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Behavioural Immune System;COVID-19;Disgust Sensitivity;Political Affiliation;Vigilance;Visual Discrimination


Lori Buchanan



Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


The behavioural immune system (BIS) is a coordinated set of cognitive, affective, and behavioural responses that minimize pathogen contact. Prior to the COVID-19 pandemic, the majority of research on the BIS was limited to situations of acute pathogen threat. These studies identified that personal predispositions and environmental stimuli interact and lead to cognitive changes, including perceptual enhancements and attentional biases, as well as sensations of disgust. The cognitive and affective changes that follow pathogen exposure motivate pathogen avoidance behaviours and reduce the risk of infection. The BIS is highly adaptive in the context of acute pathogen threat, but less is known about its responsiveness when the pathogen threat is chronic. The primary objective of the current study was to explore how chronic BIS activation impacts visual vigilance. Cross-sectional data were collected at four timepoints within the first seven months of the COVID-19 pandemic (i.e., April, June, August, and October 2020). Participants completed two visual discrimination tasks, one with pathogen-relevant stimuli (i.e., faces) and the other with pathogen-irrelevant stimuli (i.e., shapes); accuracy and reaction times were used as objective measures of vigilance. Participants also completed a questionnaire to gather information about their demographics, predispositions toward pathogen avoidance (i.e., disgust sensitivity), and COVID-19 experiences. Participants that enrolled in the study in August and October were also asked to self-report their political affiliation. Only participants currently living in the United States were included in data analyses. Results indicated that participants with high disgust sensitivity were less vigilant than those with low disgust sensitivity at later timepoints regardless of whether visual discrimination stimuli were pathogen-relevant (Experiment 1) or pathogen-irrelevant (Experiment 2). Discrimination accuracy on trials that required the detection of subtle differences between stimuli was greater at earlier timepoints than later timepoints for both disgust sensitivity groups. Experiment 3 investigated visual vigilance differences between participants with self-reported liberal and conservative political affiliations. Results indicated that liberals displayed greater vigilance on both visual discrimination tasks than conservatives. Disgust sensitivity, conservatism, and anxiety about contracting COVID-19 were positively correlated. Supplementary analyses indicated that participants with high disgust sensitivity and conservative political values were more likely to be diagnosed with COVID-19 and endorse COVID-19 symptoms than participants with low disgust sensitivity and liberal political values, respectively. This study demonstrated that BIS responding is dynamic and chronic BIS activation is associated with a decline in vigilance. Importantly, vigilance changes across timepoints did not correspond with the number of active COVID-19 cases, indicating that factors beyond pathogen contact risk influence chronic BIS activation. A comparison of previous literature with the current findings suggests that the personal characteristics that enhance BIS responding in acute settings, may dampen BIS responding following chronic activation (i.e., disgust sensitivity, conservative values). Overall, the results of this study expand current understanding of BIS functioning in the context of prolonged pathogen threat.