Personality tests claim to provide accurate descriptions of who we are. Before they came along, it was fashionable to study the shape and size of the skull as an indication of character and mental ability. People thought how you interpreted ambiguous images of inkblots would reveal your personality characteristics. Lombroso’s phrenology and Rorschach’s inkblot tests were long ago discredited as diagnostic devices, yet the Myers-Briggs Type Indicator lives on.

Katherine Briggs and Isabel Briggs Myers

NPR’s WNYC Studios says Katharine Briggs was a mother and homemaker who in the early 1900s had three children. When two of them died in infancy, she set out to raise the third as a perfect child. When neighborhood mothers noticed how well-behaved Isabel was, Katherine began her Cosmic Laboratory of Baby Training in her living room, professionalizing motherhood by using “No, no” drills to teach such things as obedience and where to walk. She also told mothers that “spanking is medicine.”

Katharine started writing articles

Her first three were called Meet Yourself Using the Personality Paintbox, Up From Barbarism, and when a neighbor woman’s daughter failed the first grade, she wrote an article called Ordinary Theodore and Stupid Mary.

Katharine had a dream about Carl Jung, author of the book

She lacked any sort of psychoanalytic training but was drawn to his book, Psychological Types, calling it “my Bible.” Using Jung’s language to give her version authority and rigor, she grossly oversimplified his theories so that anyone could understand them.

Briggs took Jung’s theories and gave them her own spin

A psychiatrist, Dr. Jung built a theory of personality that categorized people in terms of archetypes (stereotypes). Jung had created his stereotypes as points of orientation, not as the solutions claimed by Myers and Briggs. He believed each archetype plays a role in personality but much depends on each person’s cultural influences and personal experiences.

During WW2, the Myers-Briggs Type Indicator was pitched as a way to identify the sort of wartime jobs that would be “most comfortable and effective” for women. Psychologists rejected it as invalid, describing Katharine as a very bright lady, with a lot of enthusiasm but full of naïve notions.

As psychologists were their target market, this was a huge disappointment

So they decided their new market would be businesses that would use it as an aptitude test. for women entering the workforce for the first time.

Circular Reasoning

People use the Myers-Briggs Type Indicator because it’s valuable and it’s valuable because people use it. Just like a perpetual motion machine, its popularity is interpreted as an indication of its accuracy and utility, which leads to wider use and less inclination to question its foundations. Today, the MBTI website says it is a “robust tool for self-assessment used by more than 88 percent of Fortune 500 companies.”

Two spurious assumptions of the Myers-Briggs Type Indicator

• One assumes that personality type is inborn and never changes. Most don’t know that half of the people who take the test again fall into a different category than they did the first time. Are you the same person today as you were as a middle schooler? Of course not.
• Another assumes categories are mutually exclusive, meaning one or the other, but never both. Test results do not distinguish between someone who is 99% introverted from someone who is 51% introverted. If the MBTI measured intelligence, everyone would be either stupid or brilliant. You already know most people fall in the middle somewhere, so mutually exclusive categories don’t even make sense.

None of the types are better or worse than any of the others

The types measure only preference, not aptitude. Some suggest a better way to use the type indicator is to read them all and decide for yourself which of the categories best describes you.

So why does your company’s HR department use Myers-Briggs?

• It is a prepackaged solution that is easily administered and analyzed by people with no training in measuring human behavior.
• People like it because it is simple and its prefabricated “answers” are easy to understand.
• HR employees’ lack of training means they are blissfully ignorant of the test’s shortcomings and limitations.
• Another lure is that the 4-day, 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 reason both horoscopes and the Myers-Briggs descriptions appear accurate is the Barnum Effect –  the tendency for individuals to view flattering and vague statements as highly accurate descriptions of themselves.

Test takers are forced to choose one of only two options

Take 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 beyond unlikely.

Bonus

Psychometricians found statistical irregularities in the test results. One big one: thousands of test takers showed no evidence of a clear preference for thinking over feeling), for example. As a matter of fact, most people gathered in the middle.

There is no scientific evidence that the Myers-Briggs measures anything of value. It is widely considered by psychologists and psychoanalysts to be no more than pseudoscience. Most well-informed people agree it provides a ridiculously limited and simplified view of human personality, a concept known to be very complex.

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