The next facet of the BPC that I will discuss is the introversion/extroversion level (I/E level) that each individual has in their brain.
In the early 1900’s, Carl G. Jung published his theory on personality types. Many personality assessments are actually based on research that Dr. Jung conducted. Of course, this was long before the technical brain imaging machines were around. However, his thoughts on the subject were quite insightful and are referred to by many a psychologist and personality expert today. The first and primary aspect of personalities that he emphasized was the difference between introverts and extroverts.
When trying to calm a personality conflict between, his friend at the time, Sigmund Freud and, colleague, Alfred Alder, he was quoted as saying, “There you have it. The problem that we are having here with these two is simply that one of them, Herr Freud, is an introvert, while Professor Adler is an extrovert. No wonder that they do not understand each other. Now that the answer is clear let us proceed.” Sometimes, a large reason why individuals have a BPC conflict is because one is an introvert and the other an extrovert.
Dr. Kathryn Benziger has also written much about the importance of fully understanding the I/E ratio in yourself and others. She states that, “In some ways it is more important for us as individuals to satisfy our introverted/extroverted needs than it is for us to honor and use our natural lead function.”
But, again, please understand that the differences are innate to the brain. We are most likely born with a comfortable position on the I/E scale, and learning to honor this in ourselves and others is crucial to creating good relationships. It is also very important when considering jobs or careers. A career mismatched with our naturally preferred stimulus level could cause us undue stress, unhappiness, and, as we will see in unit 8, damage our very health.
This is the unit where understanding the functions of the Reticular Activating System (RAS) is important. It is that portion of the brain (remember it is housed in the action portion not the cognitive portion) that sets and regularly monitors your I/E level. Brain function experts, such as Arlene Taylor and Rita Carter feel that, if we are not in an environment that matches our I/E level, we may be unable to engage in quality thinking. Needless to say, it is an important facet to consider when trying to understand self and others, as well as when we are coaching or working with clients.
Hans Eysenck did research in this area and concluded that humans, in general, are distributed along a continuum according to a normal bell curve. The division of the population looks something like this:
- Approximately 15% of the population.
- Prefer to spend 85-100% of their time in very low stimulus environment.
- A term used to describe those with a balanced I:E ratio.
- They prefer to spend an equal amount of time between a stimulating environment and a low stimulus environment.
- Approximately 15% of the population.
- Prefer to spend 85-100% of their time in a very high stimulus environment.
Sometimes a person’s I/E level, especially if they fall at either extreme, can be apparent within days of coming into this world. Some babies prefer to be in homes where it is quiet, low stimulus, and can sleep for long periods of time. While others need to be held a lot, tend to be happier when there is external noise and stimulus, and sleep for shorter periods of time.
As Carl Jung put it, the extrovert has a natural leaning towards outward validation, meaning they seek comfort primarily from external objects or activity. Introverts, on the other hand, are people with an inward orientation. Arlene Taylor uses a camera metaphor to explain the difference, saying, “The brain’s metaphorical camera comes with an aperture size that is innate for that brain. Metaphorically, when the opening to the brain’s camera is of small diameter, that type of brain (extremely extroverted) needs to take many pictures to obtain the stimulation it requires. Conversely, a brain with a larger aperture (extremely introverted) takes in huge amounts of data second-for-second and can become overloaded and over stimulated quite quickly.”
Keep in mind that only approximately 15% of the population falls into the extreme category at either end of the scale. However, that only accounts for 30% of the population; right in the middle are the ambiverts. The range between each extreme and the ambiverts in the middle would be moderate extroverts and moderate introverts. Their time alone or with stimulus will vary depending on where they fall on the scale. Think about it this way: If you look at the hours in a day that a person is awake, the amount of time they desire to spend alone or with stimulus will determine where on the scale they will fall.
Next I will list personality traits that you might find apparent in each of the extremes. Moderates of either extreme might have some of these characteristics but not all. Ambiverts can possibly have characteristics of both.
 Model of Personality, Hans J.A. Eysenck, Springer-Verlag
 Living Authentically-Your Brain & Innate Giftedness, Arlene Taylor 2003