Many releases in the Call of Duty series have an 18 certificate but are often played by school-age boys.

London - Computer games can make people aggressive – but only if they are not very good at playing them, a study shows.

Researchers found the level of violence in games made little difference to anger levels. Instead, lack of practice, awkward controls and high levels of difficulty were the causes of uncontrollable frustration.

The counter-intuitive finding comes from an Oxford University team that tested students for aggression after they had played games. More violent games made people feel on edge but had no clear effect on levels of anger.

But players became noticeably more aggressive when the game or controls were difficult or frustrating, the Journal of Personality and Social Psychology reports.

Researcher Dr Andrew Przybylski said it seemed that how well a player did was more important than the level of violence involved in the game. “You can get very angry playing a card game,” he added. - Daily Mail