Napping and toddlers’ memory for fast-mapped words

When toddlers hear a novel word, they quickly and independently link it with a novel object rather than known-name objects. However, they are less proficient in retaining multiple novel words. Sleep and even short naps can enhance declarative memory in adults and children and this study investigates the effect of napping on children’s memory for novel words. Forty two-and-a-half-year-old children were presented with referent selection trials for four novel nouns. Children’s retention of the words was tested immediately after referent selection, four hours later in the afternoon, and the following morning. Half of the toddlers napped prior to the afternoon retention test. Amongst the toddlers who napped, retention scores remained steady four hours after exposure and the following morning. In contrast, for the wake group, there was a steady decline in retention scores by the following morning and significantly lower retention scores compared to the nap group. Napping following exposure to novel word–object associations could help in maintaining memories and limiting decay. Nap duration was also associated with better retention scores, but there were no effects of sleep quality, habitual napping, or sleepiness. The findings have implications for the role of napping in children’s language acquisition.