Two- to four-year-old children's differentiation of knowing and guessing in a non-verbal task

In two experiments, 2- to 4-year-old children's understanding of knowing and guessing was studied in a non-verbal task, requiring the choice of a helper in a hide-and-seek task. Results indicate marked developmental progress in the age range between 30 and 36 months. While 2-year-old children performed at chance level, children above the age of 35 months consistently discriminated between a knowledgeable and an ignorant person, based on this person's perceptual access, in an interactive non-story task. Performance in control tasks indicated that young children were near ceiling in a non-epistemic task of the same format, and that the age trend persisted when only those children were considered whose failure in the epistemic task could not be attributed to memory problems or a failure to understand the task format. These findings are consistent with earlier research in the theory of mind literature (using verbal paradigms), indicating that children begin to understand the relation of perceptual access and knowledge around their third birthday. We discuss the results with respect to recent research indicating that an understanding of knowledge and belief emerges in communication around or before the age of 36 months.