psychotherapy:

…First the experimental subjects watched people playing a game in which some cheated (bad people) and others played fair (good people). Then they watched the same people suffering from a painful stimulus. The empathy circuits lighted up in both men and women when bad things happened to good people. When bad things happened to bad people, the women in the study were still empathic. But not the men. Not only did they show less empathy toward bad people, but the reward center in the left nucleus accumbens lighted up. All that translates as “Serves him right!”

Love a good pysch tumblr.