Bushman, B. J., & Gibson, B. (2011). Violent video games cause an increase in aggression long after the game has been turned off. Social Psychological And Personality Science, 2(1), 29-32. doi:10.1177/1948550610379506

Experimental studies show that violent video games cause people to behave more aggressively, but how long does the effect last? In most experiments, aggression is measured immediately after game play. The present experiment is the first to test the long-term causal effects of violent video games on aggression. By the flip of a coin, participants played a violent or nonviolent game for 20 min. Within each group, half ruminated about the game. The next day, participants competed with an ostensible opponent on a competitive task in which the winner could punish the loser with painful noise blasts through headphones. Results showed that violent video games increased aggression 24 hr later, but only among men who ruminated about the game. Rumination keeps aggressive thoughts, feelings, and behavioral tendencies active. If players ruminate about the violence in a game, the aggression-stimulating effects of the game persist long after it has been turned off. (PsycINFO Database Record (c) 2012 APA, all rights reserved)