Devilly, G., Callahan, P., & Armitage, G. (2012). The effect of violent videogame playtime on anger. Australian Psychologist, 47(2), 98-107. doi:10.1111/j.1742-9544.2010.00008.x

Studies have found evidence that, after playing violent videogames for 20 min, people experience a mean short-term increase in aggression, hostility, and anger. The current research investigated whether or not players habituate during longer, more realistic lengths of play. Participants (N = 98) were randomly assigned to play the game Quake III Arena for either 20 or 60 min. Participants in the long condition showed a smaller change in state anger (CSA) from pre- to post-game play than those in the short condition, although this did not reach significance. Change in scores for gamers (not novice players) showed that short gaming led to a larger increase in anger ratings than long gaming. When the results for violent videogame players were analysed separately, there was no significant increase in anger post-game play—irrespective of length of time playing. Results also supported the hypotheses that females would show a significantly larger CSA than males and that participants previously unexposed to violent videogames would show a significantly larger CSA than exposed participants. (PsycINFO Database Record (c) 2012 APA, all rights reserved)