How do people assess the truth of partially-familiar claims, relative to both familiar and unfamiliar claims?

Abstract

People rate familiar claims as more true than unfamiliar claims, possibly because familiarity makes these claims feel easier to process. But little is known about how people assess the truth of claims that consist of a combination of familiar and unfamiliar information. It is important to know how people assess such “partially-familiar” claims because false claims often contain a familiar “kernel of truth” that may make the claim as a whole seem more believable. If this were the case, we would expect people to rate more partially-familiar claims true than unfamiliar claims, yet fewer than familiar claims. Across three experiments, we investigated how people assess the truth of partially-familiar claims, relative to both familiar and unfamiliar claims. We found that people classified more familiar claims as true than unfamiliar claims, and roughly the same number of partially-familiar claims true as unfamiliar claims. In other words, we replicated the known finding that people inflate their judgements of truth for familiar claims compared with unfamiliar claims; however, we found no evidence that a “kernel of truth” similarly inflates people’s judgements. This research contributes to our understanding of how people decide whether a claim is true.