Behavioral and physiological sensitivity to natural sick faces

Infection detection in faces: Children's development of pathogen avoidance

“…Note: Children's unprompted comments about faces during the avoidance task (left) and the recognition task (right). These comments are consistent with reports in adults that ratings of health-related facial expressions, including affect and tiredness, are positively correlated with actual health (i.e., face donor-reported levels of sickness; Axelsson et al, 2018;Leung et al, 2023). Together, these findings are consistent with our hypothesis that children, like adults, may be sensitive to sickness-related information in faces.…”

“…One way adults recognize sickness in others is through their faces (Leung et al, 2023). Faces are readily available stimuli that can be processed rapidly from a distance (Jack & Schyns, 2015; Meissner et al, 2018); therefore, we hypothesize that accurate avoidance and detection of illness using faces may be adaptive.…”

“…In these types of studies, adults generally rated faces manipulated to appear ill, compared to healthy faces, as sicker and more negative in expression. However, to the best of our knowledge, there are only two studies in adults that have used natural sick faces (Leung et al, 2023; Tskhay et al, 2016), and none in younger populations. Natural facial sickness may be more variable and, in some cases, more subtle than artificially induced sickness, manipulated stimuli (e.g.…”

“…We examined children's (4‐ to 5‐year‐olds' and 8‐ to 9‐year‐olds') and adults' sensitivity to genuine sick and healthy face pairs measured in two ways: (1) avoidance and (2) recognition of sick people. This study is among the first to use face photos from individuals experiencing natural symptoms of illness and the same individuals when they are healthy (also see Leung et al, 2023 for a study in adults). Given children's growing understanding of cues of contagion between 4 and 9 years of age (Altman & Revenson, 1985; Myant & Williams, 2005; Williams & Binnie, 2002) and their sensitivity to other facial cues (e.g., facial identity and expression recognition: Laurence & Mondloch, 2016; Rodger et al, 2015, respectively), we hypothesized that sensitivity to facial cues of sickness would emerge in childhood (in 4‐ to 9‐year‐olds).…”

“…Another set of cues that the behavioral immune system may use to identify sickness are those conveyed in faces. Indeed, adults readily detect health from faces (Axelsson et al, 2018;Bressan, 2021;Leung et al, 2023;Regenbogen et al, 2017;Sarolidou et al, 2019Sarolidou et al, , 2020Tskhay et al, 2016). While this sickness detection system is theorized to emerge in early childhood (i.e., around 2-6 years of age; Boyer & Bergstrom, 2011;Rottman, 2014), there are few empirical tests of this hypothesis (Blacker & LoBue, 2016;Rottman et al, 2020).…”