The word “psychopath” evokes a terrifying heart-thump. Someone murderous, remorseless, emotionless, unstoppable, like Hannibal Lecter or Anton Chigurh. Emerging recent research has, however, been painting a gradually more nuanced portrait of psychopathy. Not all psychopaths are thoroughly unrepentant killers, and not all psychopaths have every single characteristic of psychopathy. Some researchers maintain that psychopathy is best seen as a spectrum disorder.

Psychopaths are more or less callous, unempathetic, glib, grandiose, manipulative, dishonest, promiscuous, and unable to recognize negative emotions in other people. They also tend to be impulsive. (Contrary to many movies, they are not the most meticulous, rational planners of us all.) Punishment is strikingly ineffective in deterring them from undesirable behavior.

A new study in Lancet Psychiatry shows that psychopaths are not, however, actually impervious to any sort of punishment. Rather, psychopaths process rewards and punishments differently from most people. Further, as a result of their processing of rewards and punishments, their decision-making skills are markedly atypical.

“Previous studies had shown a difference in brain structure. Now we can see a difference in brain function,” Sheilagh Hodgins, Professor of Psychiatry at Université de Montréal and one of the study’s authors, told The Daily Beast. The researchers looked at MRIs of psychopaths adjusting their behavior as the consequences for a task switched from positive to negative. “We deliberately made the task so simple that all they had to do is push one button or another,” said Hodgins. “Even on this very, very simple task we see very dramatic differences.”

“When these violent offenders completed neuropsychological tasks, they failed to learn from punishment cues, to change their behavior [sic] in the face of changing contingencies, and made poorer quality decisions despite longer periods of deliberation,” Nigel Blackwood, a study co-author and Clinical Senior Lecturer at King’s College London, stated in a press release.

Previous studies had shown that psychopaths have much more trouble than typical people at switching behaviors when consequences shift from positive to negative. Most of us are able to adjust our behavior pretty quickly when an action that had previously been rewarding suddenly becomes punishing. Psychopaths, however, persist at a given behavior even though it has become punishing.

The MRIs in the Lancet study indicated that this was not because psychopaths don’t feel punishment or aren’t aware of punishment. In fact, the psychopaths actually showed increased activity in certain parts of the brain, specifically the posterior cingulate cortex and anterior insula, when they received unexpected punishment. (In case you’re wondering how this passed an ethics board, the punishment in this case was just a loss of points.) Rather, psychopaths process punishment differently. They also showed anomalous brain activity for unexpected rewards.

Given that psychopaths process rewards and punishments differently, it’s not surprising that they tend to be different, riskier decision-makers. Some people think decision-making, or proper decision-making, is personified (Vulcanified?) by Spock on Star Trek: reasoning in the absence of emotion. Yet practical reasoning and emotion are inextricably linked.

Suppose you get a $2,000 tax refund this year. You might imagine buying a bottle of Louis XIII de Rémy Martin and drinking it all in one hell of a debauched night. Then you might imagine making practical house repairs—a new dishwasher or fixing a damaged roof. People who weigh rewards and punishments differently will make different decisions about which of these options provides, to them, the greater pleasure or poison.

“Decision-making and learning both require emotions. We decide what to do based on expected rewards and punishments, and we learn through emotional reinforcement,” wrote Jesse Prinz, Distinguished Professor of Philosophy at CUNY who specializes in cognitive science, in an email. “If psychopaths have unusual patterns of emotional responsiveness, then they are likely to make decisions and learn somewhat differently than others.”

“Psychopaths show overoptimism. They always think behaviors will be rewarded. They don’t pay attention to punishment. Predicting punishment tells you behavior is inappropriate,” explained Hodgins. Now, after this study, she added, we can see that “what we observe behaviorally has a neural reason.”

Prinz agreed that psychopaths are more likely believe that no matter the option they choose, the rewards will come. “When interviewed, criminal psychopaths sometimes sound indignant about their incarceration. They are surprised to be caught and think the punishment is undeserved. That seems to be what’s going on here. They think they have the right rule, and then suddenly there is a punishment, telling them they are wrong,” he said.

“For non-psychopaths, that’s no big surprise; they are told in advance that the rule will change,” Prinz said. “Psychopaths are more surprised, or perhaps even indignant: ‘How could I be wrong? How dare they change the rule!’ Activations in the posterior cingulate and insula are consistent with these negative emotions.”

However, Prinz applied the brakes, at least a little, on recent psychopathy research. He expressed some reservations about attributing too much importance to either symptom checklists or structural and functional differences in the brains of psychopaths. “Psychopathy may not even be a cohesive disorder. It’s really a diverse hodgepodge of symptoms, and people with very different profiles can end up with the same diagnosis,” he said. “There is always a danger of making it look as if criminality is biologically determined. Neuroimaging studies increase that impression by making it sounds like this is a cohesive category, and implying that it is biologically based. But differences the brain takes by averaging across individuals imply neither of these things.”

The Lancet study determined whether its subjects were psychopaths by using a widely-accepted checklist of symptoms, the PCL-R. Even using the checklist strictly, two people with the same presentations might have different diagnoses. The researchers relied on a previous study that determined that in the North America, you need a score of 30 out of 40 to be a psychopath, whereas in Europe, you only need to get a 25 to be a psychopath. The suggested explanation by the authors is that since North Americans in general are more glib, grandiose, and promiscuous than Europeans (ahem!), the North American psychopath will be more glib, grandiose, and promiscuous than his European psychopathic counterpart.

Taken together (if indeed it all should be taken together), the recent research on psychopathy might suggest that there is some way in which psychopaths are not merely unwilling to make decisions just as others do, but unable to. If a psychopath is unable to make moral decisions, some say any punishment not only ineffective, but also undeserved. One (very interesting) article in The Telegraph on psychopathy cites neuroscientist David Eagleman’s belief that “instead of thinking in terms of blameworthiness, the law should deal with the likelihood that someone will reoffend, and issue sentences accordingly, with rehabilitation for those likely to benefit and long sentences for those likely to be long-term dangers.”

Matthew Talbert, Associate Professor of Philosophy at West Virginia University, who studies moral responsibility, disagrees. He argues that even though there is a way in which psychopaths don’t fully understand—or at least feel the pull of—moral reasons the way typical people do, psychopaths can nonetheless be morally blameworthy. “What’s important is that a psychopath acts for bad reasons, acts with contempt for other people. Typically, if he hurts someone, it’s a choice, not a compulsive act. If a cop had been standing there he wouldn’t have done that,” Talbert told The Daily Beast. “If you believe that all our mental states originate in our brains, any wrongdoing is always explicable in terms of brain process or structure.”

The psychopath himself is highly unlikely to decide he is blameworthy. Psychopaths generally don’t have an interest in being treated or cured. Their lives are not, in their opinion, deprived. They don’t have remorse over their lack of remorse. This is chilling to consider in the case of the violent offenders, as well as the non-violent aggressors such as con artists and swindlers.

But there are also psychopaths who are non-violent and who hold jobs in the community. Do they need to be treated? It’s easy to look at their lives and see them as emotionally shallow, lacking in everything gives most people their shape and purpose: love, relationships, moral development. However, presumably they look at others’ lives and see them as unbearably and wastefully encumbered by guilt, shame, pity, and fear.

“Is psychopathy an impairment? That’s hard to say,” said Prinz. “Psychopathic traits are widespread in the population, and many who score positively on diagnostic criteria lead productive and successful lives. Coming back to overconfidence, those who believe in themselves often have an advantage in the world. Sometimes poor judgment pays off.”

This recalls what William James, the philosopher and psychologist, once said about how you need to believe you are liked before anyone actually likes you, otherwise no one actually will like you:

“Do you like me or not?—for example. Whether you do or not depends, in countless instances, on whether I meet you half-way, am willing to assume that you must like me, and show you trust and expectation. The previous faith on my part in your liking’s existence is in such cases what makes your liking come. But if I stand aloof, and refuse to budge an inch until I have objective evidence, until you shall have done something apt, as the absolutists say, ad extorquendum assensum meum , ten to one your liking never comes.”

Hodgins hopes her group’s study will be the beginning of work that might lead to effective interventions in children who exhibit conduct disorders that might eventually develop into psychopathy. Interventions must occur in childhood since adults are so resistant to treatment. A better understanding of the distinctive flavor of the psychopath’s processing of punishment would certainly give us a better way to handle such children. Parent-training programs can be very effective with other conduct disorders, but are far less effective with those who eventually become psychopaths.

“We want effective interventions for young children with conduct problems who receive rejection from peers, parents, teachers to stop those conduct problems from escalating,” Hodgins said. Violent crimes by psychopaths, she hopes, could one day be averted—before punishment needs to be considered.