This NPR episode delves into discussion on the difference between play fighting and actual fighting. Apparently this difference is wired into people and dogs and presumably many other animals. So when you see your kids play fighting, think about when dogs play fight. Surprise–this same instinct is engaged during video game play. The non-gamer video-game critic also is in the role of the parent watching their kids sword fight with sticks: instinctually removed — they forget that someone in a play-fighting mindset might instinctively know the difference of their own actions. (The metaphor is approximate and is not parenting advice, of course.)

NPR Story