By its very nature as a visual, time-limited medium,television news places a high premium on short stories that permit attractive and dramatic pictures.Because airtime is very shot (about twenty-two minutes per half hour)and very expensive,directors of news programs want to be sure that the news they air attracts an audience.Thus,a story about a candidate in a parade,surrounded by cheering crowd,is more likely to be broadcast than is story with prople discussing public policy at length.