JOIN USThe analysis has revealed how psychopathic killers utter specific words beyond conscious control while talking about heinous crime.
The words of psychopaths match their personalities, reflecting selfishness, detachment from their crimes and emotional flatness, says Jeff Hancock, professor of computing and information science at Cornell University and colleagues.
Hancock and colleagues analysed stories told by 14 psychopathic murderers held in Canadian prisons and compared them with 38 convicted murderers who were not diagnosed as psychopathic.
Each subject was asked to describe his crime in detail. Their stories were taped, transcribed and subjected to computer analysis, the journal Legal and Criminological Psychology reports.
Psychopaths used more conjunctions like "because", "since" or "so that", implying that the crime "had to be done" to obtain a particular goal, according to a Cornell statement.
They were more likely to use the past tense, suggesting a detachment from their crimes, say the researchers. They tended to be less fluent in their speech, using more "ums" and "uhs".
They used twice as many words relating to physical needs, such as food, sex or money, while non-psychopaths used more words about social needs, including family, religion and spirituality.
Unveiling their predatory nature in their own description, psychopaths often included details of what they had to eat on the day of their crime, according to a Cornell statement.
The exact reason for this is not clear, but the researchers speculate that the psychopath is trying harder to make a positive impression, needing to use more mental effort to frame the story.
This research potentially opens the way for better diagnosis and treatment of such conditions and have implications for law enforcement and social media.