I don't know of any studies, but my 15 year old son watches a lot of Japanese anime. Despite all the violence in many of the shows, he is still squeamish seeing blood and gore on TV. I have not explored any other factors in my observational analysis of my n=1. :)
Good question. Although my knowledge too is quite limited on this yet as a part of observation, animated way of talking, thinking about being in possession of superpowers, imaginary world of living can be observed in some of the teenagers.