Heuristics for Truth Across the Lifespan

Misleading claims surround us – we encounter them in news stories, advertising campaigns, and political propaganda. How do people separate facts from fiction? Decades of work implicate fluency, or subjective ease. Repeated statements feel easier to process, and thus more truthful, than new ones (i.e., illusory truth). This dissertation identifies additional cues for truth and takes a lifespan perspective. Older adults accumulate impressive amounts of knowledge (which may protect them), but also unduly attend to positive information (which may leave them vulnerable to emotional appeals). In two experiments, older adults exhibited illusory truth only when they lacked knowledge about claims, unlike young adults. Three additional experiments encouraged young adults to “stick with” what they knew. Evaluating truth at exposure prompted young adults to use their knowledge later, wiping out the illusion. Three final experiments disproved the idea that positivity “feels like” truth. Young adults exhibited a negativity bias, where negative faces made claims seem less true than neutral ones. Neither positive nor negative faces swayed older adults’ judgments. These results inform many theoretical perspectives – from fluency and referential theories of truth, to dual-process and socioemotional selectivity theories of aging. They also have important practical implications for preventing and correcting misconceptions in a “post-truth world,” where falsehoods travel farther and faster than the truth.