Less than one percent of people are psychopaths, but they make up about 20 percent of the prison population. Psychopaths are prone to impulsive, destructive behavior, committing murders, and other horrendous crimes. But previous work has found that psychopaths are aware of right and wrong, and give typical responses to moral dilemmas. Elsa Ermer and Kent Kiehl of the University of New Mexico wanted to look at another category of reasoning: thinking about precautions and social contracts.
Most people aren’t very good at logical reasoning—thinking through the implications of any rule in the form “if P, then Q.” But we do much better on logic problems that involve a social contract, like “If you borrow the car, then you have to fill up the tank with gas.” This is the kind of reasoning humans need to function in society.
Ermer and Kiehl gave 67 prisoners a series of problems based on rules of three types: descriptive rules (such as, “If a person is from California, then that person will be patient”), social contracts (”If you borrow my motorcycle, then you have to wash it”), and precautions (”If you work with tuberculosis patients, then you must wear a surgical mask”). Some of the prisoners were psychopaths and some were not.
The prisoners who weren’t psychopaths did about as well on all kinds of reasoning as non-prisoners; they were much better at problems that involved social contracts and precautions. The psychopaths scored similarly on straight logical reasoning, but not nearly as well as the non-psychopaths with regard to social contracts and precautions.
This may help explain some of the peculiar behaviors of psychopaths, Ermer says. “This work suggests that psychopaths don’t understand cheating in the normal way, so they might not realize when they’re cheating other people or when other people would react badly to cheating,” she says.
Their inability to reason about precautions may help explain why psychopaths take risks and do impulsive things that get them in trouble. Psychopaths may have a problem “understanding when they can avoid negative consequences of a risk by taking a precaution,” says Ermer.
For more information about this study, please contact: Elsa Ermer at [email protected].
The APS journal Psychological Science is the highest ranked empirical journal in psychology. For a copy of the article “Psychopaths Are Impaired in Social Exchange and Precautionary Reasoning” and access to other Psychological Science research findings, please contact Keri Chiodo at 202-293-9300 or [email protected].
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