I don't believe what you said before: Preschoolers retrospectively discount information from inaccurate speakers.

Children use speakers' past accuracy to make inferences about novel word meanings those individuals provide in the future. An open question is whether children can retrospectively reevaluate information after learning that the source was inaccurate. We addressed this question in two experiments where a speaker first introduced labels for novel objects and then revealed that she is either accurate or inaccurate in naming familiar objects. Experiment 1 showed that 3.5- to 6.5-year-olds displayed enhanced performance on a word knowledge test when they had learned novel words from a speaker who then showed herself to be an accurate labeler as opposed to an inaccurate labeler. Experiment 2 replicated this procedure but had a different speaker provide inaccurate label information. This manipulation did not affect learning, suggesting that children discount speakers and are not simply influenced by the demands of processing inaccurate information. Together, these results indicate that 3.5- to 6.5-year-olds continue to monitor the speakers' accuracy after learning new words from them, update their beliefs as accuracy data become available, and selectively retain words learned from speakers who they deem to be epistemically competent.