Wiktionary
n. (context psychology English) External show of emotion or affect, such as by voice, expression, gesture, or posture, whether voluntary or not.
Wikipedia
In psychology, affect display or affective display is a subject's externally displayed affect. The display can be by facial, vocal, or gestural means (APA 2006, p. 26). When displayed affect is different from the subjective affect, it is incongruent affect. Some professionals use the term "affect" to mean "affect display".
Affect display refers to the impetus for observable expression of emotion; for the human being that expression or feeling displayed to others through facial expressions, hand gestures, tone of voice and other emotional signs such as laughter or tears is a part of a series of non-conscious or conscious cognitive events. Many aspects of the expressions vary between and within cultures and are displayed in various forms ranging from the most discreet of facial expressions to the most dramatic and prolific gestures (Batson, 1992).
Affect display is also a critical facet of communication in the social domain. Interpersonal communication is colored by displayed affect and there are various theories on affective reactions to stimuli to include conscious and non-conscious reaction and positive or negative affect.