Anton Chigurh
Anton Chigurh in No Country for Old Men is the best depiction of a psychopath in films, researchers found last year. 2007 Paramount Vantage - Miramax

People with psychopathy feel regret after something bad happens to them – but they are unable to use this to guide their future decision making, scientists have suggested. It is widely thought the antisocial behaviour and apparent lack of regret associated with psychopathy comes from an inability to feel empathy, but the latest findings suggest decision making processes could also play a role.

Understanding why people with psychopathy act the way they do is important to prevent the anti-social behaviour that can accompany it. Writing in the journal PNAS, scientists from Yale and Harvard note that psychopathic individuals who show disregard for moral and legal norms are more likely to carry out crimes and re-offend at a higher rate.

"Psychopathy is defined by a combination of superficial charm, blunted empathy and punishment sensitivity, shallow emotional experiences, persistent antisocial behaviour, and marked sensation seeking and impulsivity," they wrote.

"The behavioural manifestations of such deficits in psychopathic individuals are diverse, encompassing pathological lying, interpersonal manipulation, and the absence of guilt, remorse, and regret following decisions that cause harm to themselves or others. Such symptoms are considered by many to be defining features of the disorder. However, the cognitive and neurobiological mechanisms that produce them remain the subject of debate."

Scientists carried out a test on 62 men aged between 18 and 55. They rated each scale of psychopathy and then had them carry out a gambling task. After each test, they were asked to rate how they felt about the outcome – ranging from very disappointed, neither pleased nor disappointed and very pleased.

The goal of the gambling task was to get as many points as possible, with participants offered the choice between two wheels with differing values. Each wheel offered four outcomes (−210, −70, +70, and +210), with probabilities marked on them. They then had to pick a wheel and a ball was thrown to determine the score and their emotional response was recorded.

The task was supposed to test their counterfactual decision-making – their ability to understand possible alternatives to things that have already happened (thinking 'what if' or 'if only').

Researchers found all participants showed a similar level of retrospective regret (after the event). However, people who had higher levels of psychopathy continued to make riskier choices and were less influenced by prospective regret (before the event) when making decisions.

"In sum, the present study identifies a specific deficit in the ability of individuals with psychopathic traits to integrate prospective counterfactual signals into decision making," the team wrote. "By contrast, their ability to perform retrospective counterfactual comparisons appears to be preserved, as evidenced by their self-reported negative affect when faced with regret-inducing counterfactual information.

"These findings raise the possibility that maladaptive decision making in psychopathic individuals is not a consequence of their inability to generate or experience negative emotions. Rather, antisocial behaviour in psychopathy may be driven by a deficit in the generation of forward models that integrate information about rules, costs, and goals with stimulus value representations to promote adaptive behaviour."