CONCLUSIONS

There has been significant focus on the flawed cognition associated with believing unverified conspiracies. Here we find that a tendency to reject conspiracy claims is somewhat related to cognitive sophistication, but our central conclusion is that indiscriminate disbelief, like indiscriminate belief in conspiracies, is also a marker of poor cognitive sophistication. We therefore suggest that researchers consider measuring belief in both verified (plausible) and unverified (implausible) claims, and use signal detection approaches that have already been adopted in other areas of misinformation research (e.g. fake news; Batailler et al., 2022). This might offer a valuable way to examine trade‐offs in conspiracy thinking. For example, evaluating interventions using SDT can clarify whether they lower credulity or improve conspiracy discrimination (see O'Mahony et al., 2024). Considering both response bias and discrimination could offer a richer understanding of the causes and consequences of conspiracy belief.