Interpersonal Pupillometry: The Pupil as an Indicator of Emotion and Its Utility as a Social Cue

When interacting with others, people rely on verbal and nonverbal cues; one such cue is pupil size. This chapter examines the social elements of pupil size and its perceived and actual utility as a cue in social interactions. The chapter begins with a review of the literature regarding the role of emotion on pupil size and the extent to which pupil size acts as a reliable indicator of emotional states. The chapter considers not only how pupillary size might vary but also how this alteration might be unconsciously detected and mirrored by conversational partners (pupillary contagion). Finally, the chapter considers how pupillary dilation influences the interpersonal judgments of others. These topics include how variations in pupil size result in drawing conclusions regarding others’ emotional states, attentional allocation, impression formation, and attraction. While the literature on how pupil size is impacted and influences social interactions is still in its nascent stages, this chapter provides a review of the area and suggestions for future research.