Emotion is for influence
Functional approaches to emotion are rapidly gaining in popularity. Thus far the functions of emotions have been conceptualised and studied mainly at the intrapersonal level of analysis, the key question being how individuals are influenced by the emotions they experience. Relatively little is known about the interpersonal effects of emotions; that is, how one person's emotions influence other people's cognitions, attitudes, and behaviours. We propose that a primary function of emotion at this interpersonal level of analysis is to engender social influence. Our analysis is informed by emotion as social information theory (EASI; Van Kleef, 2009). This theory posits that emotional expressions produce interpersonal effects by triggering affective reactions and/or inferential processes in targets, depending on the target's information processing and the perceived appropriateness of the emotional expression. We review supportive evidence from various domains of social influence, including negotiation, leadership, attitude change, compliance, and conformity in groups. We consider the viability of emotional expressions as tools of social influence, discuss the functional equivalence of various forms of emotional expression, and address implications for theorising about emotion regulation and the functionality and evolution of emotion.