Researchers studied the brains of 121 prison inmates who were categorized as weakly, moderately or highly psychopathic. While in an fMRI brain imaging machine, the inmates were shown photos of someone experiencing physical pain, for example, a finger caught in a door.
Asked to imagine it was their finger, the psychopaths’ brains showed typical neural responses. But asked to imagine it was another person’s finger, the psychopathic brains did not register a pain response. They showed a pleasure response.
Neurological basis for lack of empathy in psychopaths, on ScienceDaily.com.
Here’s another similar study:
Psychopaths are not neurally equipped to have concern for others, on ScienceDaily.com.