A psychological term for an observable expression of emotion.

A person's affect is the expression of emotion or feelings displayed to others through facial expressions, hand gestures, voice tone, and other emotional signs such as laughter or tears. Individual affect fluctuates according to emotional state. What is considered a normal range of affect, called the broad effect, varies from culture to culture, and even within a culture. Certain individuals may gesture prolifically while talking, and display dramatic facial expressions in reaction to social situations or other stimuli. Others may show little outward response to social environments, expressing a narrow range of emotions to the outside world.

Persons with psychological disorders may...