Children's judgments of expected value.

Expected value judgments of 5-, 6-, 8-, and 10-year-olds were studied by using an information integration approach. Children saw roulette-type games with prizes of crayons. They made judgments on a continuous scale of how happy a puppet playing the game would be. In one task, probability and value of a single winning outcome were varied factorially. All ages took both cues into account. Young children used an additive integration rule, whereas children 8 years and older used the multiplying rule as predicted by mathematical theory. A 2nd task contained games with both 1 and 2 alternative prizes. At all ages, data patterns were similar to the normative predictions. Even young children showed some understanding of probability dependence. A serial version of the addition strategy may contribute to advanced performance in the 2-prize task. These results are consistent with conceptual understanding of expected value.