LONDON (Reuters) - Having an unusual personality structure could be the secret to making other people laugh, scientists said on Thursday after research showed that comedians have high levels of psychotic personality traits.

In a study in the British Journal of Psychiatry, researchers analyzed comedians from Australia, Britain and the United States and found they scored significantly higher on four types of psychotic characteristics compared to a control group of people who had non-creative jobs.

The traits included a tendency towards impulsive or anti-social behavior, and a tendency to avoid intimacy.

“The creative elements needed to produce humor are strikingly similar to those characterizing the cognitive style of people with psychosis - both schizophrenia and bipolar disorder,” said Gordon Claridge of the University of Oxford’s department of experimental psychology, who led the study.

Although the traits in question are known as “psychotic”, Claridge said, they can also represent healthy equivalents of features such as moodiness, social introversion and the tendency to lateral thinking.

“Although schizophrenic psychosis itself can be detrimental to humor, in its lesser form it can increase people’s ability to associate odd or unusual things or to think ‘outside the box’,” he said.

“Equally, manic thinking - which is common in people with bipolar disorder - may help people combine ideas to form new, original and humorous connections.”

The researchers recruited 523 comedians - 404 men and 119 women - and asked them to complete an online questionnaire designed to measure psychotic traits in healthy people.

The traits scored were “unusual experiences”, such as belief in telepathy and paranormal events, “cognitive disorganization” such as difficulty in focusing thoughts, “introvertive anhedonia” - reduced ability to feel social and physical pleasure, and “impulsive non-conformity”, or tendency towards impulsive, antisocial behavior.

The same questionnaire was also completed by 364 actors - who are also used to performing in front of an audience - as a control group, and the comedians’ and actors’ results were compared to each other as well as a general group of 831 people who had non-creative jobs.

The researchers found that comedians scored significantly higher on all four types of psychotic personality traits compared to the general group. Most striking were their high scores for impulsive non-conformity and introverted personality traits, the researchers said.

The actors scored higher than the general group on three types - but did not display high levels of introverted personality traits.