Thirty-two years ago, the cartoonist Alison Bechdel proposed a test to determine whether a movie portrayed girls and women as fully formed characters: Does it have two female characters who talk to each other about something other than a man? A yes meant pass. Now the nonprofit media watchdog group Common Sense Media is applying a new test to its ratings of movies and television shows: Do they combat gender stereotypes?

Founded in 2003, Common Sense Media provides parents with an online rating system that suggests age-appropriate shows for children, highlighting those that underscore admirable character traits like courage, empathy and perseverance. On Tuesday it will introduce a new metric: the portrayal of gender. At its website, a symbol with the phrase “positive gender representations” will appear with a film or TV show, meaning that reviewers judged it to prompt boys and girls to think beyond traditional gender roles.

In trying to develop the new gender reviews, Common Sense examined existing research, finding that the way gender roles are portrayed in movies and television can shape career choices, self-image, tolerance of sexual harassment and dating behavior. It then surveyed parents in April and found that they were very worried about how gender stereotyping in the media could affect their children.

“When my daughter was a toddler, I was absolutely floored to see that there seemed to be far more male characters than female characters in what we’re making for kids in the 21st century,” said the actress Geena Davis, founder of the Geena Davis Institute on Gender in Media and an adviser on the project. Ms. Davis said she hoped the Common Sense ratings would help guide parents, who might, in turn, increase pressure on the entertainment industry to produce more content with positive female role models. (Her daughter is now 15.)