Don't you see the possibilities? Young preschoolers may lack possibility concepts.

Preschoolers struggle to solve problems when they have to consider what might and might not happen. Instead of planning for all open possibilities, they simulate one possibility and treat it as the fact of the matter. Why? Are scientists asking them to solve problems that outstrip their executive capacity? Or do children lack the logical concepts needed to take multiple conflicting possibilities into account? To address this question, task demands were eliminated from an existing measure of children's ability to think about mere possibilities. One hundred nineteen 2.5- to 4.9-year-olds were tested. Participants were highly motivated but could not solve the problem. Bayesian analysis revealed strong evidence that reducing task demands while holding reasoning demands constant did not change performance. Children's struggles with the task cannot be explained by these task demands. Results are consistent with the hypothesis that children struggle because they cannot deploy possibility concepts that allow them to mark representations as merely possible. RESEARCH HIGHLIGHTS: Preschoolers are surprisingly irrational when faced with problems that ask them to consider what might and might not be the case. These irrationalities could arise from deficits in children's logical reasoning capacities or from extraneous task demands. This paper describes three plausible task demands. A new measure is introduced that preserves logical reasoning demands while eliminating all three extraneous task demands. Eliminating these task demands does not change performance. These task demands are not likely a cause of children's irrational behavior.