The previous chapters offered rational analyses of various informationprocessing goals that the system had. In particular, they were concerned with how to order retrieval from memory and how to make predictions about unseen features of objects and forthcoming events. The underlying
assumption was that accurate and appropriate information was useful. We turn now to the question of "useful for what?" The answer is that it is useful for deciding what action to take. This is the heart of the matter. Everything else is just serving a supporting role. Unless we take action, all of the fine information-processing in the world would be worthless. We would be in the situation of Tolman’s apocryphal rat (Guthrie, 1952; p. 143), lost in thought in the maze of life.