Simple concepts such as mother, ball, and red are the building blocks of human thought. What sort of knowledge is involved in acquiring and having concepts like these? This question has been pursued vigorously in recent years, but there is still no satisfactory answer. Part of the reason may be that many of the existing studies have looked only at knowledge of concrete objects such as birds and chairs. However, a wide range of other concepts, such as those concerning kin relations, social status, emotions, colors, and physical states, are equally important to human thought. The data available on these other concepts suggests that current theories of concepts may be limited in several important ways. This research will address these limitations by asking three related questions about the nature of concepts: (1) What sorts of knowledge are involved in having concepts from diverse domains such as kin, emotion, and color? (2) What implicit beliefs do people have about what it means to have knowledge in the different domains, and how do those beliefs affect the way that they use words for concepts in these domains? (3) How do concepts held by experts in various fields differ from "ordinary" concepts, if they do at all? The research will address these issues through a combination of laboratory studies on the nature of everyday concepts, observational studies on how words for certain concepts are used in daily conversation, and interview studies of experts on the nature of their specialized concepts. Answers to the three questions will help pinpoint limitations of the traditional theories and will provide the basis for a more complete account of what it means to have these concepts. The study of concepts has provided the foundation for many applications in the health and mental health fields, including research on the nature of diagnostic categories in psychiatry and other branches of medicine, the nature of concepts used in related fields such as biology, and the acquisition of concepts by normal and mentally retarded children. The results of this project will lead to improved theories that can provide more effective applications in these areas. The results will also be useful in designing computer systems that store information in ways compatible with what the human user knows, so that the human user can have easy and productive interactions with the computer.
