On December 14, 2012, 20-year-old Adam Lanza shot and killed 26 people at Sandy Hook Elementary School, including 20 children, before committing suicide.

In their struggle to understand why this tragedy occurred, public figures drew attention to the fact that Lanza was an avid video game player. He played video games that glorify violence like “Grand Theft Auto” and “Call of Duty.” From there, pundits asked the larger question: are video games making kids violent?

A Daily Dose of Violence

More than 90 percent of American kids play video games. The number might be as high as 99 percent of boys and 94 percent of girls. It’s not just kids playing, either — according to the Entertainment Software Association (ESA), 58 percent of all Americans play video games, and nearly half of Americans over 50 play. The organization also found that 45 percent of gamers are women and that the average gamer is 30 years old.

Gameplay is also on the rise — one study shows that average daily video game play among kids ages 8 to 18 rose from 26 minutes per day in 1999 to almost 110 minutes (nearly two hours) per day by 2009. The numbers are even higher for boys, 25 percent of whom play video games for four or more hours per day.

91 percent of kids play video games90 percent of popular games portray violence

And playing video games means playing violent games, it seems. More than 90 percent of games rated E10+, Teen, or Mature have some kind of violent imagery, and “that violence is often portrayed as justified, fun, and without negative consequences,” write researchers Douglas Gentile and Craig Anderson, of Iowa State University.

Even E-rated video games, which the Entertainment Software Rating Board (ESRB) says are suitable for all ages and “may contain minimal … violence,” are suspect. One study found that 35 of 55 E-rated games involved deliberate violence, and 33 reward violence or require violence to advance in the game. That study also found that of 32 games that did not have a content description for violence, 14 games contained violence anyway.

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Video Games, Aggression, and Risky Behavior

In the short term, it’s fairly easy to measure the effects of violent video games: set a group of people down, have them play a violent or nonviolent game, then measure the results. A slew of studies have found that in comparison to nonviolent or prosocial video games, violent games promote feelings of hostility and aggressiondesensitize the player to violence, and skew the player’s perception of what constitutes violence.

Do these effects last long-term? To find out, scientists ran longitudinal studies, tracking how children’s video game use changed over time, and with it, measures of aggression. One study tracked more than 3,000 kids for three years and found that playing violent video games increased their impulsiveness. In a vicious cycle, higher base levels of impulsiveness increased their video game use. A second study on the same set of kids also found increases in aggression.

“We know that violence in general ... is associated with mental health problems. We also know, given brain research, that our brain sometimes doesn’t distinguish between what’s real and what we see on TV.” — Susan Tortolero, University of Texas

Another study published this year tracked 5,000 teenagers for four years and found that playing Mature-rated video games predicted later risky behaviors.

“Play of these Mature-rated, risk glorifying games was associated with subsequent increases in sensation seeking, rebelliousness, hanging out with kids who smoke cigarettes and drink alcohol, thinking kids who drink and smoke are cool, and thinking that one would like to try drinking and smoking,” explained Jay Hull, department chair of psychological and brain sciences at Dartmouth College, in an interview with Healthline. “In turn, changes in these variables were associated with subsequent changes in drinking, smoking, fighting, risky sex, and delinquent behavior.”

The effects were much stronger among kids who played violent games with an antisocial protagonist (i.e. “Grand Theft Auto III,” “Manhunt”) than with a heroic protagonist (i.e. “Spider-Man 2”).

Another study by Susan Tortolero, director of the Center for Health Promotion and Prevention Research at the University of Texas, examined the link between violent video game play and depression.

“We know that violence in general — whether it’s being a victim of violence, or just witnessing violence — is associated with mental health problems,” she told Healthline. “We also know, given brain research, that our brain sometimes doesn’t distinguish between what’s real and what we see on TV.”

She found that playing more than two hours a day of violent video games is linked much more strongly with depression than playing less than two hours a day of nonviolent video games.

However, other studies didn't find any such negative effect, or they found that the effect goes in the opposite direction.  One study followed 324 elementary school children for a year. It found that children who were aggressive at the beginning of the study were more likely to have grown to prefer bloody or brutal video games by the end of the study, suggesting that innate aggression can lead to violent video game use. Violent video game playing, on the other hand, didn't predict later aggression. Another study followed 302 kids for one year and found no connection between video game violence and aggression, violent crime, or bullying behaviors.

Criminologist Ray Surette of the University of Central Florida researched the video-game-playing habits of 249 inmates in a county jail. He found that video game playing did not predict who had committed copycat crimes. However, he did find that the degree of immersion in media (regardless of type) did predict copycat crime.

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The Positive Effects of Video Games

Most video games don’t match the degree of violence in titles like “Grand Theft Auto.” In fact, many promote prosocial behaviors, such as cooperation, teamwork, sharing, and empathy. One analysis found that playing first-person shooter games increases visual-spatial skills and that playing strategy or role-playing games boosts creative problem-solving skills. It also showed that games can improve mood, promote relaxation, and decrease stress and anxiety.

Another study found that role-playing games allow people to “try on” different personalities, offering a range of freedom of identity never seen before in the pre-gaming era. Meanwhile, activity-based games like “Dance Dance Revolution” help promote physical activity and exercise. Education- and health-oriented video games also have their place. For example, one game called “Re-Mission” successfully teaches child cancer patients to adhere to their treatment regimen.

Do any of these skills translate into real-world success? Experts have mixed views.

“The heart of the issue is that commercial pilots, those we train now to become [drone pilots], have a set of skills that are location- and environment-specific,” said Richard Van Eck, a professor of instructional design and technology at the University of North Dakota, in an interview with Healthline. “They look out the windows, hear the plane, feel present in the plane as it moves. Piloting a [drone] is nothing like that; the primary interface is 2D screens. So it turns out that video games may provide better training for some of those skills than actual flight training does.”

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However, video games also teach skills that are undesirable in drone pilots, such as the tendency to shoot at anything that moves. “If gaming can instill the habit patterns needed to fly a [drone], then it seems to me that the efforts are beneficial,” said John Bridewell, a professor of aviation at the University of North Dakota, in an interview with Healthline. “If there is a negative transfer of learning, then it is not so good. Habit patterns are very difficult to break. Even when one is able to break a habit pattern, in an emergency, people typically resort to the actions first learned.”

Major Uriah Orland of the United States Air Force concludes, “What is harder to capture in current simulators are the roles of pilots, which is much more than just hand-eye coordination. They are a mission commander for a complicated combat weapon system, often requiring the coordination of other platforms and crews. The pilots are coordinating with an operational chain to determine the appropriate employment of munitions and are following the appropriate rules of engagement while making the final decisions on releasing munitions. This leadership, coordination, and responsibility is something that video games cannot begin to replicate.”

So What’s the Verdict?

To examine the wealth of data on the psychological effects of video games, Anderson, director of the Center for the Study of Violence at Iowa State, and Christopher Ferguson, of Stetson University, have performed meta-analyses. These studies combine data from a large number of papers to tease out general trends.

According to Anderson’s findings, video games boost the body’s fight-or-flight response, increase aggressive thoughts and feelings, and decrease prosocial and empathetic behavior. Ferguson, on the other hand, found that the evidence was ambiguous, and attributed the wealth of data on aggression to publication bias, in which studies that find an effect of some kind are more likely to be published than studies that find no effect.

There’s a chicken-and-egg question here — do violent video games cause aggression, or do kids who are predisposed to aggression later in life also play more violent video games? Anderson espouses the General Aggression Model, which states that the short-term aggression triggered by video game play generalizes into other areas of life. Ferguson’s theory is the opposite: he champions the Catalyst Model, in which video game use activates pre-existing tendencies toward aggression caused by biology, personality, and peer and family environment.

Video game sales 2000-2013Homicides and Aggressive Assaults

Hull worries about this latter model, which he dubs the “bad seed” hypothesis. “This proposes that some kids are just born bad and this ‘badness’ first shows up as attraction to playing games of the type we examined,” he said. “The bad seed hypothesis has to say that not only does the seed grow toward these bad behaviors, but it does so in exactly the way we document. It has to dismiss any lab studies that do find a causal effect of playing these games on behavior (e.g., evidence of increased aggression, stealing, cheating in the lab — all of which have been documented), as trivial and temporary.” 

There are, however, other reasons why video games might be linked to aggression. Andrew Przybylski, a research fellow at the Oxford Internet Institute, found that it wasn’t violence in video games that predicted aggression but rather how frustrating or challenging a game was to complete. Other research of his also found that “games featuring violent stories and content tend to be more appealing for those who are higher in trait-level aggression,” he told Healthline.

Przybylski also noted that while virtually all children play video games, most don’t get into trouble. A recent study of his found that kids who played video games for less than an hour a day had higher life satisfaction and better social functioning than kids who didn’t play video games at all. Kids who played one to three hours of games a day didn’t see any changes, and kids who played three or more hours a day turned out worse. This suggests that video games are indeed normal for kids, and that the factors that cause kids not to play games may be linked to other problems. The size of the effect, however, was very small, he said.

Why Is It So Hard to Get a Clear Answer?

Although plenty of studies have linked violent video game play to aggression, the real question — whether violent video games cause real-world violence — is still up in the air.

For starters, the effect size of video games on children’s thoughts and behaviors is very, very small — less than half of 1 percent, Ferguson told Healthline. Anderson says this doesn’t mean that the effect is insignificant. Instead, video game violence exposure is one of a great many risk factors for real-world violence.

“No one risk factor can be said to be ‘the’ cause,” Anderson told Healthline. “Risk factors accumulate, as do protective factors. This is true for extreme acts of violence (school shootings) as well as less extreme acts. Media violence is not the largest risk factor for later aggressive or violent behavior, but it also isn't the smallest. It is the one risk factor that can be greatly influenced by parents or caregivers without great expense.”

Meanwhile, Ferguson found that innate aggression, family violence, and male gender were all linked to real-world violence, but not violent video game play. He finds the idea that game violence might promote real violence “ridiculous.” He points out that Adam Lanza’s favorite game was “Dance Dance Revolution,” which is decidedly nonviolent, and that the Virginia Tech shooter didn’t play violent video games at all.

“In the end, whether violent or non-violent, [video games] are merely fun, thoughtful, new forms of 'art' that don’t really have any more impact than books, music, or other forms of art.” — Christopher Ferguson, Stetson University

James Fox and Monica DeLateur, criminologists at Northeastern University, point out that mass shootings are not on the rise, and that there is no connection between violent video game play and mass shootings. Researchers Patrick Markey and Juliana French, of Villanova University, and Charlotte Markey, of Rutgers University, found that while video game sales are at an all-time high, violent crime is at an all-time low, with noticeable dips in crime after the release of games like “Grand Theft Auto.”

“The reality is that we have probably both exaggerated the negative and positive impact of video games on children,” Ferguson said. “This is typical of the ‘moral panic’ that follows the introduction of new media into society, which can cause even scholars, at least in the short term, to [make] exaggerated claims. I think all of us can remember media-based moral panics from our own childhoods … from rock music … to comic books in the 1950s, to Harry Potter, to rap music, to Dungeons and Dragons, etc. In the end, whether violent or non-violent, they are merely fun, thoughtful, new forms of 'art' that don’t really have any more impact than books, music or other forms of art.”

Who should we believe? Przybylski found that people who did not grow up with video games and who lack video game experience are most likely to believe that violent video games cause real-world violence. Meanwhile, Brad Bushman, professor of communication and psychology at Ohio State University, noted that most Americans get their information on video games from the mass media, and that mass media has increasingly denied the effects of video games on violence over time. 

In 2011, the Supreme Court ruled in Brown v. Entertainment Merchants Association that restrictions on selling Mature-rated video games to minors violated free speech, on the basis that “Psychological studies purporting to show a connection between exposure to violent video games and harmful effects on children do not prove that such exposure causes minors to act aggressively. Any demonstrated effects are both small and indistinguishable from effects produced by other media.”

One area of agreement is that parents can, and should, get involved. “It might not be accurate to think just of controlling a child’s gaming time as a way to encourage healthy regulation of play,” Przybylski said.

Ferguson added, “I would also suggest to parents to be involved in their children’s media lives. Simply banning everything objectionable I don’t think will work, but play games with your kids. The best thing for parents to look for is whether the child is seriously neglecting other responsibilities, skipping school, etc. Even heavy playing isn’t a psychological problem if the child is able to get their other responsibilities in line. Every parent has the right to decide what works best for their family.”

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