The Role of Nap Status in Source Memory for Similar and Distinct Objects in Preschool Age Children

Abstract

Naps play an important role in long term retention of new memories with much work investigating memory for distinctly different items. However, the difficulty children encounter in retaining memories associated with specific sources, varies for similar and distinct objects. Here, we investigated the development of source memory for similar and distinct objects across 3.5-, 4.5-, and 5.5-year-olds and the impact of naps and napping patterns on retention. In Experiment 1, we investigated short-term retention of new source memories over a 15-minute delay, observing improvement in source memory between 3.5- and 5.5-years of age. Having established baseline 15-minute delay retention, in Experiment 2 we asked how naps in habitually napping 3.5-year-olds support long-term retention. Children napped or not in the 4-hour interval after training and were tested 24 hours later. Children who napped showed excellent source memory—the nap boosted source memory for similar and distinct targets over a 24-hour delay. In Experiment 3, we investigated source memory after a 24-hour delay in habitually and non-habitually napping 3.5- to 4.5-year-old children, none of whom napped in the 4-hour interval after training, to replicate the finding that children who no longer nap do not need a nap to retain new learning after a 4-hour delay relative to habitual nappers who do (Esterline & Gomez, 2021). We failed to replicate this finding at a 24-hour delay with children in both groups showing similarly low retention. In Experiment 4, we compared short-term retention of similar and distinct source memories from Experiment 1 with long-term retention of such memories from Experiment 3 in non-habitually napping 3.5-, 4.5-, and 5.5-year-old children to determine if they retained new memories over time. 3.5- and 4.5-year-olds showed numerical but not significant loss due to small N. We observed significant loss in the number of 5.5-year-old perfect learners after the long-term delay. Although more data are needed to allow for a stronger interpretation, the approach we take here demonstrates the importance of investigating long-term retention of source memory as a function of developmental changes in nap habituality and memory formation during early childhood.