Have you taken a personality test online or at your workplace? Unfortunately, researchers often question their accuracy; but one new study may have opened the way to scientific, solid personality assessments.

Personality tests are popular with people and companies alike.

This is because each and every one of us is interested in "cracking the code" of who we truly are, and how we fit into the world.

However, experts question and criticize even the most widely cited of personality tests—such as the Myers-Briggs assessment—claiming that they are inaccurate.

In short, specialists explain that it is hard to come up with inflexible personality types since we will all fall somewhere along a spectrum and tick more than one box.

Now, though, armed with big data and a fresh outlook, researchers from Northwestern University—which is a research institution with campuses and facilities located across the United States—may have finally identified four accurate personality clusters.

The research, published yesterday in the journal Nature Human Behaviour, analyzed the data of over 1.5 million people who filled in questionnaires assessing their personality traits.

"People have tried to classify personality types since Hippocrates' time, but previous scientific literature has found that to be nonsense," explains study coauthor Professor William Revelle.

"Now, these data show there are higher densities of certain personality types."

–Professor William Revelle

The emergence of a new personality 'map'

The researchers analyzed data collected through large cohort endeavors that assessed personality traits. These included John Johnson's IPIP-NEO, the myPersonality project, and the BBC's Big Personality Test.

To accurately assess these data, the team also developed a novel algorithm that allowed it to "plot" a map of personality traits. The five most accepted traits are:

• neuroticism, which refers to how likely a person is to feel moody, anxious, lonely, depressed, or angry
• extraversion, which refers to how sociable and assertive a person is
• openness, which speaks of a person's curiosity and their willingness to have new experiences
• agreeableness, referring to whether a person is perceived as sympathetic, considerate, and friendly
• conscientiousness, or a person's likelihood of being organized and dependable

In the end, four personality clusters emerged on the researchers' new map. They were: average, reserved, self-centered, and role model.

"The data came back, and they kept coming up with the same four clusters of higher density and at higher densities than you'd expect by chance, and you can show by replication that this is statistically unlikely," explains Professor Revelle.

"Personality types only existed in self-help literature and did not have a place in scientific journals," says lead study author Professor Luís Amaral, adding, "Now, we think this will change because of this study."

The four personality clusters

The study authors point out that the four personality clusters that they identified feature different combinations of stand-out personality traits.

"Average" personalities have high extraversion and high neuroticism but are low in openness. "I would expect that the typical person would be in this cluster," notes study coauthor Martin Gerlach.

"Reserved" personalities are not particularly open, or extraverted, and neither are they neurotic. However, they score higher on conscientiousness and agreeableness.

The "role model" cluster, the authors say, had low neuroticism, but all of the other personality traits—extraversion, openness, agreeableness, and conscientiousness—are high. The scientists also add that more women than men are likely to fall into this category.

"These are people who are dependable and open to new ideas. These are good people to be in charge of things. In fact, life is easier if you have more dealings with role models," notes Professor Amaral.

Finally, people in the "self-centered" cluster have very high extraversion but fall below average in openness, agreeableness, and conscientiousness.

Revelle says that, most likely, "these are people you don't want to hang out with." However, he also assures that with age, both women and men tend to "graduate" from self-centeredness toward other personality clusters.

Growing out of neuroticism

As we grow and become more mature, our personalities also develop in different ways. Although adolescents—boys, in particular—tend to fall into the "self-centered" category during their teenage years, they will likely evolve differently in adulthood.

The study authors claim that older people, in general, tend to score higher in conscientiousness and agreeableness and lower in neuroticism, compared with people younger than 20.

"When we look at large groups of people," notes Professor Amaral, "it's clear there are trends, that some people may be changing some of these characteristics over time," suggesting that "this could be a subject of future research."

Professor Amaral and team also explain that this kind of research would have been impossible years ago, without the easy access to big data provided by large projects that rely on the Internet to source participants.

"The thing that is really, really cool is that a study with a dataset this large would not have been possible before the web," says Amaral.

"Previously," he adds, "maybe researchers would recruit undergrads on campus, and maybe get a few hundred people. Now, we have all these online resources available, and now data is being shared."