Family's Choices Can Blunt The Effect of Video Violence
Senate hearings on violent entertainment focus on how violent films, recordings and electronic games are marketed to children, but some childhood development experts say issue is not just what children see, but how and where they see it; they say private household choices can greatly affect impact entertainments have, arguing that as more televisions, video games and computers find their way into rooms, children become more isolated from parental guidance and control; say even where programming is benign, array of video games, televisions, computers, DVD's and music systems creates virtual world where adults often fear to tread; note that as recently as few decades ago, most children did not have own bedrooms, let alone electronic isolation available to current teenagers; photos (M)