Some neurological patients exhibit a striking tendency to confabulate -- to construct false answers to a question while genuinely believing that they are telling the truth. A stroke victim, for example, will describe in detail a conference he attended over the weekend when in fact he has not left the hospital. Normal people, too, sometimes have a tendency to confabulate; rather than admitting "I don't know," some people will make up an answer or an explanation and express it with complete conviction. In Brain Fiction, William Hirstein examines confabulation and argues that its...