People who play violent video games are more likely to act aggressively in everyday life, a US study has suggested.

Previous studies have found people who play such games are more likely to be aggressive.

Critics of these studies say violent video games attract players more prone to violence and that the games themselves do not change behaviour.

However, a study by researchers at University of Missouri-Columbia (MU) suggests a causal link between video games and violence.

"Most of us naturally have a strong aversion to the sight of blood and gore," said Bruce Bartholow, assistant professor of psychological sciences at MU.

"Surgeons and soldiers may need to overcome these reactions in order to perform their duties. But, for most people, a diminished reaction to the effects of violence is not adaptive.

"It can reduce inhibitions against aggressive behavior and increase the possibility of inflicting violence on others."

Bruce Bartholow, assistant professor of psychological sciences at MU: "These findings are among the first to link chronic violent video game play, diminished brain responses and aggressive behavior."

The researchers asked 39 game players how often they played their five favourite video games and how violent the games were.

Next, they showed participants a series of images on a computer screen, including emotionally neutral images, such as a man riding a bicycle; violent images, such as a man holding a gun to another man’s head; and negative, but nonviolent images, such as a dead dog.

As participants viewed these images, the researchers measured a type of brainwave, known as P300, which is believed to reflect how people evaluate images like these.

After viewing the pictures, participants were told that the last part of the experiment involved a competition with another participant to see who could press a button faster following a series of tones. Before each tone, participants set the level of a noise blast that their opponent would receive if the opponent lost. There actually was no opponent.

The research team found that the participants who routinely played violent video games showed less brain reactivity, measured by diminished amplitude of the P300 brainwaves, when they viewed the violent images compared to the equally negative, nonviolent image.

They also found that the smaller a participant's brain response to violent images, the more aggressively he behaved during the final part of the experiment.

"These findings are among the first to link chronic violent video game play, diminished brain responses and aggressive behavior," added Bartholow.

"People often assume that any negative effects of playing violent games are short-lived, but these results suggest that repeated exposure to violent video games has lasting negative consequences for both brain function and behavior."

The video game industry is a $10bn dollar industry in the US and more than 90 per cent of all US children and adolescents play video games, on average for about 30 minutes daily.

The study findings will be published in an upcoming issue of the Journal of Experimental Social Psychology.

The article Violent games make people more aggressive originally appeared on 999 Today