While people sleep, the brain replays the same neural firings that resulted from waking activities that day. This results in greater memory strength following a sleeping delay than a waking delay. The current project built upon this fact in a series of three experiments. Experiment 1. Although previous research has demonstrated a benefit of sleep to memory strength, the literature has not established the impact of sleep on memory specificity. Computational models of medial temporal lobe function posit that discrimination and generalization across similar memories are accomplished through processes known as pattern separation and pattern completion, respectively. To discover whether sleep predisposes people toward pattern separation or pattern completion, participants studied pictures of common objects. After a 12-hour delay, during which participants either slept or stayed awake, participants indicated whether “lure” images were exactly the same or merely similar to those they studied. There was better memory discrimination in those who slept, consistent with a bias toward pattern separation following sleep. Experiment 2. In order to discover whether the pattern of memory demonstrated in Experiment 1 would carry over to semantic memories, participants studied textbook material and took a true/false test 12 hours later. There was a shift in the response trends following sleep, such that participants were more likely to mistakenly endorse highly similar false statements as “true” but were also more likely to correctly endorse more dissimilar false statements as “false.” However, we did not detect evidence of an increased bias toward pattern separation or pattern completion following sleep for this material. Our findings appear consistent with the prediction that memory specificity is benefitted by sleep. Experiment 3. Previous research has demonstrated that memories encoded later in the day are consolidated better than memories encoded earlier in the day. However, these studies have not controlled for the differential decay that memories suffer across these two elapsed periods. In this study, we attempted to show the degree of improvement afforded by sleep using a before-sleep comparison group. However, post hoc analyses revealed a significant interaction between the proposed outcomes and whether participants had napped during the day. These preliminary findings may suggest that napping differentially affects the consolidation of information studied before and after napping.
College and Department
Family, Home, and Social Sciences; Psychology
BYU ScholarsArchive Citation
James, Jesse Ray, "The Effect of Sleep-Dependent Consolidation on Pattern Separation and Pattern Completion in Delayed Retrieval" (2014). Theses and Dissertations. 4377.
memory, sleep, consolidation, pattern separation, pattern completion