Convictions or plausibility judgements? The ambiguity of self-reported agreement with conspiracy theories

In three studies (ns = 582, 790, 495), we examined whether self-reported agreement with conspiracy theories primarily captures convictions (i.e., firmly held beliefs) or plausibility judgments. Such disambiguation efforts are necessary because interpreting findings in terms of conviction versus plausibility judgements can lead to divergent conclusions (e.g., about the rationality of conspiracy believers). In Study 1, most (76.9%) participants who reported complete (dis)agreement with specific conspiracy theories considered that the available evidence definitively proved their position. They also reported being relatively knowledgeable about conspiracy theories—more so than undecided participants—a pattern replicated in Study 2. In Study 3, agreement was more strongly associated with veracity (r = .92) than plausibility (r = .82) assessments. These findings suggest that extreme scores on agreement scales primarily capture convictions but that such scales capture both constructs. Finally, the absence of moderation by subjective knowledge for robust correlates of conspiracy beliefs in Study 2, together with the strong intercorrelations in Study 3, suggests that these conceptual distinctions might have limited empirical implications, and do not fundamentally question the validity of past research. That said, future research should acknowledge the heterogeneity of self-reported conspiracy beliefs when interpreting findings and designing measures.