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The study of memory has traditionally been the province of cognitive psychology, which has postulated different memory systems that store memory traces to explain remembering. Behavioral psychologists have been unsuccessful at empirically identifying the behavior that occurs during remembering because so much of it occurs rapidly and covertly. In addition, behavior analysts have generally been disinterested in studying transient phenomena such as memory. As a result, the cognitive interpretation has been the only one that has made and tested useful predictions. Recent experimental evidence acquired while having participants “think aloud” suggests that a behavioral approach to memory may provide a superior account of memory performance and allow applied scientists to observe and modify memory-related behavior with well-known applied behavior-analytic techniques. We review evidence supporting and extending the interpretation of memory provided by Palmer (1991), who described memory in terms of precurrent behavior that occurs at the time of acquisition in preparation for problem solving that occurs at the time of remembering.

List-method directed forgetting involves encoding 2 lists, between which half of the participants are told to forget List 1. When participants are free to study however they want, directed forgetting impairs List 1 recall and enhances List 2 recall in the forget group compared with a control remember group. In a large-scale experiment, the current work demonstrated that when item-specific encoding instructions were enforced during learning, directed forgetting impaired List 1 recall, but it did not enhance List 2 recall. This pattern was found regardless of whether encoding was incidental or intentional. Whenever directed forgetting did not enhance List 2 recall, it nevertheless reduced cross-list intrusions. These results indicate that directed forgetting can help differentiate memories from one another, thereby reducing intrusions from irrelevant competing memories.

Daydreaming mentally transports people to another place or time. Many daydreams are similar in content to the thoughts that people generate when they intentionally try to forget. Thus, thoughts like those generated during daydreaming can cause forgetting of previously encoded events. We conducted two experiments to test the hypothesis that daydreams that are more different from the current moment (e.g., in distance, time, or circumstance) will result in more forgetting than daydreams that are less different from the current moment, because they result in a greater contextual shift. Daydreaming was simulated in the laboratory via instructions to engage in a diversionary thought. Participants learned a list of words, were asked to think about autobiographical memories, and then learned a second list of words. They tended to forget more words from the first list when they thought about their parents’ home than when they thought about their current home (Experiment 1). They also tended to forget more when they thought about an international vacation than when they thought about a domestic vacation (Experiment 2). These results support a context-change account of the amnesic effects of daydreaming.

What appears to be a simple pattern of results—distributed-study opportunities usually produce better memory than massed-study opportunities—turns out to be quite complicated. Many “impostor” effects such as rehearsal borrowing, strategy changes during study, recency effects, and item skipping complicate the interpretation of spacing experiments. We suggest some best practices for future experiments that diverge from the typical spacing experiments in the literature. Next, we outline the major theories that have been advanced to account for spacing studies while highlighting the critical experimental evidence that a theory of spacing must explain. We then propose a tentative verbal theory based on the SAM/REM model that utilizes contextual variability and study-phase retrieval to explain the major findings, as well as predict some novel results. Next, we outline the major phenomena supporting testing as superior to restudy on long-term retention tests, and review theories of the testing phenomenon, along with some possible boundary conditions. Finally, we suggest some ways that spacing and testing can be integrated into the classroom, and ask to what extent educators already capitalize on these phenomena. Along the way, we present several new experiments that shed light on various facets of the spacing and testing effects.

Participants studied sentences describing two different characters and then were told to forget the sentences about only one of the characters. A second list contained sentences attributed to a third character. Subsequently, they received a recall test on the sentences about the original two characters. When the sentences could be thematically integrated, participants showed no directed forgetting relative to a control group that was never told to forget. However, with unrelated sentences, participants selectively forgot the target character's sentences without forgetting the other character's sentences. This selective directed forgetting effect is a novel empirical result. We interpret the results as consistent with Radvansky's (1999) ideas about inhibition with textual materials.

Three experiments evaluated whether the magnitude of the list-method directed forgetting effect is strength dependent. Throughout these studies, items were strengthened via operations thought to increase context strength (spaced presentations) or manipulations thought to increment the item strength without affecting the context strength (processing time and processing depth). The assumptions regarding which operations enhance item and context strength were based on the "one-shot" hypothesis of context storage (K. J. Malmberg & R. M. Shiffrin, 2005). The results revealed greater directed forgetting of strong items compared with weak items, but only when strength was varied via spaced presentations (Experiment 3). Equivalent directed forgetting was observed for strong and weak items when strengthening operations increased item strength without affecting the context strength (Experiments 1 and 2). These results supported the context hypothesis of directed forgetting (L. Sahakyan & C. M. Kelley, 2002).

The authors present 3 experiments demonstrating ways to reduce illegal moves in problem-solving tasks. They propose a 3-stage framework for the rejection of illegal moves. An illegal move must come to mind and be selected, checked for legality, and correctly rejected. Illegal move reduction can occur at any stage. Control group participants benefited from solving the same problem twice but failed to show transfer to an isomorph, replicating results from S. K. Reed, G. W. Ernst, and R. Banerji (1974). Participants who were penalized for making illegal moves showed reductions in illegal moves even when solving a novel isomorph without penalty. The authors propose that illegal move reduction occurs when solvers are cautious and check moves for legality frequently.

Instructing people to forget a list of items often leads to better recall of subsequently studied lists (known as the benefits of directed forgetting). The authors have proposed that changes in study strategy are a central cause of the benefits (L. Sahakyan & P. F. Delaney, 2003). The authors address 2 results from the literature that are inconsistent with their strategy-based explanation: (a) the presence of benefits under incidental learning conditions and (b) the absence of benefits in recognition testing. Experiment 1 showed that incidental learning attenuated the benefits compared with intentional learning, as expected if a change of study strategy causes the benefits. Experiment 2 demonstrated benefits using recognition testing, albeit only when longer lists were used. Memory for source in directed forgetting was also explored using multinomial modeling. Results are discussed in terms of a 2-factor account of directed forgetting.

After extensive laboratory testing of the famous memorist Rajan, Thompson, Cowan, and Frieman (1993) proposed that he was innately endowed with a superior memory capacity for digits and letters and thus violated the hypothesis that exceptional memory fully reflects acquired "skilled memory." We successfully replicated the empirical phenomena that led them to their conclusions. From additional analyses and new experiments, we found support for an alternative hypothesis, namely that Rajan's superior memory for digits was mediated by learned encoding techniques that he acquired during nearly a thousand hours of practice memorizing the mathematical constant pi. Our paper describes a general experimental approach for studying the structure of exceptional memory and how Rajan's unique structure is consistent with the general theoretical framework of long-term working memory (Ericsson and Kintsch, 1995).