This is a post about psychometric (personality) testing techniques; in particular the Myers Briggs Type Indicator (MBTI), a popular (though flawed in my opinion) personality test and the more academically accepted OCEAN, or Big 5 personality test.

Before we get into the nuts and bolts, it's worth stating that I am qualified to administer and interpret the Big 5 personality test and am registered as such on the British Psychological Society'sRegister of Qualifications in Test Use. You can check this by going to the register and searching by my surname. This will also confirm my membership of the London and Home Counties Branch of the British Psychological Society.

Back to the discussion. First of all some history. MBTI was formulated by a mother-daughter team called Katharine Cook Briggs and Isabel Briggs Myers, neither of whom were trained psychologists or statisticians, though both had a keen amateur interest in the subject and had read Jung's work on personality types.

The theories of MBTI were developed at home between the two ladies and eventually tests were developed which, it was assumed, would enable everyone to be categorised into one of sixteen different combinations of the four types.

Apart from the developmental model disregarding scientific rigour, what are the main objections that one might have to MBTI? Well, the first, and I think foremost, is its lack of consistency. Adam Grant, in this artcile in Psychology Today, shares how he was idenfitied as a INTJ then, a few months later as an ESPF. I myself have taken the test several times, always with a different result - the first time I was an ENTJ, later an INFP. For a test to be meaningful it has to be reproducable, by MBTI is not.

Dr. David J. Pittenger, psychometric researcher and Dean of the College of Liberal Arts, Marshall University, who has done extensive reseach into MBTI , has this to say of MBTI retest scores:

[Even] even when the test-retest interval is short (e.g., 5 weeks), as many as 50 percent of the people will be classified into a different type.” This is to say that the test fails to meet standards of ‘test-retest’ reliability.”(“Measuring the MBTI…And Coming Up Short”, Journal of Career Planning and Employment, 1993. 54: p. 48-53.)

That's a pretty high failure rate especially as the background assumptions as provided by MBTI  is that types don't change over time. So maybe his research is flawed or based on a old version of MBTI? Well that's what the MBTI people will tell you. I'm not allowed to quote anything from their website (no one is, they explicitly withhold permission); however you can head on over yourself to the Misconceptions about the MBTI Assessment page of their website where (at leats on 12 April 2019) in an attempt to prove scientific validity they claim that over a retest period of four weeks only 35% of respondents had changes in their type. Hardly a vindication.

One of the stranger phenomena one encounters when discussing the limitations of MBTI is the fervent anger that challenging it raises in some people. The feelings it raises almost classify as relgious, and some of the justifications border on at best lazy thinking, at worst wilfull confirmatory bias. Here are some of those arguments, with my own refutations:

  1. It's been around a long time and is very popular. Yes, well, both of these assertions are true, but neither is justication of validity. Racism has been around a very long time and is currently (sadly) quite popuar in a number of countries. I wouldn't call it valid.
  2. It provides a framework for people to use that helps them make sense of their lives. Yes, maybe... But if you're using the wrong framework, you're liable to make suboptimal or even poor decisions. You may also be boxing yourself in; denying yourself opportunities that could be great for you. Besides, this form of validation could be claimed for almost all of the world's ideologies and relgions. We can leave aside the questions of whether religion is a force for good or bad; it's enough to understand that this validation mechanism can be applied to all of them - Christianity, Islam, Hinduism, Judaism, the Scientologists, and, for that matter, the ideologies of far-right neonazism, and so on. It should be self-evident that this is nonesense.
  3. I've used it and I've seen how transformative it can be. This is another cult-like justification, when you think about it. I've seen people go into cults, like the School for Economic Science, and their lives transform. Hopefully no one with even a passing interest in psychology seriously thinks that just because something is transformative, we should rush out and adopt it.
  4. I intuitively know it to be right. It speaks to me. As Randy Stein and Alexander Swan explain, in this artice, intuition is a poor judge:
People's intuitions do them no favours... [and] often undermine scientific thinking on topics like physics and biology. Psychology is no different. People arbitrarily divide parts of themselves into "true" and superficial components and seem all too willing to believe in tests that claim to definitively make those distinctions. But the idea of a "true self" doesn't really work as a scientific concept.

To paraphrase Stein and Swan, a close belief in the veracity of MBTI could lead you to know less about yourself, not more.

So what of OCEAN, or the Big-5 personality test. There is a lot of good scientific research to the effect that OCEAN actually works to help us understand more about our personalities. The five letters stand for Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism (a measure of your stress levels, rather than how neurotic you are as a person). Rather than the binary MBTI indicators, OCEAN measures each facet over a range of possible values. The result is a unique profile.

The retest results for OCEAN tend to be fairly static and have only been shown to change in response to major, often traumatic, life events, e.g. death of a loved on, divorce, etc.

You can take a shortened version of the Big-5 OCEAN test at the Pschology Today website. It's free to take. If you prefer, you can take a more comprehensive version using a qualified test giver / interpreter (I am both or you can find another practitioner at the BPS website's Register of Qualified Test Users[^1:]).

OCEAN is growing. It's long been recognised that it doesn't cover every apsect of personality. Recent suggestions are for a sixth dimension to be added: that of Social Dominance. You can read more about that here. And, then, there is the HEXACO model, which correlates quite closely to OCEAN, but hasn't gained as much academic accreditation (yet).

[^1:]The link will open with my data prepropulated; just overwrite it and hit enter or select one of the letters of the alphabet to find someone else.

Photo credit: Chris Tweten on Unsplash