In February 2018, President Trump stated in response to the school shooting in Parkland, Florida that “the level of violence (in) video games is really shaping young people’s thoughts.” He’s far from the first to suggest that violent video games make children violent.

It certainly looks like they do. Jimmy Kimmel humorously pointed this out when he challenged parents to turn off their children’s TVs while they were playing the popular shooter game Fortnite and film the results. Unsurprisingly, many of the children lashed out, some cursing, others striking their parents.

The research

Decades of research seem to support this, too. Three common ways that researchers test levels of in a laboratory are with a “hot sauce paradigm,” the “Competitive Reaction Time Test,” and with word or story completion tasks.

In the hot sauce paradigm, researchers instruct participants to prepare a cup of hot sauce for a taste tester. They inform them that the taste tester must consume all of the hot sauce in the cup and that the taste tester detests spicy food. The more hot sauce the participants put into the cup, the more “aggressive” the participants are said to be.

In the Competitive Reaction Time Test, participants compete with a person in the next room. They are told that both people must press a button as fast as possible when they see a light flash. Whoever presses the button first will get to “punish” the opponent with a blast of white noise. They are allowed to turn up the volume as loud and as long as they want. In reality, there is no participant in the next room; the test is designed to let people win exactly half of the games. The researchers are measuring how far they turned the dial and how long they held it for. In theory, people who punish their opponent more severely are more aggressive.

During a word or story completion task, participants are shown a word with missing letters or a story without an ending. Participants are asked to guess what word can be made from those letters or to predict what will happen next in a story. When participants choose “aggressive” words (such as assuming that “M _ _ _ E R” is “murder” instead of “mother”) or assuming that characters will hurt one another, they are considered more aggressive.

These tests have been used to examine whether violent games increase aggression. Several representative studies are summarized below. In each study, the participants assigned to play a violent game seemed more prone to acting or thinking aggressively than those who played a non-violent game for an equivalent amount of time.

2000: Undergraduate psychology students played a video game for 30 minutes and were given the Competitive Reaction Time Test. Those who played Wolfenstein 3D (a violent game) turned the “ ” dial for a longer period of time than those who played Myst (a non-violent game).

2002: Participants played a video game for 20 minutes and were given a story completion task. Players who played Carmageddon, Duke Nukem, Mortal Kombat, or Future Cop (violent games) were more likely to predict that the characters in an ambiguous story would react to conflict aggressively than those who had played Glider Pro, 3D Pinball, Austin Powers, or Tetra Madness (non-violent games).

2004: Participants played a video game for 20 minutes and were given a word-completion task. Players who played Dark Forces, Marathon 2, Speed Demon, Street Fighter, and Wolfenstein 3D (violent games) were more likely to predict that word fragments were part of aggressive words than non-aggressive words than those who had played 3D Ultra Pinball, Glider Pro, Indy Car II, Jewel Box, and Myst (non-violent games).

2004: Participants played a video game for 20 minutes and were given the Competitive Reaction Time Test. Those who played Marathon 2 (a violent game) turned the “noise punishment” dial to higher levels than those who had played Glider PRO (a non-violent game).

2014: Participants played a video game for 30 minutes and were given the hot sauce test. People who played Call of Duty: Modern Warfare (a violent game) put more hot sauce into the cup than people who played LittleBigPlanet 2 (a non-violent game).

It is easy to conclude from this research that violent games make people more aggressive. In 2015, The American Psychiatric Association (APA) Task Force on Violent Media analyzed 31 similar studies published since 2009 and concluded that “violent video game use has an effect on... aggressive behavior, cognitions, and affect.”

Is this research valid?

However, experienced gamers would notice a critical problem with the studies’ construction.

Although Wolfenstein 3D, Call of Duty, and Duke Nukem are certainly more violent than Myst, LittleBigPlanet 2, and Glider Pro, violence is far from the only variable.

For example, Wolfenstein 3D is an action-packed, exciting, and fast-paced shooting game, while Myst is a slow, methodical, exploration and puzzle game. To help illustrate this point, here is footage of people playing Wolfenstein and Myst.

Comparing the two and assuming that any differences in the level of aggression after playing must be due to the different levels of violence ignores all of these other variables.

If it’s not violence, what is it?

Some researchers have taken note of this criticism in recent years and begun exploring alternative hypotheses for the differences found, such as that the violent games chosen were also harder to master and that many people had aggressive thoughts simply because they lost. When they have conducted more nuanced studies to explore these other hypotheses, they have found that the violence was not the critical variable.

For example, one clever set of studies examined whether players acted out simply because some games “impeded competence.”

The first study demonstrated that two of the games in the previous studies differed significantly in how difficult the games were to master; Glider Pro 4 uses just two buttons, while Marathon 2 requires the mouse plus 20 different buttons. This additional variable they identified makes it inappropriate to compare the two and draw a scientifically credible conclusion.

The researchers then created two first-person-shooter games with differing levels of violence. In the violent game, characters who the players shot suffered horrific, bloody deaths. The other was a paintball game in which characters simply disappeared when shot. The two games were otherwise identical. When they tested the level of aggression afterward, they found no differences between the groups.

In two other studies, these researchers manipulated the game Tetris to be more complicated for half of the participants, either by making the controls complicated or by giving them pieces that could not fit into the grid easily. The groups playing complicated, frustrating versions of the game showed more aggression afterward.

In each of these studies, it was the level of difficulty—not the presence of violence—that predicted aggressive thoughts and actions afterward. When the games were better matched than the previous studies, violence did not appear to affect aggression after playing.

In other words, these researchers concluded that games can make people angry just by being difficult to win.

A clear example of how frustration alone can lead to aggression in a non-violent game can be seen on YouTube, on well-known streamer Markiplier’s first attempt to beat Getting Over It. The game is bizarre; players try to guide a shirtless man in a cauldron up a mountain using only a hammer. It is designed to be extraordinarily unforgiving; one minor misstep might undo an hour of progress. Here’s a video of him throwing a chair when he slipped down the mountain.

Others have suggested that it is the level of competition present in many games which fosters aggressive thoughts and actions. This is easy to understand—how many of us have yelled at friends or overturned the board at the end of a tense game of Monopoly? One gaming writer quipped, “What makes you angrier: dying to a horde of violent aliens in Gears of War, or losing a close match to your taunting brother in the very non-violent Mario Kart?”

Anecdotally, I have found these two hypotheses to be true for my clients. I frequently hear from them or their parents that they act aggressively while playing video games, e. . breaking controllers or yelling at their parents or other players. When I ask my clients about the situation, they talk about feeling frustrated, usually because of difficult gameplay, opponents playing unfairly, losing, or having to stop playing at an inopportune time in the game. These outbursts happen for violent and non-violent games alike.

What if violence is the variable?

In order to understand the results of the experiments, it is important to understand the difference between “statistical significance” and “clinical significance.” Statistical significance is a way to assess whether the results of the study were due to a real difference between groups or whether the results might have been due to chance. Clinical significance is whether the results are important for individuals or the population as a whole.

For example, the 2000 study which found that, on average, players turned the “punishment” dial longer when they played Wolfenstein 3D than those who had played Myst did reach statistical significance.

However, the actual difference was between 6.81 and 6.65 seconds, a difference of 0.16 seconds. To put that number into context, blinking takes roughly 0.1 to 0.4 seconds. That is, subjects who played violent and non-violent games both chose to punish an imaginary opponent for roughly seven seconds. The difference between how long the groups held the dial was less than the blink of an eye.

A 2 percent difference in how long someone holds a dial in a laboratory is hardly cause for alarm. Further, studies have shown that this tiny increase in aggression fades quickly, lasting less than 10 minutes.

Despite this, the researchers linked violent video games to the school shooting at Columbine High School in the first paragraph of the paper.

The APA’s Society for Media Psychology and Technology has since firmly stated that this kind of comparison is inappropriate: “Journalists and policymakers do their constituencies a disservice where they link acts of real-world violence with the perpetrators’ exposure to violent video games...there’s little scientific evidence to support the connection...Discovering that a young perpetrator also happened to play violent video games is no more illustrative than discovering that he or she happened to wear sneakers or used to watch Sesame Street.”

In fact, the Secret Service’s report studying characteristics of school shooters showed that only 14 percent of school shooters enjoyed violent video games, compared to 70 percent of their peers.

What about long-term effects?

Some researchers who study aggression use the General Aggression Model (GAM), a unified theory of aggression created by the researcher who authored many of the papers that found a link between aggression and violent video games. The theory explains that many things may increase aggression in the short-term, including being insulted, unpleasant noises, and the temperature of the room.

The GAM theory further suggests that repeatedly acting on aggressive impulses may push people toward becoming permanently more aggressive. For example, a normally peaceful person may act out when insulted. The more times the person acts out, the more “accessible” violent responses become and the more likely this person is to act violently in future situations.

This makes intuitive sense, and researchers sometimes state that even a tiny increase in aggression, like the aforementioned 2 percent, could be cumulative and lead to long-term aggressive tendencies.

However, it does not appear that this is true. Researchers recently surveyed more than 1,000 British teens ages 14-15 on how often they play games, independently examined how violent those games are, and asked their parents to report how aggressively their children acted over the past month. They examined whether each variable was connected and found no evidence of a correlation. Teens who played violent games many hours per week did not act more aggressively than those who played peaceful games or no games at all.

Should children play violent games?

Of course, I am not suggesting that it is appropriate for young children to play violent games. I would not recommend that young children play Call of Duty for the same reason that I would not recommend they watch Saving Private Ryan until they are mature enough to understand it.

Even though it is not likely to make peaceful people aggressive, media which contains graphic violence can be frightening and hard to understand, especially for young people. Parents should take reasonable steps to ensure that their children are playing age-appropriate games, in the same way that they should ensure their children are watching age-appropriate movies.

Some parents choose to play video games with their children, ask them to play in a common area, or sit with them while they play to help provide context to the content of the games. These are great ideas; they allow parents to teach their children the difference between violence in games and in real life, to have conversations about the actions their characters take, and to comfort children who become scared.

It also helps parents understand what their children are experiencing while playing games so they can help them learn to manage these feelings of frustration. Parents who are familiar with their children’s video games can determine whether they are age-appropriate, their children’s motivations for play, how their children are affected, and how to set appropriate limits.