First, we need to discuss three terms that are closely intertwined: affect, emotions, and moods. Affect is a generic term that covers a broad range of feelings, including both emotions and moods. Emotions are intense, discrete, and short-lived feeling experiences that are often caused by a specific event. Moods are longer-lived and less intense feelings than emotions and often arise without a specific event acting as a stimulus.

Affect, emotions, and moods are separable in theory; in practice the distinction isn’t always defined. Psychologists have tried to identify basic emotions by studying how we express them. Cultures also have norms that govern emotional expression, so the way we recognize an emotion isn’t always the same as the way we show it. Still, many researchers agree on six universal emotions—anger, fear, sadness, happiness, disgust, and surprise. We sometimes mistake happiness for surprise, but rarely do we confuse happiness and disgust.