Classic studies of play behavior among primates suggest that apes make basic distinctions between play fighting and actual combat. In some circumstances, they seem to take pleasure wrestling and tousling with each other. In others, they might rip each other apart in mortal combat. Game designer and play theorist Eric Zimmerman describes the ways we understand play as distinctive from reality as entering the "magic circle." The same action — say, sweeping a floor — may take on different meanings in play (as in playing house) than in reality (housework). Play allows kids to express feelings and impulses that have to be carefully held in check in their real-world interactions. Media reformers argue that playing violent video games can cause a lack of empathy for real-world victims. Yet, a child who responds to a video game the same way he or she responds to a real-world tragedy could be showing symptoms of being severely emotionally disturbed. Here's where the media effects research, which often uses punching rubber dolls as a marker of real-world aggression, becomes problematic. The kid who is punching a toy designed for this purpose is still within the "magic circle" of play and understands her actions on those terms. Such research shows us only that violent play leads to more violent play.
Source:
http://www.spiritsd.ca/teachers/Marcus.Tessem/8%20Myths%20about%20Video%20Games.doc