Psychopaths Respond to Punishment Differently

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Photo: Eric Robert/Corbis

Psychopaths are a big obsession in popular science, and for understandable reasons: What could be more chilling or compelling than a group of people who lack empathy and manipulate others, sometimes committing terrible crimes? But there’s still a huge amount researchers don’t know about the condition, of course. In a new article in The Lancet, a team led by Sarah Gregory of King’s College London, has uncovered interesting new findings about how psychopaths — particularly those who have antisocial personality disorder — process punishment and rewards.

Most people learn how to regulate their behavior via what behavioral scientists call “reinforcement learning” — as we grow up and gain life experience, prosocial behaviors are reinforced and antisocial behaviors are punished by parents and other authority figures. These rewards and punishments help teach us which behaviors are most likely to lead to good things and which will get us into hot water.

As Gregory and her colleagues write, people with antisocial personality disorder and psychopathy appear to have reinforcement-learning systems that don’t operate in the “normal” way. For example, the behavior of men with antisocial personality disorder “seems to be driven more by potential rewards than potential punishments (reward dominance).” And those who have both antisocial personality disorder and who score highly on psychopathy measures (a population that is uniquely difficult to deal with from a behavioral standpoint) “have shown notable impairment in using reinforcement information when choosing between punished and rewarded objects” in studies.

To better understand the mechanisms at work, the researchers had 50 men — 12 of them “violent offenders with antisocial personality disorder and psychopathy, 20 [of them] violent offenders with antisocial personality disorder but not psychopathy,” and 18 healthy non-criminals — get into an fMRI machine and perform a task in which they chose either a line drawing of an animal or furniture. To slightly oversimplify, in the first stage of the experiment they were rewarded with points for choosing animals (for instance) but lost points for choosing furniture, but in the second stage this was reversed. The idea was to test how the brain reacted to this reversal: “Hmmm, I used to be rewarded for doing this, but now I’m being punished for it … 

The results:

Offenders with antisocial personality disorder and psychopathy displayed discrete regions of increased activation in the posterior cingulate cortex and anterior insula in response to punished errors during the task reversal phase, and decreased activation to all correct rewarded responses in the superior temporal cortex. This finding was in contrast to results for offenders without psychopathy and healthy non-offenders.

To translate: The posterior cingulate cortex is a part of the brain associated with tracking changes in reward and punishment; it helps signal “the need to adapt behaviour,” the researchers write. The anterior insula “is involved in motivation and … reward[ing] and track[ing] the salience of outcomes, including recognition of errors.” Damage to it has been correlated with increases in risky behavior. What all of this adds up to is increased evidence that psychopathy does affect people’s ability to adapt their behavior and respond to reward and punishment, particularly when it comes to newly introduced punishments of behavior that had been rewarded in the past (the usual caveats about lab behavior versus real-world behavior do apply, of course).

And while it’s easy to get lost in some of the neuro-jargon here, for people trying to figure out how to control individuals who don’t respond in familiar ways to normal incentives, this stuff matters: “As most violent crimes are committed by men with … early-onset stable pattern[s] of antisocial and aggressive behaviour,” the researchers write, “interventions that target the specific underlying brain mechanisms and effect change in the behaviour have the potential to significantly reduce the rate of violent crime.” Researchers aren’t there quite yet, but this study is a step in that direction.