People who endorse implausible conspiracy theories prefer complexity to simplicity

Conspiracy theories are often appealing despite their complexity. Here, we examine whether conspiracy theories are appealing precisely because of their complexity, which allows them to maximise the likelihood of (i.e., “overfit”) immediate data and hence minimise epistemic uncertainty. Specifically, we test the hypothesis that individuals who endorse conspiracy theories tend to have a domain-general preference for complex explanations over simpler ones. In two-preregistered studies (N Study 1 = 246; N Study 2 = 794), participants viewed scatterplot data together with curves differing in complexity (polynomial degree). Participants selected the curve that they believed best represented the data. Participants who endorsed implausible conspiracy theories preferred complex over simpler curves, even when the simpler curves did not provide objectively lower goodness-of-fit. We conclude that conspiracy belief is linked to a domain-general complexity preference that results from a need to minimise epistemic uncertainty.