(HealthDay)—Violent movie characters are also likely to drink alcohol, smoke cigarettes and engage in sexual behavior in films rated appropriate for children over 12, according to a new study.
"Parents should be aware that youth who watch PG-13 movies will be exposed to characters whose violence is linked to other more common behaviors, such as alcohol and sex, and that they should consider whether they want their children exposed to that influence," said study lead author Amy Bleakley, a policy research scientist at the University of Pennsylvania's Annenberg Public Policy Center.
It's not clear what this means for children who watch popular movies, however. There's intense debate among experts over whether violence on screen has any direct connection to what people do in real life. Even if there is a link, the new findings don't specify whether the violent characters are glamorized or portrayed as villains.
And the study's definition of violence was broad, encompassing 89 percent of popular G- and PG-rated movies.
The study, which was published in the January issue of the journal Pediatrics, sought to find out if violent characters also engaged in other risky behaviors in films viewed by teens.
Bleakley and her colleagues have published several studies warning that kids who watch more fictional violence on screen become more violent themselves.
Their research has come under attack from critics who argue it's difficult to gauge the impact of movies, TV and video games when so many other things influence children. In September, more than 200 people from academic institutions sent a statement to the American Psychological Association saying it wrongly relied on "inconsistent or weak evidence" in its attempts to connect violence in the media to real-life violence.
For the new study, the researchers analyzed almost 400 top-grossing movies from 1985 to 2010 with an eye on violence and its connection to sexual behavior, tobacco smoking and alcohol use. The movies in the sample weren't chosen based on their appeal to children, so adult-oriented films little seen by kids might have been included.
The researchers found that about 90 percent of the movies included at least one moment of violence involving a main character. Violence was defined as virtually any attempt to physically harm someone else, even in fun.
A main character also engaged in sexual behavior (a category that includes kissing on the lips and seductive dancing), smoked tobacco or drank alcohol in 77 percent of the movies.
These co-occurring behaviors were less common in G-rated movies. Movies rated PG-13 and R had similar rates of risky behaviors, although R-rated films were more likely to show tobacco use and explicit sex.
Bleakley said the Hollywood ratings system, which has been criticized for being more concerned about sex than violence, should consider cracking down on movies that show a "compounded portrayal" of risky activities.
Bleakley said that, although the study doesn't mention this, non-violent characters in the same films engaged in about the same levels of sex, drinking and smoking. "Violent characters are being portrayed virtually the same as any other character in these films," she said.
Some experts disagree that the study provides cause for concern.
Patrick Markey, an associate professor of psychology at Villanova University, said the study relies on speculation, not facts, regarding the potential risk to kids of these on-screen portrayals.
Markey also pointed to the decline in U.S. crime rates over the past 30 years, even as depictions of violence in movies appear to have increased.
Christopher Ferguson, chairman of the psychology department at Stetson University in DeLand, Fla., accused the researchers of being "moralistic."
They are following "an old-school 'monkey see, monkey do' thought on human behavior that is increasingly falling into disrepute," he said.
"There's no evidence that this is a public-health concern, nor do the authors of this study provide any evidence of a public-health concern," Ferguson said.
Explore further: Gun use in PG-13 movies has more than tripled since 1985
Learn more about movie ratings from the Motion Picture Association of America.