Violence in Hollywood films has increased dramatically in recent decades, so much so that PG-13 movies today are more violent than R-rated films, a new study (pdf) published in the journal Pediatrics shows.

Researchers reviewed nearly a thousand movies released from 1950 to 2012, based on a selection of 15 of the 30 top-grossing movies from each year. They focused in particular on violent acts, and concluded gun violence has tripled in movies since 1985, the year PG-13 was first introduced into the rating system.

By 2009, PG-13 movies contained as much or more violence than R-rated films released at the same time. Last year, PG-13 films featured more shootings than that year’s R-rated ones.

An example from the movies analyzed in the study was the “Die Hard” film series. The 1990 adventure “Die Hard 2” was rated R, but a later sequel, 2007’s “Live Free or Die Hard,” was rated PG-13 in spite of having more gun violence.

“We think that the PG-13 rating is no longer very helpful,” Dan Romer, a study co-author and the director of the Adolescent Communication Institute of the Annenberg Public Policy Center, told The Washington Post. “If they’re going to allow content like that in PG-13 movies…it sort of goes against the grain of how they define the difference” compared with an R-rated movie.

Overall, film violence has nearly tripled since the 1950s, according to the researchers, who warned of the implications of this trend in popular entertainment.

“Even if youth do not use guns, these findings suggest that they are exposed to increasing gun violence in top-selling films,” the study’s authors wrote. “By including guns in violent scenes, film producers may be strengthening the weapons effect and providing youth with scripts for using guns. These findings are concerning because many scientific studies have shown that violent films can increase aggression.”

-Noel Brinkerhoff, Danny Biederman

To Learn More:

Gun Violence Trends in Movies (by Brad J. Bushman, Patrick E. Jamieson, Ilana Weitz and Daniel Romer; Pediatrics) (pdf)

PG-13 Movies Are Now More Violent Than R-Rated '80s Flicks –Study (by Melissa Dahl, NBC News)

PG-13 Movies Match R Rating for Violence, Study Says (by Brady Dennis, Washington Post)