Why It’s Easy to Mistype Before Your Mid 20s (Myers-Briggs Deep Dive)

I thought I was an INFJ for years.

My dad introduced me to personality type theory sometime in junior high and I’ve been intrigued (and borderline obsessed) ever since. I took the Myers Briggs Type Indicator multiple times and each time my result was the same: INFJ. Which stands for Introverted, Intuitive, Feeling, and Judging. Each letter seemed correct… and the bonus? It was the rarest of the 16 personality types! I felt so validated in my uniqueness and I fully embraced the INFJ identity.

That is… until I went to college.

Somehow my roommate, my best friend, and five other extroverted, bubbly first year girls ALL claimed to be INFJs. We were all the rarest personality type. Together.

Uh, no.

I knew something had to be off. Not just statistically, although that was my first clue, but just practically: all the INFJs I knew were so, so different. And so many of them seemed Extroverted, too. So, why were we all typing as INFJs?

I forgot about the Myers-Briggs for the next few years. It was slightly discredited in my eyes and I didn’t have the knowledge or energy to deep dive into why the online tests were so inaccurate. I knew that we weren’t all INFJs… but there’s always that thought: “well they’re not an INFJ, but at least I am!” I just figured that they were wrong, I was right, and they would find out eventually.

Not exactly.

I still think 80% of the INFJs I met were not actually INFJs, but I was actually among them.

I re-took the Myers-Briggs Type Indicator when I was a Senior and this time, my results were different. I took the test again and again and each time the results confirmed that I was actually an ENFP.

Two letters changing? Can a person’s personality type really shift that much from Freshman to Senior year?

It seems like an evolution of personality type on the surface, but the beauty of MBTI is that it goes so much deeper than that. When you get into the cognitive function level, it all makes sense.

How Cognitive Functions Work

To understand how cognitive functions work, we’ll need a quick history lesson.

The Myers-Briggs Type Indicator is a self-assessment tool developed by mother/daughter team Katharine Briggs and Isabel Briggs Myers in the 1940s. Their goal was to make Carl Jung’s psychological type theory accessible to the average person.

Carl Jung was one of the first people to define introversion and extroversion as he observed some people were oriented to the external world and others to the internal. From there he continued to notice and name personality differences which are now known as cognitive functions. According to Jung’s study and observation, he identified two cognitive processes: perception and judgment. The two perceiving functions are Sensing and Intuition (which learn and absorb information); the two judging functions are Thinking and Feeling (which make decisions based on given information). Every mental act consists of using one of these four functions: Sensing, Intuition, Feeling, or Thinking.

A cognitive function can be introverted or extroverted based on whether it is oriented inward toward the individual or outward toward the world. The eight known cognitive functions are as follows:

• Extroverted Sensing (Se)
• Introverted Sensing (Si)
• Extroverted Intuition (Ne)
• Introverted Intuition (Ni)
• Extroverted Feeling (Fe)
• Introverted Feeling (Fi)
• Extroverted Thinking (Te)
• Introverted Thinking (Ti)

Katharine Briggs and Isabel Briggs Myers chose to focus on Jung’s notion of opposites and they defined the dichotomies in order to reveal one’s personal type pattern. The Myers-Briggs Type Indicator tests one’s preference between Introversion vs. Extroversion, Intuition vs. Sensing, Thinking vs. Feeling, and Perception vs. Judging. Based on one’s preferences they are assigned a four letter code (ex. ISFP, ENTJ) which points to their four dominantly used cognitive functions.

The dichotomies are simply a roadmap to someone’s cognitive functions: a beginning, as opposed to a final destination.

ENFP vs. INFJ Cognitive Functions

Knowing that each Myers-Briggs type uses four preferred cognitive functions, let’s compare an ENFP and an INFJ.

An ENFP’s dominant cognitive function is Extroverted Intuition, their secondary cognitive function is Introverted Feeling, their tertiary cognitive function is Extroverted Thinking, and their inferior function is Introverted Sensing.

An INFJ’s dominant cognitive function is Introverted Intuition, their secondary cognitive function is Extroverted Feeling, their tertiary cognitive function is Introverted Thinking, and their inferior function is Extroverted Sensing.

An ENFP and INFJ do not share any cognitive functions, although their dominant cognitive function is an intuitive one, their secondary function is a feeling function, their tertiary function is thinking, and their inferior function is sensing. What makes them so different is that they use intuition, feeling, thinking, and sensing all in different ways… what makes them so similar (especially to an online MBTI quiz), is that they’re heavy intuition-users and heavy feeling-users (the only difference is in their function’s orientation).

If an ENFP believes that they’re more introverted than they are, or they misunderstand the meaning of introversion in a Jungian sense, it is very easy to mistype as an INFJ. Especially when taking cognitive development into account.

When Do Cognitive Functions Develop?

So when do cognitive function typically develop? The average timeline is as follows (although this can be significantly altered by life circumstances, trauma, mental illness, or other growth stunting/accelerating events):

Dominant/Driver Function: This is the function used most often (approximately 80% of the time) by an individual. Development begins at birth and continues through childhood. The dominant function is so natural that it will feel like home for the user.

Auxiliary Function: This function is used second-most often and together with the dominant function defines approximately 90% of someone’s experience. The auxiliary function works as a side-kick to the dominant function and will “flavor” everything the user does. Development usually begins in adolescence.

Tertiary Function: This function starts to develop around mid-20s and can be a secret weapon and a blind spot for many types. Because it will never be as well-developed as the dominant and auxiliary, this function can act as a stumbling block or noble vice.

Inferior Function: This function starts to develop around mid-life and will often act as a zone of tremendous weakness. This is a place where growth can happen but shouldn’t receive too much attention because it will always be weaker than the other functions.

I believed that I was an INFJ for many years not because my personality “changed” in that time frame, but because my secondary cognitive function wasn’t finished developing until I was in my mid-20s. Moving from the development of my introverted feeling function to my extroverted thinking function helped me grasp my true strengths and weaknesses and see my personality type clearly. I believe this is the key reason why so many people tend to mistype before their mid-20s: their second function isn’t finished developing yet.

Before diving into cognitive functions, I knew that I favored intuition and feeling. What I misinterpreted, based on my stage of development, was where I feel on the introvert-extrovert scale. From adolescence to mid-20s, an ENFP is developing Introverted Feeling. From my limited perspective, I was extremely introverted because I was learning how to navigate the inner world of Fi and was absolutely consumed by it. As I learned to navigate Fi and filter Ne ideas through an inner Fi lens… I was able to put both functions in their proper place and see myself more clearly as the ENFP that I was.

Knowledge of cognitive function development can truly make all the difference when it comes to typing correctly.

So, what about you? Where do you fall in your own cognitive function development? Do you believe you’re right on track, or ahead/behind the average timeline? Were you mistyped for a period of time? Leave your thoughts below!