As the articles in this issue attest, U-shaped curves in development have stimulated a wide spectrum of research across disparate task domains and age groups and have provoked a variety of ideas about their origins and theoretical significance. In the authors' view, the ubiquity of the general pattern suggests that U-shaped curves can arise from…

This article reports 2 experiments examining the changing role of iconicity in symbol learning and its implications regarding the mechanisms supporting symbol-to-referent mapping. Experiment 1 compared 18- and 26-month-olds' mapping of iconic gestures (e.g., hopping gesture for a rabbit) vs. arbitrary gestures (e.g., dropping motion for a rabbit).…

Previous research on infant swimming has reported contradictory findings. Cross-sectional observations revealed a disorganized phase between about 3 and 12 months, which was attributed to "cortical inhibition" and implied slow learning (McGraw, 1939). However, training with a single infant during this period revealed rapid acquisition (McGraw,…