ABSTRACT
Emotion is a construct of the relationship among affect (subjective feelings), physiological arousal, facial expressions, action readiness, and behaviors that achieves the aim of an emotion. Emotions evolved to cope with enduring environmental challenges that threatened human survival. Common emotions are happiness, love, surprise, sadness, fear, anger, disgust, and self-conscious emotions (embarrassment, shame, guilt, pride). Physiological arousal provides information for affect and for fight or flight responses. The valence of a stimulus determines whether an emotion is positive or negative. The strength of a challenging stimulus determines the intensity and duration of an emotion. Positive and negative moods are a milder and longer form of emotional affect. Stimuli creating mood changes have a gradual and subtle beginning, such as hour of the day, day of the week, and season of the year.
