A Closer Look at Personality Tests

Personality tests claim to provide accurate descriptions of who we are and why we do the things we do. So do horoscopes.

Lombroso and Rorschach.

It was once fashionable to study the shape and size of the skull as an indication of character and mental ability. How people interpreted ambiguous images of inkblots was supposed to reveal their personality characteristics. Phrenology and Inkblot tests have been discredited as diagnostic devices, yet the Myers-Briggs Type Indicator lives on.

How did the MBTI come to be?

Isabel Myers and Katherine Briggs were two well-meaning amateurs not formally educated in any scientific discipline. They began creating their Type Indicator in their homes before doing any extensive scientific research, instead of the other way around.

Then they shopped around for a veneer of legitimacy and found Carl Jung.

A psychiatrist, Dr. Jung had created his stereotypes as points of orientation, not as the solutions claimed by Myers and Briggs.

During WW2, their MBTI was used to identify the sort of war-time jobs that would be “most comfortable and effective” for women. 

Today, it is a $20 million a year industry that administers two million tests a year.

Circular Logic.

People use the MBTI because it’s valuable and it’s valuable because people use it. This “logic” is self-perpetuating. Its popularity is interpreted as an indication of its accuracy and utility, which leads to wider use and less inclination to question its foundations.

Why your company’s HR department uses Myers-Briggs.

It is a prepackaged solution that is is easily administered and analyzed by HR people in countless organizations. It does not mind these people have little or no training in measuring human behavior and more often than not are unaware of the MBTI’s limitations.

The 4-day, $1,800 certification course promises instant expertise.

Unlike the Undergraduate degree that must be earned before entering a Graduate program, no background in Psychology, testing, or psychometrics is required for admission.

The Barnum Effect.

Like horoscopes, the MBTI descriptions appear accurate because of the tendency for individuals to view generally flattering and sufficiently vague statements as highly accurate descriptions of themselves.

Two spurious assumptions of the MBTI.

One assumes that personality type is inborn and never changes. But did you know that half of the people who take the test again fall into a different category than they did the first time? Types that are supposed to never change over a lifetime do so in as little as 5 days.

Another assumes mutually-exclusive categories when most people fall in the middle somewhere. Test results do not distinguish between someone who is 90% introverted from someone who is 55% introverted. How does this make sense?

If the MBTI measured height, everyone would be tall or short. You probably know that humans range in height from less than two feet to more than eight feet.

No middle ground.

The biggest problem is that we are forced to choose one of only two options – Thinking and Feeling, for example. Those who choose 11 thinking and 9 feeling items are deemed to be exactly the same as those who choose 20 thinking and zero feeling items. This is more than unlikely.

There is no scientific evidence that the MBTI measures anything of value. Many well-informed people agree it provides a ridiculously limited and simplified view of human personality, known to be a very complex concept.

For a famous sailor’s take on personality types, watch this 7-second video.