How Useful Are Personality Tests?

In our search for self-knowledge, we’ve all likely taken one (or several) personality tests. The goal is to gain insights about ourselves—why we are the way we are. But are these tests any good? Do they accurately measure personality? Are they actually helpful for self-understanding? The answers are complex.

Let me focus on three of the most popular personality tests: The Myers-Briggs Type Indicator (MBTI), the Enneagram, and the Big Five.

The Myers-Briggs is the most widely administered psychological test. It is based on Carl Jung’s theory of psychological types. It was constructed by the mother and daughter team of Katherine Cook Briggs and Isabel Briggs Myers. Katherine Briggs used Jungian notions of personality to analyze characters in literature. Although the MBTI is based on Jungian theory, it was really Isabel Myers’ interpretation of that theory that lies beneath the test’s construction. The MBTI has four dimensions (Introversion-Extraversion; INtuition-Sensing; Thinking-Feeling; Judging-Perceiving). Combinations yield 16 personality types, and users get to know their four-letter “type” (e.g., ESTJ; INFP).

The Enneagram has ancient roots, derived from Babylonian and Sufi traditions. It yields nine types, represented numerically. The types have descriptive labels (e.g., “The Reformer,” “The Achiever,” “The Peacemaker,”). Unlike the MBTI, whose “official” test is published by the Myers-Briggs Corporation, there are various tests for assessing the Enneagram.

The Big Five was primarily developed as a research tool to help understand how personality relates to a variety of outcomes, from well-being to academic success, to potential as an employee. It consists of five dimensions: Neuroticism, Extraversion, Openness to Experience, Conscientiousness, and Agreeableness. Although there are various measures to assess the Big Five the most common is the "NEO," so named for the first 3 dimensions.

Is This Test Any Good?

A first concern is the underlying theory behind the test. As mentioned, the MBTI was based loosely on Jung’s theory. The Enneagram theory pre-dates the field of psychology and is an interpretation of ancient traditions regarding personality types. The Big Five evolved after decades of research on different personality traits and was the result of reducing dozens of proposed traits into five core, stable, “higher-order” traits.

Any good test needs to demonstrate good validity, measuring what it’s supposed to measure, and reliability (i.e., stability, so that you don’t get different scores for the same person at different times).

Both the MBTI and the Enneagram have been criticized by personality psychologists for a lack of solid evidence of validity and reliability. For example, the forced-choice format of the self-report MBTI might lead to a change from an Extravert to an Introvert because the test-taker changed their responses to a couple of items, suggesting problems with test reliability. In addition, typologies suffer from the fact that the test-taker is put into a category. For example, you may be labeled an Extravert (“E”) or an “Introvert” (I) and that is your type. In actuality, personality dimensions are continuous, with persons being more or less introverted or extraverted, and the typology doesn’t differentiate strong introverts from relatively weak introverts.

On the other hand, the Big Five measures, such as the NEO, have been extensively validated. They offer continuous scores on each of the five personality traits, so the user can tell if they are strong or weak on each trait. The Big Five measures, however, are mostly used for research and don’t typically offer the detailed interpretations characteristic of the other two measures.

In addition to these well-known personality measures, there are a lot of so-called personality tests out there on the Internet. One should be especially concerned about the interpretation of personality test results.

The Barnum Effect

Named for P.T. Barnum, who famously said, “there’s a sucker born every minute,” the Barnum Effect occurs when people are given vague interpretations of their personality test scores that could fit just about anyone. This is the effect that horoscopes, fortune tellers, and charlatans create when they suggest the information they provide applies to an individual when it could really apply to almost anyone (e.g., “Sometimes you can be loud, outgoing, and a people person, but other times you can be quiet, shy, and reserved.”) Be wary. Many online “personality tests” give these vague interpretations that could apply to just about anyone (and some of the MBTI and Enneagram type descriptions seem a bit “Barnumy” to me.)

Personality Tests: What Are They Good For?

Personality tests were originally developed as research tools to better understand individual differences in people. Later, they were used for multiple purposes. Some personality tests, such as the MMPI (Minnesota Multiphasic Personality Inventory), are used to diagnose different psychological disorders. Other personality tests, such as the Hogan Assessments, are used for personnel selection and for developing employees and managers.

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What about tests that individuals take for self-exploration: the MBTI, Enneagram, and the Big Five? Simply put, they should be “taken with a grain of salt.” Realize that these only give you some indication of the personality traits that you may possess, but they are not exact and can be totally wrong. Any one test result could be affected by the test-taker, who might try to “second guess” the test, or answer in a socially-desirable way.

Remember too, that personality is not destiny. Possessing certain desirable (or undesirable) traits doesn’t mean that you are locked into certain behavioral patterns. Traits represent tendencies—patterns of behavior—and we can break out of tendencies. Moreover, the situation also comes into play. For example, an introvert might, in certain situations, behave more like an extravert, and vice versa.

In short, don’t get too hung up on the results of your personality tests.