We experience happiness when we get a raise at work, surprise when we bump into an old classmate, disgust when we smell something rotten, and fear when we see a nightmare. Human emotions help us cope with everyday life, allowing us to communicate what we feel toward certain situations, people, things, thoughts, senses, dreams, and memories.
Many psychologists believe that there are six main types of emotions, also called basic emotions. They are happiness, anger, fear, sadness, disgust, and surprise. Happiness is our reaction to the positive, as disgust is to the revolting and surprise is to the unexpected. Similarly, we react to aversion through anger, to danger through fear, and to difficulty or loss through sadness.
All other emotions are varieties of basic emotions. Depression and grief, for instance, are varieties of sadness. Pleasure is a variety of happiness, and horror is a variety of fear. According to psychologist Robert Plutchik, secondary emotions form by combining varying degrees of basic emotions. Thus, surprise and sadness produce disappointment, while disgust and anger produce contempt. Multiple emotions can produce a single emotion, as well. For instance, anger, love, and fear produce jealousy.
Each emotion is characterized by physiological and behavioral qualities, including those of movement, posture, voice, facial expression, and pulse rate fluctuation. Fear is characterized by trembling and tightening of the muscles. Sadness tightens the throat and relaxes the limbs. Surprise is a particularly interesting emotion, characterized by gaping eyes and a dropped jaw, which only lasts a moment and is always followed by another type of emotion.