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

Arnaud Tognetti; Evelina Thunell; Marta Zakrzewska; Jonas Olofsson; Mats Lekander; John Axelsson; Mats J Olsson

doi:10.1093/emph/eoad032

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

Evol Med Public Health. 2023 Sep 27;11(1):386-396. doi: 10.1093/emph/eoad032. eCollection 2023.

Authors

Arnaud Tognetti^{1

2}, Evelina Thunell¹, Marta Zakrzewska¹, Jonas Olofsson³, Mats Lekander^{1

4

5}, John Axelsson^{1

4}, Mats J Olsson¹

Affiliations

¹ Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
² CEE-M, CNRS, INRAE, Institut Agro, University of Montpellier, Montpellier, France.
³ Department of Psychology, Stockholm University, Stockholm, Sweden.
⁴ Department of Psychology, Stress Research Institute, Stockholm University, Stockholm, Sweden.
⁵ Osher Center for Integrative Health, Karolinska Institutet, Stockholm, Sweden.

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 disease-related 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. Furthermore, 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.

Keywords: behavioral immune system; disease-related personality traits; facial cues of sickness; sex differences; sickness detection.