Psychologists have confirmed that playing violent video games is linked to aggressive and callous behaviour.
A review of almost a decade of studies found that exposure to violent video games was a "risk factor" for increased aggression.
The findings have prompted a call for more parental control over violent scenes in video games from the American Psychological Association (APA).
A report from the APA task force on violent media concludes: "The research demonstrates a consistent relation between violent video game use and increases in aggressive behaviour, aggressive cognitions and aggressive affect, and decreases in pro-social behaviour, empathy and sensitivity to aggression."
The report said no single influence led a person to act aggressively or violently. Rather, it was an "accumulation of risk factors" that resulted in such behaviour.
It added: "The research reviewed here demonstrates that violent video game use is one such risk factor."
The APA has urged game creators to increase levels of parental control over the amount of violence video games contain.
In pictures: Comic-Con 2015
In pictures: Comic-Con 2015
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Co-hosts/actors Bella Thorne (L) and Tyler Posey perform onstage during the MTV Fandom Fest San Diego Comic-Con at PETCO Park
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Executive producer/creator Bryan Fuller waves as he arrives at the 'Hannibal' Savor the Hunt panel during Comic-Con International 2015
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Actor Ron Perlman poses for a portrait with Ron Perlman impersonators at Comic-Con International 2015 in San Diego
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Cosplay enthusiasts Jonathan Michael (L) and Connor Breen are dressed like the Mad Hatter from "Alice in Wonderland" during the 2015 Comic-Con International Convention in San Diego
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Guests attend the Dragon Ball Z: Resurrection 'F' San Diego Comic-Con opening night VIP party held at Whiskey Girl in San Diego
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Actor Denis Leary speaks on stage at the FX TV Block featuring 'Sex&Drugs&Rock&Roll,' 'The Strain,' and a sneak peek of 'The Bastard Executioner' panel during Comic-Con International 2015
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Actor Greg Grunberg (left) and writer/producer Tim Kring take a selfie on stage at the 'Heroes Reborn' exclusive extended trailer and panel during Comic-Con International 2015
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Actress Lea Michele walks onstage at the 'American Horror Story' and 'Scream Queens' panel during Comic-Con International 2015
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Actresses Emma Roberts (L) and Lea Michele of the show 'Scream Queens' visit the Scream Queens Mega Drop Ride during Comic-Con International 2015
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(L-R) Actors Liam Hemsworth, Josh Hutcherson, Jennifer Lawrence and director Francis Lawrence of "The Hunger Games: Mockingjay - Part 2" attends the Lionsgate press room during Comic-Con International 2015 at the Hilton Bayfront in San Diego
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Actor Jeffrey Dean Morgan and actress Halle Berry speak onstage during CBS TV Studios' panel for "Extant" during Comic-Con International 2015 at the San Diego Convention Center
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Cosplayers pose for pictures while a picketer holds a pro-religion sign outside of the Convention Center at the 2015 Comic-Con International in San Diego
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Brandon Moriesta (R) interacts with a Cosplay character at the 2015 Comic-Con International in San Diego
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A person who goes by the name of Nomad poses for a photo during the 2015 Comic-Con International Convention in San Diego
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Lee Shannon, dressed as Ming the Merciless, and his girlfriend Kira Krend, of Kaneohe, Hawaii, chat on the escalator at Comic-Con International in San Diego
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Fans wear costumes at the convention center on opening day of the 2015 Comic-Con International in San Diego
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Attendee Jerry Lee holds up his baby Dylan Lee, seven months, between Lego figures of Iron Man and The Hulk at Comic Con International in San Diego
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Dustin Agosta, whose drag name is Discord Adams, is dressed as a drag Joker at Comic Con International in San Diego
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Super heroes on display at the Comic-Con in San Diego
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An attendee dressed in cosplay as the character Ash from the movie "The Evil Dead" outside the 2015 Comic-Con International in San Diego
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Ronnie Nadal poses for a photograph with his two daughters, Kalissa, 9, and Kailah, 6, at Comic-Con 2015 in San Diego
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Sabastian and Julia Sanzberro, dressed as Fred Flinstone and Barney Rubble, walk the trade floor at the 2015 Comic-Con International in San Diego
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Participants dressed in Zombie outfits walk down the Gaslamp Quarter outside of the 2015 Comic-Con International in San Diego,
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A dressed participant at Comic-Con International in San Diego Convention Center
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Dressed participants at Comic-Con International in San Diego Convention Center
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Participants pose for the photograph at the Comic-Con International 2015 in San Diego
At a meeting in Toronto, Canada, earlier this month the association's ruling council also called for a video game rating system that took more notice of violence and for games to be more appropriate to players' age and psychological development.
Dr Mark Appelbaum, who chaired the APA task force, said: "Scientists have investigated the use of violent video games for more than two decades but to date, there is very limited research addressing whether violent video games cause people to commit acts of criminal violence.
"However, the link between violence in video games and increased aggression in players is one of the most studied and best established in the field.
"We know that there are numerous risk factors for aggressive behaviour.
What researchers need to do now is conduct studies that look at the effects of video game play in people at risk for aggression or violence due to a combination of risk factors. For example, how do depression or delinquency interact with violent video game use?"
The task force conducted a comprehensive review of more than 300 violent video game studies published between 2005 and 2013.
"While there is some variation among the individual studies, a strong and consistent general pattern has emerged from many years of research that provides confidence in our general conclusions," said Dr Appelbaum.
"As with most areas of science, the picture presented by this research is more complex than is usually included in news coverage and other information prepared for the general public."
The psychologists identified a number of shortcomings in the literature, including a failure to look for differences in the behaviour of boys and girls who play violent video games.
They also criticised a lack of research on the effects of violent video games on children younger than 10, or their impact over the whole course of a child's development.