Human emotions are complex. They express positive or negative reactions to external and internal stimuli. According to modern psychology, emotion, behavior and cognition influence each other. Thus, each emotion distinctly affects human motivation, nervous function, learning, physical acts, physiological arousal and communication with others. Sadness, for instance, is an emotion that causes a person to cry and withdraw from social circles, while surprise is an emotion that causes a person to sigh and raise their eyebrows, and the emotion of anger causes trembling and aggressive behavior.
Robert Plutchik, Paul Ekman, Wallace Friesen, Carrol Izard and Silvan Tomkins are among the names that have made significant contributions to the study and classification of human emotions. They believe that certain emotions are basic or primary. According to respected psychologist Paul Ekman, the basic emotions are: sadness, happiness, anger, fear, disgust, and surprise. These emotions combine in different ways to form other emotions, including compassion, boredom, embarrassment, rage, hunger, and more.
Through their studies, Plutchik and Ekman confirmed the evolutionary nature of emotions, a topic previously discussed in detail by Charles Darwin. Like Darwin, Plutchik believed that emotions evolved for the sake of human survival and reproduction. Ekman agreed with Darwin, as well: After studying an isolated tribe in Papua New Guinea, he concluded that some emotions are universal and innate. Research like this proves that emotions affect and shape the essence of life for mankind. It is no wonder that psychology, neuroscience,ethics, sociology, and metaphysics, among other fields, all deal with the study of human emotions.