The subjects rate whether the picture is a moral violation on a scale of 1 to 5. Kiehl says most psychopaths do not differ from normal subjects in the way they rate the photos: Both psychopaths and the average person rank the KKK with a burning cross as a moral violation. But there's a key difference: Psychopaths' brains behave differently from that of a nonpsychopathic person. When a normal person sees a morally objectionable photo, his limbic system lights up. This is what Kiehl calls the "emotional circuit," involving the orbital cortex above the eyes and the amygdala deep in the brain. But Kiehl says when psychopaths like Dugan see the KKK picture, their emotional circuit does not engage in the same way.