…young children are readily inclined to believe extraordinary claims, such as that there are invisible organisms on your hands that can make you ill and that you need to wash off, and that there is a man who visits you each 24th December to bring presents and candy if you are nice (see e.g., Harris & Koenig, 2006, Child Development, 77, 505 – 524). But children are not blindly credulous either, as Reid supposed. In a series of experiments, Harris could show that even children of 24 months pay attention to the reliability of the testifier. When they see two people, one of which systematically misnames known objects (e.g., saying “that’s a bear”, while presenting a bottle), toddlers are less likely to trust later utterances by these unreliable speakers (when they name unfamiliar objects), and more likely to trust people who systematically gave objects their correct names (see e.g., Paul L. Harris and Kathleen H. Corriveau Phil. Trans. R. Soc. B 2011 366, 1179-1187.) Experiments by Mills and Keil show that 6-year-olds already take into account a testifier’s self-interest: they are more likely to believe someone who says he lost a race than someone who says he won it (Candice M. Mills and Frank C. Keil Psychological Science 2005 16: 385).
The reliability of witnesses is a crucial element when young children gauge testimony, not so much whether or not the information squares with their experience (the Humean account). In a way this makes sense, especially for children, who regularly learn new information that is not in line their prior experience and beliefs, and may sometimes even apparently conflict with it, e.g., the first-grade teacher telling children that the Earth moves around the Sun….
Read it all: http://prosblogion.ektopos.com/archives/2012/03/trust-in-testim.html (found via First Things)