Psychopaths are people who are diagnosed with traits such as a lack of empathy.  Other psychopath traits include superficial charm and pathological lying.  Lack of empathy allows psychopaths to do grievous harm to people.  Criminals are often psychopathic.

The ability to empathize with others is a crucial skill learned in social development.  If a person is abused and does not get needed brain growth stimulation in the first years of life, it can lead to a psychopathic personality structure. 

Scientists in a new study have found that psychopaths do in fact have empathy, and that when asked to consciously exercise an empathy reaction, had brain circuits light up the same way that they naturally did for controls (non-psychopaths).

Empathy is related to a mirror neuron system in which neurons light up when we watch others do a task.  Mirror neurons are thought to play a role in empathy.

Christian Keysers, professr at the University of Groningen, the Netherlands, and senior author of the study commented on the study's findings to BBC News.

"The predominant notion had been that they are callous individuals, unable to feel emotions themselves and therefore unable to feel emotions in others.

"Our work shows it's not that simple. They don't lack empathy but they have a switch to turn it on and off. By default, it seems to be off."

"The notion psychopaths have no empathy at all was a bleak prospect. It would make it very hard for them to have normal moral development.

"Now that we've shown they have empathy - even if only in certain conditions - we can give therapists something to work with."

However, critics of the study, such as Essi Viding, do not think that the comparable brain activity necessarily signifies the same experience:

"It's dangerous to look at brain activation and say that it means they're empathising. They are able to generate a typical neural response, but that doesn't mean they have the same empathetic experience."

"We know they can generate the same response but they do that in an active and effortful way. Under free-viewing conditions they don't seem to. Just because they can emphasise, doesn't mean they will.

"Psychopathic criminals are clearly different. The million-dollar question is whether we can devise therapeutic interventions that would shift them do this more automatically."

Watch Psychopaths Empathy Video Here: