Personality tests, like horoscopes, seem accurate because of the Barnum Effect.
“The phenomenon that occurs when individuals believe that personality descriptions apply specifically to them (more so than to other people), despite the fact that the description is actually filled with information that applies to everyone.”Britannica wesbite (1)
The popular Myers-Briggs personality test was developed during World War 2 by a mother-daughter team who were self-taught in psychology and psychometric testing. The mother, Katherine Briggs, was heavily influenced by Carl Jung’s work and book, Psychological Types. Jung introduced the concept of Introverts and Extroverts, and Myers-Brigg’s extrapolated his work into sixteen personality types.
Jung’s theories and work have been widely critiqued as unscientific because the concepts cannot be proven via the scientific method. Additionally, his beliefs in mysticism and the occult – i.e., the argument that synchronicity can be used to validate the paranormal and his belief in UFOs – lessens his authority in the realm of social sciences.
The DiSC Assessment is based on the DiSC model of personality traits, created by William Marston and based on a book he’d written in 1928 called “Emotions of Normal People”. It divides people into four colours or dominant traits: Dominance, influence, Steadiness and Conscientiousness (DiSC).
After creating the DiSC model, Marston developed Wonder Woman for DC comics, using his personality model to create a dominant female character. He also designed the lie detector test, which is still used but has also been discredited as ineffective and is no longer admissible in court (in Canada & the UK).
The Myers-Briggs website has explicitly stated that it is unethical to use their test to make hiring decisions. It should be voluntary, not tied to any decision-making, and people must own their results and only share them if they want to.
“The information is not to be used to label, evaluate, or limit any individual in any way.”Myers-Briggs website (2)
Personality tests all come with similar reservations. The accuracy of these tests is impossible to verify. Binary choice questions are essentially meaningless: no one neatly fits into one of two categories, especially when those choices are something like Thinking versus Feeling (you can be both!). Scale ratings are notoriously imprecise. There’s no way to make sure a six on a scale of ten means the same thing from person to person. One person’s experience and understanding of what it means to be ‘cheerful’ will not be the same as anyone else’s.
So many things can affect the results: level of self-awareness, mood, mental health, life circumstances, etc. It’s also easy to manipulate and get the results you want or think the tester wants.
“Although there are data suggesting that different occupations attract people of different types, there is no convincing body of evidence that types affect job performance or team effectiveness.”Adam Grant, Organizational psychologist at Wharton (3)
Personality tests appeal to the human affinity for putting things into categories. However, humans are far more complex than four or sixteen generic traits. It’s just too simplistic.
Tools like the Myers-Briggs and the DiSC Assessment can give people terminology to discuss interpersonal dynamics. Still, the danger of using personality tests in professional settings is that people may be pigeon-holed and, say, not promoted or hired because they don’t fit the “right” type for that role.
Organizations should save their money and skip the personality tests – especially during the hiring process.