Psychopaths just don't grasp punishment the way normal people do. So say researchers who used MRI scans to analyze the brains of 12 violent psychopathic criminals, 20 violent criminals who are not psychopaths, and 18 healthy controls who are not criminals. It turns out that the psychopath cohort had a much harder time changing their behaviors and choices when playing an image matching game, as well as adapting when the rules of the game changed, reports Time. Abnormalities were seen in brain regions that process things like moral reasoning, guilt, and embarrassment. This may explain why previous research has shown that rehabilitation using negative reinforcement like punishment rarely works on psychopaths.
"Psychopathic offenders are different from regular criminals in many ways," one researcher tells LiveScience. "Regular criminals are hyper-responsive to threat, quick-tempered, and aggressive, while psychopaths have a very low response to threats, are cold, and their aggressive behavior is premeditated." On the plus side, researchers hope that earlier behavioral interventions in young kids could potentially change actual brain structure and function, though not much is yet understood about how one's genes and upbringing contribute to the making of cold-blooded, psychopathic killers. (Psychopaths also seem to have a terrible sense of smell.)