Whether or not your personality type can change is quite a point of debate in the Myers-Briggs® community. Officially, Myers-Briggs® theory holds that your personality type is inborn and does not change. In other words, you cannot start out as an ISFP and then transform into an ESFJ (or any other types) over the course of your life.
Practically, though, we know that people take personality tests all the time and get different results. It’s one of the big arguments leveled against Myers-Briggs® theory — that the tests don’t deliver consistent results and are therefore not valid, repeatable, or scientific. On top of all that, you might have seen articles about new research over the last few years that indicates your personality can change over your lifetime. How do we make sense of all that in relation to type theory?
Personality Traits vs. Personality Type
On the surface, it seems that Myers-Briggs® disagrees with psychology studies that say personality can and does change. But when you take a closer look, you’ll see there’s not really a disconnect. There’s a big difference between personality traits and personality type. The personality model that most psychologists favor today is called Big Five. It includes five key traits — extroversion, agreeableness, neuroticism, contentiousness, and openness.
Where you fall on these traits can change, though they’re considered relatively stable. When change happens it tends to do so gradually over many years (change is more likely and more rapid when something significantly life-changing occurs, such as a traumatic experience) . We also tend to be more stable in some traits and less stable in others. You can read more about this in the following articles:
- “Can Your Personality Change Over Your Lifetime?” by Jill Suttie, Psy.D
- “Can You Change Your Personality?” by Romeo Vitelli Ph.D.
- “Personality Can Change Over A Lifetime, And Usually For The Better” by Christopher Soto, Ph.D
Personality type is a different thing. In the Personality Hacker Podcast Episode 0335 – Does Your Personality Type Change Over Time (with Dr. Dario Nardi), one of the first things they talk about is the difference between the trait model and the type model. Traits are characteristics that are “behavioral” and “measurable.” They are surface-level “echoes” of the underlying cognitive mental processes that are part of your psychological type.
Myers-Briggs® theory is built around describing how we each use a specific set of preferred cognitive processes. It describes how our minds are hard-wired to work. Those cognitive processes, also called “functions,” influence and underlay your personality traits, but they are not the same thing. If you’re not familiar with functions or want a refresher on the topic, you can check out my post “The Simplest Guide to Myers-Briggs® Functions Ever” and Susan Storm’s post “The Cognitive Functions – What Are They?”

Why Does It Look As If Type Can Change?
Having established that psychological type does not change even though personality traits can and do, that still leaves us with a question. Why do some people get inconsistent results when they take a Myers-Briggs® test?
One explanation is that most people aren’t taking the official MBTI® test. Free online quizzes are not tested as rigorously as the official MBTI® and the quality of them varies widely depending on which website you go to. It’s not surprising that you’ll get mixed results. That said, there are a couple of online tests that I feel comfortable recommending:
- Psychology Junkie Personality Test from Susan Storm, who’s a certified certified MBTI® practitioner.
- Personality Hacker Genius Test (note that this is an affiliate link. You won’t be charged to take the test, but if you choose to buy any of their products after taking it I’ll receive a commission at no extra cost to you)
These are two of the best tests out there, but even they can give you different results if you take them at different times. That’s because of another issue with Myers-Briggs® style tests. They’re based on self-reporting, and so the results you get will vary depending on how well you know yourself and how you decide to present yourself on the test. In addition, taking a test while you’re stressed can skew your results. Having a fairly balanced personality can also make it hard for a test to pin you down. That’s why tests are just a starting point. Finding your best-fit personality type also involves researching the different types and functions and/or talking about your type with a trained coach.
Change and Growth Within Your Type
The other reason that test results can change, which makes it seem as if your personality type is flexible, is because it’s possible to grow within your type. Indeed, we’re meant to develop, mature, and change over the course of our lives. Your personality type isn’t a box for you to stagnate inside. Rather, it’s a way of describing the mental processes that form the foundation you work with as you create your own unique life and personality.
According to Myers-Briggs® theory, all people use four favorite functions but they’re not equally well developed (we also have four shadow functions, but we’re not getting into those today). Generally speaking, these functions develop at predictable ages. From birth to about 7 years old, you’re working on your dominant function. From 7 into your 20s, your auxiliary function develops. We develop the tertiary during our 20s, 30s, and 40s. From 50s and 60s onward, we start to develop the inferior function. (My reference for this is Susan Storm’s article “Can Your Myers-Briggs® Personality Type Change?“.)
Practically speaking, however, things are a bit more complicated than this. For example, I’m an INFJ and I didn’t really start to get comfortable with my co-pilot Extroverted Feeling until my mid-2os. I’ve also been using my tertiary Introverted Thinking longer than that, and I’ve been consciously working on developing my inferior extroverted Sensing even though I’m only in my early 30s. For another example, I know an Extrovert who started developing his more introverted side fairly early in life because his family encouraged introspection and quiet activities like reading. Our circumstances can change when and how our functions develop.

This is born out by Personality Hacker’s research as well as something that Myers-Briggs® theory describes. Types have a tendency to “loop” between their dominant and tertiary process, by-passing the auxiliary function. Our auxiliary function is often less comfortable for us, and so we may need to give it some extra attention in order to develop it properly. Personality Hacker calls using this function being in a “growth state” because it’s essential in order to be a well-rounded person. We don’t all develop the different aspects of our psychological type and cognitive functions at the same time or in the same way.
Which functions are strongest will dramatically affect our results on a personality test. An INFJ with a well-developed co-pilot may find that they sometimes test as an ENFJ or even ESFJ. Another INFJ that relies more on their tertiary side might have a hard time figuring out if they’re a Feeling or Thinking type, and they might even test as an INTJ or INTP. As someone grows and develops different aspects of their type, it might look like their personality traits are changing and their test results may shift. They’re not, however, morphing into a new personality type. Rather, they’re growing and developing within their type.
I’ve linked resources from the experts mentioned in this article below if you’d like to purchase a copy for yourself. Please note that these are affiliate links which means that, at no additional cost to you, I will receive a commission if you click on the link and make a purchase.
- Discovering You: How to Unlock the Power of Personality Type by Susan Storm
- Neuroscience of Personality: Brain Savvy Insights for All Types of People by Dario Nardi
- Personality Hacker: Harness the Power of Your Personality Type to Transform Your Work, Relationships, and Life by Joel Mark Witt and Antonia Dodge
Featured image credit: GLady via Pixabay