The same type of hierarchy is involved in our ability to recognize objects and situations. We recognize the faces of people we know well and also recognize that these faces contain eyes, a nose, a mouth, and so on—a hierarchy of patterns that we use in both our perceptions and our actions. The use of hierarchies allows us to reuse patterns. For example, we do not need to relearn the concept of a nose and a mouth each time we are introduced to a new face.
