The Physiology of Jung's 4 Psychological Functions

This is an essay on the physiolgy of Type. For Jung, the word Type was a convenient short hand which allowed him to identify with one label, both a person's preference for either Introversion or Extraversion, and as well their Natural Lead Function: Thinking, Sensing, Feeling, Intuition.

This is an essay on the physiolgy of Type. For Jung, the word Type was a convenient short hand which allowed him to identify with one label, both a person's preference for either Introversion or Extraversion, and as well their Natural Lead Function: Thinking, Sensing, Feeling, Intuition. He might, for example, have referred to one person as "An Introverted Feeler" and another as "An Extraverted Sensor." As it happens, today the physiological foundations for both elements of Jung's model are known. This is particularly exciting as it not only confirms Jung's observations as science, but as well provides exciting new insights.

So much has been discovered in the past ten years that it is now possible to be relatively certain about the physiological bases for the personality characteristics Dr. Jung identified as Introversion and Extraversion. What's more, it is now possible to provide scientific support for Jung's position that it is more important for us as individuals to satisfy our introverted / extraverted needs than it is for us to honor and use our natural lead function.

To begin to understand these elements of Jung's model better, it is important to develop a working familiarity with the following physiological terms:

Given the above, it is possible to understand the following definitions for Extraversion and Introversion as well as to understand their implications for an individual.


Additionally, it is important and helpful to understand the:

Subsequently, by juxtaposing what we have learned physiologically, with Jung's own observations on extraversion and introversion, we have a clearer appreciation for Jung and as well as tools such as the MBTI and BTSA, others are using to help people apply Jung's model to empower and guide themselves. Here for example are five questions, which have left many people confused about Jung, Type or the MBTI for several years. In the light of the new information science provides, the confusion surrounding each question dissolves.

  1. Jung saw Introversion as "saying no to life" and at the same time, a natural, normal way of being?

    According to Dr. Hans Eysenck, Jung was 100% correct when he said that Introversion is a normal and healthy way in which many people live life, based on their physiology. At the same time, Jung was also 100% correct when he noticed that at least some Introverts seem to be saying no to life.

    In point of fact, Introverts actually take in so much information second per second that they might be said to be "gulping in information" - a definite yes to life. Yet, the fact that overly loud environments in which a lot is happening can cause them to be "overwhelmed" can cause them to appear to be saying — in that highly stimulating context — no to life, when in fact what they are saying no to is simply the experience of being overwhelmed.

    As well, some Introverts develop a negative attitude towards life as a result of being continually shamed or devalued when they live in a culture which seems to value and reward Extraversion more than Introversion. This is certainly the finding of Elaine Aron in The Highly Sensitive Person: How to Thrive When the World Overwhelms You.

    Yet another factor which "gives Introverts a bad name" is this one. Many people, under chronic anxiety — brought about by many consecutive years of high stress — develop a negative attitude because of the stress they have had to face. At the same time, these people experience a shift as a result of the chronic anxiety, in their arousal system. They become more Introverted. Indeed some natural Extraverts become so "stressed out" their arousal shift so much they actually appear to be Introverts. All these people — who are experiencing a higher level of Introversion as a result of chronic anxiety — reinforce the older belief that "Introverts say no to life."

  2. Why are Extraverts sometimes mistakenly identified as Feeling Types?

    Many Extraverted people have been thought to be Feelers when they were actually natural Sensors, Thinkers or Intuitives. The reason is that all Extraverts are attracted to people because people are a dependable source of stimulation — from conversations to playing games to fighting or arguing. Quite often, in a business meeting, someone will identify another person as "a real people person". This person may be a Feeler, but he or she is just as likely to be a Sensor, Thinker or Intuitive.

  3. Why do those working with the MBTI sometimes have difficulty determining whether a person is actually Extraverted or Introverted?

    The answer here is two fold. On the one hand some people according to Eysenck actually have a Balanced level of arousal such that they are neither highly Extraverted or Introverted. On the other hand, people do shift in response to chronic anxiety. Some people who are naturally Extraverted may appear markedly less so as a result.

  4. Why some persons profiled with the MBTI two or more times several years apart report being told they were Introverted on one occasion and Extraverted on another occasion — or visa versa.

    As noted above, a natural Extravert may measure as Introverted when he or she has been living for some years in a state of heightened anxiety. Prior to this period of stress and anxiety, the person may well measure as an Extravert. Subsequent to the onset of this period of stress / anxiety, the person may well measure Introverted. And yet, again, when the source of stress and anxiety has been resolved, the person might be tested again and be found to be once more Extraverted.


    • Why do Extraverts and Introverts need to take their Extraversion / Introversion into account when seeking or designing a comfortable place to work.

      Extraverts may be given a job that matches their natural lead function, but which is generally done in an isolated or subdued environment. When this happens, the Extravert will attempt to remedy the "problem" he senses internally as he notices he has difficulty focusing and or is falling asleep. He or she will adjust their environment so that they feel and actually are alert. They could do this by: 1) leaving their place of work for an area in which there is more happening — where there are other people talking or where there is more noise in general; or 2) increasing the noise / stimulation level where they work, by turning on a radio or if there are any other people working in the same area, starting to talk to these people.

      Similarly, Introverts may be given a job that matches their natural lead function, but which is generally done in the midst of lots of "action" or in an environment which is in some other way intensely stimulating: because there is a fire, or a crisis, for example. When this happens, the Introvert will attempt to remedy the "problem" he senses internally as he notices he has difficulty concentrating and to some extent is feeling overwhelmed by what is going on around him. He or she will adjust their environment so that they feel and actually are comfortable and once again able to focus. They could do this by: 1) leaving their place of work for an area in which there is less happening — where there are fewer people talking or where there is very little noise; or 2) decreasing the noise / stimulation level where they work, by closing their office door, wearing ear-plugs, or if there are any other people working in the same area, asking them to not talk so much / so loudly — or go somewhere else to talk.

      By contrast, those which Eysenck identifies as having a Balanced arousal level, have an easier time when trying to assure their own peak performance. While at work they may "adjust" to satisfy their employer, or their own drive to be successful, so that can work in an Extraverted, Balanced or Introverted environment. The difficulty is that if they adjust at work to perform a job which is more Extraverted, they will use the evening to achieve Balance — by Introverting, which may mean they do not spend much time or energy with their spouse or children, or dating for that matter. By contrast, if they adjust at work to do a job that is more Introverted, the person will use the evening to achieve Balance by Extraverting — partying, dancing etc.

So we see, bringing neuroscience to bear on Jung's model can enhance our appreciation for Jung's model while, at the same time, helping us to apply his model with greater sensitivity and accuracy.

Bibliography on Extraversion / Introversion

For those wishing to read more in-depth and technical sources, the following bibliography is recommended.

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