Introverts and extroverts have been shown to differ in brain processing and function. This difference may also be the underlying factor for their overall behavioral differences. (Jarrett)
Over the past few months, I have explored what the behavioral differences between introverts and extroverts are, and I have debunked some myths/fallacies regarding the two groups. Moreover, I have addressed some of the reasons and factors behind these behavioral differences, those being environment, base arousal level, and genetics. However, I do not feel as if I have thoroughly explained what really causes an individual to be an introvert or an extrovert, or what causes their typical behavioral differences. One of the leading causes in this phenomenon is difference in brain processing. Introverts and extroverts have been found to register and process information differently, which likewise can lead to their differences in behavior.
This is a sample of what a PET (positron emission tomography) scan might look like, with the different colors representing different levels of brain activity. ("Positron Emission Tomography Facilities Through Imperial Consultants")
According to Debra Johnson, Ph.D., from the University of Iowa, and John S. Wiebe, Ph.D., from the University of Texas, there is a correlation between personality and brain activity. In their studies, these researchers have found that introverts and extroverts use different parts of their brain in processing information, as evidenced by differences in increased brain flow. Asking individuals (some were introverts and others were extroverts) to "think freely," the scientists used positron emission tomography (PET) to measure cerebral brain flow, which is an indicator of brain activity. After comparing the results that they yielded from the two groups, Johnson and Wiebe found that "introverts showed increased blood flow in the frontal lobes, the anterior hypothalamus, and other structures associated with recalling events, making plans, and problem-solving," whereas "extroverts displayed more activity in the posterior hypothalamus and posterior insula, regions involved in interpreting sensory data." By looking at these differences, the two researchers deduced that this difference in brain activity confirms that introverts have more of an inward focus and extroverts have more of an outward focus, both as a result of how their brains function. Whereas the brain function of introverts complements attention to internal thoughts, that of extroverts is driven by sights and sounds, in lieu of sensory stimulation. This study was published in an article by Michelle Gallagher in Psychology Today, and even though the article is admittedly a bit dated (first published on July 1, 1999) and somewhat biased (the author assumes that introverts have to be quiet thinkers and extroverts have to be partygoers), the research itself still reveals that the differences in behavior between introverts and extroverts are due to differences in brain processing. Not only do these differences in brain processing and function determine how an individual will behave, but they also thereby lead to the individual's classification as an introvert or an extrovert. Fortunately, individuals can still fight this disposition (even though the author of the article mistakenly asserts one's behaviors and classification are set in stone). (Gallagher)
("Psychic Energy and MBTI")
Another example in which introverts and extroverts generally differ in brain activity, other than the regions in which they show increased processing, are their dopamine/neurotransmitter systems. Among other neurotransmitters, dopamine is responsible for giving the individual the experience of pleasure and happiness. When an individual's brain registers a certain experience as satisfying, it releases dopamine, which essentially communicates to the individual as a whole that they are/should be pleased and happy. Placing individuals under a brain scanner, researchers have found that, when taking gambles, extroverts show "a stronger response in two crucial brain regions: the amygdala and the nucleus accumbens." While the nucleus accumbens affects how individuals learn and "is generally known for motivating individuals to search for rewards," the amygdala "is responsible for processing emotional stimuli." In essence, because extroverts exhibit a stronger response to dopamine in their amygdala and nucleus accumbens, their "brain tends to push them towards seeking out novelty, taking risks, and enjoying unfamiliar or surprising situations," giving "that rush of excitement when they try something highly stimulating that might overwhelm an introvert." This stronger response in the dopamine systems of extroverts versus those of introverts is likely due to the fact that, as previously explained, these two groups process information differently. The pathway for processing information for extroverts is shorter than that of introverts. This pathway for extroverts "runs through an area where taste, touch, and visual and auditory sensory processing take place. For introverts, on the other hand, this pathway is more long and complicated, running through "areas of the brain associated with remembering, planning, and solving problems." Because the processing pathways for extroverts are shorter, they receive more instant gratitude, and thus they also crave/need this instant gratitude more than introverts. Introverts can be overwhelmed by some situations that extroverts flourish in, and their processing pathway leads them to evaluate the quality of an experience, before receiving gratitude. Thus, whereas extroverts can and will act more on the spur of the moment, introverts usually need more time to assess a situation. At times, introverts will remove themselves from a situation that extroverts will actually throw themselves into. (Cooper)
Like dopamine, acetylcholine is a neurotransmitter. This visual representation's mention of acetylcholine may be a mistake, but regardless, it illustrates that extroverts have shorter information and gratitude processing pathways than introverts, which may thereby encourage their behavioral differences. (Cooper)
The behavioral differences between introverts and extroverts are greatly due to the differences in how their brains function and information is processed. From areas of increased brain activity to length and route of dopamine pathways, introverts and extroverts are different because their brains handle information differently. At the same time, individuals are not forever fixed in the manner in which they process information. Often times, brain processing and function has only been found to correlate with, not necessarily cause, an individual's classification as an introvert or an extrovert. Therefore, to some degree, these differences in brain function and processing may actually be due to the individual's actions (the reverse of the proposed hypothesis), or both items may be similarly affected by a variety of confounding factors. By and large however, the differences in behavior between introverts and extroverts may be explained by the way(s) in which their brain function and process information.
As a reminder, I could use as many responses as possible to my survey concerning your opinion(s)/public opinion(s) on the behavioral differences between introverts and extroverts, so if you have not participated yet, please consider responding soon. In addition, I would appreciate it if you would encourage others to participate in the survey as well. You can reach my survey by clinking on the link, and I thank you in advance for your support/response.
If you would like to read the articles that I pulled my information from, please use the following links:
Works Cited:
Cooper, Belle Beth. "Are You An Introvert Or An Extrovert? What It Means For Your Career." Leadership Now. Mansueto Ventures, LLC, 21 Aug. 2013. Web. 27 Feb. 2015.
Gallagher, Michelle. "The Difference Between Introverts and Extroverts." Psychology Today. Sussex Publishers, LLC, 11 Jun. 2014. Web. 27 Feb. 2015.
Jarrett, Christian. "What Neuro-Revolution? The Public Find Brain Science Irrelevant and Anxiety-Provoking." Center for Genetics and Society. CGS, 5 Nov. 2014. Web. 27 Feb. 2015.
"Positron Emission Tomography Facilities Through Imperial Consultants." Imperial Consultants. IC Consultants, Ltd, n.d. Web. 27 Feb. 2015.
"Psychic Energy and MBTI." One Over Epsilon. WordPress.com, 14 May 2014. Web. 27 Feb. 2015.
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