People '˜fall into four personality types'

Human beings can be sorted into four personality types depending on how strongly certain traits '“ from neuroticism to openness '“ feature in their character, according to a new study.

The findings by a team at Northwestern University in Illinois are claimed to be the first to categorise personalities on a scientific basis. Picture: Lewis Clarke/Geograph

Scientists have long disputed whether people can be accurately labelled as having a particular personality but the authors of new research claim mass data gathered via the internet has allowed them to prove the existence of four distinct groups of individuals.

Based on responses to questionnaires answered by 1.5 million people, including responses to a survey run by the BBC, the researchers said they were able to categorise humans as having a “reserved”, “self-centred”, “role model” or “average” type of personality.

The findings by a team at Northwestern University in Illinois are claimed to be the first to categorise personalities on a scientific basis rather than using hypothetical labels such as those found in “self-help literature”.

Professor William Revelle, a co-author of the study, said: “People have tried to classify personality types since Hippocrates’ time, but previous scientific literature has found that to be nonsense.

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

The researchers used the results of four large-scale online questionnaires, each featuring up to 400 questions, to plot the prevalence of five character traits. The strength of these traits – neuroticism, openness, agreeableness, conscientiousness and how extrovert a person is – allowed the scientists to use algorithms to spot four distinct “clusters” or groupings of personality.

The most admirable personality group identified by the scientists was the “role model” - described as being low on neuroticism and high in all other traits.

Luis Amaral, professor of chemical and biological engineering at Northwestern and leader of the study, said that older people and women were the most likely fall into the category. He said: “These are people who are dependable and open to new ideas. These are good people to be in charge of things.”

The most common type – “average” – were found to be high in neuroticism but also in extrovert behaviour; while “reserved” people were “emotionally stable” without being open or neurotic.

The least attractive group were the “self-centred” – described as being highly extrovert but below average in other traits. With a degree of predictability, the researchers said they had found teenage boys heavily represented in this group.

A key finding of the study was that these personality traits do not appear to be set in stone and people change character over time. Older people tend to be less neurotic and more conscientious and agreeable than those under 20, according to the research.

Prof Amaral said: “When we look at large groups of people, it’s clear there are trends, that some people may be changing some of these characteristics over time.”

The researchers said their results could be of potential use to mental health workers trying to diagnose extreme personality traits and also hiring managers looking for a particular character in applicants for a post.