We tend to think of psychopaths as dangerous, antisocial, lacking in key human emotions like empathy or remorse. Psychopaths can be obsessed evil tyrants like Hitler or cunning and monstrous like the fictional Hannibal Lecter. Now a new study casts a surprising look at psychopaths, finding that whatever qualities they might have, high intelligence is not one of them. In fact, psychopaths were found to be less intelligent than average people. 

Scientifically, to be classified as having the personality disorder of psychopathy, a person would need to achieve a corresponding score on a test of psychopathic traits like aggression, inflated sense of self-importance and dishonesty. Around 1% of the population would fall into this category.

“Not all psychopaths will break the law or hurt someone, but the odds of them doing so are higher,” explained Brian Boutwell of St. Louis University in Missouri, who led the study.

One reason that spurred his research was the prevalence of the popular culture version of a psychopath, referred by psychologists as the Hannibal Lecter myth”. But that kind of Hollywoodized psychopath did not sit well with observed facts. 

“Psychopaths are impulsive, have run-ins with the law and often get themselves hurt,” said Boutwell. “That led me to think they’re not overly intelligent.”  

Boutwell and his team conducted a meta-analysis of 187 previous studies on the relationship between psychopathy and intelligence, involving over 9,000 participants, some in prison and others in successful careers. The researchers found that psychopaths scored lower on intelligence tests. A surprising result, according to Boutwell. 

“The results of the current meta-analysis produced a small, but significant effect size suggesting that individuals who score higher on measures of psychopathic traits tend to score lower on measures of IQ,” the researchers wrote in the paper.

The researchers hope that their finding will contribute to our understanding psychopathy, currently an untreatable condition. 

“Psychopathy isn’t amenable to psychotherapies,” pointed out Boutwell. “As we better understand psychopathy, we should be better able to develop treatment and rehabilitation for psychopaths."

Further research might also change how psychopaths are treated by the criminal justice system. 

“If they have low intelligence, you could say that they are likely to offend again, or you could say that if they have cognitive difficulties, a lengthier prison sentence is not going to help them,” said Boutwell. “You could make the argument in either direction.”

You can read the study here, currently in pre-print.

Cover photo: Anthony Hopkins playing Hannibal Lecter. © 1991 - MGM