Rationality in conspiracy beliefs: the role of perceived motive.

Previous work has raised the possibility that the perception of motive may contribute to conspiracy beliefs. The current study tested the prediction that conspiracy beliefs will strengthen as the apparent motive of the alleged conspirators strengthens. Participants (N = 57) rated the plausibility of fictional conspiracy theories, manipulated for the strength of direct evidence for the conspiracy and the type of outcome (gain vs. no gain) experienced by the alleged conspirators after the event. Ratings revealed that participants were more likely to believe conspiracy claims not only if the evidence was strong but also if the apparent motive was high, and that the effect of apparent motive was independent of the strength of the evidence. The findings suggested that information about apparent motive may help create and sustain conspiracy beliefs.