Adults don't always know best: preschoolers use past reliability over age when learning new words.

Children learn much of what they know—from words to their birth dates to the fact that the earth is round—from what other people tell them. But some people are better informants than others. One way children can estimate the credibility of a speaker is by evaluating how reliable that person has been in the past. Even preschoolers prefer learning new words from an adult who has previously labeled objects correctly rather than one who has labeled objects incorrectly (Koenig, Clement, & Harris, 2004). Children may also make predictions about a speaker on the basis of that person’s membership in a particular group. For example, 4-year-olds expect that an unfamiliar adult, but not necessarily an unfamiliar child, knows the meaning of the word hypochondriac (Taylor, Cartwright, & Bowden, 1991). Which of these two cues to a speaker’s credibility—reliability or age—do 3and 4-year-old children find more compelling?