The average American child watches 8,000 murders and 100,000 acts of violence before finishing elementary school -- thanks to the miracle of television. Suggestions of a link between make-believe TV violence and aggression in real life have been raised since television's formative years in the 1950s -- and always dismissed by the TV industry. But recently the three major networks signed a first- ever joint statement outlining practices aimed at reducing violence, and the cable, video and film industries are showing signs of cooperating. Some in Congress are encouraged and maintain hopes that change will come about voluntarily, without the need for federal regulation. But anti-violence activists and scholars of television accuse the industry of merely paying lip service to the problem.