Efficient question-asking in early childhood: Evidence of near-optimal sequential binary search in 5- to 7-year-olds

Children's ability to ask effective questions is central to self-directed learning and cognitive development. However, surprisingly little is known about how strategically efficient their spontaneous inquiries can be. Prior research has largely relied on tasks that either provide instructional scaffolds explicitly guiding children toward strategic questions, thereby boosting performance, or impose high cognitive demands that may hinder performance. These design features make it difficult to assess children's independent capacity for strategic inquiry. In this study, 90 children aged 5-7 and 30 adults played a 20-questions-style game in both concrete and abstract versions. The task was designed to minimize unnecessary complexity and instructional support, thereby reducing cognitive load. This approach allowed us to examine spontaneous, self-guided performance. The results revealed that, although efficiency increased with age, even 5-year-olds demonstrated near-optimal performance in the concrete condition. By age 7, children approached adultlike efficiency and flexibly adapted their strategies across contexts. Interestingly, strategic question use can be described as a function of the size of the hypothesis space, with a higher proportion of questions being strategic early in the search when many options remained and a lower proportion as the space narrowed. These findings offer novel insights into young children's information-seeking abilities, suggesting that when children are left to their own reasoning in settings that are cognitively accessible, efficient, and adaptive, questioning emerges spontaneously, earlier, and more robustly than previously documented. (PsycInfo Database Record (c) 2026 APA, all rights reserved).