Disease threat increases moral vigilance across domains Nicholas Kerry1, Damian R. Murray1, Will Gervais2 Tulane University1, University of Kentucky2 Introduction Abstract Infectious disease has likely accounted for more deaths than any other factor throughout history (Inhorn & Brown, 1990). Along with the physiological immune system, a substantial body of research now demonstrates that humans have evolved dedicated cognitive, and affective mechanisms that facilitate proactive disease-mitigating behaviors (e.g., Fleischman & Fessler, 2011). There is mixed support for idea that disgust is linked to increased moral vigilance (see Landy & Goodwin, 2015). Cross-cultural work suggests that areas with greater pathogen prevalence show greater sensitivity for violations of ‘binding’ foundations - Authority, Loyalty, and Purity (Van Leeuwen et al., 2012). However, no previous research has rigorously addressed the link between disease risk and moral judgment across moral domains simultaneously. Across three tests, we examined relationships between disease risk and moral vigilance across different moral foundations. Across three studies we investigated the role of perceived disease threat in shaping moral judgment across moral domains, and hypothesized that perceived disease threat would cause people to make harsher moral judgments. All three studies found a positive relationship between dispositional worry about disease transmission and moral judgment—a relationship that was slightly stronger with vigilance towards Binding moral foundations. In Study 3, people made harsher moral judgments after being exposed to a disease threat manipulation for both binding and non-binding moral violations, relative to both a neutral and a non-disease threat manipulation. These results suggest that perceived disease threat may influence people’s moral judgments across moral domains. Figure 1: Effects of condition in Study 3. Error bars show standard error. Participants in the disease threat condition were significantly more morally vigilant than participants in both the neutral condition (3.83 vs. 3.58, 95% CI of difference [.07, .43], p = .01, Cohen’s d = 0.44), and the non-disease threat condition (3.83 vs. 3.58, 95% CI of difference [.06, .44], p = .01, Cohen’s d = 0.44). This pattern was consistent for both binding and non-binding moral vigilance. Method Results Across three studies, a total of 981 adults were recruited from the Mturk crowdsourcing website (Study 1) and through the Tulane participant pool ( Studies 2 and 3). All three studies sought to establish a correlation between perceived vulnerability to disease and moral judgment. Participants were asked to fill in the 15-item ‘Perceived Vulnerability to Disease’ questionnaire (Duncan Schaller, & Park, 2009). They were later asked to respond to 54 vignettes (Clifford et al., 2015) describing actions which could be considered immoral and state how immoral they considered the action on a five-point scale. Study 1 -Germ Aversion was weakly but significantly related to overall moral vigilance, r(473) = .12, p = .007. Study 2 - Weak but significant relationship between Germ Aversion and overall moral vigilance, r(272) = .15, p = .01. Germ Aversion significantly predicted Binding moral vigilance, r = .24, p < .001, but not non-Binding moral vigilance, r = .06, p = .30. Discussion Predictions Across three studies we found correlative evidence of a positive association between perceived vulnerability to disease (Germ Aversion) and severity of moral judgments. In one study, this correlation was present in binding but not individualizing moral foundations. In Study 3, participants primed with disease threat made harsher moral judgments, supporting a causal explanation. There was no significant difference between effects on binding and individualizing foundations. Results suggest that US adults respond to disease risk by increasing vigilance for moral judgments. This is consistent with the idea that the behavioural immune system influences moral judgment. People who perceived themselves at greater risk of disease will make harsher moral judgments. Priming disease risk will increase severity of moral judgments. In Study 3 participants were randomly assigned to one of three conditions: Disease Threat, Non-disease Threat, or Control. Later, participants were asked to respond to both the PVD questionnaire and the 54-item moral judgment questionnaire used in Studies 1 and 2. Study 3 - correlation between Germ Aversion and overall moral vigilance, r(205) = .21, p = .002. Germ Aversion was significantly associated with binding moral vigilance, r = .27, p < .001, and weakly with non-binding moral vigilance, r = .14, p = .04