Proceedings of the Annual Meeting of the Cognitive Science Society

How do children learn to use language as a social tool flexibly calibrated to the identities and relationships of their interlocutors? While developmental research has benchmarked when children recognize social registers (e.g., matching casual vs. formal registers to specific conversational partners), the mechanisms by which they acquire these context-dependent mappings remain unclear. We leverage the high-resolution morphological signal of Korean honorifics to investigate the dynamic processes underlying early register socialization. Through analysis of cross-sectional and longitudinal corpora from CHILDES, we demonstrate that caregivers spotlight the socio-pragmatic functions of honorifics in child-directed speech (CDS) by selectively clustering them within specific communicative acts. Furthermore, we reveal a pragmatic handover in which caregiver scaffolding systematically fades as the child's independent sociolinguistic competence emerges. Together, these findings suggest that register learning is supported by an adaptive tutoring process—one that facilitates the child's transition from a passive linguistic recipient to a register-flexible social agent.