Have today's action movies out-gunned their PG-13 ratings?

Yes, parents say, and it's even worse when bad guys are doing the shooting, according to a new study about movie violence by the Annenberg Public Policy Center of the University of Pennsylvania that is to be published Monday online in the journal Pediatrics. PG-13 is the Motion Picture Association of America rating that means "parents strongly cautioned – some material may be inappropriate for children under 13."

Parents who were shown clips of several popular PG-13 motion pictures, or movies with PG-13-level violence, said the amount of gun violence that now gets a ready-for-middle-schooler rating is more suitable for older kids, at least age 15 or 16.

Parents were somewhat less offended by movies with a lot of gun violence if the firepower seems to be justified — such as good-guy characters played by actors such as Bruce Willis or Liam Neeson whacking villains to save a family member — than bad guys shooting up people for morally dubious reasons.

"The findings suggest that parents may want a new rating, PG-15, for movies with intense violence," said lead author Daniel Romer, policy center research director. "Violent movies often get a PG-13 rating by omitting the consequences of violence such as blood and suffering, and making the use of violence seem justified. But parents of teenagers say that even scenes of justified violence are upsetting and more appropriate for teens who are at least 15."

The goal of the study was to assess how parents' willingness to let their children view films that portray gun violence might vary by whether they thought the violence was justified.

Since the PG-13 rating was introduced in the mid-1980s, the level of violence, including gun violence, shown in these films has increased greatly. Some parents had seemed to become desensitized to it, earlier research by the policy center has shown.

"Violence is very popular, and they sanitize it so it isn't as disturbing," said Romer, either by not showing the blood and gore that would be permissible in an R-rated film or by making it more palatable by showing a good guy being violent.

In this new survey of more than 600 parents, the researchers found that parents who watched a lot of violent movies were less likely to find the PG-13 rating inadequate. They were a relatively small proportion of the participants.

All the parents were shown clips of films of justified violence – for example, shooting in self-defense or to save someone else from harm such as the president in White House Down – or unjustified violence, such as a sniper shooting at innocent passersby in the film Jack Reacher.

The other justified-violence films in the study were Live Free or Die Hard, Terminator Salvation, and Taken. The remaining  movies with violence deemed unjustified were Skyfall, Sicario, and Training Day.

The parent participants who watched the movies with justified violence had less of an adverse emotional reaction than those who were shown the clips of unjustified violence.

However, the majority of both groups thought the movies merited a higher minimum-viewer age. The parents who saw the clips of justified violence favored a minimum age of 15. The parents' recommended minimum age for the movies with unjustified violence was 16.

The degree of violence youngsters get exposed to in motion pictures can have an effect, research suggests.

"We have a gun epidemic going on," Romer said.

In a recent study, researchers found that children ages 8 to 12 who watched scenes from a PG-13 movie with guns played with a real gun longer and pulled the trigger more often than children who saw a film without guns.

That was a short-term effect, but the impact could be more serious for children who view such violence repeatedly over time and have real-life access to guns, Romer said.

"I would like to see them get rid of the guns" in movies, the researcher said. "Like this latest one, The Avengers. It's all magic. There isn't a lot of guns. It's still violent, but it's not realistic. You can make a pretty good action movie without people shooting each other all the time."