Overconfidence in ability to discern cancer misinformation: A conceptual replication and extension

This study conducts a conceptual replication and extension of prior research on overconfidence in discerning political misinformation, shifting focusing to health. Using data from a nationally representative survey of American adults linked to web-browsing records (N = 593), we investigated the prevalence and correlates of overconfidence in this domain. Consistent with earlier findings, overconfidence was most pronounced among low-performing individuals, replicating the ``Dunning-Kruger Effect.'' However, decomposition analyses revealed that the associations between overconfidence and behavioral correlates --- exposure to low-credibility health websites and belief in cancer-related misinformation --- are primarily accounted for by deficits in actual discernment ability rather than a lack of metacognitive insight. This replication highlights the robustness of the link between poor discernment and behavioral outcomes across domains. These results highlight the need for interventions that improve evaluation skills or address underlying dispositional factors, such as distrust in science and conspiracist worldviews.