Personality tests are BS, so why do 89/100 Forbes companies still use the Myers-Briggs?

From employers to parole boards, an obsession with measuring things has perpetuated a worrying over-reliance on outdated tests, writes decision-making specialist Dr Ashleigh Morse.

If you’ve ever *studied* for a personality test in preparation for a job application, you probably already know what I’m going to tell you about their validity. Apparently, no one told 89 out of the Forbes 100 companies who still use the Myers-Briggs Type Indicator (MBTI), that it’s one of the most unreliable personality tests available.

Personality measures are self-reported. Even if they didn’t have well-established problems with validity and reliability, and even if you’re not actively trying to game the test, they rely on you being honest about yourself.

The MBTI takes your answers to a series of preference questions and neatly places you into one of 16 personality categories. These categories aren’t the product of a scientific theory of personality, but of a mother-daughter team with little more than a fascination with the 19-Century psychoanalyst Carl Jung and “two decades of type-watching”. Even the Myers and Briggs Foundation admits it would be "unethical" to use their test for recruitment purposes.

Even the Myers and Briggs Foundation admits it would be "unethical" to use their test for recruitment purposes.

It’s well established that the MBTI isn’t widely used because it’s a good personality measurement (it’s not), but because it has “intuitive appeal” for employers. Ironically, we’re drawn to these tests because we believe they’re more objective than our intuition when they’re just as biased as their human creators.

Like so many similar personality tests, traits the MBTI supposedly test for are introversion and extroversion. The introvert/extrovert binary is definitely outdated, but we still cling to the idea that 'extroverts' are more desirable candidates. One reason is because the general belief is that introverts are antisocial when really introversion and extroversion are just ways of thinking about where you derive your energy from: do you recharge by being around people, or being alone? 

Our infatuation with testing to predict future behaviour extends far beyond job interviews. The US legal system uses a Psychopath Checklist to determine sentencing and parole, based on the supposed connection between psychopathy and likelihood of reoffending. Using a test to determine criminality is especially troubling considering that the outcome is biased towards the motivations of the examiners. Prosecution examiners rate suspects an average of seven points higher on the scale than defence examiners. Even the creator of the checklist is troubled by its use in denying parole. The Psychopathy Checklist can also be gamed, all you have to do is buy a study guide, which, let’s face it, is exactly what a psychopath would do.

Even the creator of the Psycopathy Cecklist is troubled by its use in denying parole. 

Employers and parole boards are looking for some way to identify ‘right’ and ‘wrong’ personality types – one site for job-seekers promises to help you “get an ‘A’ for personality” (which dog-whistles to my high neuroticism even though I know it’s ridiculous). Beyond the notion of ‘right’ and ‘wrong’, evidence suggests that personality isn’t quite as stable as we would like to think, and that peak stability is reached late in life.

Tests aren’t objective prophecies of future behaviour, but they can become self-fulfilling prophecies. If you believe that the outcome is accurate, and that it measures immutable traits, then why fight it?

I’ll tell you why: your beliefs about yourself can change even the most seemingly innate abilities. Children who believe that intelligence is a skill, not a gift, outperform their essentialist peers, and make greater improvements over their schooling. Children can even learn to see intelligence as malleable, giving even those of us with high stubbornnessscores hope that we can change.

But maybe I’m just being a bit of an INFP

Dr Ashleigh Morse is a specialist in the science of decision making.