Hippocrates was a good judge of character after all

SINCE Hippocrates first suggested personality types might exist in the fourth century BC, there have been attempts to group people by character.

However, until now, scientists have largely dismissed the idea that humans can be pigeonholed into a handful of defined dispositions. But researchers at Northwestern University in Illinois have sifted through data from more than 1.5million questionnaire respondents and found that four distinct personality types exist: average, reserved, self-centred and role model.

And there is good news for parents of teenagers: as people mature, their personality types shift, with older people growing more conscientious and agreeable than those under 20.

The researchers claim the findings are so important that they challenge existing wisdom in psychology.

“Personality types only existed in self-help literature and did not have a place in scientific journals,” said Luis Amaral, the study’s author, and Erastus Otis Haven, professor of chemical and biological engineering.

“Now, we think this will change because of this study.”

The researchers decided to take advantage of the new phenomena of people taking online quizzes to learn more about their own personality. “A data set this large would not have been possible before the web,” said Dr Amaral.

The study, published in the journal Nature Human Behaviour, used answers to four online questionnaires, including the BBC Big Personality Test. The team plotted five widely accepted traits: neuroticism, extroversion, openness, agreeableness and conscientiousness. And, after developing new algorithms, the four clusters emerged.

“People have tried to classify personality types since Hippocrates’s time, but previous scientific literature has found that to be nonsense. Now, these data show there are higher densities of certain personality types,” said co-author William Revelle, professor of psychology in the Weinberg College of Arts and Sciences.