Recent research has shown that similarity plays crucial roles not only in lower-level cognition, but also in higher-level ones such as problem-solving and learning including analogy. At the same time, these findings have made clear the insufficiency of the traditional model of similarity that assumes a flat representation of a fixed set of properties of an object. This paper explores the possibility of extending similarity to the variety of cognitive activities. For this purpose, by reviewing recent studies on similairty judgment, we examined whether human similarity judgment could reflect a.) structural information, b.) task goals, and c.) knolwedge relevant to achieving the task. The review revealed that human mechanisms of similarity judgments incorporate structural and goal-related information in computing similarity.
