Forgetting is frustrating, usually because it is unintended. Other times, one may purposely attempt to forget an event. A global theory of recognition and free recall that explains both types of forgetting and remembering from multiple list experiments is presented. The critical assumption of the model is that both intentional and unintentional forgetting are often due to contextual interference. Unintentional forgetting is the natural result of contextual changes between study and test. Intentional forgetting is accomplished by a rapid, metacognitively instigated change in mental context that renders to-be-forgotten information relatively inaccessible and renders to-be-remembered information more accessible (L. Sahakyan & C. M. Kelley, 2002). This occurs for both recognition and free recall. Implications for item-method directed forgetting, exclusion recognition, source memory, and encoding operations are discussed.

Atkinson and Shiffrin's (1968) dual-store model of memory includes structural aspects of memory along with control processes. The rehearsal buffer is a process by which items are kept in mind and long-term episodic traces are formed. The model has been both influential and controversial. Here, we describe a novel variant of Atkinson and Shiffrin's buffer model within the framework of the retrieving effectively from memory theory (REM; Shiffrin & Steyvers, 1997) that accounts for findings previously thought to be difficult for such models to explain. This model assumes a limited-capacity buffer where information is stored about items, along with information about associations between items and between items and the context in which they are studied. The strength of association between items and context is limited by the number of items simultaneously occupying the buffer (Lehman & Malmberg, 2009). The contents of the buffer are managed by complementary processes of rehearsal and compartmentalization (Lehman & Malmberg, 2011). New findings that directly test a priori predictions of the model are reported, including serial position effects and conditional and first recall probabilities in immediate and delayed free recall, in a continuous distractor paradigm, and in experiments using list-length manipulations of single-item and paired-item study lists.

Practicing retrieval is a powerful way to promote learning and long-term retention. This chapter addresses the theoretical underpinnings of retrieval-based learning. We review methodological issues in retrieval practice research, identify key findings to be Psychology of Learning and Motivation, Volume 61 # 2014 Elsevier Inc. ISSN 0079-7421 All rights reserved. http://dx. 237accounted for, and evaluate current candidate theories. We propose an episodic context account of retrieval-based learning, which explains retrieval practice in terms of context reinstatement, context updating, and restriction of the search set. Retrieval practice involves attempting to reinstate a prior learning context, and when retrieval is successful, the representation of context is updated to include features of retrieved contexts and the current context. Future retrieval is enhanced because updated context representations can be used to restrict the search set and hone in on a desired target. The context account accommodates a wide variety of phenomena in the retrieval practice literature and provides a comprehensive and cohesive account of retrieval-based learning.

We tested the predictions of 2 explanations for retrieval-based learning; while the elaborative retrieval hypothesis assumes that the retrieval of studied information promotes the generation of semantically related information, which aids in later retrieval (Carpenter, 2009), the episodic context account proposed by Karpicke, Lehman, and Aue (in press) assumes that retrieval alters the representation of episodic context and improves one's ability to guide memory search on future tests. Subjects studied multiple word lists and either recalled each list (retrieval practice), did a math task (control), or generated associates for each word (elaboration) after each list. After studying the last list, all subjects recalled the list and, after a 5-min delay, recalled all lists. Analyses of correct recall, intrusions, response times, and temporal clustering dissociate retrieval practice from elaboration, supporting the episodic context account.

The long-term effects of the compartmentalization of task-irrelevant memories were investigated using a directed forgetting procedure. Many models tacitly assume the persistence of the costs and benefits of directed forgetting or otherwise fail to predict what factors might reduce or eliminate them. In contrast, a retrieving effectively from memory model (REM; Lehman & Malmberg, 2009) predicts that intentional forgetting should only be observed for free recall when temporal context is used to probe memory. By manipulating whether study lists were constructed from category exemplars or from a random set of words, and by either providing temporal or category cues at test, we tested the prediction. The effects of directed forgetting were eliminated when categorized lists were studied and category cues were provided. When categorized lists were used but category cues were not provided, the usual costs and benefits of directed forgetting were observed. These results specify the conditions under which the consequences of intentional forgetting can be overcome.

The elaborative retrieval account of retrieval-based learning proposes that retrieval enhances retention because the retrieval process produces the generation of semantic mediators that link cues to target information. We tested 2 assumptions that form the basis of this account: that semantic mediators are more likely to be generated during retrieval than during restudy and that the generation of mediators facilitates later recall of targets. Although these assumptions are often discussed in the context of retrieval processes, we noted that there was little prior empirical evidence to support either assumption. We conducted a series of experiments to measure the generation of mediators during retrieval and restudy and to examine the effect of the generation of mediators on later target recall. Across 7 experiments, we found that the generation of mediators was not more likely during retrieval (and may be more likely during restudy), and that the activation of mediators was unrelated to subsequent free recall of targets and was negatively related to cued recall of targets. The results pose challenges for both assumptions of the elaborative retrieval account. (PsycINFO Database Record

Processing items for their survival relevance often produces a robust memory advantage. The current experiments assessed possible proximate mechanisms responsible for this advantage by assessing output strategies during free recall. Previous research has shown that item clustering during recall can provide diagnostic information about the structure of representations in episodic memory, particularly the encoding of temporal, semantic, and source information. Following survival processing and moving or pleasantness controls, measures of temporal and semantic clustering were generated. A robust recall advantage was found for survival processing, but no evidence for temporal clustering was detected. Above-chance levels of semantic clustering were obtained, but there were no differences between the survival and control conditions. An additional clustering measure based on scenario-based relevance ratings also failed to explain recall differences, as did absolute and relative measures of remembered temporal position. Our results indicate that neither enhanced temporal coding nor increased semantic processing among the items on the study list can easily explain the oft-replicated survival processing advantage. Our results also suggest that the ubiquitous temporal clustering patterns seen in free recall studies may be a product, in part, of using intentional learning and multiple study trials.

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