Domain-Generality is an Emergent, not Inherent, Property of Metacognition

We experience some level of confidence in all decisions we make, yet our understanding of how confidence is generated remains elusive. Here, we examine three potential ways that metacognitive confidence judgments could be similar across the distinct domains of memory and perception in adults and children. Using episodic memory and perceptual tasks, we reveal that while confidence bias correlates across domains at all ages, confidence sensitivity and efficiency are both distinct. Crucially, children aged 6 and older can flexibly compare their confidence across memory and perceptual decisions, indicating a shared internal metric. In contrast, younger children struggle with cross-domain comparisons, highlighting a developmental transition in metacognitive processing. Overall, findings highlight the distinct yet commensurable nature of memory and perceptual confidence, with domain-general processes emerging by age 6.