The "good guys" in superhero films engage in more violent acts than the villains, according to a study which warns that such movies may send a strongly negative message young viewers.
Researchers from Pennsylvania State University in the US analysed 10 superhero-based films released in 2015 and 2016.
They classified major characters as either protagonist ("good guy") or antagonist ("bad guy") and used a standardised tool to compile specific acts and types of violence portrayed in the films.
The researchers tallied an average of 23 acts of violence per hour associated with the films' protagonists, compared with 18 violent acts per hour for the antagonists.
They also found the films showed male characters in nearly five times as many violent acts (34 per hour, on average), than female characters, who were engaged in an average of seven violent acts per hour.
"Children and adolescents see the superheroes as 'good guys,' and may be influenced by their portrayal of risk-taking behaviours and acts of violence," said Robert Olympia, a professor at Pennsylvania State University.
"Pediatric health care providers should educate families about the violence depicted in this genre of film and the potential dangers that may occur when children attempt to emulate these perceived heroes," he said.
The most common act of violence associated with protagonists in the films was fighting (1,021 total acts), followed by the use of a lethal weapon (659), destruction of property (199), murder (168) and bullying/intimidation/torture (144).
For antagonists, the most common violent act was the use of a lethal weapon (604 total acts), fighting (599), bullying/intimidation/torture (237), destruction of property (191), and murder (93) were also portrayed.
"Co-viewing these movies as a family can be an effective antidote to increased violence in superhero-based films," said principal investigator John N Muller, a medical student at Pennsylvania State University.
But the key, he said, is discussing the consequences of violence actively with their children.
"In passively co-viewing violent media, there is an implicit message that parents approve of what their children are seeing, and previous studies show a corresponding increase in aggressive behaviour," Muller said.
"By taking an active role in their children's media consumption by co-viewing and actively mediating, he said, parents help their children develop critical thinking and internally regulated values," he said.