In a paper billed as the first empirical scholarly study of celebrity personality, two researchers have proved what many people have guessed: Celebrities are more in love with themselves than the average person.

And reality TV stars are the biggest narcissists of all.

The study, to be published in the Journal of Research in Personality, was performed by Dr. Drew Pinsky, a radio show host and psychiatrist, and S. Mark Young of the University of Southern California.

Their study also addresses a puzzling question: Which came first — the celebrity status or the narcissism?

Their conclusion — people who are narcissistic seek out jobs in show business.

"Our research also shows that many celebrities exhibit narcissistic behaviour prior to becoming famous, which could indicate a self-selection bias for the entertainment industry by certain personality types," Young said in a news release.

To determine just how narcissistic celebrities are, Pinsky and Young interviewed 200 celebrities selected at random from among guests on Pinsky's sexual-advice show, Loveline.

They applied a personality research instrument, the Narcissistic Personality Inventory, which has been used by researchers for more than two decades.

The test ranks narcissism by measuring seven components: superiority, exhibitionism, entitlement, vanity, authority, exploitiveness and self-sufficiency.

"Narcissists generally crave attention, are overconfident of their abilities, lack empathy, and can evince erratic behavior," said Pinsky, who is an assistant clinical professor of psychiatry at USC, as well as an author and TV personality.

"However, they are also well-liked, especially on first meeting, are extroverted and perform well in public."

All these traits help them do well in professions that put them in the public eye, he said.

Celebrities participating in the study had statistically significantly higher narcissism scores than a control group of MBA students and the general population.

The biggest narcissists of all were reality TV personalities, who ranked higher than musicians, comedians and actors.

While in the general population men are more likely than women to be self-adoring, the authors found that, among celebrities, females were more narcissistic than their male counterparts.