What’s Your Type?

“People have tried to classify personality types since Hippocrates’ time, but previous scientific literature has found that to be nonsense,” says William Revelle, professor of psychology and a self-proclaimed skeptic when it comes to personality types.

So when his Northwestern colleagues Luís Amaral of the McCormick School of Engineering and Martin Gerlach, a postdoctoral fellow in Amaral’s lab, proposed a study to outline new personality types, Revelle, who specializes in personality measurement, theory and research, balked.

From left, William Revelle, Martin Gerlach, Luís Amaral and Beatrice Farb. Photo by Sally Ryan.

The concept of personality types remains controversial in psychology, with hard scientific proof difficult to find. Previous attempts based on small research groups created results that often were not replicable.

However, with access to several large datasets, the researchers combined an alternative computational approach, using an algorithm to sort personality data from four questionnaires completed by more than 1.5 million respondents around the world. The questionnaires, developed by the research community over the decades, have between 44 and 300 questions. People voluntarily take the online quizzes attracted by the opportunity to receive feedback about their own personality.

From those robust datasets, the team — which included summer intern Beatrice Farb, now a sophomore at Harvard University — plotted the five widely accepted basic personality traits: neuroticism, extraversion, openness, agreeableness and conscientiousness.

The researchers found at least four distinct clusters of personality types exist:

• Average — Average people are high in neuroticism and extraversion, while low in openness. “I would expect that the typical person would be in this cluster,” says Gerlach, first author of the study, which appeared in Nature Human Behavior. Females are more likely than males to fall into the Average type.
• Reserved — The Reserved type is emotionally stable, but not open or neurotic. The Reserved are not particularly extraverted but are somewhat agreeable and conscientious.
• Role Models — Role Models score low in neuroticism and high in all the other traits. The likelihood that someone is a Role Model increases dramatically with age. “These are people who are dependable and open to new ideas,” Amaral says. “These are good people to be in charge of things. In fact, life is easier if you have more dealings with Role Models.” More women than men are likely to be Role Models.
• Self-Centered — Self-Centered people score very high in extraversion and below average in openness, agreeableness and conscientiousness. “These are people you don’t want to hang out with,” Revelle says. There is a very dramatic decrease in the number of self-centered types as people age, both with women and men.

Along with serving as a tool that can help mental health service providers assess for personality types with extreme traits, Amaral says the study’s results could be helpful for hiring managers looking to ensure a potential candidate is a good fit or for people who are dating and looking for an appropriate partner.

“Personality types only existed in self-help literature and did not have a place in scientific journals,” says Amaral, the Erastus Otis Haven Professor of Chemical and Biological Engineering. “Now, we think this will change because of this study.”

Want to contribute to the research? Take the personality trait test.