Do violent video games make for violent teenage gamers? Only if they're not very nice to start with, according to new research.
Dr Patrick Markey of Villanova University found that a certain combination of personality traits can help predict who will be most affected.
"The results suggest that it is the simultaneous combination of these personality traits which yield a more powerful predictor of violent video games," he says. "Those who are negatively affected have pre-existing dispositions, which make them susceptible to such violent media."
Markey used the most popular psychological model of personality traits, the Five-Factor Model. This classifies people according to five personality traits: neuroticism, extraversion, openness to experience, agreeableness and conscientiousness.
Analysis of the model showed a 'perfect storm', says Markey, of traits for the children most likely to become hostile after playing violent video games.
They were high neuroticism, low agreeableness and low conscientiousness.
Markey then created his own model, focusing on these three traits. He used it to help predict the effects of violent video games in a sample of 118 teenagers, who played a violent or a non-violent video game and had their hostility levels assessed.
The teenagers who were highly neurotic, less agreeable and less conscientious tended to be worst affected by violent video games. Those who didn't have these personality characteristics were barely, if at all, affected.
"Violent video games are like peanut butter," commented Dr Christopher J Ferguson of Texas A&M International University.
"They are harmless for the vast majority of kids but are harmful to a small minority with pre-existing personality or mental health problems."
The research appears in a special issue of the Review of General Psychology.