Prior Beliefs not Cognitive Reflection Predict People’s Accuracy when Judging Health (Mis)Information

Health misinformation affects individual and public health decisions and erodes trust in medical institutions. Online, people are often confronted with a large variety of both evidence-based and misleading content, making credibility assessments challenging. Judgment errors are not simply the result of a lack of access to accurate information but depend on a variety of cognitive, social and affective factors. In this study, we asked a quota-representative sample of the Austrian population (N = 343) to assess the veracity and credibility of 50 health claims drawn from real-world online information. Using a signal-detection approach, we examined which individual differences predicted accuracy, perceived credibility and response bias. Results indicate that stronger belief in alternative medicine and in conspiracy theories were associated with lower accuracy, whereas cognitive reflection, motivation for cognition and intellectual humility were not. Stronger belief in alternative medicine, more trust in science, and older age were also associated with being more likely to believe any information regardless of veracity. Overall, our results point towards prior beliefs, not cognitive variables, playing a larger role in what information people choose to believe. Implications for interventions are discussed.