Group psychological roots of conspiracy beliefs in the UK, US, and Turkey

Many studies have investigated the proximate mechanisms of belief in conspiracies, but few have addressed their evolutionary roots. Drawing from cultural evolutionary theory, we propose that conspiracy beliefs arise from our tendency to form cultural groups, tapping into our mistrust of outgroup members and the need for belonging to a distinct group. The defining feature of conspiracies- existence of a secret group of people working on harmful purpose- is deeply associated with outgroup mistrust. Challenging mainstream perspectives, conspiracies provide a venue for conformity for nonconformists and attract reactant people (non-conformists). We tested these hypotheses using a demographically representative cross-cultural survey of over 4500 participants from the UK, US, and Turkey and employed hierarchical linear models. We used two measures of conspiracy beliefs: conspiracy mentality and belief in health conspiracies. As predicted, outgroup mistrust and psychological reactance had the largest effect sizes for belief in health conspiracies, and reactance had the largest predictive power for conspiracy mentality. Control variables such as belief in science, political orientation, religiosity, and demographic factors had minimal effects. Turkish participants had the highest conspiracy mentality and health conspiracy scores, along with higher levels of outgroup mistrust and reactance, while UK participants had the lowest. Belief in health conspiracies and conspiracy mentality were strongly associated with vaccine hesitancy across all three countries, with the highest hesitancy in Turkey. Moderation analyses revealed that outgroup mistrust was a stronger predictor of health conspiracy beliefs in Turkey, while reactance was more significant in the UK and US. These results suggest that group psychology, particularly mistrust of outsiders and the need for belonging to a distinct cultural group, plays a crucial role in conspiracy beliefs and variations in their levels across cultures. Based on these insights, we propose strategies to address conspiracy beliefs and vaccine hesitancy.