When I first took an online test for the Myers Brigg Type Indicator (MBTI), I came back as an INTJ (Introverted, iNtuitive, Thinking, Judging). Generally, I consider personality tests to be little better than astrology, and they don’t tell me anything I didn’t already answer in the test. When I took a look at the INTJ description, however, I was quite surprised by how accurately it described me. Most intriguingly, the description was more than just a rehashing of the categories that I had just answered. It seemed to find something deeper. At the time, it felt like a magic black box. Over time, I started to dig deeper into the MBTI, including the theory of dominant, auxiliary, tertiary, and inferior functions.

Eventually, I realized that the model of representing personality types by the four axes of the MBTI hid what was actually happening behind the scenes. Here’s my take on the MBTI.

There are two types of things going on in a person’s brain. First, there are the “lower” activities. These happen almost behind the scenes and we often fail to notice them. These lower activities are intuition (speaking the understanding or grasp of things) and sensing (the familiarization with things). Then, there are the “higher” activities. We are generally aware of these. These “higher” activities are thinking and feeling. People tend to have preferences between the two “lower” activities and between the two “higher” activities. For example, I prefer intuition to sensing and thinking to feeling. These preferences constitute two of the axes in the MBTI.

Individuals tend to use both their preferred “higher” activity and their preferred “lower” activity. But they defer in which they apply to the outer world around them (through extraversion) and which they apply to the inner world/mind (through introversion). In my case, I apply my “higher” thinking to the outside world, and my “lower” intuition to the inner world. Those who apply their preferred “higher” activity to the outside world can be considered to judge the world, while those who apply the “lower” activity can be considered to perceive the world. This constitutes another axis on the MBTI classification – the judging vs. perceiving axis.

Finally, some people prefer to spend the majority of their time/energy on extraverted activity, while others prefer introverted activity. Remember that this is a preference, not an absolute rule that applies all the time. Thus, we may classify people as extraverted or introverted – the remaining category in the MBTI classification.

So in my case, I could be classified as an INTJ – an introverted intuitive thinking judger. But this classification is hard to understand. Instead, it would be appropriate to classify me as an Ni-Te i.e. someone who uses introverted intuition first and extraverted thinking second (in MBTI notation, NI, Te, etc. denote “functions”). My most common mental activity is to create an intuitive understanding – but this activity is augmented by my thinking interaction with the outside world. This personality makes me perfect at analysis.

Of course, just cause thinking and intuition are my preferred higher and lower activities doesn’t mean that I never use feeling or sensing. Since I’m used to using the higher activity of thinking when I interact with the outside world, my feeling activity is nearly always applied to the internal world. That is, I use Fi (introverted feeling). Similarly, since I’m used to the lower activity of intuition when I interact with the internal world, I keep the opposite activity of sensing away from that, and tend to apply it to the outside world, i.e. Se (extraverted sensing). So, in addition to my commonly used Ni and Te, I also sometimes use Fi and Se.

Thus, one can classify someone by which higher function and which lower function they apply to the external and internal worlds, and wether they prefer extraversion or introversion. From this, one can also figure out the rest of the person’s personality, by keeping in mind that the less preferred “higher” activity is applied to the opposite world of what the preferred “higher” activity is applied to. The same holds for the less preferred “lower” activity.

One other example: consider Jimmy, who is an Ne-Fi. The MBTI type is ENFP, as he prefers extraversion to introversion, and applies the “lower” activity – intuition – to the external world, making him a perceiver. He would be someone who enjoys intuitive interactions with others, and channels his internal feeling to that goal. We can work out that his sensing will be introverted in contrast to his extraverted intuition, and similarly his thinking will be extraverted. Thus, as an Ne-Fi, his remaining “functions” are Te and Si.

What do you think? Comments or questions?