Violence and sex dominate today's Hollywood movies, but a new study shows parents have grown indifferent to the age at which their children view such disturbing content.

Parents became desensitized to violence and sex in movies as they viewed multiples scenes including such content, according to research conducted by The Annenberg Public Policy Center (APPC). The study called "Parental Desensitization to Violence and Sex in Movies" will be published in the November issue of the Pediatrics journal.

"We know these scenes are somewhat disturbing to parents," said Dan Romer, associate director of the APPC and the study's lead author. "When they first see them, they say you shouldn't let someone younger than 17 see them - which is comparable to an R rating. But they get more and more accepting of that content as they're watching it."

The researchers found parents cared more about the sex scenes than the violence, but not by much. Parents were shown three pairs of clips with either violent or sexual content. After the first movie clip, parents suggested a minimum age of 16.9 years old for violence, and 17.2 years old for sex.

The numbers dropped significantly after viewing the sixth and final movie clip. Parents then suggested a minimum age of 13.9 years old for violence and 14 years for sex - a drop of three or more years.

Parents viewed scenes from six of the eight following films: "8 Mile" (2002, rated R), "Casino Royale" (2006, PG-13), "Collateral" (2004, R), "Taken 2" (2012, PG-13), "Die Hard" (1988, R), "Live Free or Die Hard" (2007, unrated DVD), "The Terminator" (1984, R), and "Terminator Salvation" (2009, PG-13).

A previous study by APPC researchers found violence in PG-13 movies has tripled in popular movies since 1985. Gun violence in PG-13 movies also has surpassed the same violence in R-rated movies.

"Our entire culture may be undergoing desensitization to violent movies with consequences that remain unknown," the study's authors wrote. They suggested on consequence could be the greater acceptance of gun use in society.

Researchers surveyed 1,000 parents who had children between the ages of 6 and 17 in the online study.