Below is the Conclusion Section of an article (The efect of video game violence on physiological desensitization to real-life violence) dealing with the effects of violent video games on people.
"The present experiment demonstrates that violent video
game exposure can cause desensitization to real-life violence.
In this experiment, violent game players were less
physiologically aroused by real-life violence than were nonviolent
game players. It appears that individuals who play
violent video games habituate or “get used to” all the violence
and eventually become physiologically numb to it.
The integration of systematic desensitization processes
and models of helping behavior with GAM is heartening in
the insights provided to a long-standing and somewhat
muddled research literature. But it is also frightening in
some of its implications. The existing rating systems (Bushman
& Cantor, 2003), the content of much entertainment
media, and the marketing of those media combine to yield a
powerful desensitization intervention on a global level.
Children receive high doses of media violence. It initially is
packaged in ways that are not too threatening, with cute
cartoon-like characters, a total absence of blood and gore,
and other features that make the overall experience a pleasant
one, arousing positive emotional reactions that are
incongruent with normal negative reactions to violence.
Older children consume increasingly threatening and realistic
violence, but the increases are gradual and always in a
way that is fun. In short, the modern entertainment media
landscape could accurately be described as an eVective systematic
violence desensitization tool. Whether modern societies
want this to continue is largely a public policy
question, not an exclusively scientific one (Anderson et al.,
2003; Gentile & Anderson, 2006)."
N.L. Carnagey et al. / Journal of Experimental Social Psychology 43 (2007) 489–496