Sleep and directed forgetting: A dual-route multinomial tree model

Zhuangzhuang Xi, Purdue University

Abstract

Many studies have established the beneficial effect of sleep on various cognitive tasks. In particular, sleep serves as a mechanism in facilitating memory consolidation and memory retention (Diekelmann & Born, 2010). However, given the enormous amount of information one may perceive and encode during a day, an optimal active sleep dependent consolidation mechanism would not help retain all encoded memories equally, but instead would selectively or preferably consolidate memories that are relatively important. In this paper, we report a study that examined the differential effects of sleep on memory retention using the list method directed forgetting paradigm. We were interested in whether the beneficial sleep effect on memory retention could be modulated by one's intention to forget the encoded memories and the perceived relevance of the memories for future. The study provides evidence for a selective memory consolidation mechanism during sleep. Sleep did not uniformly help retain all encoded memories and two factors could modulate the beneficial effect of sleep. On the one hand, we found a small differential effect of sleep on future relevant and future irrelevant memories – sleep selectively benefited retention only if the items were considered as relevant for a retest. On the other hand, sleep selectively benefited memories with accurate source monitoring but not memories with inaccurate source monitoring, suggesting that memory strength was one criterion for the selective sleep-dependent memory consolidation process. Data of the reported experiment also provides strong evidence for dual-retrieval routes underlying free recall. Free recall, like recognition, can arise from both recollection and familiarity (or automaticity). In this paper, we introduce the first Multinomial Processing Tree (MPT) model that attempts to capture such dual-retrieval processes underlying free recall. We propose that recollective free recall is composed of two sequential processes, context reinstatement and item retrieval, and recall with inaccurate source monitoring is the result of non-recollective (or familiarity) retrieval and inaccurate source judgment of the familiar item.

Degree

Ph.D.

Advisors

Schweickert, Purdue University.

Subject Area

Quantitative psychology|Cognitive psychology

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