The Myers-Briggs personality test is used by companies the world over but the evidence is that it's nowhere near as useful as its popularity suggests

I was recently reviewing some psychological lectures for my real job. One of these was on personality tests. The speaker mentioned the Myers-Briggs test, explaining that, while well known (I personally know it from a Dilbert cartoon) the Myers-Briggs test isn't recognised as being scientifically valid so is largely ignored by the field of psychology. I tweeted this fact, thinking it would be of passing interest to a few people. I was unprepared for the intensity of the replies I got. I learned several things that day.

1. The Myers-Briggs Type Indicator (MBTI) is used by countless organisations and industries, although one of the few areas that doesn't use it is psychology, which says a lot.

2. Many people who have encountered the MBTI in the workplace really don't have a lot of positive things to say about it.

3. For some organisations, use of the MBTI seemingly crosses the line into full-blown ideology.

So how did something that apparently lacks scientific credibility become such a popular and accepted tool?

The MBTI was developed during World War 2 by Myers and Briggs (obviously), two housewives who developed a keen interest in the works of Carl Jung. They developed the MBTI based on Jung's theories, with the intention of producing a useful test that would allow women entering the workforce to be assigned jobs that would be best suited to their personalities.

This is already enough to make some people wary. Myers and Briggs weren't trained scientists, but you don't need to be scientifically qualified to make a very valid contribution to science. Look at Galaxy Zoo. Also, deriving all your information from a single source is always questionable in science, even if it weren't the work of Jung, whose theories were/are very influential and far reaching but largely scientifically untestable and subject to numerous criticisms. But the debate around the validity of Jung's theories certainly isn't something I could settle in a blogpost.

The trouble is, the more you look into the specifics of the MBTI, the more questionable the way it's widespread use appears to be. There are numerous comprehensive critiques about it online, but the most obvious flaw is that the MBTI seems to rely exclusively on binary choices.

For example, in the category of extrovert v introvert, you're either one or the other; there is no middle ground. People don't work this way, no normal person is either 100% extrovert or 100% introvert, just as people's political views aren't purely "communist" or "fascist". Many who use the MBTI claim otherwise, despite the fact that Jung himself disagreed with this and statistical analysis reveals even data produced by the test shows a normal distribution rather than bimodal, refuting the either/or claims of the MBTI. But still this overly-simplified interpretation of human personality endures, even in the Guardian Science section!

Generally, although not completely unscientific, the MBTI gives a ridiculously limited and simplified view of human personality, which is a very complex and tricky concept to pin down and study. The scientific study of personality is indeed a valid discipline, and there are many personality tests that seemingly hold up to scientific scrutiny (thus far). It just appears that MBTI isn't one of them.

But so what? People often benefit from things with a limited scientific basis, for many reasons. Scientific validity is necessary if you're trying to diagnose a disorder of some sort, but in the everyday workplace for team building and the like? This is what MBTI is used for most, so why go on some major nerd-rant about how unscientific it is when it doesn't really matter?

Yes, the MBTI is harmless and potentially useful if you're aware of its limitations. That's the problem, though; the MBTI is predominately used in the workplace by HR departments, development/training teams and the like, who can often be clearly unaware of its limitations.

I've been fortunate enough in my career to never have been profiled by someone utilizing the MBTI, but many others haven't been so lucky.

(N.B. The following comments were among numerous emailed to me directly in response to a tweeted request. Commenters are anonymous as their livelihoods could be threatened if their identities were known).

As a member of the [Development] team I am expected to, at the very least, support the use of Myers Briggs. MBTI is the default training solution for any kind of team building event... People very often say something like "Erm, I think that I am not just a T or an F. Can I be somewhere in the middle?" And my colleagues will patiently explain that you must be one or the other. This is the most disputed aspect of the whole thing. And yet there we are explaining with complete authority that "No, you ARE either a thinker or a feeler." It is stupid. I wince when I see one of the members of my team trying to convince an employee (who I happen to know has a Psychology degree) that MBTI is infallible.

Several reports like this revealed just how deeply entrenched and rigid this faith in the MBTI really is. Training in the MBTI and its variations is typical for those in Human Resources etc. and can be quite expensive. The MBTI as an industry apparently makes $20 million a year. When you've spent so much time and money on learning something, of course you're going to have a faith in it, even to the point of cognitive dissonance.

This sort of thing has been going on for quite some time, as the next commenter reveals.

When I was back in school (25+ years ago) a lot of teachers gave the test at the beginning of the year… In one class I was asked to write about "what I learned about myself" by taking the test. I wrote a whole paper about how unscientific the test was and how I didn't learn anything. That teacher had me removed from her class within a week for unrelated trumped up reasons. It was like I was questioning her religion.

It's easy to assume that this unthinking faith in the MBTI is the preserve of businesses and companies, but it seems it's found in schools too. And I've been told about people enduring MBTI-based assessment with negative consequences in our beloved cash-stricken cuts-ravaged NHS. That's right; the health service seemingly spends a lot of money on training and assessment methods that aren't as supported by evidence as many would expect. Worrying.

The extent to which the MBTI is relied upon can reach quite farcical levels, as another commenter revealed.

I interviewed for a new job, and after the first interview stage, I received an email from my recruiter that the second stage interview wouldn't be an interview at all, but a set of tests, which would help the company to understand my mathematical and reasoning ability, my understanding of language, and my personality. That's right, just like something out of a teen magazine, my second interview would not involve me meeting the people I would work with, meeting again with management, or even a technical test, but instead, would be the grown-up, corporate world equivalent of a "Could You Date Justin Beiber" quiz!

Some employers trust the MBTI more than their own judgement? Even if potential employees were entirely passive and unfailingly honest, this would be unwise. I've even been told about companies that make a point of putting employee MBTI profiles on the doors to their offices, so people entering know how best to engage with them. Whether the employees had the results of their drugs tests tattooed on the back of their necks too wasn't mentioned, but wouldn't surprise me.

I obviously can't verify the above quotes, and I know anecdotal evidence should be taken lightly, but this is just a small selection of the responses I got from one casual query.

There are many possible reasons why the MBTI is so entrenched in workplaces and promoted so enthusiastically. There's the expense and training involved, mentioned above. It may be because everyone uses it, so people conclude it must be reliable, and thus its success becomes self perpetuating. Also, any personality type you get assigned is invariably positive. There is no combination of answers you could give on the MBTI which says 'you're an arsehole'.

I personally feel it's more to do with people's tendency to go for anything that offers an easy solution. People will always go for the new fad diet, the alternative remedy, the five dollar wrinkle trick that makes dermatologists hate you for some reason. For all that it may be well-intended, the MBTI offers a variation on that. People are very complex, variable and unpredictable. Many users of the MBTI believe that a straightforward test can simplify them to the point where they can be managed, controlled and utilised to make them as efficient and productive as possible. It's no wonder businesses are keen to embrace something like that; it would be the ideal tool if it were guaranteed to achieve this.

Evidence suggests it isn't though. People are far more sophisticated than any basic yes/no test could ever hope to encompass. Employers who assume otherwise in the face of all available evidence run the constant risk of alienating and infuriating those they intend to manage more effectively.

Dean Burnett's personality can be effectively assessed from his Twitter feed, @garwboy

[Spoiler warning; it's awful]