Contribution of rationality to vaccine attitudes: Testing two hypotheses.

Although previous studies have demonstrated an association between vaccine attitudes and cognitive biases, often resulting in vaccination hesitancy, the exact contribution of rationality has not been fully clarified. We tested two hypotheses regarding the impact of rationality on vaccine attitudes stemming from bounded and expressive rationality. We focused on parental vaccine attitudes operationalized by the affective, behavioral, and cognitive attitude components and investigated how these are influenced by disillusionment toward authorities and ability to engage in rational thinking operationalized using cognitive reflection and heuristics and biases tasks. The study was of a cross-sectional correlational design with a non-probabilistic sample of 823 volunteer participants surveyed online in April and May 2018 in Croatia. The results identified disillusionment toward authorities as a predictor of all components. Furthermore, performance on heuristics and biases tasks also predicted the affective and cognitive, but not the behavioral component, whereas cognitive reflection had no impact on vaccine attitudes. Next, a moderation effect of disillusionment toward authorities on the association between the omission bias task and all attitude components was identified. Parents with low disillusionment demonstrated positive vaccine attitudes regardless of their rationality, whereas for parents with high disillusionment a significant positive correlation between performance on the omission bias task as assessed with a vaccination vignette and attitudes was identified. This suggests that the ability to resist vaccine specific omission bias, that is, higher rationality, can decrease the negative effects of disillusionment, which supports the bounded rationality hypothesis.