Thanks to technology that captures brain activity in real time, experts are no longer limited to examining psychopaths' aberrant behavior. We can investigate what is happening inside them as they think, make decisions and react to the world around them. And what we find is that far from being merely selfish, psychopaths suffer from a serious biological defect. Their brains process information differently from those of other people. It's as if they have a learning disability that impairs emotional development. ...These differences show up early, as early as five years old. The good news is that once the abnormality is detected, it may be treatable with "novel forms of therapy" that "show promise."
To read the entire article, see Inside the Mind of a Psychopath