The study was conducted by Jane Barnett and her colleagues at Middlesex University, who recruited 292 male and female gamers aged 12 to 83 to play World of Warcraft. The players were asked to complete a questionnaire on anger, aggression and personality before playing the game for two hours, after which they took the test again.

In their results, the psychologists found that participants were more likely to feel calm or tired after playing, though there were differences depending on age, sex and personality.

"There were actually higher levels of relaxation before and after playing the game as opposed to experiencing anger but this did very much depend on personality type," said Barnett. "This will help us to develop a emotion and gaming questionnaire to help distinguish the type of gamer who is likely to transfer their online aggression into everyday life."

The press release published by the British Psychological Society did not disclose which tasks players were made to do in their two hours of play. In addition to PVP and PVE combat, World of Warcraft also features exploratory elements, crafting, and numerous other activities.

Many previous studies on the subject of violent video games have focused on games such as id's Quake II and other arguably more violent titles than World of Warcraft, which is rated rated T for Teen by the Entertainment Software Ratings Board.