Why are certain individuals persistent in opposing immigration? The behavioral immune system framework implies that a psychological mechanism, which adapted to detect and avoid pathogen threats, is also reflected in contemporary social attitudes. Moreover, prejudice towards outgroups might be partially driven by implicit pathogen concerns related to the perceived dissimilarity with these groups' hygiene and food preparation practices. Disgust, a universal core emotion supposedly evolved to avoid pathogen threats, as well as olfaction, both play a pivotal role in evoking disgust. In an online study (N = 800), we investigated whether individual differences in body odor disgust sensitivity (BODS) correlate with negative attitudes towards a fictive refugee group. The data analysis plan and hypotheses were preregistered. Results show that body odor disgust sensitivity is associated with xenophobia: BODS was positively associated with negative attitudes towards the fictive group. This relationship was partially mediated by perceived dissimilarities of the group in terms of hygiene and food preparation. Our finding suggests prejudice might be rooted in sensory mechanisms.

Body odors are universal elicitors of disgust, a core emotion that plays a key role in the behavioral immune system (BIS) - a set of psychological functions working to avoid disease. Recent studies showed that body odor disgust sensitivity (BODS) is associated with explicit xenophobia and authoritarianism. In the current experimental pre-registered study (), we investigated the association between olfactory pathogen cues, BODS and implicit bias toward an outgroup (tested by an implicit association test). Results show that BODS is positively related to implicit bias toward an outgroup, suggesting that social attitudes may be linked to basic chemosensory processes. These attitudes were not influenced by background odors. Additionally, BODS was related to social, but not economic conservatism. This study extends the BIS framework to an experimental context by focusing on the role of disgust and body odors in shaping implicit bias.

Body odor disgust sensitivity (BODS) reflects a behavioral disposition to avoid pathogens, and it may also involve social attitudes. Among participants in the USA, high levels of BODS were associated with stronger xenophobia towards a fictitious refugee group. To test the generalizability of this finding, we analyzed data from 9 countries across five continents (N = 6836). Using structural equation modeling, we found support for our preregistered hypotheses: higher BODS levels were associated with more xenophobic attitudes; this relationship was partially explained by perceived dissimilarities of the refugees’ norms regarding hygiene and food preparation, and general attitudes toward immigration. Our results support a theoretical notion of how pathogen avoidance is associated with social attitudes: “traditional norms” often involve behaviors that limit inter-group contact, social mobility and situations that might lead to pathogen exposure. Our results also indicate that the positive relationship between BODS and xenophobia is robust across cultures.  

Odors are important disease cues, and disgust sensitivity to body odors reflects individual differences in disease avoidance. The body odor disgust sensitivity scale (BODS) provides a rapid and valid assessment of individual differences. Nevertheless, little is yet known about how individual differences in BODS might correlate with overall odor perception. We investigated how BODS relates to perceptual ratings of pleasant and unpleasant odors. We aggregated data from 4 experiments (total N=190) that were conducted in our laboratory, and where valence and intensity ratings were collected. Unpleasant odors were body-like odors (e.g., sweat-like valeric acid), which may provide disease cues. Pleasant odors included those associated with hygiene (e.g., lilac; a common fragrance in soap). Across experiments, we show that individuals with higher BODS levels perceived smells as more highly valenced overall: unpleasant smells were rated as more unpleasant, and pleasant smells were rated as more pleasant. These results suggest that disease avoidance is reflected in odor valence perception. Furthermore, we found that disgust sensitivity to odors coming from external sources (e.g., someone else’s sweat) was the best predictor of odor valence ratings. The BODS scale has external validity as it reflects odor valence perception.