Children show heightened knew-it-all-along errors when learning new facts about kinds: Evidence for the power of kind representations in children's thinking.

Several proposals in the literature on conceptual development converge on the claim that information about kinds of things in the world has a privileged status in children's cognition, insofar as it is acquired, manipulated, and stored with surprising ease. Our goal in the present studies (N = 440) was to test a prediction of this claim. Specifically, if the early cognitive system privileges kind (or generic) information in the proposed ways, then learning new facts about kinds should be so seamless that it is often accompanied by an impression that these facts were known all along. To test this prediction, we presented 4- to 7-year-old children with novel kind-wide and individual-specific facts, and we then asked children whether they had prior knowledge of these facts. As predicted, children were under the impression that they had known the kind-wide facts more often than the individual-specific facts, even though in reality they had just learned both (Experiments 1, 2, 3, and 5). Importantly, learning facts about (nongeneric) plural sets of individuals was not similarly accompanied by heightened knew-it-all-along errors (Experiment 4), highlighting the privileged status of kind information per se. Finally, we found that young children were able to correctly recognize their previous ignorance of newly learned generic facts when this ignorance was made salient before the learning event (Experiment 6), suggesting that children's frequent knew-it-all-along impressions about such facts truly stem from metacognitive difficulties rather than being a methodological artifact. In sum, these 6 studies indicate that learning information about kinds is accompanied by heightened knew-it-all-along errors. More broadly, this evidence supports the view that early cognition privileges kind representations.