When alcohol is involved, people are more inclined to view sexual aggression as morally ambiguous. New research, however, suggests that men who harass women in bars and clubs aren’t misinterpreting women’s signals because they are drunk. Rather, they may be singling out women who appear intoxicated as easy targets.

In a study of sexual aggression in bars researchers have found that the invasiveness and persistence of unwanted come-ons is not correlated with how much the perpetrator has had to drink, but is instead related to how drunk the person on the receiving end seems to be. The paper, aptly titled “Blurred Lines? Sexual Aggression and Barroom Culture,” after the summer hit by Robin Thicke, was published earlier this week in the journal Alcoholism: Clinical & Experimental Research. “Its not a blurred line, its a pretty easy line,” says Kathryn Graham, senior scientist at the Center for Addiction and Mental Health in Toronto and co-author of the paper. “The whole culture that thinks blurred lines is some kind of truth or inevitability, from our data, is a little bit astray.”

The researchers hired and trained pairs of observers to go into bars and record every incident of sexual aggression that they witnessed. In about 90 percent of the 258 cases they documented the person on the receiving end of the sexual aggression was a woman and the aggressor was a man. The other 10 percent of incidents split about evenly between female on male, male on male and female on female aggressions. Because these situations occurred infrequently, the researchers decided to analyze only the interactions between heterosexual couples in which the male was the perpetrator.

Sexually aggressive behaviors ranged in terms of invasiveness from suggestive and harassing remarks to groping and grinding up against strangers. “Invasiveness in particular was related to how intoxicated the woman was, not how intoxicated the man was. That provided further evidence that it probably wasn’t misperception,” Graham says. “There isn’t much question if someone comes by and anonymously grabs a woman’s breast and then disappears into the crowd that he really thought she wanted it. I mean that’s just for his own gratification,” she adds.

In about one third of cases the observers agreed that the aggressor obviously realized his behavior was unwanted and inappropriate but persisted anyway. In the remaining two thirds the observers scored the sexual aggressions as “probably intentional,” meaning that the perpetrator likely knew what he was doing was wrong but could potentially have misperceived his target’s receptiveness.

One limitation of the study is that the observers estimated each person’s intoxication level based on the number of drinks they had and how they were acting, rather than by measuring blood alcohol content. The results are backed up, however, by other research indicating that the influence of alcohol on sexual aggression may be as much psychological as pharmacological.

William H. George, a psychologist at the University of Washington who studies how alcohol influences sexual health and behavior, says that consuming alcohol often turns sexual aggression into a self-fulfilling prophecy if the perpetrator enters the situation with the widely held cultural belief that drinking makes people more sexually uninhibited.

Tina Zawacki, a psychology professor at the University of Texas at San Antonio, agrees with that assessment. “It could be that drinkers use intoxication as an excuse to engage in a number of socially unacceptable behaviors, including sexual harassment and sexual assault.”

George considers the Blurred Lines study “an important contribution” that “brings the evidence from experimental and survey work together in a real environment.”

Graham and her colleagues note that the men in the study appeared to harass women for the amusement of their friends, who in many cases would egg them on. For this reason, the authors endorse the adoption of preventative strategies that encourage bystanders to intervene, rather than trying to unfairly limit women’s behavior. They cite their own “Safer Bars” program adopted by more than 300 bars and clubs in the Toronto area, which trains bar managers and bouncers to step in when they see troubling behavior in their establishment, as an example of an intervention that has shown promise in reducing sexual aggression.

In addition, Zawacki points to the bystander-intervention strategy currently being implemented in the U.S. military, whereby soldiers are encouraged to call out their peers for inappropriate sexual behavior.

Interventions like these attempt to change the norms of what kind of behavior is considered acceptable in situations where people are drinking. “It’s not easy to make cultural change,” Graham admits, pointing out that there has been a similar revolution in regard to the acceptability of smoking and drunk driving.