For example, when connectionist models degrade gracefully, or when they survive damage, their performance depends crucially upon the similarity of presented material to material that has already been stored. We are forever carving nature at its joints, dividing it into categories so that we can make sense of the world. The functional role of categorization is information reduction. For now, let us take a category to be a class of objects that we believe belong together. A category is a set of objects that seem to belong together.
Categories code our experience.
Coding by category is fundamental to mental life because it greatly reduces the demands on perceptual processes, storage space, and reasoning processes, all of which are known to be limited. When a category is applied to an object, we can make inductive inferences about that object. Very early on, we know that members of the same category are likely to share many invisible properties even if they do not resemble one another. Similarity Similarity, particularly physical similarity, is a defining characteristic of categories. In general, we divide the world so as to maximize within category similarity while minimizing between-category similarity.