MBTI, If You Want Me Back, You Need to Change TooI wrote this breakup letter to the MBTI a decade

Dear Myers-Briggs Type Indicator, Do you remember the day we met? I was a wide-eyed high school senior, and you were an exotic beauty. It was love at first sight. Our first date was magical: I opened up to you like I had never done with anyone before. In return, you opened my eyes to a whole new way of seeing the world. We had so much in common back then. Sadly, as the months passed, we started to grow apart. It began when I met your family.

Your mother and grandmother were obsessed with Carl Jung, who made up his three “types” based on his personal experiences rather than science (with the help of your mother, who made up the fourth). You had years of those experiences, and I was young and naïve, so why would I doubt you? But when I studied for a doctorate of my own, I learned that this was Mesearch, not Research. And a new girl caught my eye. Her name was Big Five, and she was raised by an entire extended family with PhDs in psychology, over multiple generations. They gave birth to her through a very different process. Instead of relying on their own limited experiences, they went out and polled thousands of people in different parts of the world, to find out how they viewed personality. Instead of inventing categories, Big Five’s ancestors realized that the major dimensions of personality could be found in natural language. If we look across the world’s cultures, we should find words to describe the most important psychological characteristics of people. One study included 1,710 adjectives in English, which ultimately made up five major categories of personality, not four. She was multicultural: the same basic categories replicated in many languages, from Chinese to Filipino, German to Italian, Dutch to Polish, and Hebrew to Russian. They called her Big Five. Of course, Big Five’s parents realized that language is only one of many ways to see personality. To make sure that their categories were meaningful, they collected genetic evidence and fMRI data. They also found that there was really no such thing as a type — every personality trait was on a continuum, and it was very rare to be on one extreme or another. Type wasn’t the only one of Jung’s original ideas that didn’t pan out. You said extraverts focused on the outer world and introverts on the inner world, but Big Five’s ancestors discovered that this was really about sensitivity to rewards, stimulation, and social attention. You said extraversion is about where you get your energy, but that’s false; both introverts and extraverts get energy from interacting with other people. You taught me that most people had a dominant preference for thinking or feeling, but research demonstrates that whether you prefer to use logic when making decisions has nothing to do with whether you’re concerned about how those decisions affect others. Giving me a thinking-feeling score is not like assessing whether I’m right-handed or left-handed. It’s more like evaluating whether I prefer soccer or Swiss cheese. Research is usually more accurate than Mesearch, so you can imagine my chagrin when you told me you weren’t going to change. You were like the Catholic Church clinging fiercely to the idea that the sun revolved around the earth, even after the discoveries of Copernicus, Galileo, Kepler, and others showed the opposite. One of your family members called Jung’s book her Bible, and you clung to it like it was an actual religion. No wonder you’ve been called astrology for nerds. I tried valiantly to open your mind. I even sent you a rad mix tape with Big Five’s favorite songs on it! I told you that theories should be revised based on data — if we don’t learn from our research, what’s the point? — but you were blinded by Jung’s armchair theory. I couldn’t take it anymore; we were caught in a bad romance. I broke up with you. Sure, I hurled some insults. I called you unreliable and shallow. I compared you to a physical exam that ignores your torso and one of your arms. And I said you might be more like a horoscope than a heart monitor. (See Say Goodbye to MBTI, the Fad That Won’t Die). In response, you left me a message. When you and I were together, you only knew a part of me. Big Five knows me much better; I’m an open book with her. (That includes my voicemail password, which is why I’m in the doghouse right now — she didn’t know we were back in touch. For the record, she was exploring her future with HEXACO, so I wasn’t cheating on her. WE WERE ON A BREAK!) The truth is, MBTI, you were my first love. Since then, I’ve changed, and a relationship is a two-way street. If you want me back, you need to change too. All I ask is that you follow a few basic rules of science… Embrace the Latest Data to Improve the Theory MBTI, darling, you mentioned a team that’s tasked with “keeping the instrument up to date.” Who updates the theory itself? Would it be so terrible to abandon Jung’s creative but antiquated ideas, and start capturing a broader set of preferences? If that’s too much to ask, and you’re devoted to your categories, why do you still insist on calling them types, when we know traits are more reliable and accurate? As Pittenger advised in his review, “those interested in using the MBTI should examine the advantages of replacing the four-letter type formula with more traditional magnitude assessments of personality.” Also, how about amending your thinking-feeling scores to separate these two dimensions? Your current flame acknowledges that “The T-F scale tends to have the lowest reliability,” so why not give it a tune-up? While you’re at it, it would mean a lot to me if you refined your definition of extraversion to reflect all that we’ve learned from half a century of systematic research. Some of your cousins have been perfectly comfortable with all of these ideas for a while. A quarter century ago, Cowan (an MBTI proponent!) wrote, “there is no obvious reason why the current status quo of this theory and its measurement cannot be improved.” This will not be a simple task: to quote Little, a personality psychologist, “It’s a little bit like taking a Dodge Caravan and trying to turn it into a Rolls Royce.”

Give Us Real Evidence for Efficacy You told me that if the MBTI “lacked a solid research-based foundation, it wouldn’t be used by the world’s top organizations, including Hallmark Cards and Southwest Airlines.” Since when do “the world’s top organizations” have the capabilities to evaluate the quality of evidence for a practice? Most of the world’s top organizations continue to use unstructured interviews, even though evidence shows that they’re highly ineffective. Many use forced-rankings to evaluate employees, despite a lack of consistent or convincing evidence that they work. Acceptance by non-experts isn’t a marker of validity. It’s a signal of popularity. You said “its efficacy is so well-established,” but your supporting evidence for that efficacy was a series of case studies. Experts in medicine and management agree that case studies are exceptionally weak forms of evidence. In science, the best evidence comes from meta-analyses of randomized controlled trials. To validate the “efficacy” of the MBTI, you need randomized, controlled experiments demonstrating that participants gain more insight from the MBTI than other comparable tools. I’m willing to bet that if you take the Big Five or HEXACO and walk participants through the same process — provided that the trainers are equally zealous — the MBTI will fare no better. But I’m also willing to be wrong, because I’m committed to revising my beliefs based on high-quality evidence.

After I dumped you, one of your relatives, Hile Rutledge, weighed in on our breakup. He has some perspective to offer, since he’s partially familiar with our history, and he’s been in an open relationship with you and Big Five. I happened to agree with most of his thought-provoking comments. There was one point, though, that puzzled me. He called you a “client-centered tool that builds self-awareness and helps lead to better self-management and growth.” To paraphrase my buddy Jerry, show me the data! Where are the experiments documenting that (a) taking the MBTI leads to self-awareness, self-management, and growth, (b) these benefits can emerge even in the absence of a zealous trainer or coach, and (c) it offers insight that exceeds, or at least matches, other psychological assessments?

Also, can you show us in a randomized, controlled trial that the “insight” you describe is, as you promised, “extremely beneficial… in enabling groups of people of varying personality preferences to work together cohesively”? If you believe that insight leads to cohesion when working with people of different preferences, why haven’t you conducted experiments to test whether cohesion rises when people learn about their “types”? And since there is already extensive evidence that cohesive groups tend to perform more effectively, why can’t you link this anticipated cohesion benefit to group effectiveness? You said “it is true that the MBTI instrument does not predict performance or satisfaction within an occupation.” Big Five has no trouble with this. Now, you may tell me that you’re not interested in Big Five’s way of looking at the world. But you do have one relative in common, and that’s introversion-extraversion. Consider this evidence from Big Five’s extraversion measure:

• Teams with a mix of introverts and extraverts tend to outperform those with mostly extraverts or mostly introverts

• Extraverts sell more when they’re directly rewarded, and ambiverts bring in more revenue than introverts or extraverts

• Extraverted leadership is linked to higher unit profits when employees are passive but lower profits when employees are proactive

Big Five didn’t just give me insight; she helped me figure out where I was most likely to be satisfied and effective. Why doesn’t your extraversion measure do that? I want you to be a better person, MBTI, and it makes me sad that you don’t seem to care about the happiness or success of your lovers. Can we work on your feeling score, just a little bit? I Remember the First Time We Broke Up MBTI, this isn’t just about you and me. You see, many of your exes have come out of the woodwork. They happen to be scientists, and they left you for the same reasons that I did. Plus, we’re not okay with the fact that some of your ancestors were racist and sexist. One of the virtues of research is that we can agree on the standards for a fair experiment. When experts disagreed vehemently, the chief antagonists can resolve their debate by collaborating on the design of a joint experiment. If you’re willing to embark on such an experiment with one of your antagonists, I’ll take it as a sign that you’re no tool — you might be ready for a committed relationship. If not, we are never, ever, ever getting back together. *** For more on the science of personality:

• Listen to our WorkLife podcast on Your Hidden Personality (Apple / Spotify / Transcript)

• Check out Brian Little’s TED talk and book, Who Are You Really?

• Take a free, scientifically valid personality assessment: Big Five (short 538 version or 300-question NEO version), the Hogan Personality Inventory, or PrinciplesYou, an assessment I helped develop to expand beyond Big Five. I still love her, though.