Do some kinds of video games cause violence? Scientific studies do not suggest a link.But the idea that there is a link between violent video games and violent acts reappeared following the mass shooting in El Paso, Texas, last weekend.An online statement thought to be written by the El Paso gunman mentioned the combat game "Call of Duty."On Monday, President Donald Trump said that "gruesome and grisly video games" contribute to a "glorification of violence."American politicians have long made similar statements."Politicians on both sides go after video games...it is this weird unifying force,"said Patrick Markey, a psychology professor at Villanova University who studies video games.Benjamin Burroughs is a professor of media at the University of Las Vegas."...There is no linkage to gun violence," he said about video games.Burroughs said that some studies show a short-term increase in aggressive thoughts and feelings after playing video games,but nothing that rises to the level of violence."Plenty of gamers...get upset when they lose or feel the game was ‘cheating,' but it doesn't lead to violent outputs," Burroughs said.In 2006, a small study by researchers at Indiana University found that teenagers who played violent video gamesshowed higher levels of emotional arousal – strong emotions like anger or fear.The teenagers also showed less activity in the parts of the brain associated with the ability to plan, control and direct thoughts and behavior.Patrick Markey, the psychology professor, found in his research that men who commit severe acts of violenceactually play violent video games less than the average male.Another study by Markey and other researchers showed that violence tends to go down when a new violent movie or video game comes out.One possible explanation: people are at home playing the game or in theaters watching the movie.Markey believes that video games might excite people, but they do not change who people are."It is like going to see a sad movie," Markey said of playing video games."It might make you cry but it doesn't make you clinically depressed," he said.