Learning Natural Categories: Effects of Interleaving Practice in Children and Young Adults.

While interleaved learning has been shown to enhance young adults' acquisition of confusable natural categories, its effects on children's natural category learning remain underexplored. The present study investigated the effects of study schedule (interleaving vs. blocking) on both categorization accuracy and the accuracy of metacognitive judgments during the learning of natural rock categories, comparing children and young adults. In Experiment 1, participants studied under blocked or interleaved conditions and subsequently provided global judgments of their learning. In Experiment 2, we employed a self-paced learning paradigm that required learners to regulate their own study time. Additionally, participants made item-by-item judgments of their learning during the study phase. Across both experiments, we found that interleaved learning significantly improved categorization accuracy, with young adults benefiting more than children. Regarding metacognitive monitoring, interleaving reduced overconfidence in children but led to underconfidence in young adults, as reflected in both global and item-level judgments. These findings suggest that the benefits of interleaved learning for category performance and metacognitive monitoring vary with age, highlighting age-related differences in the effectiveness of interleaved learning.