Across the globe, people feel more comfortable with germ-transmitting actions when interacting with individuals they value socially. This finding comes from an international study surveying 42,756 people across 61 societies on six continents, published in PNAS.
Participants feel more at ease in everyday situations that could lead to infection – like drinking from a water bottle that another person has drunk from – when the other person is a close friend rather than someone they dislike. They are also more willing to touch such individuals during greetings.
Senior author Joshua Tybur, Professor of Psychology and Infectious Disease at Vrije Universiteit Amsterdam, notes: “The pattern in our study was strikingly consistent: across all 61 societies, the willingness to accept infection risks was linked to the value people placed on the other person. Only about three percent of the variation in comfort regarding potential infection risk could be attributed to the society in which a person lived; the relationship with the person posing the infection risk played a far greater role.”
Societal differences in germ sharing behaviors
The researchers did observe some cross-societal differences. Notably, physical greeting behaviors vary from one society to another more so than comfort with behaviors like sharing a water bottle. Physical contact during greetings is relatively common in countries such as Argentina, Kenya, Peru, Brazil, and Poland, whereas it occurs less frequently in Japan, Malaysia, China, South Korea, and Finland. Greeting behavior thus appears to be influenced by local social norms more than by intuitive comfort with other behaviors than can transmit germs.
Additionally, in societies with a higher disease burden, people are less comfortable with germ-sharing behaviors with close friends than are people in low-disease-burden societies. However, disease burden did not relate to comfort with germ-sharing behaviors with strangers or people the participants disliked. This finding diverges from theories predicting that people in areas with high infectious disease burden are especially cautious toward outsiders.
Implications for public health
The findings are relevant to the spread of infectious diseases such as influenza and COVID-19. These types of diseases might spread within social networks partially because people are less inclined to reduce contact with close associates than with strangers. Consequently, health communication could aim to explicitly address risks within close social circles, precisely because people are less likely to feel motivated to avoid such risks.
More than 150 researchers contributed to the study. The hypotheses and analyses were pre-registered, and the data and analysis code used are publicly available.
You can read the PNAS-publication here.