A psychopath's inability to learn from past transgressions is rooted in the structure of one's brain, says a new study out of the University of Montreal (U de M).
Research led by U de M Prof. Sheilagh Hodgins and Dr. Nigel Blackwood of King's College London shows that psychopathic violent offenders don't process punishment the way that other people might, said a news release.
And the reason, they found, is due to abnormalities in parts of the brain that are associated with guilt and learning from punishment.
"One in five violent offenders is a psychopath," Hodgins said in a statement. "They have higher rates of recidivism (repeating past behaviours) and don't benefit from rehabilitation programmes."
Psychopathy is known as a mental condition in which the person doesn't show much emotion or empathy, explains an article in Psychology Today.
A psychopath can appear charming and overconfident, though characteristics can also include manipulation, aggression and violence. The International Journal of Women's Health found significantly fewer violent women than men show these traits.
CBC News pointed out that convicted killers Clifford Olson, Paul Bernardo and Ted Bundy all exhibited signs of psychopathy.
The U de M study, which features in the February 2015 issue of The Lancet, saw researchers perform MRI scans on violent offenders from the U.K.'s probation service.
All the subjects were male, and they included 32 violent offenders with antisocial personality disorder, 12 of whom also had psychopathy. They were convicted of crimes such as rape, murder, attempted murder and causing bodily harm.
The study also examined 18 healthy non-offenders.
Participants played an image-matching game during the scans that provided some insight into how they process punishment.
"When these violent offenders completed neuropsychological tasks, they failed to learn from punishment cues, to change their behaviour in the face of changing contingencies, and made poorer quality decisions despite longer periods of deliberation," Blackwood said in a statement.
Scans also found "structural abnormalities in both gray matter and specific white matter fiber tracts among the violent offenders with psychopathy," Hodgins said.
White matter directs information between different regions in the brain, while gray matter is associated with cognition and information, U de M pointed out.
The research found reductions in gray matter in parts of the psychopaths' brains that were associated with empathy, embarrassment and guilt. There were also white matter "abnormalities" in parts that were linked with learning from punishment and rewards, Blackwood said.
Offenders with psychopathy also showed "abnormal responding" to punishment, while violent offenders without psychopathy showed "brain functioning similar to that of the non-offenders," Blackwood said.
"These results suggest the violent offenders with psychopathy are characterized by a distinctive organization of the brain network that is used to learn from punishment and from rewards," he added.
The study concluded that psychopathic offenders might only consider the positive, and not the negative consequences of their actions.
"Punishment signals the necessity to change behaviour," Hodgins said. "Clearly, in certain situations, offenders have difficulty learning from punishment to change their behaviour."
The news release went on to say that behavioural issues and signs of psychopathy can emerge early in a male's life, at a time when "learning-based interventions" can change how the brain works.
Hodgins said these interventions could reduce violent crime by targeting the brain functions that enable psychopathic behaviour.
While the findings suggest psychopaths' brains work differently from other people's, a Queen's University-led study has said they're not mentally ill, QMI Agency reported in 2012.
Author Daniel Krupp said at the time that psychopaths "know full well the consequence of their behaviour."
ALSO ON HUFFPOST: