Problems in Defining Emotion
The word "emotion" comes from the Latin emovere, which means to stir up, agitate, or excite.
The language of every literate culture includes hundreds of words that describe feelings or emotions.
It is easy to identify intense reactions of fear, anger, grief, or joy as emotions.
There is general agreement that joy differs from sorrow and that disgust is unlike pleasure.
Nevertheless, students of behavior have faced problems in attempting to formulate a precise definition of emotion. It would seem that the person who experiences some emotion could be used as the source for an accurate description and definition of the state. However, two people experiencing joy, for example, may provide strikingly different descriptions of feeling joyful.
Also, an outside observer might protest that joy was not really aroused, and that the individual was not really very happy.
Thus individuals who claim to experience the same emotion may describe dissimilar feelings, and an outside observer may insist that neither is describing what the observer has in mind for the particular emotional feeling.
Late in the 19th century, scientists believed that they could solve the dilemma by studying the physiological reactions that occur during emotional experiences. Subsequent research, however, indicated that even this approach does not provide a precise definition. It has been found that different emotions show highly similar physiological reactions. In many instances the physiologist can tell that an emotional reaction is occurring, but he cannot determine exactly which emotion the individual is experiencing.
Another theory of emotion was proposed in the 19th century by Charles Darwin. His investigation of evolution led him to believe that man's behavior contains residuals of responses that had been necessary in lower forms of animals and in earlier times for man but are no longer as essential for survival. In 1872 he compared certain emotional expressions in man to the role of such reactions in animals. He pointed out that baring the teeth was typical in animals when preparing to fight, and he saw a relationship between this and man's tendency to bare his teeth when extremely angry. Darwin concluded that there is something very primitive about emotion. His theory has not been generally useful to psychologists.