Detecting Psychopaths by their Speech Patterns
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.
To examine the emotional content of the murderers’ speech, Hancock and his colleagues looked at a number of factors, including how frequently they described their crimes using the past tense. The use of the past tense can be an indicator of psychological detachment, and the researchers found that the psychopaths used it more than the present tense when compared with the nonpsychopaths. They also found more dysfluencies—the “uhs” and “ums” that interrupt speech—among psychopaths. Nearly universal in speech, dysfluencies indicate that the speaker needs some time to think about what they are saying.
I worry about people being judged by these criteria. Psychopaths make up about 1% of the population, so even a small false-positive rate can be a significant problem.