Does size matter when it comes to literary fiction? While American writers still strive to produce the epic novel, British fiction seems to be shrinking. Laura Cumming explores the culture of brevity and discusses new writing from Martin Amis , Jeff Noon and others. And she talks to painter Chris Ofili - recently shortlisted for the Turner Prize - whose eclectic use of popular imagery, abstraction, paint and varnished elephant dung makes him one of the most innovative young artists working in Britain today. Producer Anthony Denselow