Pupil dilation reflects the authenticity of received nonverbal vocalizations

Gonçalo Cosme,Trevor J Crawford,Sinead Chen,Diana Prata,Sophie Scott,Pedro J Rosa,Vânia Tavares,César F Lima,Thomas D W Wilcockson

doi:10.1038/s41598-021-83070-x

Abstract

The ability to infer the authenticity of other’s emotional expressions is a social cognitive process taking place in all human interactions. Although the neurocognitive correlates of authenticity recognition have been probed, its potential recruitment of the peripheral autonomic nervous system is not known. In this work, we asked participants to rate the authenticity of authentic and acted laughs and cries, while simultaneously recording their pupil size, taken as proxy of cognitive effort and arousal. We report, for the first time, that acted laughs elicited higher pupil dilation than authentic ones and, reversely, authentic cries elicited higher pupil dilation than acted ones. We tentatively suggest the lack of authenticity in others’ laughs elicits increased pupil dilation through demanding higher cognitive effort; and that, reversely, authenticity in cries increases pupil dilation, through eliciting higher emotional arousal. We also show authentic vocalizations and laughs (i.e. main effects of authenticity and emotion) to be perceived as more authentic, arousing and contagious than acted vocalizations and cries, respectively. In conclusion, we show new evidence that the recognition of emotional authenticity can be manifested at the level of the autonomic nervous system in humans. Notwithstanding, given its novelty, further independent research is warranted to ascertain its psychological meaning.

Highlights

Literature, laughter is an emotional expression of a positive state and has the role of promoting and maintaining social bonding[13]
Given the unprecedented examination into the autonomic nervous system’s activity during authentic discrimination and the dual-proxy nature of pupil response, we had two possible predictions alternative to the null hypothesis, one assuming a preponderance of arousal, the other of cognitive effort: (1) authentic vocalizations would elicit higher pupil dilation compared to acted, because they have been found to be more arousing in general[19,33], and pupil dilation increases with a rousal[23]; or (2) by the contrary, authentic vocalizations would elicit lower pupil dilation, because authenticity discrimination, at least in laughter, has been found to decrease the engagement of prefrontal cognitive empathy-relevant brain a reas[1,18], suggesting lower cognitive demand
In this work we asked if the process of authenticity recognition in nonverbal emotional cues induces an autonomic nervous system response in the listener

Summary

Introduction

Literature, laughter is an emotional expression of a positive state and has the role of promoting and maintaining social bonding[13]. Given the unprecedented examination into the autonomic nervous system’s activity during authentic discrimination and the dual-proxy nature of pupil response, we had two possible (directional) predictions alternative to the null hypothesis, one assuming a preponderance of arousal, the other of cognitive effort: (1) authentic vocalizations would elicit higher pupil dilation compared to acted, because they have been found to be more arousing in general[19,33], and pupil dilation increases with a rousal[23]; or (2) by the contrary, authentic vocalizations would elicit lower pupil dilation, because authenticity discrimination, at least in laughter, has been found to decrease the engagement of prefrontal cognitive empathy-relevant brain a reas[1,18], suggesting lower cognitive demand.

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