Alpha-Band Suppression Reveals a Tightening of Social Norms Caused by Pathogen Threat

Pathogen contamination poses a great threat to both individuals and societies. As a consequence, people may become more vigilant towards deviant behavior to protect themselves against such contamination. Indeed, prior work shows that when the threat of pathogens is imminent, people often protect themselves from contamination by avoiding others who may go against social norms. However, other theories suggest that social norms may be stricter in contexts with greater threat in order to enable social coordination to deal with the threat. Although these two theories predict greater threat will be associated with stricter norms, they suggest different mechanisms for how individuals may deal with the threat. Specifically, the first would suggest avoidance of others, while the second would entail social coordination. Importantly, both these adaptive mechanisms may be at play, but may be used to a different extent based on individual differences in relational orientations and perceptions of vulnerability to disease. Here, we tested two distinct neural components: (i) detection of norm-violating behaviors (captured by an N400 event-related potential component) and (ii) increased vigilance (indexed by alpha suppression). 58 American undergraduates received a pathogen threat or control prime and then were asked to judge how violating a series of behaviors (e.g., crying) were in various settings (e.g., funeral or class lecture) that were pre-tested to be normal or norm violations respectively. Norm-violating (vs. normal) behaviors elicited a stronger negative deflection of electro-cortical response around 400ms post-stimulus (called the N400). This component indicates that norm violations were seen as more incongruent than normal behaviors. Supporting our hypothesis, the N400 base to peak amplitude was significantly greater for norm violating versus normal behaviors in the pathogen threat (versus control) condition. Moreover, Alpha-band (8-10.5Hz) power was suppressed (indicating greater vigilance) for the norm-violating (vs. normal) conditions, indicating participants were more vigilant of norm violations than normal behaviors. Interestingly, in the pathogen threat condition, this vigilance effect became less pronounced for people high in interdependent self-construal, fear of negative evaluation, need to belong, and germ aversion. Curiously, the N400 for norm-violating (vs normal) behaviors was uninfluenced by these variables. Our data suggest that pathogen threats induce heightened vigilance to deviant behaviors, although this is primarily driven by those low on perceptions of disease vulnerability and need to belong. Our data demonstrate two important neural signatures (N400 and alpha band suppression) that may constitute a crucial part of the behavioral immune system against pathogen contamination. Future work should test how those high in perceptions of vulnerability to disease and need to belong may cope with threat since they are not more vigilant to norm violations.