We all naturally fall somewhere on the introvert-extrovert playing field. Many of us fall on either side of the 50 yard line—say between 30 and 70 yards—and are ambiverts, people who enjoy a mighty mix of introvert and extrovert traits.
The puzzle of why some people tend to be remarkably reserved or obviously outgoing is slowly being put together by researchers. They have verified some differences in the brains of extroverts and introverts which reflect their differences in behavior.
An Early Explanation
Back when the Beatles were starting to rock the music world, a psychologist named Hans Eysenck suggested that extroverts were internally wired to need more stimulation than introverts to engage in life. So, they seek the lively company of others and the rush of high energy environments.
Introverts, being more easily aroused, can become alert and engaged through intimate conversations and in quieter environments. An introvert might become overstimulated by an atmosphere that an extrovert requires just to get going.
Suspecting Dopamine
Another extrovert-introvert theory has to do with the role of dopamine, a neurotransmitter involved with our sense of pleasure and reward. If extroverts have highly active dopamine systems, scientists conjecture, it would explain their heightened responses to stimulation and novelty.
In 2005, a study was published that looked into this idea. Participants in the research received a mouth swab for genetic profiling, completed a personality assessment, and then had their brains scanned as they took part in a gambling activity.
Results showed extroverts experienced a bigger emotion-dopamine kick than introverts during reward oriented activity:
- When the gambling activity started paying off, extroverts had stronger brain activity in the amygdala, a part of the brain involved with processing emotions.
- When extroverts were winning they had more activity in the nucleus accumbens, part of the brain’s reward and dopamine processing system.
The researchers also found that participants who carried a gene that is known to elevate dopamine response, experienced an increase reward reaction when gambling was going well.
Two Very Different Experiential Routes
More recent research reveals that introverts and extroverts process environmental stimuli via different brain routes:
- The extrovert’s dopamine-driven processing pathway is shorter and runs primarily through gray matter that sorts out auditory; visual, taste, and touch sensory data. No wonder extroverts are energized by people and parties.
- In an introvert’s brain, incoming stimulation takes a complex, circuitous acetylcholine-driven route through areas linked to planning, remembering, and problem solving. No wonder introverts are known for thinking things through.
Whatever our natural tendencies are, they do not have to define or limit us. If they wish, introverts can adapt to more stimulating environments, extroverts can adjust to quieter pursuits, and each is enriched by the making the effort.
Sources: Science Direct; Benzinger; Laney, Marti Olsen, Psy.D., The Introvert Advantage, Workman Publishing, 2002.
