Researchers behind the first study on the longer-term effects of violent video games on aggression say their findings "strongly" suggest reducing the exposure of youth to the "unnecessary" risk factor.
The results of the study on Longitudinal Effects of Violent Video Games on Aggression in Japan and the United States "confirm earlier experimental and cross-sectional studies that had suggested that playing violent video games is a significant risk factor for later physically aggressive behavior," researchers reported in this month's issue of Pediatrics, the official journal of the American Academy of Pediatrics.
Furthermore, "this violent video game effect on youth generalizes across very different cultures," they added.
For the study, researchers put together three groups of kids from both high- (United States) and low- (Japan) violence cultures.
In the United States, 364 children aged 9 to 12 were asked to list their three favorite games and how often they played them. Meanwhile, in the second group of 181 Japanese students aged 12 to 15, the researchers recorded how often the children played five different violent video game genres (fighting action, shooting, adventure, among others). In the third group of 1,050 Japanese students aged 13 to 18, researchers gauged the violence in the kids' favorite game genres and the time they spent playing them each week.
For the Japanese children, each was asked to rate their own behavior in terms of physical aggression, such as hitting, kicking or getting into fights with other kids. In the United States, the children also rated themselves, but the researchers took into account reports from their peers and teachers as well.
What the researchers found was that in every group, children who were exposed to more video game violence did become more aggressive over time than their peers who had less exposure. This was true even after the researchers took into account how aggressive the children were at the beginning of the study – a strong predictor of future bad behavior.
The findings are "pretty good evidence" that violent video games do indeed cause aggressive behavior, commented Dr. L. Rowell Huesmann, director of the Research Center for Group Dynamics at the University of Michigan's Institute for Social Research in Ann Arbor, according to CNN.
"These findings also further suggest that common social learning processes underlie media violence effects across cultures, and contradict another popular alternative hypothesis: that only highly aggressive children (either by nature, culture, or other socialization factors) will become more aggressive if repeatedly exposed to violent video games," the researchers added in their report.
The results are particularly foreboding as children in America today play around three to four times longer than children two decades ago.
While American children played video games around 4 hours per week in the late 1980s, they now average 13 hours overall, with boys averaging 16 to 18 hours per week. Furthermore, 90 percent of American children between the ages of 8 and 16 play video games at home.
"Children's favorite games often are violent," researchers acknowledged in their report, noting the general public's definition of "violent media" as typically only those television shows, films, and video games that include graphic images of blood and gore.
For their study, researchers included products without blood and gore, establishing violent media as "those that depict characters intentionally harming other characters who presumably wish to avoid being harmed."
"[E]ven children's video games that lack depictions of blood and gore can, and frequently do, include violence," they explained.
In their report, researchers highlighted the importance of their findings, noting that youth violence is a public health issue in the United States because it accounts for so many deaths.
In 2005, 12- to 20-year-olds committed 28 percent of the single-offender violent crimes in the United States and 41 percent of the multiple-offender crimes despite comprising only 13 percent of the population.
"Only accidental injury consistently leads homicide as the cause of death of 1- to 24-year-olds," the researchers added.
They also noted that over 90 percent of all games classified by the industry's ratings group as appropriate for everyone aged 10 and older (E10+) contain violence.
Furthermore, over 75 percent of teenaged gamers under 17 report playing mature-rated video games (the most graphically violent type) despite industry-wide restrictions.
"If playing violent video games has harmful effects on some portion of players, then the vast majority of American youth are highly exposed to an unnecessary risk factor," the researchers stated.
Until the recent research, there had only been one published longitudinal study with children that specifically examined longer-term effects of exposure to violent video games, and no studies had investigated longitudinal effects in low violence cultures.
A similar longitudinal analysis with several additional variables and fewer participants was reported in 2007, using the 364 U.S. participants of the latest study.