ABSTRACT
RATIONALE: Vaccines save lives. Despite the undisputed value of vaccination, vaccine hesitancy continues to be a major global challenge, particularly throughout the COVID-19 global pandemic. Since vaccination decisions are counter-intuitive and cognitively demanding, we propose that vaccine hesitancy is associated with executive function-a group of high-level cognitive skills including attentional control, working memory, inhibition, self-regulation, cognitive flexibility, and strategic planning. OBJECTIVE: We set out to test (i) whether vaccine hesitancy is driven by individual differences in executive function beyond established socio-demographic factors (e.g., education, political orientation, gender, ethnicity, age, religiosity) and depressed mood, and (ii) whether this relationship is exacerbated by situational stress. METHODS: Two studies were conducted with U.S. residents. Using a cross-sectional design, Study 1 examined the associations between executive function, socio-demographic factors, COVID-19 conspiracy beliefs, trust in health authorities, and COVID-19 vaccine hesitancy. Using an experimental design, Study 2 focused solely on unvaccinated individuals and tested the interactive effect of executive function and stress on willingness to receive a COVID-19 vaccine. We used ordinal logistic regressions to analyze the data. RESULTS: Individual differences in executive function predicted participants' COVID-19 conspiracy beliefs, trust in health authorities, and their willingness to vaccinate against COVID-19. Importantly, the unique contribution of executive function to vaccine hesitancy could not be explained by socio-demographic factors or depressed mood. Furthermore, Study 2 revealed that weaker executive function had detrimental effects on COVID-19 vaccine acceptance and trust in health authorities mainly under heightened stress. CONCLUSIONS: Individual differences in executive function and situational stress jointly impact COVID-19 vaccination decisions and need to be considered together when designing health communications aimed at reducing COVID-19 vaccine hesitancy. Interventions that lower stress and promote trust have the potential to increase vaccine acceptance, especially for individuals with weaker executive function.