Do Personality Trait Tests Predict What You’ll Do?

You have probably completed a personality test sometime—for fun, or as part of a job application process, perhaps. What do your results mean? Do they reveal what you will do in the future?

Probably the most popular use of personality tests for predictive purposes is when companies give them to job candidates to try to select people who will be the best fit at their companies. In fact, it’s a big part of an estimated $9.5 billion industry.

But behavior is incredibly complicated. There are likely thousands of factors that influence each of our actions every day. We don’t know enough about those factors to accurately predict what a single person will do at a certain moment.

In fact, people have a wide range of behaviors they’re capable of doing. For example, people who score as introverts often act in extraverted ways. The same goes for many other traits.

People can also learn and adapt their behavior patterns. They can learn new skills and change their habits, so much so that their personality traits can change.

Personality test scores cannot account for all this complexity and flexibility. They cannot predict whether you will do a certain behavior at some point later in time.

Why do companies spend billions measuring people’s personality traits?

Over time, on average, for a large group of people, traits predict outcomes. For example, a workforce that is generally high on conscientiousness will probably be on time more often, produce things more efficiently, and work harder to finish projects.

So, hiring individuals who score higher on conscientiousness, over time, for large groups, will probably pay off.

That association also implies that individuals who are more conscientious might make better workers. The general finding, however, should not be applied to individuals. What’s true on average may not be true for an individual.*

Introverts can learn skills that make them good leaders. People who love to think deeply can also be very empathetic. In other words, people’s trait scores often do not line up with what they do.

How personality tests can be useful

There are personality tests that predict someone’s willingness or ability to learn. Valid tests that measure certain skills or general intelligence can help predict whether particular people will struggle in certain roles.

But basic personality traits are variable and cannot predict people’s specific reactions to specific situational factors. A big promotion may motivate someone to buckle down and learn new skills, even if they generally haven’t shown that tendency in the past.

Another popular use of personality tests is to give people some new ideas about how to think of themselves. Trait scores might help you identify some things about yourself you weren’t aware of. Or, if you get scores you didn’t expect or don’t agree with, that might prompt some self-examination and contemplation of which verdict—your self-assessment or the trait test—is correct.

A personality test score can give you general ideas about how someone will probably be described by others over time. It can’t tell you what someone will do given certain motivation, training, or social cues.

Are we using personality tests wrongly?

Research in personality science has shown that people are capable of acting, and often do act, at all different levels of traits. Introverts can be extraverted, thinkers can be feelers, perfectionists can be sloppy. The evidence of this variability within individuals seems quite clear. Trait tests cannot account for all the factors that cause that variability.

To conclude that a specific individual will act in certain ways based on trait scores is, I believe, unsupported. It risks losing out on talented people who could have excelled in a job just because they had a wrong trait score, which may or may not have been in line with their actual potential. For an individual interpreting their own trait scores, it may make you think that just because you got a certain score on a test, you’re doomed to act in certain ways.

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Using personality trait tests to help screen candidates for large-volume jobs or across a whole company does make sense. Trait scores can also give you an idea of how a person will generally act over time. It also makes sense to use (valid) personality tests to help people explore themselves and think about how they’re perceived by others, even if they can't predict your or others’ specific behaviors.