Almost everyone agrees that the study of emotion is one of the most confused (and still open) chapters in the history of psychology. By one estimate, more than 90 definitions of" emotion" were proposed over the course of the 20th century. If there is little consensus on the meaning of the term, it is no won der that there is much disagreement among contemporary theoreticians con cerning the best way to conceptualize emotion and interpret its role in life. In everyday human existence we con ceive of an emotion? anger, despair, joy, grief? as a feeling, an inner state. The in ternal experience of emotion is highly personal and often confusing, particular ly because several emotions may be ex perienced at the same time. Imagine, then, how difficult the objective study of emotion must be. Most of us often censor our own thoughts and feelings, and we have learned to be cautious about ac cepting other people's comments about their feelings. The empirical study of a psychological phenomenon so complex and so elaborately cloaked cannot help but present a special challenge. Compounding the distrust of verbal reports of emotion are the influences of behaviorism and psychoanalysis on psy chological research. The behaviorists of the 20th century believed that the only truly reliable, objective information ob tainable from living creatures was infor mation about their behavior. A classical