What Do Personality Tests Really Reveal?


Over the course of the past century, psychology has been consumed with the search for a kind of magical instrument to determine personality. Hermann Rorschach proposed that great meaning lay in the way that people described inkblots. We’ve moved on considerably since then. But have we moved on too far?

The creators of the Minnesota Multiphasic Personality Inventory believed in the revelatory power of true-false items such as “If the money were right, I would like to work for a circus or a carnival.” Annie Murphy Paul tells us in her fascinating book,Cult of Personality, that there are twenty-five hundred kinds of personality tests. Testing is a four-hundred-million-dollar-a-year industry. A hefty percentage of FTSE 250 companies use personality tests as part of the hiring and promotion process. The tests sometimes figure in custody battles and in sentencing and parole decisions. “Yet despite their prevalence—and the importance of the matters they are called upon to decide—personality tests have received surprisingly little scrutiny,” Paul writes. We can call in the psychologists. But will any of it help?

One of the most popular personality tests in the world is the Myers-Briggs Type Indicator (M.B.T.I.), a psychological-assessment system based on Carl Jung’s notion that people make sense of the world through a series of psychological frames. Some people are extroverts, some are introverts. Some process information through logical thought. Some are directed by their feelings. Some make sense of the world through intuitive leaps. Others collect data through their senses. To these three categories— (I)ntroversion/(E)xtroversion, i(N)tuition/(S)ensing, (T)hinking/(F)eeling—the Myers-Briggs test adds a fourth: (J)udging/(P)erceiving. Judgers “like to live in a planned, orderly way, seeking to regulate and manage their lives,” according to an M.B.T.I. guide, whereas Perceivers “like to live in a flexible, spontaneous way, seeking to experience and understand life, rather than control it.” The M.B.T.I. asks the test-taker to answer a series of “forced-choice” questions, where one choice identifies you as belonging to one of these paired traits. The basic test takes twenty minutes, and at the end you are presented with a precise, multidimensional summary of your personality-your type might be INTJ or ESFP, or some other combination. Three and a half million Americans a year take the Myers-Briggs. Eighty-nine companies out of the Fortune 100 make use of it, for things like hiring or training sessions to help employees “understand” themselves or their colleagues. Annie Murphy Paul says that at the eminent consulting firm McKinsey, ” ‘associates’ often know their colleagues’ four-letter M.B.T.I. types by heart,” the way they might know their own weight or (this being McKinsey) their S.A.T. scores.

Unfortunately, the notion of personality type is not nearly as straightforward as it appears. For example, the Myers-Briggs poses a series of items grouped around the issue of whether you—the test-taker—are someone who likes to plan your day or evening beforehand or someone who prefers to be spontaneous. The idea is obviously to determine whether you belong to the Judger or Perceiver camp, but the basic question here is surprisingly hard to answer. I think I’m someone who likes to be spontaneous. On the other hand, I have embarked on too many spontaneous evenings that ended up with my friends and me standing on the pavement, looking at each other and wondering what to do next. So I guess I’m a spontaneous person who recognizes that life usually goes more smoothly if I plan first, or, rather, I’m a person who prefers to be spontaneous only if there’s someone around me who isn’t. Does that make me spontaneous or not? I’m not sure. I suppose it means that I’m somewhere in the middle.

This is the first problem with the Myers-Briggs. It assumes that we are either one thing or another—Intuitive or Sensing, Introverted or Extroverted. But personality doesn’t fit into neat binary categories: we fall somewhere along a continuum.

Here’s another question: Would you rather work under a boss (or a teacher) who is good-natured but often inconsistent, or sharp-tongued but always logical?

On the Myers-Briggs, this is one of a series of questions intended to establish whether you are a Thinker or a Feeler. But I’m not sure I know how to answer this one, either. I once had a good-natured boss whose inconsistency bothered me, because he exerted a great deal of day-to-day control over my work. Then I had a boss who was quite consistent and very sharp-tongued—but at that point I was in a job where day-to-day dealings with my boss were minimal, so his sharp tongue didn’t matter that much. So what do I want in a boss? As far as I can tell, the only plausible answer is: It depends. The Myers-Briggs assumes that who we are is consistent from one situation to another. But surely what we want in a boss, and how we behave toward our boss, is affected by what kind of job we have.

This is the gist of the now famous critique that the psychologist Walter Mischel has made of personality testing. One of Mischel’s studies involved watching children interact with one another at a summer camp. Aggressiveness was among the traits that he was interested in, so he watched the children in five different situations: how they behaved when approached by a peer, when teased by a peer, when praised by an adult, when punished by an adult, and when warned by an adult. He found that how aggressively a child responded in one of those situations wasn’t a good predictor of how that same child responded in another situation. Just because a boy was aggressive in the face of being teased by another boy didn’t mean that he would be aggressive in the face of being warned by an adult. On the other hand, if a child responded aggressively to being teased by a peer one day, it was a pretty good indicator that he’d respond aggressively to being teased by a peer the next day. We have a personality in the sense that we have a consistent pattern of behavior. But that pattern is complex and that personality is contingent: it represents an interaction between our internal disposition and tendencies and the situations that we find ourselves in.

It’s not surprising, then, that the Myers-Briggs has a large problem with consistency: according to some studies, more than half of those who take the test a second time end up with a different score than when they took it the first time. Since personality is continuous, not dichotomous, clearly some people who are borderline Introverts or Feelers one week slide over to Extroversion or Thinking the next week. And since personality is contingent, not stable, how we answer is affected by which circumstances are foremost in our minds when we take the test. If I happen to remember my first boss, then I come out as a Thinker. If my mind is on my second boss, I come out as a Feeler. When I took the Myers-Briggs, I scored as an INTJ. But, if odds are that I’m going to be something else if I take the test again, what good is it?

We need to make careful use of personality tests, and take them with a large pinch of salt. Or perhaps we should be sending them out at every step of an interview process, and taking a sort of average, an interpretation based on the many different answers given? Or perhaps we shouldn’t be using them at all, and relying instead upon good old fashioned intuition. Or the intuition of a good headhunter…