There are several factors like personality differences, belief in stereotypes about women and the man's own experience of being an abuse victim, which leads to sexually coercive behaviour, researchers say.
A new study of single young men has revealed that 43 percent report pressuring or forcing a woman to do something sexual against her will at least once. But according to the results, there may be differences between those men who are sexually coercive only as teens and those who continue into adulthood.
"We were trying to understand who are the most extreme members of the group, and who might have done this a few times but felt regret or learned [not to behave this way]," said study researcher Antonia Abbey, a psychologist at Wayne State University in Detroit.
The results should help researchers understand how to target the different groups of men with specific anti-sexual assault education.
Abbey and her colleagues conducted phone interviews in the Detroit area to gather single men between the ages of 18 and 35 who had dated women in the past two years. They chose this group because they wanted to find men on the dating scene who were in the "transitioning to adulthood" phase of life.
The men were offered 50 dollars to complete two guided computer surveys one year apart. They were told the study was on dating and sexual experiences. Four hundred and seventy men signed on, and 90 percent completed the follow-up a year later, for a final sample of 425.
The surveys covered everything from personality profiles to a man's sexual history to his attitudes toward women and his beliefs about alcohol. Men were also asked if they had ever been abuse victims.
The results echoed those in college students: Levels of sexual aggression were high. Forty-three percent of the men who participated had perpetrated some sort of sexually aggressive act since age 14. A quarter of participants reported engaging in sexual coercion in the year between the first survey and the second.
In the year between surveys, 8 percent had forced sexual contact upon someone, 10 percent had verbally coerced a woman into sex when they knew she wasn't interested, 1.4 percent had attempted rape, and 5.4 percent had actually raped someone, usually an impaired or unconscious victim, they reported.
Abbey and her colleagues were interested in more than raw numbers. They compared the men who had started sexual aggression before the first survey and continued throughout (18 percent of all men in the study) with those who had done something aggressive before the survey but had not done anything in the year between surveys (25 percent) and with those who started acting sexually aggressive between the first and second surveys (7.5 percent).
Unsurprisingly, the persistent sexual offenders were the worst on every risk factor for sexual aggression and mental health variable measured.
"They had more experience of being a victim of some kind of abuse as a child, they tended to have personality traits like being low in empathy toward other people, more risk-taking, more delinquent, more sexual partners," Abbey said.
The men also reported more often that they misconstrued women's signals, believing they wanted sex when they didn't. They also believed more strongly in stereotypes about women.
"On a host of different type of factors that you would think could contribute to someone''s willingness to use another person for their purposes, this group scored high," Abbey said.
"So it fit a profile that you often see."
The "desistors," or men who had been sexually aggressive in the past but had since stopped, showed a shift over the year-long study period. At the second survey, they reported a drop in sexual partners and said they had fewer misunderstandings about women''s sexual intentions. For lack of a better term, Abbey said, they seemed to be "growing up."
"Some adolescents and adults act out in various ways," she said.
"But you can kind of grow out of it, you mature. So this is clearly part of you, these people did these things, but on the other hand, it seems to be something where when circumstances change, they change."
The third group, those who started acting sexually aggressive during the study period, seemed to be late bloomers.
Over the year-long study, they began drinking more and more often said that they believed alcohol makes people want sex. They also began to misunderstand women's sexual motives more, the opposite of the "desistor" group.
These men may be falling into crowds and situations where alcohol and sex mix, Abbey insisted.
"With that seems to be this pressure, internal or not, to push sex," she said.
"And certainly there's lots of reasons to think that alcohol can allow people to cross a line," she added.
The study has been recently published in the journal Psychology of Violence.