Psychopaths cannot process clues of context very easily:
The key deficit in psychopaths, he [Newman] says, is an inability to process contextual cues, which makes them oblivious to the implications of their actions, both for themselves and for their potential victims…
Newman has published several studies showing this inability to consider peripheral information. In 2004, Newman reported in the journal Neuropsychology one study in which subjects were presented with mislabeled images, such as a drawing of a pig with the word "dog" superimposed on it. Newman’s researchers timed how long it took them to name what they saw. They found that people in the control group — non-psychopaths — were confused by the mislabeled images, while the psychopaths answered swiftly and barely noticed the discrepancy.
"Although it is somewhat counterintuitive that superior selective attention be associated with psychopathology, it is consistent with the importance of incidental contextual and associative cues for regulating behavior," Newman wrote.
Addendum: Speaking of neurology, here is Will Wilkinson on whether neuroeconomics implies paternalism.