The importance of first impression judgements in interspecies interactions

Abstract

Close human-wildlife interactions are rapidly growing, particularly due to wildlife tourism popularity. Using both laboratory and ecological observation studies we explored potential interspecies communication signalling mechanisms underpinning human-animal approach behaviour, which to date have been unclear. First impression ratings (n = 227) of Barbary macaques' social and health traits were related to the macaques' facial morphology and their observed behaviour supporting a shared facial signalling system in primates. These ratings significantly predicted intended approach to the macaques during hypothetical interactions. Finally, real-world interspecies proximity was observed and found to be best predicted by the interaction between human first impression perception and animal behaviour. Specifically, perceived macaque health in interaction with actual macaque dominance drives close interactions despite human proclivity to avoid dominant animals, raising safety concerns in interspecies interactions.A growing body of evidence suggests that we automatically form first impressions of people from their faces. These first impressions are made quickly 1 , non-consciously 2 , and incidentally without instruction 3 . These first impression judgements have been shown to influence people's behaviour toward an individual, determining the initiation of positive or negative interactions 4 . For instance, dominance is considered to be a cue of a person's intentions, and a dominant person could be considered as a potential threat 5 . Although the accuracy of first impression judgements has been largely debated 5-7 , previous studies have shown that first impressions of survival-related traits, e.g. dominance, were more accurate and consistent than more subtle characteristics such as intelligence, suggesting a potential evolutionary advantage of accurate first impression judgements. First impressions are important in interactions as they allow for the prediction of future behaviour 8 , which, if these judgements are inaccurate, could lead humans to put themselves at risk. However, to date, little is known about how humans make judgements of whether and how to interact with individual non-human animals (hereafter animals), and whether these judgements are accurate.It has been suggested that humans and non-human primates (hereafter primates) have a shared personality facial signalling system, and that both species could use first impression judgements to accurately assess other primate species' social and health traits 9 . For example, naïve participants have been shown to accurately rate extraversion social traits such as dominance in chimpanzees (Pan troglodytes) from static, neutral faces when compared to personality ratings from the chimpanzees' keepers 9,10 . Japanese and rhesus macaques (Macaca fuscata & Macaca mulatta) have also been shown to have a visual attentional preference for 'trustworthy' human faces 11 . Indeed, morphometric measures of facial structure such as the facial width to height ratio (fWHR) has been e...

Understanding trait impressions from faces

“…Vice versa, humans are able to distinguish personality traits and health cues from chimpanzee faces, with judgements by strangers corresponding with zookeeper reports of the chimpanzees' behaviour (Kramer et al, 2011; Kramer & Ward, 2012). Human impressions of Barbary macaque faces also predict human intentions to approach or avoid particular individual monkeys as well as actual macaque behaviour (Clark et al, 2020). Taken together, these results are supportive of a shared primate facial signalling system.…”

Examining infantile facial features and their influence on caretaking behaviors in free-ranging Japanese macaques (Macaca fuscata)

“…Given that the research subjects were wild macaques, a non-contact method of measuring animal morphology was necessary to support the welfare of the subjects and minimize the ecological impact. Two non-contact methods have been employed to quantify wild primate faces: geometric morphometrics [ 24 , 25 ] and allometry-based methods [ 9 , 35 , 36 ]. The former approach explores principal components elucidating the comprehensive facial morphology, with the distribution of the principal component scores subsequently used to attribute meaning to each principal component.…”

Examining infantile facial features and their influence on caretaking behaviors in free-ranging Japanese macaques (Macaca fuscata)

“…We used a non-contact technique to measure the monkey faces, which assesses the proportional size of facial features based on frontal facial photographs [8, 33, 34]. This methodology facilitated data acquisition while minimizing potential stress on the subjects.…”