Testimony and observation of statistical evidence interact in adults' and children's category-based induction

Hearing generic or other kind-relevant claims can influence the use of information from direct observations in category learning. In the current study, we ask how both adults and children integrate their observations with testimony when learning about the causal property of a novel category. Participants were randomly assigned to hear one of four types of testimony: generic, quantified "all", specific, or only labels. In Study 1, adults (N = 1249) then observed that some proportion of objects (10%-100%) possessed a causal property. In Study 2, children (N = 123, M_age = 5.06 years, SD = 0.61 years, range 4.01-5.99 years) observed a sample where 30% of the objects had the causal property. Generic and quantified "all" claims led both adults and children to generalize the causal property beyond what was observed. Adults and children diverged, however, in their overall trust in testimony that could be verified by observations: adults were more skeptical of inaccurate quantified claims, whereas children were more accepting. Additional memory probes suggest that children's trust in unverified claims may have been due to misremembering what they saw in favor of what they heard. The current findings demonstrate that both child and adult learners integrate information from both sources, offering insights into the mechanisms by which language frames first-hand experience.