Ancillary cognitive demands impact children's behavior in common possibility reasoning tasks.

The ability to consider multiple, incompatible possibilities supports human decision making, but there is considerable variability in estimates of the age of emergence and development of this ability in young children. What accounts for this variability? We suggest that one major source is task-specific demands on developing cognitive processes that are not solely dedicated to possibility reasoning. In this article, we outline a set of ancillary cognitive demands in a variety of common tasks that are currently used to study young children's possibility reasoning (cups, gumball, slides, branching tube, and playground tasks). We identify five key cognitive demand dimensions-physical reasoning, action planning, working memory, language, and temporal context-and show that these demands can and do impact children's behaviors in tasks designed to examine possibility reasoning. We discuss implications for understanding the cognitive mechanisms driving possibility reasoning and challenges for identifying developmental trajectories. (PsycInfo Database Record (c) 2026 APA, all rights reserved).