Also: "Around 1980, Nicholas Groth, director of Forensic Mental Health Associates, established a typology of rapists. Groth arrived at his conclusions by distilling his observations of more than 3,000 sex offenders over the course of 25 years of practice. (Most of his patients, Groth points out, were not sexually deprived at the time they committed rape, thereby exploding that most common of rape myths: that men rape because they're unable to get sex any other way.)

In a general sense, rapists fall into three motivational types: anger, power, and sadism. In anger assaults, the rapist is getting even for "some wrong he feels has been done to him, by life, by his victim at the time. He's in a frame of rage and attacks someone sexually." The anger rape is usually unpremeditated and impulsive, but the impulse drives the rapist into excessive force: the victim is punched, choked, and kicked into submission. Most such offenders derive little pleasure from the act, says Groth, but "they want to degrade their victims, and sex is something bad, dirty, the worst thing you could do to someone. That reflects a lot of our values in society."

An anger rapist could be discouraged by a potential victim who yells at him or puts up a physical struggle, thanks to the unpremeditated nature of the attack. Because the aggressor may not yet have fully decided to pursue this course of action, resistance may well change his mind. Here, even a half-hearted attempt might prove to be all it takes to end the assault. On the other hand, the rage the attacker is feeling might well be further fed by active resistance — this could be taken as yet another instance of one more person trying to deny him something he wants.

Power rape, according to Groth, is a form of compensation, committed usually by men who feel unsure of their competence. Rape gives them a sense of mastery and control. Power rapists usually hunt for victims or seize opportunities that present themselves unbidden. A power rapist is unlikely to be discouraged by resistance because his whole self image is wrapped up in his attempt to prove mastery. A woman who chooses to fight one of these had better do a darned good job of it, because she could well end up fighting for her life.

Groth defines his third type, sadistic rape, as eroticized aggression perpetrated by those whom the very act of forcible sex excites in ways that consensual sex can't. "If the anger components of aggression are eroticized," he explains, "then you see sadistic acts, such as deliberate sexual torture, using an instrument to rape the victim." A sadistic rapist is interested in inflicting pain and lasting harm. Any countering aggression on the part of the victim could well add to the attacker's enjoyment of the experience, prompting him to further acts of depravity in an effort to provoke further resistance."