MBTI and the 16 personality types: what is actually worth taking seriously

If you have ever filled in your LinkedIn profile, sat through a team-building workshop, or simply scrolled social media, chances are you have seen a four-letter code like INFP, ESTJ or ENFP. That is the MBTI, the Myers-Briggs Type Indicator, probably the most popular personality test in the world. It is also one of the most debated among psychologists, and for good reasons.

This article is neither an attack on the MBTI nor a defence of it. It is a map of what the research actually shows, so you can use the 16 types with curiosity, without giving them more weight than they can carry.

What the MBTI is and where it comes from

From Jung to Katharine Briggs and Isabel Myers

The MBTI was not born in a psychometrics lab. It was born at a curious mother's kitchen table. In 1915, when her daughter Isabel brought her fiancé, Clarence Myers, home, Katharine Cook Briggs was struck by how differently the young man thought and reacted to the world compared with her own family. She began observing and cataloguing temperament differences around her.

In 1921, Swiss psychiatrist Carl Jung published "Psychological Types", a theoretical work on how people process information and make decisions, organised around attitudes (introversion and extraversion) and psychic functions (thinking, feeling, sensing and intuiting). Katharine Briggs read the book soon after it came out and spent the next two decades studying and expanding on Jung's ideas.

It was her daughter, Isabel Briggs Myers, who had no formal training in psychology, who turned these observations into a questionnaire. She selected questions that reliably separated people into the categories she and her mother had been mapping, and in 1943 created the first version of the instrument, Form A. The first formal MBTI manual was only published in 1962, backed by the US Educational Testing Service.

The four dichotomies and the 16 types

The MBTI organises personality into four pairs of opposite preferences. Each person is placed on one side of each pair, producing 16 possible combinations, the well-known four-letter types.

• Extraversion (E) vs. Introversion (I): where you draw energy from, the outer world and social stimulation, or the inner world and reflection.
• Sensing (S) vs. Intuition (N): how you prefer to take in information, through concrete facts and details, or through patterns, possibilities and abstract ideas.
• Thinking (T) vs. Feeling (F): how you prefer to decide, based on logic and objective criteria, or based on values and impact on people.
• Judging (J) vs. Perceiving (P): how you prefer to engage with the outer world, with structure and closed conclusions, or with flexibility and open options.

Combine the four letters and you get types like INFJ, ESTP or ENTJ, each with its own description of strengths, tendencies and potential difficulties.

Why the MBTI became so popular

There are concrete reasons for the MBTI's success, regardless of what science says about it.

First, the language is accessible. You do not need to know statistics to understand "I am more introverted, I prefer planning over improvising". Second, no type is presented as worse than another, which makes the result comfortable to share, unlike clinical tests that point to deficits. Third, it entered the corporate world early as a team-building and communication tool, and stayed there. According to the company that markets the instrument today, 88 of the Fortune 100 companies use the MBTI. Source: The Myers-Briggs Company on the MBTI

Popularity, however, is not the same as scientific validity. And that is where the MBTI starts to divide opinion.

What the research says: the problems with the model

Test-retest reliability is weak

A good psychological test should give similar results if the same person retakes it shortly after, without major life changes in between. This is called test-retest reliability. In the case of the MBTI, the studies are not encouraging.

The most cited review on the topic, by researcher David Pittenger, published in 1993, found that around half of the people who retake the MBTI within a few weeks receive a different four-letter type than the first time. Source: Pittenger, "Measuring the MBTI...And Coming Up Short", 1993 The most likely explanation is not that the person's personality changed in those weeks, but that the MBTI forces a binary choice (E or I, for example) on traits that are, in reality, continuous. Someone who answers near the middle of a scale can land on one side at one point and the other side a few weeks later, from pure mood or context fluctuation, without any real personality change.

Closed types hide a continuous spectrum

This is the most discussed structural problem. The MBTI presents introversion and extraversion, for instance, as distinct categories, as if there were a clear boundary between the two groups. Personality research does not confirm that boundary. What the data consistently show is a continuous distribution, with most people somewhere in the middle, not two groups separated by a gap.

A landmark study by psychologists Robert McCrae and Paul Costa, published in 1989, directly compared the MBTI's four dichotomies with the Big Five model. They found strong correlations between MBTI introversion/extraversion and Big Five extraversion, and between MBTI intuition/sensing and Big Five openness to experience, among other correspondences. The authors' conclusion was clear: the MBTI does measure genuine aspects of four of the five broad personality dimensions, but does so through artificially closed categories, where the evidence points to continuous scales instead. Source: McCrae & Costa, "Reinterpreting the Myers-Briggs Type Indicator...", Journal of Personality, 1989

If you have read our article on the Big Five, you will recognise the parallel. The MBTI and the Big Five ask, to a large extent, similar questions. The difference is that one returns a closed label and the other returns a position on a scale.

The MBTI is not inventing differences that do not exist. It is squeezing real, continuous differences into closed boxes that human personality, in practice, does not respect.

The Barnum effect and descriptions that fit everyone

Another frequent criticism has a name of its own, the Barnum effect, the tendency to accept as accurate a vague, generic description written in a way that could apply to almost anyone. The descriptions attached to each of the 16 MBTI types tend to be generous, positive and broad enough that most people recognise themselves in them, which reinforces the feeling of "this is really me", even when the actual precision of the categorisation is questionable.

What is genuinely worth taking from the MBTI

Not everything should be thrown out. Used with the right expectations, the MBTI still has practical value, mainly as a starting point for conversation and reflection, not as a definitive diagnosis.

• Shared vocabulary. Saying "I prefer to decide based on logic" or "I recharge alone" is easier once you have a framework to name those preferences, even if the four-letter label is not perfectly stable.
• An entry point into self-knowledge. For many people, the MBTI is the first contact with the idea that personality has structure and can be observed with some systematic method. It is a legitimate door in, even if it is worth continuing to explore from there.
• Team communication. In companies, the real value of the MBTI is rarely the label itself; it is creating structured space for colleagues to talk about different working styles, something that might otherwise never get said out loud.

What is not worth doing is treating the result as a fixed diagnosis, using it to screen out candidates in hiring, or concluding that two people are incompatible just because they have "opposite" types on paper. For a more robust take on how personality profiles intersect in a relationship, it is worth visiting Agapone's relational category, where compatibility is treated as something richer than four letters.

MBTI vs. Big Five, side by side

How to use the MBTI without falling into traps

If you have already taken the test and have a four-letter type in mind, three questions help you use it wisely. Does the result describe tendencies you recognise in concrete situations, or is it a vague description that would fit almost anyone? Would you be comfortable accepting a different type if you retook the test in a month, knowing that is statistically likely? And, more importantly, are you using the type to understand yourself better, or to confine yourself to a box?

If you are looking for a more robust framework to understand yourself, Agapone's mental category crosses this kind of instrument with other layers of reading, beyond a four-letter code. And if you regularly fill in personality tests online, it is worth pausing to check how each platform handles that sensitive data, a topic we explore in Agapone's personal data category.

What to take with you

The MBTI is not pseudoscience invented from nothing; it has roots in a serious psychological theory and captures real differences between people. The problem is not what it measures, it is how it presents it, in closed boxes where human personality, in reality, spreads across continuous spectrums. Use it as an opening conversation about how you think and decide, not as a final answer about who you are.

Agapone starts precisely from here, from instruments like the MBTI or the Big Five, to build a fuller portrait that crosses personality with other layers of self-knowledge. If you want to see that reading in practice, visit Agapone and explore your profile.