Whether it’s the ancient Greeks trying to divine one’s character from the stars, or modern surveys that purport to tell you what type of person you are, experts have struggled to come up with a trustworthy personality test. Now, the largest study of its kind suggests people reliably shake out into four major personality types—including a brand new one that, surprisingly, most people will possess at some point during their life.
“I think this is an extremely impressive study,” says Richard Robins, a social psychologist at the University of California, Davis, who has been researching human personality for decades. Until now, “The field was plagued by relatively small samples and the use of different methods and data sets,” he says. “We needed somebody to come along and clean things up.”
After decades of tweaking and standardizing their methods, most Western psychologists generally agree that humans exhibit five major personality traits: neuroticism, extraversion, openness, agreeableness, and conscientiousness. Depending on the combination, these traits spawn three broad personality types: resilient, overcontrolled, and undercontrolled. Resilient people tend to be able to handle their emotions, get along with others, and bounce back from life’s adversities; “overcontrolled” individuals are aloof or shy, keeping their feelings hidden; and “undercontrolled” people can be emotionally impulsive, sometimes even acting out aggressively.
But others argue the studies behind these categories don’t use enough volunteers and are often hard to replicate.
So in the new work, physicist Luís Nunes Amaral at Northwestern University in Evanston, Illinois, and colleagues turned to four very large data sets of internet-based personality survey responses. The English-language online forms ask participants to rate how much they agree or disagree with statements like “I keep others at a distance” or “I am afraid to draw attention to myself.” Some people find the surveys through idle curiosity; others were directed there by the researchers who designed them. The tests are frequently used in psychological research, Amaral notes, and they map the responses to scores on each of the big five personality traits.
In total, the team had data from more than 1.5 million people. Not all the surveys recorded demographic info, but the fact that respondents had access to the internet and spoke English suggests the majority probably are comparatively well-off and hail from Western society, Amaral says.
The researchers used a series of complex algorithms to sort through the responses and look for clusters of individuals who answered the survey questions in largely the same ways.
Ultimately, four—rather than three—reliable personality clusters emerged. Those in the “self-centered” cluster scored highly in extraversion but lower than average in the other four traits. The “reserved” cluster had slightly above average scores in agreeableness and conscientiousness, and relatively lower scores in the others. The “role model” cluster scored highly in extraversion, openness, agreeableness, and conscientiousness, and lowly in neuroticism—in other words, steady, stable individuals.
Those three clusters roughly match the previously discovered undercontrolled, overcontrolled, and resilient personality types, respectively, Robins notes. But a totally new fourth cluster also came to light: “average.”
It’s named that because, during our lives, most of us will fall into this personality type, the researchers say. And despite its ho-hum description, “average” people actually have slightly above average scores for neuroticism, extraversion, agreeableness, and conscientiousness. They are similar to role models, except they are higher in neuroticism and lower in openness. “It turns out that being middle-of-the-road is actually kind of positive for most things,” Amaral says.
Looking at age trends, the researchers learned that younger people are more likely to have the self-centered personality type, and older people tend toward the role model type. Women appear to make that transition more quickly than men do, the team reports today in Nature Human Behaviour, with women over age 60 representing the highest fraction of role models among respondents. “Role models really make society work better,” Amaral says.
But don’t fret if you’re pegged with a less desirable personality type, he says. “It’s not a life sentence, and most people who start out as self-centered grow out of it pretty quickly.”
Still, Amaral cautions against making any kind of practical decisions, like career moves or dating compatibility, based on the study. It’s also unclear whether the personality types are universal. In the future, he wants to expand his analysis to include surveys given in different languages and in different settings to see whether these types are cross-cultural.