Good research S.
I agree that the things mentioned in the study make sense, especially when it comes to autonomic functions such as dawing back from pain. We don't have to burn ourselves to prove that it will hurt if we see someone else experience it (unless, of course, you are one of the Jackass guys!). I guess I don't quite see the connection from empathy to morality...even if I never saw or experienced murder, I would not be tempted to commit murder.
Psychopaths are unique...obviously, abnormal brain changes allow them to do what they do. And yes, they hide to avoid repercussions...because they know what they do is not accepted by society as a whole. They may not feel guilt or empathy, but they still know it is wrong based on societal values.
Great discussion!