What is this thing called Personality Type?

Have you ever wondered what causes two people to meet each other and feel an instant vibe?

Why do some people seem to be your people, while others seem to be different species?

You meet those people repeatedly and probably developed a stereotypical persona in your mind for those kinds of people.

Personality types are a scientific approach to naming and measuring those kinds of people.

Naming and measuring are important because we cannot understand and study a phenomenon until we can measure it.

Personality types provide a measurement of traits we associate with each kind of person.

Before the invention of the thermometer, we could not resolve disputes about heat as there was no objective method of telling what is hot and what is merely warm. We could not know where it comes from and how it influences other phenomena.

The invention of the thermometer catalysed our understanding of heat, allowing us to quickly detect a fever, and even talk about the temperature of the sun.

Personality models like MBTI, BigFive, Enneagram, NERIS and others, try to provide thermometers to people’s traits so that we can objectively name what we subjectively and vaguely call kind of people.

In this article, I will explain what is this thing called Personality Type. I will start with the most popular model — MBTI, and discuss the controversy about it. Then I will present the scientific model — Big Five, and its handy modification used by websites like 16personalities.com. I will talk about possible applications in the workplace, as a tool for self-discovery, for inspiration, and the most controversial topic — relationship compatibility. Finally, open discussion with some questions.

Table of contents:

The hardest victory is the victory over self.
~ Aristotle

Sato defined personality type as “a characteristic pattern of thinking, feeling, or behaving that tends to be consistent over time and across relevant situations.” In other words, personality types are commonalities and differences in the behaviour of people that do not change over time.

According to the theory, personality type is mostly heritable. A Twin Study shows that twins that were split at birth, ended up with similar personality traits.

Personality type describes patterns in your behaviours, your preferences, your strengths as well as weaknesses. Like right- and left-handedness — although you may develop both hands, one of them is always dominant. Same with personality types, although you may act like every other type, your default, idle, preferred, comfortable mode of acting is constant.

Kant described it in terms of inclinations. If you put a ball on an inclined surface, it will move along the inclination towards the force of gravity.

Similar to personality type, it explains your thoughts and actions when you are not putting any effort to control them—you move with the gravity of the environment according to the inclination of your personality type.

Yes, personality types are incredible oversimplifications. Same as labelling someone as “authoritarian vs libertarian” or “left vs right”. But we, human beings, do not have the capacity to run anything close to accurate simulations of humanity inside our heads, and so sometimes incredibly oversimplifications are something we need to understand the world.

Everyone is individual and unique. The personality types are not strict classifications, but stereotypes that are akin to landmarks on a map. Just as a few landmarks can help you find many unique locations, so too the personality stereotypes can help you understand your unique personality.
~ Carl Jung

Introversion vs Extraversion

If we had to split people into two categories, intuitively we would split them in terms of introversion and extraversion.

Jung explains the difference in terms of directness, sources of energy, interest, and ideas.

Extraverts are tuned outwards, they are more interested in the external world, as it is often more interesting than the inner world. They are focused on objects. They try to decouple themselves from the object. They are objective. They interact with the objects directly. They focus on the object itself without personal interference.

Introverts are tuned inwards, they are more interested in the inner world, as it is often more interesting than the world outside. They are focused on their response to objects. They care more about their impressions than the objects themselves. They focus on how the object influences them, not on the object itself.

However, as we will see in the following sections, classifying a person as an introvert or extrovert is not that simple.

Carl Jung’s Psychological Types

Besides widely known classification into introversion and extraversion. Jung observed that people differ in their interactions with both the inner and outer world. He called them psychological processes, which were later renamed to cognitive functions.

Cognitive functions

Jung outlines two categories of functions 1) how we perceive information, and 2) how we make decisions.


Perceiving is a process of becoming aware of something. It is how we gather and access information.

There are two kinds of perceiving functions, via:


Using the gathered information, the judging functions let us organise, conclude, evaluate, and make decisions either via:

What is better?

Natural questions arise: what is better, sensing or intuition? Feeling or thinking?

Sensing vs intuition

Sensing looks for provable facts first and then seeks the abstract connection. Intuition looks for abstract connections first, then seeks the provable facts.

Sensors are like police—they gather facts, details, data, and statistics, and see the relation of current information, before jumping to a conclusion. They don’t say anything besides the facts they gathered. They know what happened but don’t know why it happened. They struggle with understanding the causes or the “why” behind things that occur.

iNtuitives are like wizards, they get two facts and then immediately draw a line. And it’s usually wrong, but they are not aware of that since they are not tracking them (those are sensory). They understand why it happened but not, what happened. Intuition is the function used to discover and understand why things are connected with abstract grouping and contextual pattern recognition. They struggle with tracking the details or trusting the facts.

It can be visualised as follows. Sensors gather facts—yellow dots. After we’ve gathered enough facts, intuition comes in and figures out the connection between the facts and the pattern they form (purple line). You get the hunch about why facts are the way they are. This is the “aha!” moment. Then, it tries to fill the gaps of missing information and guess future facts.

However, the intuitives who have not learned to collect a sufficient number of facts before jumping to conclusions are usually wrong.

Intuition is powerful, but accurate only when fed with a huge amount of experiences otherwise it’s gullible and naive. People who are too confident in their intuition have tendencies to perceive meaningful connections between unrelated things (Apophenia). They guess so much that when finally something matches, they say “I knew it will happen”, ignoring all the missed guesses; they are prone to Hindsight bias.

Senses may not be as insightful as intuitives, but they are more reliable and often closer to the truth. In fact, scientific truth is what we can observe by senses. Science is associated with the highest reliability because it’s proven by observable facts and data. Good science is about proving the point with facts and data. However, revolutionary science is about intuitive leaps.

Feeling vs thinking?

Feeling looks to prioritize the value of something and then figures out the reasons. Feeling (F) is the function used to prioritize and process feelings and values. People who have feeling higher (F) will generally be better at knowing what is better for them and others but struggle with figuring out how things work.

Thinking (T) looks to figure out the reasons for something, then figures out the priorities/values. Thinking (T) is the function used to figure out things, puzzles, ideas, and how something works. People who have thinking higher (T) will generally be better at figuring out how things work and understanding the reasons, but struggling with prioritising and knowing what is good for them and others.

Introverted and Extraverted functions

Each of these four functions comes with two flavours, augmented by the direction (also called attitude), which is either:

As a result, we get eight functions and a short description for each:

Perceiving functions:

Judging functions:

Everyone uses all eight functions, but everyone has different preferences for each function.

Similar to left- or right-handedness; even though people can write using both hands, they will prefer using one of their hands.

We can call the more preferred hand the dominant one, and the other the auxiliary one.

Same here, one of the eight functions is our dominant one, we use it most of the time.
Then, the second function (auxiliary) complements the dominant function.

Since most of the time we use the dominant function, introverts for most of the time are focused on their introverted function (Si, Ni, Ti, or Fi), i.e., internal world, thoughts, ideas, imagination, and memories.

For extraverts, since the dominant function is extraverted, their focus is mostly on their extraverted function (Se, Ne, Te, or Fe), i.e., the external world, objects, events, and people.


MBTI is a personality type system that takes Jung’s ideas and structures them into a convenient system of 16 personality types, four letter encoding, and provides a test for finding out the personality type.

Lifestyle preference (xxxJ and xxxP)

Authors of MBTI introduced another scale of people’s preference called lifestyle that describes, which function (perceiving or judging) is externalised by the person. What we see when looking at how people interact with the world and other people.

Judgers (xxxJ) externalise decision-making:

Perceivers (xxxP) externalise perceiving:

Perception without judgment is spineless; judgment with no perception is blind. Introversion lacking any extraversion is impractical; extraversion with no introversion is superficial. ~ Isabel Briggs Myers, Myers 174

Encoding convention

MBTI made another contribution by providing handy encoding using four-letter, which describes the preference order of all sixteen functions.

Instead of listing all eight functions used by each personality type, MBTI uses a four-letter encoding that let us decode all eight functions in the correct order.
Each letter represents one of two preferences regarding:

  1. Attitude: Where is your interest mostly directed? Inside (Ixxx), or outside (Exxx)?
  2. Perceiving: What information do you trust the most? Senses (xSxx), or from iNtuition (xNxx)?
  3. Judging: How do you prefer to make decisions and conclusions? Using feeling function (xxFx), or using thinking function (xTxx).
  4. Lifestyle: What do you show to the outside world (externalise)? Perceiving function (xxxP) or judging function (xxxJ).

As a result we get 16 personality types each with different stack of functions

Function Dominant Auxiliary Tertiary Inferior
INTJ Ni Te Fi Se
INTP Ti Ne Si Fe
ENTJ Te Ni Se Fi
ENTP Ne Ti Fe Si
INFJ Ni Fe Ti Se
INFP Fi Ne Si Te
ENFJ Fe Ni Se Ti
ENFP Ne Fi Te Si
ISTJ Si Te Fi Ne
ISFJ Si Fe Ti Ne
ESTJ Te Si Ne Fi
ESFJ Fe Si Ne Ti
ISTP Ti Se Ni Fe
ISFP Fi Se Ni Te
ESTP Se Ti Fe Ni
ESFP Se Fi Te Ni

Each personality type is dominated by its first (dominant) and second (auxiliary) functions as they are the most preferable, comfortable and powerful way of acting for them. They feel responsible for acting according to those functions. They are confident in their abilities in those functions. It makes them feel comfortable, powerful, and capable. However, they are obvious about using them. They see the world through those functions without realising it.

On the other side, each personality type is also terrorized by its last functions (tertiary and inferior). Those functions are the daemons they try to avoid. They don’t feel responsible for doing tasks involving those functions. They fear those functions as they make them anxious, bored, and stressed. They want to do them once and then never again.

As a result, if we don’t work on our weaknesses (last functions) we get out of balance. The demons often force themself up into consciousness, signalling us to deal with it. The symptoms are that those people have mood swings. That’s when people say “I don’t know what got into me, I couldn’t control that”.

Most of our life discoveries — “I found the hacks to life” — are in the areas of our last functions. People who discovered their demons, and overcome them, now want to share their discoveries, peacocking, writing books and giving TED talks— listen to the main theme of the talk, it’s usually in the theme of their last functions.

Until you make the unconcious concious, it will direct your life, and you will call it fate. ~ Carl Jung

MBTI is a pseudoscience!

Before we move further, let’s first settle the thought that probably came to your mind while reading this article.

There is a lot of controversy around the MBTI model, the arguments comes down to:

  1. The model was created by Carl Jung based on his personal experiences rather than science, subjective methods called Mesearch, as opposed to empirical observations using scientific methods.
  2. More than 30% of research is made by one organisation, which earns profit for the popularity of the model by selling courses and tools.
  3. It lacks a neurotic scale, which is widely agreed to be an independent personality trait.
  4. MBTI tests indicate poor validity and poor reliability. Taking the test again after five weeks, there is a 50% chance that you will fall into a different type.

The question is, does it make it useless?

BigFive — scientific method

Big Five is another model describing personality in terms of independent traits. Big Five was created using scientific methods therefore it is considered more reliable.

BigFive is built on top of Cattell’s Lexical hypothesis stating that all aspects of human personality which are important to a group of people will eventually become a part of that group’s language; moreover, the most important personality characteristics are more likely to be encoded into language as a single word.

Scientists analysed thousands of adjectives describing characteristics of people, which ultimately made up five major categories of personality:

Is MBTI a pseudoscience?

Big Five used scientific methods to explain personality using five traits. Researchers studied the correlations between “the supposedly pseudoscientific” MBTI and scientific BigFive and found high correlations between those two models.

Namely, the correlation exists for the following scales:

If the scientific and objective method (BigFive) and Jung’s Meserach theory are highly correlated, then maybe Jung was not that far from truth.


Even though Big Five’s traits are scientific, there are not as handy in use as MBTI’s types. Describing personality characteristics based on dichotomous personality types like INFJ is easy, but operating on five scales like “person who is 80% openness, 70% on Consciousness, 45% on extraversion, 60% on agreeableness” is troublesome.

As a result, the most popular website for measuring personality type, 16personalities.com, uses both MBTI and BigFive, they call their model NERIS.

They use BigFive traits, which then are converted into MBTI 16 types plus a neuroticism scale for each type (turbulent or assertive).

More specifically, they measure your personality according to BigFive methodology which gives you a result on a scale from 0 to 100. If the value is smaller than 50 then you get the type on the left and type on the right otherwise.

From now, I will refer to personality type as defined by NERIS. It’s up to you if you believe in Jung/MBTI’s cognitive functions theory, or if you prefer to stick to BigFive traits. The naming convention is shared by both systems.

Finding your type by asking other people

The most popular method of finding our personality type is via self-surveying online tests. Although the most popular, it is also the worst method.

We can not see the objective reality being locked in our heads, biased by our beliefs, values, and expectations.

Our brain does hard work to hide the objective image of our true selves. This is useful for our survival, but limiting for self-discovery.

Therefore, the best way of finding your type is by asking other people. The method is also known as triangulation and is used by smartphones to figure out their position in space via GPS satellites.

We have to ask others what is true about us — and that is hard. We don’t like exposing ourselves. Asking other people how they see us is intimidating. Hearing about our blind spots is embarrassing.

Nonetheless, often the journey of finding your type by gathering feedback from people around leads to enormous growth.


Workplace compatibility

It is not a surprise that some kinds of people are more suitable for a particular kind of job. Personality type can help you with finding a suitable career path by measuring job satisfaction among people of the same personality type.

It applies on the other side as well. Recruiters looking for a candidate may correlate job requirements with appropriate personality types which report high satisfaction at those positions.

For example, research for IT positions suggests, that when appointing:

Relationship compatibility

Here comes the most controversial part — personality types and relationship compatibility.

We can find many charts on the internet suggesting which personality types are compatible and which are not:

Or even apps (Charm, Our Personality Chemistry) that let you play with it. However, they are rarely (if ever) supported by any scientific studies.

Show me the science!

Researchers found that the highest influence on both romantic and friendship relationships has neuroticism (xxx-A/-T) and agreeableness (xxTx/xxFx). It works best when at least one person is higher on agreeableness (xxFx) as it allows for settlings conflicts easily.

Extraversion(E) is the strongest trait predictor of being liked at first, but then, the importance lessens. Extraversion helps in maintaining larger social networks, and a productive conflict style. Extraverts are more likely to resolve the conflict as they occur, without keeping them inside and postponing the confrontation. When two people are introverts they may encounter situations where neither partner draws out the other or where neither partner takes the lead in an important social event. Avoiding socialisation may lead to feeling isolated. Relationships consisting of introverts and extroverts prevent falling into a bubble of thinking that you are normal and people of different types are abnormal—it holds for all traits.

Openness (xS/Nxx) plays an important role in establishing friendship. When people are on the same level of openness conversations flow easily as you’re similarly interested in a wide range of topics and in exploring ideas. Controversial but evident, openness is highly correlated with intellect. High openness (xNxx) are relatively rare (15-25% of the population), so meeting two people with high openness may lead to the relief of finally finding someone who understands you. However, in daily life, they may struggle with everyday routines, such as chores, paying bills, shopping, and car maintenance as they may both avoid doing them.

Higher openness (xNxx) helps in building larger social networks, and more productive conflict resolution as they are more inclined to see different viewpoints. It is observed that people tend to form friendships with those of similar openness levels. However, people who are high on openness (xNxx) are more likely to make friends with different people (demographically, and culturally), compared to those who are low on openness (xSxx) who tend to be more conventional and traditional, sticking to their familiar routines and interests. Further, there is a correlation between openness, personal values and political attitudes. So, if both of you are on a similar level of openness, it is more likely that you will share similar interests, and political and world views.

High neuroticism (xxx-T) has always negative influence on both romantic and friendship relationships as it leads to more conflicts and more negative emotions. People who are high on the neuroticism (xxx-T) scale may have a tendency to escalate conflicts, which leads to making close friendships less likely. More generally, high neuroticism (xxx-T) is associated with a tendency to experience negative affect, anxiety, and depression. People with such characteristics may be avoided as friends. Depressed people elicit negative affect in those around them – subjects who have spoken to depressed people are significantly more depressed, hostile, anxious, and rejecting than subjects who have spoken to non-depressed people. Neurotic people attract with their self-consciousness, intensity, spontaneity, and emotional breadth, offering an addictive “emotional roller coaster”.

Conscientiousness (P/J) does not matter that much in friendships as friendships are less interdependent than romantic relationships. In romantic settings, it works best if two people have a similar level of conscientiousness, as everyday duties and obligations are easier to settle.


I personally felt a strong inclination towards some kinds of people and friction towards others. Therefore, I decided to verify those claims myself. I created an informal measure called “closeness” which encompasses the emotional depth, comfort, admiration, respect, frequency of conflicts (inversed), and flow in conversation.

I have asked my acquaintances, fellows, friends, and romantic partners about their personality types and gathered a list of 52 people.

When it comes to introverts and extroverts. My close friends (closeness = 4) are mostly (57%) extraverts. The significance is even greater for closest friends (closeness = 5), which consists of 75% of extroverts.

I am low on extraversion (I), which gives interesting insight that I’m more inclined to make friends with people high on extraversion (E).

When it comes to openness (S/N), the difference is even more significant, my close friends (closeness =4) are mostly (71%) intuitive (N), and the significance is even greater for closest friends (closeness = 5) which consist of 100% of intuitive (N).

I am high on openness (N), so I’m more inclined to make friends with people on a similar (high) level of openness (N).

When it comes to agreeableness (F/T), there closest the person is, the higher chance that he is higher on agreeableness which is 36% for closeness=3, 43% for closeness=4, 50% for closeness=5. However, for closest friends, there is no difference.

I am low on agreeableness (T), and there is no significant correlation between agreeableness level.

When it comes to conscientiousness (J/P), the correlation is similar to agreeableness but reversed, the closest the person is, the lower chance that he is higher on conscientiousness, that is 73% for closeness=3, 64% for closeness=4, and 50% for closeness=5. However, for closest friends the is no inclination to conscientiousness level.

I am high on conscientiousness (J), and there is no correlation between conscientiousness level.

Unfortunately, I have no information about the neurotic scale of those people.

My verifications do not support correlations for all types. They don’t even support all people of my type. They only support me; yet, they do it for both the “internet compatibility chart” and the findings of researchers.


We have natural inclinations towards uniqueness — society developed a belief to value everything that is unique.

Same with people, we like to think that we are unique, no one is like us, we are like snowflakes, different from everyone else; hence valuable.

However, we should gain our self-esteem not from a feeling of uniqueness, attention or recognition, but from our feeling of usefulness.

People are rejecting normality because they associate it with being incapable. Being normal is not being incapable, being normal is rejecting the desire to be special. Since we have natural inclinations to become special, it requires courage to be normal, as it’s against natural inclinations.

We are similar to other people, and even more to people of similar personality types. Why not use the knowledge of those similar people to boost our self-understanding?

Imagine having a book about your weaknesses, blind spots, your cognitive biases, and your beliefs that will (as you mature) turn out to be false.

To grow is to confront with your dark side, that usually means to embrace the functions that are low on your congitive function stack.

We do not change as we grow up. The difference between the child and the adult is that the former doesn’t know who he is and the latter does. ~ Carl Jung

Get inspired

There are catalogues of famous people classified to a certain type, e.g. idrlabs, or community-based personality database. It’s surprising to realise that people which you admire, are of a similar type to you.

It can build your confidence in realising that people of your type approached similar career paths and succeeded.

It also leads me to a few reflections.

Open questions


  1. The point of figuring out your personality type is not to feel better about yourself, rather it’s to feel embarrassed about your ignorance, and then use that to confront your dark side.
  2. All personality type theories are flawed but that doesn’t make them useless. Similar to physics; although quantum physics surpassed classical physics, it doesn’t mean that classical physics is useless — it still took us to the moon.
  3. Personality type is mostly biological, we don’t change our personality type, we discover our true selves.
  4. Personality types can boost your self-development. It points out your weaknesses and strengths. You get an enormous leap of self-understanding by leveraging what other people with similar traits/types, have learned about themselves.
  5. By understanding the difference between different personality types you will tolerate and appreciate the differences.



According to careerplanner.com.

Decoding the order of functions

If your dominant function is one of the perceiving functions (Se, Si, Ne, Ni), then the auxiliary is judging (Ti, Te, Fi, Fe), or the other way around.

Moreover, if your dominant function is introverted (Si, Ni, Fi, or Ti), then the auxiliary function is extraverted (Se, Ne, Fe, or Te).

Introverts’ dominant function is introverted (Si, Ni, Ti, or Fi) and their auxiliary function is extraverted (Se, Ne, Te, or Fe). The opposite is true for extroverts.

Once we know the attitude and lifestyle preferences. We can find the order of cognitive functions encoded in the four symbols.

For extroverts, lifestyle preference indicates their dominant function. For introverts, lifestyle preference indicates their auxiliary function.

So for ENTP people, the lifestyle preference (_ _ _ P) indicate their dominant function (_ N _ _) that in case of extravert (E _ _ _) is extraverted, and hence extraverted iNtuition (Ne). The auxiliary function is always the other letter of the two, in this case Thinking. The auxiliary function for extroverts is introverted, and hence introverted Thinking (Ti).
The other two (tertiary and inferior) functions are the opposite of the first two. So for Ne the opposing is Si, and for Ti the opposing is Fe. Hence: ENTP people is decoded as Ne > Ti > Fe > Si.

For introverts, the lifestyle preference indicates their auxiliary function.
So for INTJ, the lifestyle preference (___ J) indicate their thinking (_ _ T _) function as an auxiliary function, and hence extraverted Thinking (Te) becomes the extraverted auxiliary function of an introvert. The dominated function is always the other letter of the two, in this case iNtuition which for introverts is always introverted, and hence introverted iNtuition (Ni).
The other two (tertiary and inferior) functions are the opposite of the first two. So for Ni the opposing is Se, and for Te the opposing is Fi. Hence: INTJ is decoded as Ni > Te > Fi > Se.

Further reading

History and context
Cognitive functions
Answers to that criticism