Humans’ pupillary contagion extends to cats and dogs

Abstract

When viewing pupil sizes change, our own pupil sizes change, a phenomenon known as pupillary contagion. This involuntary response is reliable between humans, but can be affected by familiarity and empathy. We investigated whether the pupillary contagion response occurs for humans viewing familiar species – cats and dogs – and whether it is modulated by preferences for particular species. Pupil sizes were measured while viewing cat, dog, and human images with small, medium, and large pupils. Trait empathy, cat and dog affiliation and experience were subsequently measured. There was an image pupil size effect, but this did not vary by species. There was greater pupil size change to cats and dogs than to humans, but this might have been due to the varying size and appearance of the cats and dogs. Greater dog affiliation was also associated with smaller overall pupil size change to dogs and larger change to humans, but this did not interact with image pupil size. Dog affiliation might be associated with less arousal to dog images. In sum, pupillary contagion responses indicate a spontaneous transfer of information about internal states and the findings suggest that humans are sensitive to this across species, regardless of individual preference.

Equivalent pupillary mimicry in younger and older adults.

“…This begs the question whether the effect would be seen with more natural, true to life, and ecologically valid stimuli—full-face photographs with natural irises and realistic pupils that include the corneal reflection. As with the present experiment, most of the previous studies that have found pupillary contagion have used eye-slit stimuli showing only the eyes, the bridge of the nose, and the brow, with artificial pupils (Axelsson & Fawcett, 2020; Carsten et al, 2019; Fawcett et al, 2016, 2017; Kret et al, 2014, 2015; Kret & De Dreu, 2017; Prochazkova et al, 2018; Wehebrink et al, 2018). Derksen et al (2018); however, found pupillary contagion with eye-slit stimuli only for conditions in which observers were viewing models of their own ethnicity.…”

“…Our first question was whether pupillary contagion would be seen in older observers as it has been in younger observers. Evidence suggests that pupillary contagion is found in diverse populations and circumstances: 4-, 6-, and 9-month-old infants who viewed eye slits (Fawcett et al, 2016, 2017), individuals with autism-spectrum disorder (Galazka et al, 2019), individuals with major depressive disorder (Wehebrink et al, 2018), and even in individuals viewing dogs and cats (Axelsson & Fawcett, 2020) though not when viewing chimpanzees (Kret et al, 2014). Given the ubiquity of pupillary contagion, we hypothesized that we would observe it in older observers.…”

Small Pupils Lead to Lower Judgements of a Person’s Characteristics for Exaggerated, but Not for Realistic Pupils

“…The pupils can change very quickly in response to minor fluctuations in luminance, cognitive processes, and arousal [ 42 , 51 , 52 ]. Some studies suggest that our eyes can sense changes in another person’s pupil sizes through mimicking the pupil size of another person or animal during social interactions [ 16 , 53 , 54 ]. However, these studies cannot reliably isolate the influence of luminance on pupil dynamics [ 55 , 56 ].…”

Can a facial action coding system (CatFACS) be used to determine the welfare state of cats with cerebellar hypoplasia?

“…These included head movements (forward, backwards or right), ears downwards or forward, pupil dilator, upper lid raiser and eyes up. Paradoxically, ears forward can signify pleasure (e.g., in mice, Mus musculus 26 ) and pupil dilation can indicate opposing states in cats (e.g., play 28 and fear 13 ) and hypervigilance in humans, 29 furthermore, dilation can also be empathic and mirror heterospecifics (e.g., humans with Canis familiaris and cats) 30 . There were no cats from the healthy‐neutral/positive category in cluster one, suggesting that this cluster of AUs, particularly those which widen and expose more of the eye 31 indicate negative emotional valence.…”