MU study links playing violent video games and aggressive behavior

Thursday, June 2, 2011 | 7:29 p.m. CDT; updated 2:55 p.m. CDT, Friday, June 3, 2011

COLUMBIA — In the last 20 years, technology has evolved to make violent video games more graphic and realistic.


Top 10 U.S. video game sales for 2010

The NPD Group's Top 10 U.S. software sales at retail for all of 2010:

1. Call of Duty: Black Ops (Activision)

2. Madden NFL 11 (Electronic Arts)

3. Halo: Reach (Microsoft)

4. New Super Mario Bros. Wii (Nintendo)

5. Red Dead Redemption (Take-Two Interactive)

6. Wii Fit Plus (Nintendo)

7. Just Dance 2 (Ubisoft)

8. Call Of Duty: Modern Warfare 2 (Activision)

9. Assassin's Creed: Brotherhood (Ubisoft)

10. NBA 2K11 (Take-Two)

State governments have become involved in the violent video game debate.

In 2006 a bill was introduced by state Rep. Jeff Harris to make selling or renting a game rated Mature or Adults Only to a person younger than 17 a class A misdemeanor in Missouri, according to a previous Missourian report.

This law was not passed and there is no federal law banning the sale of video games rated Mature or Adult Only to a person under 17. However, in November the Supreme Court heard an argument on a restriction of the sale or rental of violent video games to anyone under the age of 18.

Slackers in downtown Columbia has a store policy of not selling 18 and over games to minors unless a parent is present.

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In Grand Theft Auto players get points for killing people, robbing banks, selling drugs and terrorizing prostitutes.


A Call of Duty player has the option to slit an opponent's throat as he is sleeping or stuff a victim's mouth with glass and punch him in the face.


Mortal Kombat features a fight to the death between characters where the winner can demolish an opponent execution-style.


Now, an MU study has established a link between playing violent video games and aggressive behavior, although the researchers say it doesn’t mean the players are dangerous.

Bruce Bartholow, associate professor of psychology at MU, conducted the study that demonstrates how a reduced brain response to violence, or desensitization, can forecast an increase in aggression.

Although a tie between violent video games and aggression has long been debated, the MU study identifies the process that leads to the aggression: Playing violent video games causes the brain to become desensitized to violence, and that provokes aggressive behavior.

“We now can say that we know definitively that playing a violent video game causes a reduced brain response to violence,” Bartholow said. “It’s not just that those two things are associated, but rather that the video game playing causes the brain change that we saw.”

The researchers initially looked for a change in the brain after students played a video game, either violent or nonviolent. Researchers then measured how aggressive the participants became after playing the violent game.

They stopped short of linking desensitization directly to violence, however. Playing violent video games does not turn someone into a killer or a rapist. The immediate aggression tends to be more benign, like cutting another driver off in traffic or tossing out an insult.

“I think it is an important distinction to say that violent video games do not necessarily cause an increase in violence,” said Christopher Engelhardt, a fourth-year graduate student who worked on the study. “I would never say that.”

Bartholow made it clear that there is a distinction between aggressive behavior, which he defined as any action intended to harm another, and violence, which is an extreme form of aggression.

“It’s not the case that by playing a violent video game we expect people to go out and be violent," Bartholow said. "What we do tend to see is that, for at least a short period of time following the gaming episode, people become more likely to behave aggressively."

His study, to be published in an upcoming edition of the Journal of Experimental Social Psychology, included 70 college undergraduates. Each was randomly assigned to play either a violent game — such as Call of Duty or Grand Theft Auto — or a nonviolent game — such as MVP Baseball or Tony Hawk’s Pro Skater. They were given 25 minutes to play the game.

Afterward, students looked at a series of random photos, and their brain responses were measured. Some photos were neutral, a person standing on a street corner, for example, and some were images of violence, such as a man holding a knife to a throat.

Then participants were set up in a fictitious competition and told that the player with the fastest reaction time could dish out an irritating, painfully loud noise. The loser would get the blast.


During the noise blast,  the researchers measured aggression levels according to the intensity and length of blast the “winner” selected.

In reality, there was no competition, and players didn't know their level of aggression was being monitored.

Participants were aware that the blast was noxious, Engelhardt said. "They knew it was something that someone else would be motivated to avoid.”

The researchers found that simply playing the violent game led to louder and longer blasts. Those who played a violent game in the lab were more aggressive in their blasts than those who played a nonviolent game.

Students in the study also were categorized depending on their history of playing violent games.

The study found that students who had played violent games in the past were desensitized to the violent images no matter which game they played in the lab.

Yet, researchers were intrigued to find how quickly desensitization could occur. Playing a violent game for just 25 minutes even affected those who had little prior exposure.

Desensitization occurs when an emotional or psychological response is reduced after repeated exposure to something, Bartholow said.

In some cases, he said, desensitization can be positive. It is often used in therapy for people who have phobias, Bartholow said. People with an irrational fear of snakes could reduce their anxiety after repeated exposure to snakes in a safe environment, for example.

This is Bartholow's second study at MU on violent video games. He created a similar study in 2006 where researchers saw a connection between the games and aggression but could not explain why.

“It’s been hypothesized many times that becoming desensitized to violence could be one factor that causes increased aggression, but nobody had ever really demonstrated that experimentally before,” Bartholow said.

His recent study demonstrates that desensitization can even occur rapidly — within 25 minutes — whereas before, it was thought to be a long-term process.

Social scientists and others, however, agree that playing violent games is only one aspect of an aggressive culture. Yet, other, more complicated factors such as violent movies and sports cannot be measured in a lab.

There is a double-standard between R-rated movies and rated-M games, said Ted Sharp, assistant manager of Slackers, a downtown video game retailer. He said he doesn’t see a difference between movies and video games.

Cyrus Marriner, who has worked at Slackers for nine months, called aggression a cultural problem.

“The violent video games are not a problem on their own,” he said. “We are a violent culture. We celebrated Bin Laden’s death.”

Marriner said video games can be addictive and the games that are more fun to play tend to be violent.

“It’s not the violence that makes them more fun,” he said. “The early games that were the most engaging were the violent ones.”

Games reward players for their violent behavior, Engelhardt said. Accumulating points and advancing to higher levels is the feedback they crave to assess how they are playing.

In order to get to the next level in Mortal Kombat, for example, the player must inflict a certain amount of damage on the opponent.

The 1999 Columbine High School shootings that left 13 dead have been attributed to the shooters' experience with violent video games, but Engelhardt finds that unjustified.

“Some people become much more aggressive, while others don’t become aggressive at all,” Bartholow said. “But the average effect is to increase the likelihood of aggression.”

Not every person who picks up a game controller is affected by violent video games, and this study takes that into account.

“We do not examine any one individual,” Engelhardt said. “What we see is a causal increase in aggressive behavior as a result of playing such games.”

Bartholow compared it to people who smoke cigarettes — not everyone who smokes will develop lung cancer, but there is a causal relationship.

More research is being done at MU to look into other possible effects of playing violent video games.

Engelhardt is investigating the effects on higher-level cognitive abilities.

“I’m interested in how well individuals are able to perform on executive functioning tasks as a function of exposure to violent video games," he said.

Bartholow is interested in figuring out if the effects they observed in college students could be measured in younger people.

He explained that neuroscience research has shown the brain is still going through developmental changes, especially the frontal lobes, through the teenage years, up to age 20 or 22.

“It’s possible that if young kids are being exposed to lots of violent media during those years, that could lead to some changes to how their brains develop and that might have implications long-term,” Bartholow said.

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