MONDAY, Oct. 20, 2014 (HealthDay News) -- When parents become desensitized to violence and sex in movies, they may also become more lax about their children's exposure to both onscreen, a new study suggests.
Researchers found that when they had 1,000 parents watch a series of movie clips, the group seemed to be less bothered by violent or sexual content with each successive clip. And as that happened, their willingness to let their kids watch the movies grew.
The rapid shift in parents' attitudes was surprising, said lead researcher Daniel Romer, associate director of the University of Pennsylvania's Annenberg Public Policy Center, in Philadelphia.
"We saw a really remarkable desensitization," Romer said.
He suspects that the findings, reported online Oct. 20 in the journal Pediatrics, point to one reason for the increasing levels of violence allowed in PG-13 movies. The people who rate movies, Romer said, may also be desensitized to disturbing content.
That's an interesting theory, said Dr. Jeanne Van Cleave, an assistant in pediatrics at Massachusetts General Hospital for Children in Boston.
The way that raters land on "PG-13" or "R" is something of a mystery, noted Van Cleave, who wrote an editorial published with the study. But she said that if raters do get desensitized like the parents in this study did, then more objective criteria for judging violent and sexual content might be helpful.
Since 1985, when the PG-13 rating debuted, the amount of gun violence in the top-grossing PG-13 movies has more than tripled, Romer said.
He noted that the rating board for the Motion Picture Association of America (MPAA) has acknowledged the shift, and says it's reacting to parents' changing standards.
But Romer said his findings suggest that parents do object to kids seeing violence and sex on screen -- at least initially.
For the study, the researchers had 1,000 parents of 6- to 17-year-olds watch clips from eight popular movies rated R or PG-13. Most of the scenes depicted violence, but two had sexual content; parents watched the clips in random order.
Romer's team found that after the first clip, parents typically said the content was OK for a 17-year-old, but not a younger child. By the time they saw the last clip, however, they were ready to let a 14-year-old watch.
Parents' film viewing in real life also made a difference, Romer said. The greatest desensitization was seen among parents who'd watched at least 11 movies in the past week: After viewing the last clip, they said they would let a 12-year-old watch the film.
And the attitude change was not limited to hypothetical kids. As they viewed more clips, parents' willingness to let their own kids see the movies increased, Romer said.
"I'm not sure parents realize their own movie-viewing habits might influence their decisions about what their kids can watch," Van Cleave said. "But I think that's something they should be aware of."
And what's the harm of allowing a 12-year-old to see violence or sex on screen? Both Van Cleave and Romer said there is research linking exposure to media violence and sex to kids' behavior -- though that doesn't prove cause-and-effect.
And it's not clear whether different types of violence -- a robot being destroyed, versus a person being shot -- could have different effects, according to Romer. "That's an open question," he said. "We don't know whether fantasy violence could be less harmful."
Romer suggested that parents "think more deeply" about the kinds of film content they want their kids to see. Even if a violent scene doesn't make you bat an eye, he said, consider what it might be like to see it for the first time.
Romer said he'd also like the MPAA to consider the possibility that its rating board -- which views hundreds of films per year -- can become desensitized.
The American Academy of Pediatrics has more on children and media.