Young children's predictions of illness: failure to recognize probabilistic causation.

In this study preschool-age children made predictions for a set of salient probabilistic causes. Of interest was whether the children viewed outcomes of familiar causes of illness as definite or as probabilistic. In Experiment 1, children judged that a common cause would affect all members of a group in the same way. In Experiment 2, children believed they could definitely predict illness outcomes in a single case. These judgments contrasted with adults' variable and uncertain predictions. Children did recognize uncertainty in outcomes dependent on voluntary choices. Experiment 3 presented both high- and low-potency causes of illness. Children treated all causes of illness as nonprobabilistic. These results are discussed in the context of children's understanding of causal relations and the sources of variability.