Money for microbes—Pathogen avoidance and out‐group helping behaviour

Humans have evolved various adaptations against pathogens, including the physiological immune system. However, not all of these adaptations are physiological: the cognitive mechanisms whereby we avoid potential sources of pathogens—for example, disgust elicited by uncleanliness—can be considered as parts of a behavioural immune system (BIS). The mechanisms of BIS extend also to inter‐group relations: Pathogen cues have been shown to increase xenophobia/ethnocentrism, as people prefer to keep their societal in‐group norms unaltered and “clean.” Nonetheless, little is known how pathogen cues influence people's willingness to provide humanitarian aid to out‐group members. We examined how pathogen cues affected decisions of providing humanitarian aid in either instrumental (sending money) or non‐instrumental form (sending personnel to help, or accepting refugees), and whether these effects were moderated by individual differences in BIS sensitivity. Data were collected in two online studies (Ns: 188 and 210). When the hypothetical humanitarian crisis involved a clear risk of infection, participants with high BIS sensitivity preferred to send money rather than personnel or to accept refugees. The results suggest that pathogen cues influence BIS‐sensitive individuals' willingness to provide humanitarian aid when there is a risk of contamination to in‐group members.