What Are the Odds? Preschoolers' Ability to Distinguish Between Possible, Impossible, and Probabilistically Distinct Future Outcomes

Previous research has suggested that infants are able to distinguish between possible and impossible events and make basic probabilistic inferences. However, much of this research has focused on children's intuitions about past events for which the outcome is already determined but unknown. Here, we investigated children's ability to use probabilistic information to guide their choices and actively shape future events. In two experiments, we examined whether children could successfully direct a marble through a series of tubes, selecting between routes where success was possible, impossible, or guaranteed (i.e., 50% vs. 0%, or 50% vs. 100%; Experiment 1), and routes where success was mutually possible but probabilistically distinct (e.g., 33% vs. 50%; Experiment 2). In total, we tested 136 two- to five-year-old children (76 males), recruited predominantly through a museum in Brisbane, Australia. In Experiment 1, we found that while younger children typically did not perform above chance, the vast majority of 4- and 5-year-olds consistently distinguished between possible and impossible or guaranteed outcomes. In Experiment 2, children of all ages had greater difficulty with distinguishing between two possible outcomes with different likelihoods than between possible and impossible/guaranteed outcomes, although some individual 4- and 5-year-olds demonstrated competence when making both distinctions. Public Significance StatementThis study examined the development of children's ability to reason about the possibility and probability of future outcomes. Two- to 5-year-old children were given the opportunity to choose between two actions that would be more or less likely to lead to a reward. In contrast to previous studies, the results showed that many children struggled to select the better action well into the preschool years, which may have implications for how to best introduce probability concepts in the classroom.