Discriminating between sick and healthy faces based on early sickness cues: an exploratory analysis of sex differences

Abstract

Background and objectives It has been argued that sex and disease-related traits should influence how observers respond to sensory sickness cues. In fact, there is evidence that humans can detect sensory cues related to infection in others, but lack of power from earlier studies prevents any firm conclusion regarding whether perception of sickness cues is associated with sex and personality traits. Here, we tested whether women (relative to men), individuals with poorer self-reported health, and who are more sensitive to disgust, vulnerable to disease, and concerned about their health, overestimate the presence of, and/or are better at detecting sickness cues. Methodology In a large online study, 343 women and 340 men were instructed to identify the sick faces from a series of sick and healthy photographs of volunteers with an induced acute experimental inflammation. Participants also completed several disease-related questionnaires. Results While both men and women could discriminate between sick and healthy individuals above chance level, exploratory analyses revealed that women outperformed men in accuracy and speed of discrimination. Further, we demonstrated that higher disgust sensitivity to body odors is associated with a more liberal decision criterion for categorizing faces as sick. Conclusion Our findings give strong support for the human ability to discriminate between sick and healthy individuals based on early facial cues of sickness and suggest that women are significantly, although only slightly, better at this task. If this finding is replicated, future studies should determine whether women's better performance is related to increased avoidance of sick individuals.

Olfactory Cues of Naturally Occurring Systemic Inflammation: A Pilot Study of Seasonal Allergy

“…Infectious diseases and noninfectious conditions may produce similar phenotypic changes in humans through common physiological processes, such as inflammation [8]. For example, in studies using an experimental endotoxemia model, individuals are injected with a bacterial endotoxin (lipopolysaccharide [LPS]).…”

“…Akin to an infection, an LPS injection triggers an increase in body temperature and circulating pro-inflammatory cytokine levels (such as IL-6, IL-8, TNF-α) [9]. Relative to a saline injection, an LPS injection results in discernible changes to one's facial appearance [8,[10][11][12][13], gait [14,15], and body odour [16][17][18]. These changes are perceived as unpleasant and unhealthy by others [11,12,16,17] and may serve as a cue for avoidance [11,17].…”