Valence, as used in psychology, especially in discussing emotions, means the intrinsic attractiveness/"good"-ness (positive valence) or averseness/"bad"-ness (negative valence) of an event, object, or situation. The term also characterizes and categorizes specific emotions. For example, emotions popularly referred to as "negative", such as anger and fear, have negative valence. Joy has positive valence. Positively valenced emotions are evoked by positively valenced events, objects, or situations. The term is also used to describe the hedonic tone of feelings, affect, certain behaviors (for example, approach and avoidance), goal attainment or nonattainment, and conformity with or violation of norms. Ambivalence can be viewed as conflict between positive and negative valence-carriers.
Theorists taking a valence-based approach to studying affect, judgment, and choice posit that emotions with the same valence (e.g., anger and fear or pride and surprise) produce a similar influence on judgments and choices. Stress is negative valence and opposite of this is pleasure or happiness. Stress can mean all unpleasant emotions.
The term entered English in psychology with the translation from German ("Valenz") in 1935 of works of Kurt Lewin.
Valence is one criterion used in some definitions of emotion. The possible absence of valence is cited as a reason to exclude surprise from the list of emotions, though some would include it. Trnka (2012) suggested in his research assess "the valence of 10 given negative emotions - disgust, anger, sadness, fear, contempt, hate, disappointment, jealousy, envy and guilt."
Valence could be assigned a number and treated as if it were measured, but the validity of a measurement based on a subjective report is questionable. Measurement based on observations of facial expressions, using the Facial Action Coding System and microexpressions (see Paul Ekman) or muscle activity detected through facial electromyography, or on modern functional brain imaging may overcome this objection. Emotional valence is represented in right posterior superior temporal sulcus and medial prefrontal cortex.