There’s an infinite spectrum of personality types that science will never understand

We’re complicated.
We’re complicated.
Image: Reuters/ Luke MacGregor
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Psychologists have a new way of categorizing personalities, and it’s something of a downer. Researchers from Northwestern University analyzed the questionnaires of 1.5 million respondents and came up with four distinct personality types: “average,” “reserved,” “self-centered,” and “role model.”

All but one of them sound to me like an insult, and none are appropriate descriptions for myself or anyone I know.

The team of researchers, led by Luís Amaral, professor at the McCormick School of Engineering at Northwestern University, drew on data from 1.5 million personality questionnaires based on the “big five” personality traits—openness, conscientiousness, neuroticism, agreeableness, and extraversion. These data came from Penn State University psychologist John Johnson’s IPIP-NEO, the myPersonality project, and the BBC Big Personality Test websites, all of which allow users to take personality tests online.

Of the many personality assessments that have been promoted in recent years, the “big five” is considered the most scientific because the results of questionnaires have been shown to predict certain behaviors. Those who score as more conscientiousness on the big five test, for example, tend to work harder according to the research, while those who are neurotic are more likely to suffer from anxiety and depression.

The Northwestern researchers then used algorithms to identify four clusters among the data set. It turns out that the majority of people exhibit one of four combinations of the big five traits, they write:

  • “Average” people are high in neuroticism and extraversion, and low in openness;
  • “self-centered” people are high in extraversion and below average in openness, agreeableness, and conscientiousness;
  • “role models” are low in neuroticism and high in all the other traits; and
  • “reserved” people are not extroverted or neurotic and are above average in agreeableness and conscientiousness.

But, though these categories may be statistically valid, they have no meaningful impact on anyone who cares about personality in daily life. Northwestern psychologist William Revelle, who worked on the study, has acknowledged this. “What’s the actual utility of these?” he told the Washington Post. “I don’t think we’ve really addressed that.”

To some extent, the researchers behind these categories are responsible for their poor choice of framings. Surely they could’ve come up with a better name than “average” to describe certain personality characteristics. But the shortcomings of the latest “personality types” also reflect broader problems that tend to come up when scientists attempt to diagnose and define personality.

Those who buy into personality tests (from the least scientific, such as Myers-Briggs and astrological signs, to the most, like the big five), are liable to claim they’re backed by science. The truth is that science is intrinsically ill-suited to parsing the nuances of personality. Whereas science aims to be definitive and categorical, seeking to prove facts such that the exact same experimental conditions could be recreated over and over to produce the same results, personality is inherently soft, nebulous, and ever-changing.

The American Psychological Association describes personality as “individual differences in characteristic patterns of thinking, feeling and behaving,” a definition broad enough to be interpreted wildly differently by different psychologists. “[P]sychologists borrow the concept of personality traits from ordinary language, which reflects the way ordinary people think about each other’s thoughts, feelings, and behaviors,” Johnson, of Penn State, told me for an article earlier this year year on sexism in personality tests. “It is all rather subjective, although people who grow up together in the same culture will tend to agree in their assessments of who is more or less agreeable because of their shared social standards.”

In other words, psychologists are attempting to use the scientific method to create a clear-cut understanding of personality, and yet base their understanding of what constitutes personality on popular conception. It gets pretty confused.

This confusion within the research community can lead to public misunderstanding on how to interpret scientific studies on personality. Several big-five personality-test websites accessible to the public—including the one created by Johnson —tell women that they’re more disagreeable than men who give exactly the same answers on their personality questionnaires. This is because those who created the websites chose to calculate the scores as a percentile compared to others of the same gender. In other words: women aren’t really more disagreeable than men—they’re only perceived as more disagreeable for the same behavior. This, in turn, raises the question of whether psychologists are studying innate personality or simply perception of personality. (Amaral, the researcher behind the latest personality-type findings, said that though his research relied on the answers that respondents entered into Johnson’s questionnaires, he did not weigh the results by gender.)

Scientists do occasionally recognize the fluctuating nature of personality. When I’ve reported on personality tests in the past, psychologists have noted that they often ask various people to assess one person’s personality, and know to expect quite different results from colleagues versus family or self-assessment. This reflects a truth many people instinctively know: we’re not the same person at home as we are at work. We don’t have one consistent self, but many modes of being as we shift through various contexts.

Nor are we consistent over time. In fact, researchers have found that a person’s “big five” personality can change dramatically over the decades. But most people shouldn’t need a scientific study to recognize that their personalities change as they go through various stages of life. We’re shaped by our surroundings, events, and maturity—of course few people would have the exact same personality at age 45 and surrounded by friends as they would at age 22 and working in a hostile office.

And yet, though psychologists occasionally admit that personality is far from stable, they continue to release studies that attempt to apply a definitive scientific paradigm to personality studies. The latest four personality “types” is just the latest example.

The popular interest in personality tests reflects an understandable desire to know ourselves and those around us. But, as anyone who’s spent time in the company of fellow humans should know, sometimes the most gregarious person is shy, and the most mild-mannered can lose their temper. People are sarcastic and confident and warm to wildly different degrees on different days. Ultimately, there’s an endless spectrum of human personalities and any attempt to diagnose just four will be largely meaningless to those attempting to make sense of the nuances of personality. No one is truly “average.”