In the wake of a mass shooting, the public often scrambles to understand what motivated the perpetrator to commit an act of mass murder.

More recently, religious extremism has been blamed for the Charlie Hebdo attack, the Paris attacks, and, the San Bernardino shooting.

That said, blaming a single ideology or interest for causing a mass shooting is nothing new. Violence in various forms of media – particularly video games and film – are often blamed for “inspiring” the perpetrators of mass shootings.

Though video games are a comparatively young form of media, they have had an unhappy history with anti-violence activists. The Huffington Post reports that mainstream suspicion of violent video games stretches back to 1976, when protesters seized and destroyed arcade cabinets of Death Race following accusations that the arcade game’s displays of violence (which involved running over stick-figure shaped “Gremlins”) could have potentially disastrous effects on the developing psyches of the youth.

This trend continued through the decades. Violent video games such as Doom were thought to have motivated the Columbine High School shooters. Adam Lanza, the individual responsible for the Sandy Hook shooting, was thought to have been partially motivated by violent video games.

Those opposed to violence in video games believe that displays of violence in the virtual world desensitize younger children to violence in the real world. Video games such as Call of Duty and Battlefield are particularly reviled for their perceived role in desensitizing young children to gun violence.

The belief amongst activist is that if a player spends several hours a day shooting people in a virtual setting, it will be all too easy to pull the trigger on people in the real world.

That said, these claims are often supported (and refuted) with studies of dubious scientific merit. One of the more recent credible studies conducted by the American Psychological Association has found that there is a possible correlation between playing video games and increased aggression, but not increased violence.

To put it simply, the study believes that people spend a lot of time playing video games may experience more aggressive thoughts, but are no more likely to actually act upon these thoughts.

This study has not been safe from scrutiny, however. The BBC reports that over 200 academics have signed an open letter criticizing the research methodology used by the study.

Activists who fight against the censorship of violent video games argue that it is not the media, but the person who consumes the media. Gaming website Gamasutra has called video game violence the “old scapegoat,” the one thing news outlets and activists will blame in the absence of, or in spite of, other information about the shooter.

Violence in film and television has also been a subject of public debate and scientific research. Psychology Today reported that the National Rifle Association criticized violence in television and other forms of media as the “primary cause of mass violence.” The Washington post reported in 2013 that actor Jim Carrey, star of the violent film Kick Ass 2 stated that we wished to distance himself from the movie after the Sandy Hook massacre.

Much like video games, some studies have shown that people who spend a lot of time watching violent films or television are more likely to experience aggressive thoughts. However, a particular concern amongst critics of violent movies is the risk of “imitation crime.” The BBC has reported that British woman Kuntal Patel attempted to murder her mother using abrin, a poison similar to the ricin used by character Walter White in Breaking Bad. Additionally, the Guardian has reported that the violent film A Clockwork Orange has allegedly inspired several “copycat murders.”

Though numerous studies have found a link between consumption of violent media and aggressive thoughts, there are a number of caveats. Studies by the American Psychological Association have explicitly stated that consumption of violent media is not the only cause of aggressive thoughts. Additionally, many of the people “inspired” by violent media were mentally ill.

The New York Times reports that Adam Lanza’s psychological problems went “completely untreated” prior to his massacre at Sandy Hook. Though not a gamer, ABC news reports that the Virginia tech shooter, Seung-Hui Cho, had exalted the Columbine shooters as “martyrs,” and believed that he had been “forced” to carry out his massacre of Virginia Tech students.

The truth seems to be somewhere in the middle. Consumption of violent media may lead to an increase in aggressive thoughts, but these thoughts are not necessarily acted upon. While many mass shooters were heavy consumers of violent film, television, and video games, a large majority of them were mentally ill.