Playing violent video games for just 20 minutes a day can encourage aggressive behaviour
University students were asked to play a violent video game or a driving game over three daysThey were then set a couple of tests to see how they reacted to the outside worldThose who played shoot-em-ups like Call of Duty were more likely to assume the world was hostile and react aggressively
16:57 GMT, 11 December 2012
Playing a violent video game for just an hour over a three-day period is enough to increase aggressive behaviour, according to a new study.
However, playing a non-violent video game, such as a racing game, has no effect on aggression when played for 20 minutes a day for three consecutive days.
Although previous studies have revealed a single violent gaming session can increase short-term aggression, this is the first to show longer-term effects.
Test: Students were asked to play a violent video game such as Call of Duty 4 (pictured) or a non-violent title such as the racing game Dirt 2
Lead author Professor Brad Bushman, of Ohio State University, USA, compares the effect to smoking: 'It's important to know the long-term causal effects of violent video games, because so many young people regularly play these games.
'Playing video games could be compared to smoking cigarettes. A single cigarette won't cause lung cancer, but smoking over weeks or months or years greatly increases the risk.
'In the same way, repeated exposure to violent video games may have a cumulative effect on aggression.'
A total of 70 French university students were told they would be taking part in a three-day study on the effects of brightness of video games on visual perception.
They were then told to play either a violent or non-violent game for 20 minutes everyday for three consecutive days by the researchers from the University Pierre Mendhs-France and the University of Hohenheim, Germany.
The violent video games in the study for the Journal of Experimental Social Psychology were Condemned 2, Call of Duty 4 and The Club, while those in the non-violent group played S3K Superbike, Dirt2 and Pure.
After playing each game, the students were given the beginning of a story, and then asked to list 20 things the main character will do or say as the story unfolds to measure their hostile expectations.
In one story, a driver crashes into the back of the protagonist's car – causing significant damage – and the researchers counted how many times the students listed violent or aggressive actions and words that might occur.
People who have a steady diet of playing these violent games may come to see the world as a hostile place, say scientists
The students then participated in a competitive reaction time task, which is used to measure aggression, with each participant told they would compete against an unseen opponent in a computer game where the object was to be the first to respond to a visual cue on the screen.
The loser received a blast of unpleasant noise through headphones – such as nails on a chalk board or sirens – and the winner decided how loud and long the blast would be.
In reality, there was no opponent and the participants were told they won about half the trials.
Results showed that after each day, those who played the violent games had an increase in their hostile expectations – meaning they were more likely to think the characters would react with aggression or violence.
Prof Bushman said: 'People who have a steady diet of playing these violent games may come to see the world as a hostile and violent place.
'These results suggest there could be a cumulative effect. Hostile expectations are probably not the only reason that players of violent games are more aggressive, but our study suggests it is certainly one important factor.
'After playing a violent video game, we found that people expect others to behave aggressively.
'That expectation may make them more defensive and more likely to respond with aggression themselves, as we saw in this study and in other studies we have conducted.'
He said it is 'impossible' to know how much aggression could increase for those who play video games for months or years, as most people do.
'We would know more if we could test players for longer periods of time, but that isn't practical or ethical.
'I would expect that the increase in aggression would accumulate for more than three days. It may eventually level off.
'However, there is no theoretical reason to think that aggression would decrease over time, as long as players are still playing the violent games.'