A few years ago we were all horrified to hear about a first person shooter ethnic cleansing game. We were not horrified to hear about Grand Theft Auto, a game in which you shot random pedestrians and beat hookers. The difference in our reaction was based on the natural assumption that the people who played the first game believed in what they were doing. Or at least, even if they didn't believe in literally gunning down members of other ethnic groups, they thought something like the members of those ethnic groups were subhuman. We didn't assume that the people playing Grand Theft Auto believed in beating hookers or shooting random pedestrians. At least, a lot of us didn't. Hearing the media hysteria, it was clear that someone out there really did seem to think your average teenager believed in beating hookers and shooting pedestrians.
I'm pretty sure we were right. But what lead us to view the two cases differently in that way? I think that's a surprisingly sophisticated judgment at the intersection of ethics and psychology and one that most of us perform quite naturally.