Yeah, as a former psych major, I'm calling BS on this one. Unless you show real violence happening to real people, and their reaction is the same to videogames, I'm not buying that it's a direct coorelation.
Sure, it does desensitize to violence to a certain degree, but I don't really think it'd be any more so than movies would. I'm not even sure that the fact that you're the one dishing out the pain in videogames has any more effect that watching a movie. I find it amusing that some people say, "They're disassociating themselves from people by playing as this character." and some of the same people turn around and say, "They're becoming more violent because they play these games." People need to make up their minds.
This test is BS, the results are BS, and this is exactly why I want to do sociology and social psychology, so that I'll be able to come up with better and more comprehensive tests than these. Ever think about looking into someone's background before allowing them to participate in the tests? For instance, someone that came from an abusive household might internalize it more than someone that comes from a "normal" family? There are so many outside variable here that it sickens me that this was allowed to be published.