Explaining away the illusion of consensus

Consensus among sources often signals a claim's trustworthiness. However, when all sources simply echo information from a single origin, an "illusion of consensus" can arise, leading individuals to feel equally convinced by a dependent consensus (a single, repeatedly cited source) as by an independent consensus (corroborated information from multiple sources). This effect may occur because repetition can be perceived as a cue for credibility. We conducted four experiments to test whether a negative explanation (e.g., repetition was intended to sway opinion) or a positive explanation (repetition occurred because a source was especially reliable) for repetition of a claim could reduce or enhance the illusion of consensus. Participants engaged in a political poll-reporting task to assess confidence in claims supported by an independent consensus (news outlets citing different polling companies), a dependent consensus without explanation (news outlets citing the same polling company), or a dependent consensus accompanied by explanations intended to either boost or undermine source credibility. Independent consensus was more persuasive than dependent consensus. However, the persuasiveness of dependent consensus was increased or decreased, respectively, by positive or negative explanations for repetition. These effects were found when the explanations were supplied by the experimenter (Experiments 1-2a, 2b) and when participants generated their own explanations (Experiments 3, 4). These findings suggest that social inference processes contribute to the illusion of consensus, with implications for interventions designed to mitigate the impact of misleading claims repeated in media.