Developmental differences in the timecourse of word learning:Greater improvements for children, semantic benefits for adults

Theories of memory consolidation claim that new word learning is bolstered by existing semantic knowledge. However, when semantic knowledge exerts its effects (i.e., at encoding and/or consolidation) and whether semantic benefits change across development remain unclear. In total, 61 children (Experiment 1) and 63 adults (Experiment 2) learned novel word forms paired with pictures of (a) real but rare animals akin to existing animals (Highly Linkable to existing knowledge), (b) fictitious animals that were less clearly associated with familiar animals (Less Linkable), and (c) "name tags" written with unfamiliar symbols (Unlinkable). Word form and meaning recall were tested immediately, 1 day, and 1 week after learning. Children showed greater improvements across tests than adults despite comparable performance immediately after learning. Regardless of test sessions, semantic knowledge benefited adults' recall of word form and meaning, with additional benefit from Highly Linkable versus Less Linkable knowledge. Children only showed semantic benefits in meaning (and not word form) recall, with additional benefits from Highly Linkable knowledge. Instead, children's word form recall was more globally associated with receptive vocabulary and nonword repetition. These results suggest that, when present, the benefits of semantic information permeate across the timecourse of word learning; they also point to developmental differences in word learning mechanisms. Adults made clear use of associated semantic knowledge, whereas children showed more general associations between word learning and language abilities and greater benefit from offline consolidation. These results highlight the need for models of word learning and consolidation to incorporate developmental and individual differences.