Many sex offenders suffer from a paraphilia. Paraphilias are disorders characterized by recurrent and intrusive deviant sexual impulses. One paraphilia that shares some characteristics with psychopathy is sexual sadism.

Sadism, like psychopathy, is characterized by callousness, anger, and low empathy. Sadists derive sexual gratification from inflicting physical or emotional pain and suffering on others, and may thus represent the extreme end of the moral sensitivity spectrum” ranging from compassion to callousness. They show increased arousal (measured by penile plethsymograph responses) when perceiving people in pain, in sexual or nonsexual situations.

While this clearly represents profound moral insensitivity, the capacity for “normal” moral judgment has not been directly investigated in this disorder. Sadists may be less likely than other sex offenders to show cognitive distortions that justify moral transgressions, since an understanding of the immorality of their actions (causing harm) is precisely what facilitates sexual gratification. Thus, like psychopaths they appear to understand the wrongness of their actions.

Unlike psychopaths who know right from wrong but just don’t care, I suggest that sadists, who also enjoy inflicting pain/suffering, would show increased activation in the domain specific frontoinsular (FI) cortex, hinting at a higher sense of a certain type of empathy (comparatively) and regulation of moral judgement, depending on amount of emotional processing exercised. Pleasure and reward centers should show similair activation.