I'm not sure if this is exactly what you are looking for, but two
excellent scientific studies about the effects of violence are:
 
Wilson, J. & Weiss, A.  (1991).  The effects of two reality explanations
on children's reactions to frightening movie scenes, Communication
Monographs, 58, pp. 307-325.
 
and
 
Hoffner, C. & Cantor, J.  (1991).  Factors affecting children's enjoyment
of a frightening film sequence.  Communication Monographs, 58, pp. 41-61.
 
Good luck.
 
ld