Potential pitfalls lie beyond the joystick joy of violent video games. Even infrequent immersion can cause shooter game players to become more physically aggressive, suggests newly compiled research on more than 17,000 adolescents between nine and 19. The analysis of 24 studies from 2010-17 in the U.S., Canada, Germany, Japan and other countries finds those who play games such as "Grand Theft Auto," "Call of Duty" and "Manhunt" are more likely to hit a non-family member or be disciplined at school for fighting. The effect is "relatively small, but statistically reliable,” says lead research author Jay Hull, a social science dean at Dartmouth College in New Hampshire. "The effect does exist."

Video game violence has been a hot issue for more than a decade. Research on the impact increased after it was learned that Eric Harris and Dylan Klebold, teens who committed a 1999 shooting at Columbine High in Colorado, played “Doom” (a first-person shooting game). In 2012, avid video gamer Adam Lanza killed pupils and teachers at an elementary school in Newtown, Conn. Shooter games don't necessarily lead directly to aggressive behavior, experts say, though extensive playing could be "a really bad sign," according to Hull. “Either these games are having a warping effect on right and wrong or they have a warped sense of right or wrong and that's why they are attracted to these games."

Authors of the study, published last week in a National Academy of Sciences journal, hope their findings will help researchers move "past the question of whether violent video games increase aggressive behavior," the Dartmouth dean adds, "and toward questions regarding why, when and for whom they have such effects." A just-started study at Ohio State University explores how video games affect brain activity.

Research earlier this decade indicates that violent video games can be addictive, in effect. "It affects the same pleasure centers in the brain that make people want to come back," says psychologist Michael Fraser, a medical school professor in New York City. "Kids can become physically and verbally abusive" if play is interrupted, he adds. "Most parents have trouble imagining this—that their 12-year-old boy would push his mother when she tries to unplug the game."

Researcher says: "It is clear that violent video game play is associated with subsequent increases in physical aggression." – Jay Hull, associate dean for social sciences at Dartmouth College in Hanover, N.H.

President says: "I'm hearing more and more people say the level of violence on video games is really shaping young people's thoughts." – Donald Trump, February 2018

Psychologist says: "There definitely seems to be a correlation between violent game use and aggressive behavior. Kids will throw things, they'll hit their parents, they'll start becoming violent at school. When you're actively participating, looking at various weapons, getting reinforcement and recognition for your achievements from the game and from other players . . . it desensitizes you." -- Kimberly Young, psychologist and founder of the Center for Online and Internet Addiction in Bradford, Penn.