This large-scale Internet-experiment tests whether vaccine-critical pages raise perceptions of the riskiness of vaccinations and alter vaccination intentions. We manipulated the information environment (vaccine-critical website, control, both) and the focus of search (on vaccination risks, omission risks, no focus). Our analyses reveal that accessing vaccine-critical websites for five to 10 minutes increases the perception of risk of vaccinating and decreases the perception of risk of omitting vaccinations as well as the intentions to vaccinate. In line with the 'risk-as-feelings' approach, the affect elicited by the vaccine-critical websites was positively related to changes in risk perception.

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It has been repeatedly shown that in decisions under time constraints, individuals predominantly use noncompensatory strategies rather than complex compensatory ones. The authors argue that these findings might be due not to limitations of cognitive capacity but instead to limitations of information search imposed by the commonly used experimental tool Mouselab (J. W. Payne, J. R. Bettman, & E. J. Johnson, 1988). The authors tested this assumption in 3 experiments. In the 1st experiment, information was openly presented, whereas in the 2nd experiment, the standard Mouselab program was used under different time limits. The results indicate that individuals are able to compute weighted additive decision strategies extremely quickly if information search is not restricted by the experimental procedure. In a 3rd experiment, these results were replicated using more complex decision tasks, and the major alternative explanations that individuals use more complex heuristics or that they merely encode the constellation of cues were ruled out. In sum, the findings challenge the fundaments of bounded rationality and highlight the importance of automatic processes in decision making.

The number of narratives influences risk judgments can potentially override statistical information about risk.

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