I believe tv has an unconcious effect of children. They see these violent acts and although may not copy exactly whats seen on screen they do become used to the notion of violence, and things that may have been horrible to them then are now normal.

However violent television isn't the only cause of increased violence in children. They may live in a violent household with abuse, they may have an inherit tendency to be violent, the violence can be cause by pressure and wanting to protect themselves from others.

I don't believe tv has all the fault but cannot deny that it has some. I however believe that if your a parent and have a child don't blame television for poor parenting. Just take the controll away.