The researchers interviewed 52 convicted murderers, 14 of them ranked as psychopaths according to the Psychopathy Checklist-Revised, a 20-item assessment, and asked them to describe their crimes in detail. Using computer programs to analyze what the men said, the researchers found that those with psychopathic scores showed a lack of emotion, spoke in terms of cause-and-effect when describing their crimes, and focused their attention on basic needs, such as food, drink and money.
Psychopaths make up about 1 percent of the general population and as much as 25 percent of male offenders in federal correctional settings, according to the researchers. Psychopaths are typically profoundly selfish and lack emotion. "In lay terms, psychopaths seem to have little or no 'conscience,'" write the researchers in a study published online in the journal Legal and Criminological Psychology.
Psychopaths are also known for being cunning and manipulative, and they make for perilous interview subjects, according to Michael Woodworth, one of the authors and a psychologist who studies psychopathy at the University of British Columbia, who joined the discussion by phone.
"It is unbelievable," Woodworth said. "You can spend two or three hours and come out feeling like you are hypnotized."
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