“Just Because It’s a Conspiracy Theory Doesn’t Mean They’re Not Out to Get You”: Differentiating the Correlates of Judgments of Plausible Versus Implausible Conspiracy Theories

Although conspiracy theories exhibit varying degrees of plausibility as explanations for societal events, they are typically considered epistemically problematic. Since normative ascriptions of plausibility are not essential to their definition, we sought to examine whether judgments of (im)plausible conspiracy theories have different psychological underpinnings. In two preregistered studies (N = 563), the plausibility of fictitious conspiracy theories was operationalized by pretest ratings (Study 1) or by experimentally manipulating supporting information in a belief updating paradigm (Study 2). While the general suspicious mind-set of conspiracy mentality was associated with perceiving greater plausibility in consensually plausible conspiracy theories, this was markedly stronger for implausible conspiracy theories. Cognitive variables were only negatively associated with attributing greater plausibility to conspiracy theories deemed implausible. The results suggest that a general suspicious perspective, along with limited cognitive skills and rational thinking dispositions, is related to biased plausibility judgments of conspiracy theories and the underweighting of information disconfirming them.