Bayrak, FatihKayatepe, EmreOzman, NagihanYilmaz, OnurcanIsler, OzanSaribay, S. Adil2025-05-152025-05-1520250887-04461476-8321https://doi.org/10.1080/08870446.2025.2491598https://hdl.handle.net/20.500.12469/7318Objective design:Periods of social turmoil, such as the COVID-19 pandemic, tend to amplify conspiracy beliefs, evidenced by increased vaccine hesitancy. Despite this trend, effective interventions targeting vaccine-related conspiracy beliefs remain scarce, partly due to underexplored cognitive processes. Three competing theoretical accounts offer differing predictions about the role of reflective thinking in supporting conspiracy beliefs: the Motivated Reasoning Account suggests reflection strengthens commitment to pre-existing attitudes; the Reflective Reasoning Account posits that reflection enhances belief accuracy; and the Reflective Doubt Account proposes reflection fosters general scepticism. Main outcome measures:Utilising open science practices and a validated technique to activate reflection, we conducted an experimental investigation with a diverse sample (N = 1483) segmented by vaccine attitudes. We investigated the impact of reflection on specific and generic COVID-19 conspiracy beliefs and vaccine-support behaviours across pro-vaccine, neutral, and vaccine-hesitant groups, while examining the moderating effects of scientific literacy, intellectual humility, and actively open-minded thinking. Results:The confirmatory analysis provided no direct support for the theoretical predictions. However, findings indicated that intellectual humility significantly moderated the effect of reflection, enhancing vaccine-support behaviour among participants with high intellectual humility, highlighting the complex interplay of cognitive style and prior attitudes in shaping responses to conspiracy beliefs and vaccine-support actions. Conclusion:The study highlights that while reflective thinking alone did not directly influence vaccine support behavior, its positive effect emerged among individuals with higher intellectual humility, emphasizing the importance of individual differences in shaping belief-related outcomes.eninfo:eu-repo/semantics/closedAccessConspiracy TheoriesCovid-19 Vaccine Conspiracy TheoriesVaccine HesitancyReflectionMotivated ReasoningArticleWOS:00147147200000110.1080/08870446.2025.2491598Q2Q140254737