Oct. 2 (UPI) -- In a meta-analysis of studies, researchers found violent video games are associated with small increases of physical aggression despite dueling research and theories.
Dartmouth researchers analyzed 24 studies from around the world conducted between 2010 and 2017 with more than 17,000 participants 9 to 19 years old, finding that young video game players are affected by violence on screen. The findings were published Monday in the journal Proceedings of the National Academy of Sciences.
The researchers suggest that flaws in previous studies -- either because of demographics, time frame of effects or other causes -- may be the reason theories about the effects of video games persist while research largely has not backed them up.
"Although no single research project is definitive, our research aims to provide the most current and compelling responses to key criticisms on this topic," lead author Dr. Jay G. Hull, associate dean of faculty for the social sciences at Dartmouth, said in a press release. "Based on our findings, we feel it is clear that violent video game play is associated with subsequent increases in physical aggression."
The researchers examined whether counterclaims by experts and politicians on the topic were valid. They actually found there was an association, but that the effect is not statistically significant.
To be included, the study must have measured violent video game exposure and physical aggression at least three weeks later, researchers said.
After controlling for several other factors, the meta-analysis reported an effect size of 0.08 -- meaning it accounts for less than 1 percent of the variation in aggressive behavior among U.S. teens and pre-teens. And the researchers base this difference possibly on flaws in study design.
The Dartmouth researchers found the effect appears to be significantly different among various ethnic groups. The largest association was among white participants compared with some among Asians and no effect observed among Hispanics.
The authors said this may reflect a greater emphasis on maintaining empathy toward victims of aggression among Eastern and Hispanic cultures, as compared with a "rugged individualism" emphasized in Western cultures.
"The most notable critic of the violent video game aggression literature conducted studies in primarily Hispanic populations and found no evidence of this association," said co-author James D. Sargent, director of the C. Everett Koop Institute at Dartmouth. "If all of my studies showed null findings, I, too, would be skeptical."
The overall findings support an American Psychological Association task force's 2015 conclusion that video game play is linked to increased aggression in players. However, no sufficient evidence exists about whether the link extends to criminal violence or delinquency.
Previous research shows no link
But other researchers' studies haven't found a correlation between playing the games and exhibiting violent behavior in real life.
In research in 2004 by the U.S. Secret Service, only one-eighth of school shooters regularly played violent video games. Also, researchers at the University of York in Britain found no evidence that video games make players more violent in a study with more than 3,000 participants.
In the wake of a high school shooting that killed 17 last February in Parkland, Fla., President Donald Trump met at the White House with video game industry representatives to address "violent video-game exposure and the correlation to aggression and desensitization in children."
"The video games, the movies, the Internet stuff, it's so violent," the president said, mentioning his 11-year-old son, Barron Trump. "I look at some of the things he's watching and I say, how is that possible?"
Flaws of previous analyses
In the new meta-analysis, the Dartmouth researchers pointed to flawed criticism of previous analyses among the reason many reject the idea that violent video games can have an effect on young game players.
Where previous analyses have been criticized for including "non-serious" measures of aggression, the Dartmouth team focused on studies that included reports of overt physical aggression over time. Their findings supported the hypothesis that playing violent games is associated with subsequent increases in physical aggression.
Previous studies have also been criticized for not considering other potential variables leading to aggressive or violent behavior. When factoring these variables in, the Dartmouth researchers say they had only a minor effect on the observed relation between violent video game play and aggression -- further emphasizing the disputed link.
The Dartmouth research team also found that, despite claims of bias in studies that find a correlation between gaming and violence, no evidence of bias was found after a variety of tests were conducted on the previous publications.
"We hope these findings will assist the field in moving past the question of whether violent video games increase aggressive behavior, and toward questions regarding why, when and for whom they have such effects," the researchers wrote in the study.
Hull said he plans to examine real-world significance of violent game play in future research.