Equivalent pupillary mimicry in younger and older adults.

Abstract

Pupillary contagion is a form of autonomic mimicry in which faces with dilated pupils elicit larger pupils in observers whereas faces with constricted pupils elicit smaller pupils. Autonomic reactivity may be fundamental to higher order social processes, yet older adults may be less likely to register other's autonomic signals. We explored pupillary contagion in younger and older adult observers. We presented younger and older observers with partial-face photographs of women with the pupils manipulated to be small, medium, or large. The faces were either young (20s) or old (70s). There were two tasks: To judge the model's age and to judge which pupil was larger. In the pupil judgment task, the magnitude of response was lower in older adults than in younger adults, but both younger and older observers showed equivalent pupillary contagion. In the age judgment task, which did not draw attention to the pupils, we found no evidence of pupillary contagion in either age-group. Registration of the autonomic signal of pupil dilation does not appear to be impaired in older adults. Public Significance StatementThe autonomic nervous system (ANS) regulates involuntary physiological processes such as heart rate, blood pressure, respiration, sexual arousal, and pupillary dilation. ANS activation and deactivation can provide important information about a person's state and often lead to mimicry of the state by an observer, either consciously or nonconsciously. Here, we ask whether one aspect of that nonverbal dyadic signaling is maintained into old age: Are pupillary dilation and contraction in a target reciprocated by similar or different changes in younger and older observers?

Electrophysiological concomitants of pupillary synchrony

“…The task involved a very simple perceptual judgment that specifically focused the observer on the pupils. We made these choices because we wanted a powerful manipulation and because we had found previously that these stimuli reliably elicited pupillary synchrony (Hartley & Reed, 2022). Pupillary synchrony has frequently been studied with richer stimuli—entire faces— and tasks involving social appraisal such as emotion recognition (e.g., Harrison et al, 2006) or judgments of trust (e.g., Prochazkova et al, 2018b).…”

“…It has been found with judgments of emotion (Harrison et al, 2006), responses indicating trust in the target (Prochazkova et al, 2018b), judgments of pupil size (Carsten et al, 2019;Hartley & Reed, 2022), and when there is no task specified (Axelsson & Fawcett, 2021;Derksen et al, 2018, Experiment 1;Fawcett et al, 2016Fawcett et al, , 2017Fawcett et al, , 2022Hess, 1975;Simms, 1967). Hartley and Reed (2022) found pupillary synchrony when the task was to judge pupil size, but not when the task was to judge the target's age. Again, the relation between task and pupillary synchrony remains unclear.…”

“…Since then, pupillary synchrony has been found in diverse populations and circumstances: 4-to 18-month-old infants (Aktar et al, 2020;Fawcett et al, 2016;Fawcett et al, 2017), older adults (Hartley & Reed, 2022), individuals with autism-spectrum disorder (Galazka et al, 2019), individuals with major depressive disorder (Wehebrink et al, 2018), and even in humans viewing dogs and cats (Axelsson & Fawcett, 2021). Kang and Wheatley (2017) found that synchrony between observer and target was greatest at independently rated emotional peaks in videos of autobiographical memoirs.…”

“…Kret et al (2014) found than humans showed pupillary synchrony to human but not chimpanzee targets and conversely for chimpanzees. However, Aktar et al (2020) found no effect of same‐different ethnicity either in infants or in their parents and Hartley and Reed (2022) found no same‐different age group effect in pupillary synchrony for younger and older observers responding to younger and older targets. Simms (1967) reported the opposite of an ingroup effect, with female targets eliciting pupillary synchrony in male observers and vice versa.…”