In three experiments children aged between 3 and 5 years (N = 38; 52; 94; mean ages 3;7 to 5;2) indicated their confidence in their knowledge of the identity of a hidden toy. With the exception of some 3-year-olds, children revealed working understanding of their knowledge source by showing high confidence when they had seen or felt the toy, and lower confidence when they had been told its identity by an apparently well-informed speaker, especially when the speaker subsequently doubted the adequacy of his access to the toy. After a 2-minute delay, 3-to 4-year olds, unlike 4-to 5-year-olds, failed to see the implications of the speaker's doubt about his access.Working understanding of knowledge sources 3 Children's Working Understanding of Knowledge Sources: Confidence in Knowledge Gained from TestimonyThe ability to recall or infer how we know something is crucially important for assessing the accuracy of our knowledge (Johnson, Hashtroudi & Linsday, 1993).Suppose a companion on a country walk reports spotting an unusual bird that I failed to notice. I have no reason to doubt her, and so I believe that this particular bird was indeed in the area. However, that evening my companion mentions that she was not wearing her glasses on the walk. If I recollect that she was the source of my belief about the bird's presence, I might now be less sure of its truth: I thought she had seen the bird adequately to identify it and differentiate it from a more common variety, but now I find that she had not. In contrast, if I do not recollect how my belief was acquired, I will draw no such implication from her comment about the missing glasses. I will continue to treat my belief as factually true. Importantly, this kind of source-identification and evaluation allows adults to keep a check on the likely truth of their knowledge even in the absence of contradicting information. Note that in this example I had no independent information that the bird was not present, but nevertheless I had good grounds for reducing my confidence in my belief that it was.The need to engage in such source identification and evaluation arises early in childhood. As children's mastery of language increases, they need skills to assess the likely truth of what they are told in order to benefit fully from other people's experience of the world. This holds not just at the time of originally hearing an utterance, but also, as in the example above, subsequently, once the information conveyed has become part of their own knowledge base. Without such skills, children will be at risk of believing what is false or disbelieving what is true. Working understanding of knowledge sources 4In the research reported below we examined how 3-to 5-year-old children behaved in circumstances similar to the example above. A speaker appeared to have seen a hidden toy before telling the child its color, or to have felt before telling the child whether it was hard or soft. After the child believed what she was told, the speaker doubted that he had felt or looked properly...

An established finding is that adults prefer to guess before rather than after a chance event has happened. This is interpreted in terms of aversion to guessing when relatively incompetent: After throwing, the fall could be known. Adults (N=71, mean age 18;11, N=28, mean age 48;0) showed this preference with imagined die‐throwing as in the published studies. With live die‐throwing, children (N=64, aged 6 and 8 years; N=50, aged 5 and 6 years) and 15‐year‐olds (N=93, 46) showed the opposite preference, as did 17 adults. Seventeen‐year‐olds (N=82) were more likely to prefer to guess after throwing with live rather than imagined die‐throwing. Reliance on imagined situations in the literature on decision‐making under uncertainty ignores the possibility that adults imagine inaccurately how they would really feel: After a real die has been thrown, adults, like children, may feel there is less ambiguity about the outcome.