Psychopathic violent offenders don't learn from punishment the way most people do, a new MRI study has revealed.

After scanning the brains of 32 violent offenders, researchers Canada and the UK have discovered that those who are psychopathic have abnormalities in the regions of the brain that are associated with learning from punishment.

The research is extremely important when it comes to working out the best way to stop people from committing crimes. "One in five violent offenders is a psychopath," said Sheilagh Hodgins, one of the lead researchers from the University of Montreal, in a press release. "They have higher rates of recidivism [reoffending] and don't benefit from rehabilitation programmes. Our research reveals why this is," she added.

The study also highlights neurological differences between regular offenders and those who are psychopathic.

"Psychopathic offenders are different from regular criminals in many ways. Regular criminals are hyper-responsive to threat, quick-tempered and aggressive, while psychopaths have a very low response to threats, are cold, and their aggressively is premeditated," said Nigel Blackwood, the co-leader of the study, from King's College London, in the release. "Evidence is now accumulating to show that both types of offenders present abnormal, but distinctive, brain development from a young age."

During the study, the team conducted functional MRI (fMRI) scans on 32 violent offenders in England, who had been arrested for crimes such as rape, grievous bodily harm and murder. Out of the offenders, 12 were classified as psychopaths and 20 were not. The team also compared the brains of the offenders to 18 healthy non-offenders.

Inside the MRI machine, the researchers asked the participants to play a game where they matched cards - sometimes they were rewarded for matching cards with points, but sometimes the game would change and punish them for doing so and they'd lose points

Overall, they found that the violent offenders, regardless of whether they were psychopaths or not, were worse at learning from the punishment cues, and made far poorer decisions, despite taking longer to think their options through than the non-offenders. 

But when they looked at what was happening inside the brains of the offenders during the task, they found that there was something particularly strange going on in the brains of psychopaths.

When the game stopped rewarding card-matching and started punishing it, the neural pathway in psychopaths that's usually involved in learning from punishment had abnormalities "in both grey matter and specific white matter fibre tracts", said Hodgins. Grey matter is involved with processing information and cognition, while white matter coordinates the flow of information between different regions of the brain.

The non-psychopathic violent offenders, on the other hand, showed similar brain function in this region to non-offenders. The results have now been published in Lancet Psychiatry.

"These results suggest the violent offenders with psychopathy are characterised by a distinctive organisation of the brain network that is used to learn from punishment and from rewards," said Blackwood in the release.

Knowing this information can now help researchers work out how to both identify potentially violent psychopaths at a young age, and help develop intervention strategies. 

"The results of our studies are providing insights into the neural mechanisms characterising adult violent offenders that may be used, along with other findings, in designing programs to reduce recidivism. Our results also provide hypotheses about the abnormal development of violent offenders to be tested in studies of children," said Blackwood.

"Since most violent crimes are committed by men who display conduct problems from a young age, learning-based interventions that target the specific brain mechanisms underlying this behaviour pattern and thereby change the behaviour would significantly reduce violent crime," added Hodgins.

And not to freak you out or anything, but recent research also found that men who take a lot of selfies are more likely to have psychopathic traits. Consider yourselves warned.