In 1976, a Ph.D. candidate at Claremont Graduate University placed a rather unusual personal ad in newspapers throughout Los Angeles soliciting rapists to give an anonymous account of their actions.
He sat by his phone, skeptical that it would ring. “I didn’t think that anyone would want to respond,” said Samuel D. Smithyman, now 72 and a clinical psychologist in South Carolina.
But the phone did ring. Nearly 200 times.
At the other end of the line were a computer programmer who had raped his “sort of girlfriend,” a painter who had raped his acquaintance’s wife, and a school custodian who described 10 to 15 rapes as a means of getting even with “rich bastards” in Beverly Hills.
By the end of the summer, Dr. Smithyman had completed 50 interviews, which became the foundation for his dissertation: “The Undetected Rapist.” What was particularly surprising to him was how normal these men sounded and how diverse their backgrounds were. He concluded that few generalizations could be made.
Over the past few weeks, women across the world have recounted tales of harassment and sexual assault by posting anecdotes to social media with the hashtag #MeToo. Even just focusing on the second category, the biographies of the accused are so varied that they seem to support Dr. Smithyman’s observation.
But more recent research suggests that there are some commonalities. In the decades since his paper, scientists have been gradually filling out a picture of men who commit sexual assaults.
The most pronounced similarities have little to do with the traditional demographic categories, like race, class and marital status. Rather, other kinds of patterns have emerged: these men begin early, studies find. They may associate with others who also commit sexual violence. They usually deny that they have raped women even as they admit to nonconsensual sex.
Clarifying these and other patterns, many researchers say, is the most realistic path toward curtailing behaviors that cause so much pain.
“If you don’t really understand perpetrators, you’re never going to understand sexual violence,” said Sherry Hamby, editor of the journal Psychology of Violence. That may seem obvious, but she said she receives “10 papers on victims” for every one on perpetrators.
This may be partly connected to a tendency to consider sexual assault a women’s issue even though men usually commit the crime. But finding the right subjects also has complicated the research.
Early studies relied heavily on convicted rapists. This skewed the data, said Neil Malamuth, a psychologist at the University of California, Los Angeles, who has been studying sexual aggression for decades.
Men in prison are often “generalists,” he said: “They would steal your television, your watch, your car. And sometimes they steal sex.”
But men who commit sexual assault, and are not imprisoned because they got away with it, are often “specialists.” There is a strong chance that this is their primary criminal transgression.
More recent studies tend to rely on anonymous surveys of college students and other communities, which come with legal language assuring subjects their answers cannot be used against them. The studies avoid using terms such as “rape” and “sexual assault.”
Instead, they ask subjects highly specific questions about their actions and tactics. The focus of most sexual aggression research is acknowledged nonconsensual sexual behavior. In questionnaires and in follow-up interviews, subjects are surprisingly open about ignoring consent.
Men who rape tend to start young, in high school or the first couple of years of college, likely crossing a line with someone they know, the research suggests.
Some of these men commit one or two sexual assaults and then stop. Others — no one can yet say what portion — maintain this behavior or even pick up the pace.
Antonia Abbey, a social psychologist at Wayne State University, has found that young men who expressed remorse were less likely to offend the following year, while those who blamed their victim were more likely to do it again.
One repeat offender put it this way: “I felt I was repaying her for sexually arousing me.”
There is a heated debate among experts about whether there is a point at which sexual assault becomes an entrenched behavior and what percentage of assaults are committed by serial predators.
Most researchers agree that the line between the occasional and frequent offender is not so clear. The recent work of Kevin Swartout, a professor of psychology and public health at Georgia State University, suggests that low-frequency offenders are more common on college campuses than previously thought.
“It’s a matter of degree, more like dosage,” said Mary P. Koss, a professor of public health at the University of Arizona, who is credited with coining the term “date rape.”
Dosage of what? Certain factors — researchers call them “risk factors” while acknowledging that these men are nonetheless responsible for their actions — have an outsize presence among those who commit sexual assaults.
Heavy drinking, perceived pressure to have sex, a belief in “rape myths” — such as the idea that no means yes — are all risk factors among men who have committed sexual assault. A peer group that uses hostile language to describe women is another one.
Yet there also seem to be personal attributes that have a mediating effect on these factors. Men who are highly aroused by rape porn — another risk factor — are less likely to attempt sexual assault if they score highly on measures of empathy, Dr. Malamuth has found.
Narcissism seems to work in the other direction, magnifying odds that men will commit sexual assault and rape.
What about the idea that rape is about power over women? Some experts feel that research into hostile attitudes toward women supports this idea.
In general, however, researchers say motives are varied and difficult to quantify.
Dr. Malamuth has noticed that repeat offenders often tell similar stories of rejection in high school and of looking on as “jocks and the football players got all the attractive women.”
As these once-unpopular, often narcissistic men become more successful, he suspects that “getting back at these women, having power over them, seems to have become a source of arousal.”
Most subjects in these studies freely acknowledge nonconsensual sex — but that does not mean they consider it real rape. Researchers encounter this contradiction again and again.
Asked “if they had penetrated against their consent,” said Dr. Koss, the subject will say yes. Asked if he did “something like rape,” the answer is almost always no.
Studies of incarcerated rapists — even men who admit to keeping sex slaves in conflict zones — find a similar disconnect. It’s not that they deny sexual assault happens; it’s just that the crime is committed by the monster over there.
And this is not a sign that the respondents are psychopaths, said Dr. Hamby, the journal editor. It’s a sign that they are human. “No one thinks they are a bad guy,” she said.
Indeed, experts note one last trait shared by men who have raped: they do not believe they are the problem.