, but it doesn't define your destiny.
