Psychological studies do NOT definitively prove anything at all about video games and violence, either for or against. The fact is that human beings are not rational creatures and much of psychology is pseudo-science. Just as many studies have "proven" the opposite of what you're claiming. Aristotle once said that the wisest man will admit he doesn't know. You don't know that no link exists between gamers and violence and the contrary opinion doesn't either. Loving video games doesn't mean side effects may not exist.