Talk of homicide is on the rise in films, researchers have found, in a trend they say could pose a health concern for adults and children.

A study found that over the past 50 years there had been a small but significant increase in movie characters talking about murdering or killing.

“The surprising thing is the increase occurs not just for crime genres, which you would expect because they’re violent, but also for non-crime genres,” said Brad Bushman, a professor of communication at Ohio State University, who co-authored the study.

The team suggested the rise may indicate an increase in violent behaviour in movies, and called for a promotion of “mindful consumption and media literacy” to protect vulnerable groups, especially children.

Bushman said: “Adults can make their own choices, but I’m especially concerned about children being exposed to violence in the media.”

The question of whether on-screen violence has an impact on viewers has been a topic of much debate. Some studies back the idea young people can become more aggressive after watching violent media, such as TV and video games, with children exposed to such media being more antisocial and emotionally distressed.

However, an analysis published in 2020 suggested any positive relationship between violent behaviour and violent video games is minuscule, while scientists have also suggested that whether violent movies contribute to real-life aggression depends on if the viewer is already predisposed to violence.