We’ve all heard the terms “introvert”and “extrovert.” But what, scientifically speaking, makes introverts and extroverts the way they are?
Is it genetics?
Cal Poly psychology professor Don Ryujin believes introversion and extroversion are primarily genetic.
I’ve asked myself that question for a long time— which personality characteristics are more genetically inherent and harder to change and which ones are more environmentally based and easier to change? As a personality theorist, some personality characteristics are really hard to change and some are not so hard to change. So then if you’re studying ones that aren’t very genetically rooted versus those that are, then you can get different findings. Those that probably are [genetically rooted] are things like whether you’re an introvert or an extravert.
Recently, scientists have discovered differences between the brain scans of introverts and extroverts. Medical Daily reports that scientific researchers have found these differences:
- Introverts have a thicker prefrontal cortex than extroverts
- People who are more inclined to be adventurous have two copies of one particular allele
- Extroverts respond more strongly to pictures of human faces than neutral photos of nature
- In contrast, introverts respond about the same to both types of photos
Tom Stafford of BBC News describes a 2005 study in which researchers scanned the brains of introverts and extraverts while they performed tasks related to gambling.
“The more extroverted group showed a stronger response in two crucial brain regions: the amygdala and the nucleus accumbens,” Tom explained. “The amygdala is known for processing emotional stimuli, and the nucleus accumbens is a key part of the brain’s reward circuitry and part of the dopamine system.”
As scientific research continues, it will be interesting to see if we ever get a clear answer on the exact cause of introversion or extroversion.
Cambridge University psychology professor Brian Little elaborates on the complexity of personality theory in the TED Talk below: