Something on the order of 1 to 4 million North Americans participate in a short term mission trips, at a cost of a few billion dollars a year. Conventional wisdom says these activities make a long-lasting positive impact on both the missionaries and the people they visit. Recent research by Kurt Ver Beek (his website is here and some discussion is here) argues that neither group is significantly affected in the long run.

This story from NewScientist.com argues a point I've long believed must be true: doesn't engaging in such realistic simulations of savagery affect your response to it in real life?

...psychologist Bruce Bartholow from the University of Missouri-Columbia and colleagues have found that people who play violent video games show diminished brain responses to images of real-life violence, such as gun attacks, but not to other emotionally disturbing pictures, such as those of dead animals, or sick children. And the reduction in response is correlated with aggressive behaviour.