Presupposition, assertion, and epistemic vigilance across development

This study investigates how linguistic framing—specifically, the use of presupposition versus assertion—affects the critical evaluation of incoming information across development. While presuppositions present content as taken for granted, assertions introduce information as new, leading to differing levels of epistemic scrutiny. Prior work has shown that adults are less likely to detect falsehoods when they are presupposed rather than asserted. This study explores whether similar framing effects operate in childhood, and whether children's sensitivity is modulated by Information Structure—specifically, topic–focus articulation. To this end, we tested three age groups (7-year-olds, 10-year-olds, and adults) using a truth-evaluation task involving short videos and spoken sentences that either asserted, focally presupposed, or topically presupposed false information. Results revealed that across all age groups, presuppositions increased the likelihood of accepting false statements as true, indicating their potential to mislead. However, this effect varied with age: compared to adults, the impact of topical presuppositions was especially pronounced in 10-year-olds, and this stronger effect was possibly present in 7-year-olds as well. The results have implications for theories of pragmatic development, linguistic models, and practices of epistemic vigilance, with practical relevance for understanding children's susceptibility to misleading or manipulative content.