Emotion
Most people have little problem recognizing and identifying when we are having an emotion. However, emotion is one of the most difficult concepts in Psychology to define. In fact, emotion is such a difficult concept to define adequately that there are at least 90 different definitions of emotions in the scientific literature. A simple definition of emotion is that it is a response by a whole organism, involving (1) physical arousal, (2) expressive behaviors, and (3) conscious experience.