Pupil Mimicry Correlates With Trust in In-Group Partners With Dilating Pupils

Abstract

During close interactions with fellow group members, humans look into one another’s eyes, follow gaze, and quickly grasp emotion signals. The eye-catching morphology of human eyes, with unique eye whites, draws attention to the middle part, to the pupils, and their autonomic changes, which signal arousal, cognitive load, and interest (including social interest). Here, we examined whether and how these changes in a partner’s pupils are processed and how they affect the partner’s trustworthiness. Participants played incentivized trust games with virtual partners, whose pupils dilated, remained static, or constricted. Results showed that (a) participants trusted partners with dilating pupils and withheld trust from partners with constricting pupils, (b) participants’ pupils mimicked changes in their partners’ pupils, and (c) dilation mimicry predicted trust in in-group partners, whereas constriction mimicry did not. We suggest that pupil-contingent trust is in-group bounded and possibly evolved in and because of group life.

Pupil-mimicry conditions trust in partners: moderation by oxytocin and group membership

“…The sample size is comparable with our earlier study on pupil mimicry [26] as well as with studies on oxytocin and human decision-making [43,44,55,56]. In both sessions participants were placed in the role of investor, yet in one session they received oxytocin and in the other placebo (double-blind, randomized cross-over).…”

“…The eyes are crucially important during social communication and provide information to regulate interaction, express intimacy, exercise social control, and facilitate service and task goals [24]. Not surprisingly, the making of eye-contact provides a powerful mode of establishing each other's emotions and intentions [25], which can influence trust-based decisions [26]. …”

“…This pupil mimicry is already present during the first months of life [28] and is an evolutionarily old phenomenon shared with other species [29]. Recently, pupil mimicry in humans has been shown to relate to intuitive assessments of a partner's trustworthiness [26], as Dutch participants played trust-games with partners of whom just the eye region was visible and in which the pupils were manipulated to change in size. Results showed that participants' own pupils dilated synchronously with their partner's pupils.…”

Editorial: Adaptive Hot Cognition: How Emotion Drives Information Processing and Cognition Steers Affective Processing

“…For example, the perception of implicit sources such as gaze and tears and autonomic responses such as pupil-dilation, eyeblinks and blushing are all very subtle reflections of a person's inner state of mind, yet they are visible to observers and because they can hardly be controlled or regulated by the sender, they have the potential to provide important “veridical” information. Interestingly, evidence is accumulating that these kinds of expressions, such as for example observing someone's pupils dilate during eye contact, without people being aware of them, do have profound effects on social decisions that people make including whether to trust someone or not (Kret et al, 2015). Interestingly, the automatic pick-up of facial and postural emotion has become a topic of increasing interest in the literature on persuasion through emotion in advertising.…”

“…Arousal, whether evoked by looking someone deeply in the eyes (Kret et al, 2015) or by hearing a frightening sound (Lee et al) has a strong impact on emotional and cognitive processes and can have a profound positive impact on memory as well. As mentioned before, emotional information receives preferential processing, facilitating adaptive strategies for survival.…”