Myers-Briggs personality tests are bullshit.
Oh, the basic notion of trying to classify a personality by considering a variety of independent characteristics is sound enough. But the theory that inspired the test, that humans can be neatly divided into some scheme of Jungian archetypes constructed from opposing personality traits is just ... not true.
Take extroversion vs. introversion. This is a universally acknowledged personality trait (its one of the Big Five today). Any personality test or scheme for sorting people's personalities into boxes would have to include it. But there's just one problem: M-B assumes that personality traits have a bimodal distribution; that is, most people are in one bin or another, either extroverted or introverted.
Except that people don't work like that - extroversion is normally distributed. Most people aren't particularly extroverted or introverted. And that isn't some recent discovery. For example, below is a table from 1926(!) paper showing the distribution extroversion measured by means of a questionaire:
Note that the self-ratings are clearly normally distributed, while the peer-ratings appear to be slightly bimodally distributed. Given that the Briggs Myers Type Indicator Handbook was first published in 1944, how could psychologists, committed to empiricism and familiar with literature, endorse a schema that defied known facts?
The answer is that they didn't. Katherine Cook Briggs and her daughter Isabel Briggs Meyers were writers and enthusiastic students (I dare-say fangirls) of Jung who cooked up a theory to put Jungian psychology into practice and/or prove it correct. The goal wasn't to measure people's personalities as they actually existed but to sort people according to their "ideal type" so that they could try it on for size. This is because they believed that, per Jung's theorizing, people would be happiest and (more importantly) most productive if they behaved according to their "type".
You will notice that this resembles less the standard scientific research methodology than the process by which creationists disprove evolution by hunting for the Ropen.
If I was an ungenerous sort, I might describe this as haphazardly trying to stuff the rich diversity of human personality into 16 narrow boxes in order to make the world easier to understand. If I was extremely ungenerous I would draw your attention to the many was this sort of thinking is useful to reactionaries, if not intentionally reactionary itself. There's probably a good essay to be written on that topic, but this dear reader, is not it.
But in any event, I am (or at least try to be) generous, and a more generous reading is that according to the theory of psychology that they believed, reacting to a test indicating that a person is slightly more extroverted than average and the M-B test goes and hands them a card saying "HOORAY!!!! YOU ARE AN EXTROVERT!!!! GO OUT AND BE SOCIAL!!! :)" is the correct therapeutic action. They really thought that if a person was of an "extroverted type" they would be happiest (and most productive) if they behaved in an extroverted way, and that giving them a label this really would help them, at least a bit, in a manner akin to how people with previously diagnosed psychological disorders might report that the mere fact of a diagnosis is helpful.
But the thing is, facts really don't care about your feelings, outcomes really don't care about your intentions, and that theory of how people's minds work and how to help them is, empirically wrong, and could easily have be proven wrong by anyone who cared to test it. The Meyers-Briggs personality test, its theoretical foundations, and all derived from it are essentially quackery (1).
Despite this, this construct and this test has wormed their way into all sorts of popular (and vital!) applications of psychometrics - human resources, career and academic advising, and online dating.
Why?
I think a clue is in that table from 1926. People's self-ratings of extroversion were normally distributed, but peer-ratings were bimodal. People want to sort other people into boxes, to analogize them to cultural constructs and archetypes. It makes the messy and complicated and chaotic social world easier to "understand" and to deal with. Its what makes the fundamental attribution error so fundamental. And the Meyers-Briggs test was designed and marketed towards directing students to careers where "their type" would be happiest and most productive and likewise directing workers to jobs where "their type" would be happiest and most productive. The application in online dating is essentially astrology for people who don't believe in astrology.
And all of that terrifies me. Because my happiness is very much dependent on the decisions of potential mates and potential employers, and they are making those decisions on the basis of quackery.
So I have written this, in the hopes that someone who previously gave it defunct theory weight will change their minds, and use something with an actual empirical foundation.
(1) Pace! Quackery isn't necessarily evil - I'm sure medieval doctors really did think that leeches would cure people's ailments, and under many theories of ethics acting with a desire to help is virtuous and good even your assistance actually makes things worse. And quackery isn't necessarily ineffective - there are a few diseases where applying leeches is a valid course of treatment. And of course even if the treatment itself doesn't actually do anything (like, I suspect, acupuncture) the placebo effect is so powerful a patient may be helped simply by virtue of being treated.
