Oliver Sacks, the famous neuroscientist and author, can't recognize faces. Neither can Chuck Close, the great artist known for his enormous paintings of...that's right, faces. 

Oliver and Chuck--both born with the condition known as Face Blindness--have spent their lives decoding who is saying hello to them. You can sit down with either man, talk to him for an hour, and if he sees you again just fifteen minutes later, he will have no idea who you are. (Unless you have a very squeaky voice or happen to be wearing the same odd purple hat.) Chuck and Oliver tell Robert what it's like to live with Face Blindness in a conversation recorded for the World Science Festival, and they describe two very different ways of coping with their condition (which may be more common than we think).