Benjamin C. Storm

Is retrieval success a necessary condition for retrieval-induced forgetting?

When information is retrieved from memory, it becomes more recallable than it would have been otherwise. Other information associated with the same cue or configuration of cues, however, becomes less recallable. Such retrieval-induced forgetting (Anderson, Bjork, & Bjork, 1994) appears to reflect the suppression of competing nontarget information, with this suppression facilitating the selection of target information. But is success at such selection a necessary condition for retrieval-induced forgetting? Using a procedure in which some cues posed an impossible retrieval task for participants, we report evidence that the attempt to retrieve, even if unsuccessful, can produce retrieval-induced forgetting. This finding, we believe, supports and refines a suppression/inhibitory account of retrieval-induced forgetting.

A progress report on the inhibitory account of retrieval-induced forgetting

Remembering and forgetting reflect fundamentally interdependent processes in human memory (Bjork, 2011). This interdependency is particularly apparent in research on retrieval-induced forgetting, which has shown that retrieving a subset of information can cause the forgetting of other information (Anderson et al. Journal of Experimental Psychology: Learning, Memory, & Cognition 20:1063-1087, 1994). According to one prominent theoretical account, retrieval-induced forgetting is caused by an inhibitory process that acts to resolve competition during retrieval. Specifically, when cues activate competing, contextually inappropriate responses, those responses are claimed to be inhibited in order to facilitate the retrieval of target responses (Anderson Journal of Memory and Language 49: 415–445, 2003; Levy & Anderson Trends in Cognitive Sciences 6: 299–305, 2002; Storm, 2011b). Interest in retrieval-induced forgetting has grown steadily over the past two decades. In fact, a search of the abstracts at the 5th International Conference on Memory (ICOM, York University, 2011) revealed 40 presentations specifically mentioning “retrieval-induced forgetting,” and nearly twice that number referring to the concept of inhibition. Clearly, researchers are interested in the empirical phenomenon of retrieval-induced forgetting, and inhibition is gaining increasing attention as a mechanism involved in memory. The goal of the present progress report is to critically review the inhibitory account of retrieval-induced forgetting and to provide direction so that future research can have a more meaningful impact on our understanding of human memory.

Forgetting as a consequence of retrieval: a meta-analytic review of retrieval-induced forgetting

Retrieving a subset of items can cause the forgetting of other items, a phenomenon referred to as retrieval-induced forgetting. According to some theorists, retrieval-induced forgetting is the consequence of an inhibitory mechanism that acts to reduce the accessibility of nontarget items that interfere with the retrieval of target items. Other theorists argue that inhibition is unnecessary to account for retrieval-induced forgetting, contending instead that the phenomenon can be best explained by noninhibitory mechanisms, such as strength-based competition or blocking. The current article provides the first major meta-analysis of retrieval-induced forgetting, conducted with the primary purpose of quantitatively evaluating the multitude of findings that have been used to contrast these 2 theoretical viewpoints. The results largely supported inhibition accounts but also provided some challenging evidence, with the nature of the results often varying as a function of how retrieval-induced forgetting was assessed. Implications for further research and theory development are discussed.

Overcoming Fixation: Creative Problem Solving and Retrieval-Induced Forgetting

Retrieving information from memory causes the forgetting of other information in memory, a phenomenon known as retrieval-induced forgetting (Anderson, Bjork, & Bjork, 1994). Retrieval-induced forgetting is believed to be caused by inhibitory processes that act to resolve competition (Anderson, 2003; Storm, in press). According to this account, the attempt to retrieve a target item activates nontarget items, creating competition and requiring that the nontarget items be inhibited. Retrieval-induced forgetting is the consequence of this adaptive process—one that functions to resolve competition and facilitate retrieval. Here, we report a study examining the role of inhibition in creative problem solving. Many problems are difficult to solve because old and inappropriate ideas cause mental fixation, impeding the generation of new and appropriate ideas (Smith, 2003). Inhibition may facilitate creative problem solving by providing a mechanism by which to bypass fixation and achieve a creative solution. We tested this hypothesis by measuring retrieval-induced forgetting and correlating that measure with performance on the Remote Associates Test (RAT; Mednick, 1962). To solve a RAT problem, participants must generate a common associate for three cue words (e.g., manners, tennis, round; solution: table). RAT problems are difficult to solve because the strongest associate for each cue word (e.g., polite, ball, and square, respectively) often bears no relationship to the other cue words and would not, therefore, serve as an appropriate solution. Once activated, however, these strong associates can cause fixation and impede the generation of creative and appropriate associates (Smith & Blankenship, 1991). We manipulated the extent to which participants experienced fixation by exposing half of the participants to misleading associates prior to problem solving. If inhibition underlies retrieval-induced forgetting, and if inhibition functions to resolve competition, then individuals who demonstrate more retrieval-induced forgetting in the retrieval-practice paradigm should also demonstrate a superior ability to overcome fixation in the RAT.

When intended remembering leads to unintended forgetting

As a means of clarifying the memory dynamics that underlie retrieval-induced forgetting, we explored how instructing participants either to remember or to forget a previously presented list of items influences the susceptibility of those items to inhibition. According to the inhibitory account of retrieval-induced forgetting, it is the items that interfere most with retrieval practice that should be the most susceptible to the effects of inhibition. Consistent with this prediction, items from lists that participants were told to remember suffered from significantly more retrieval-induced forgetting than did items from lists that participants were told to forget.

Accelerated Relearning After Retrieval-Induced Forgetting: The Benefit of Being Forgotten

Research on retrieval-induced forgetting has demonstrated that retrieving some information from memory can cause the forgetting of other information in memory. Here, the authors report research on the relearning of items that have been subjected to retrieval-induced forgetting. Participants studied a list of category- exemplar pairs, underwent a series of retrieval-practice and relearning trials, and, finally, were tested on the initially studied pairs. The final recall of non-relearned items exhibited a cumulative effect of retrieval-induced forgetting such that the size of the effect increased with each block of retrieval practice. Of most interest, and very surprising from a common-sense standpoint, items that were relearned benefited more from that relearning if they had previously been forgotten. The results offer insights into the nature and durability of retrieval-induced forgetting and provide additional evidence that forgetting is an enabler--rather than a disabler--of future learning.

Optimizing retrieval as a learning event: When and why expanding retrieval practice enhances long-term retention

Retrieving information from memory makes that information more recallable in the future than it otherwise would have been. Optimizing retrieval practice has been assumed, on the basis of evidence and arguments tracing back to Landauer and Bjork (1978), to require an expanding-interval schedule of successive retrievals, but recent findings suggest that expanding retrieval practice may be inferior to uniform-interval retrieval practice when memory is tested after a long retention interval. We report three experiments in which participants read educational passages and were then repeatedly tested, without feedback, after an expanding or uniform sequence of intervals. On a test 1 week later, recall was enhanced by the expanding schedule, but only when the task between successive retrievals was highly interfering with memory for the passage. These results suggest that the extent to which learners benefit from expanding retrieval practice depends on the degree to which the to-belearned information is vulnerable to forgetting.

Thinking can cause forgetting: memory dynamics in creative problem solving.

Research on retrieval-induced forgetting has shown that retrieval can cause the forgetting of related or competing items in memory (Anderson, Bjork, & Bjork, 1994). In the present research, we examined whether an analogous phenomenon occurs in the context of creative problem solving. Using the Remote Associates Test (RAT; Mednick, 1962), we found that attempting to generate a novel common associate to 3 cue words caused the forgetting of other strong associates related to those cue words. This problem-solving-induced forgetting effect occurred even when participants failed to generate a viable solution, increased in magnitude when participants spent additional time problem solving, and was positively correlated with problem-solving success on a separate set of RAT problems. These results implicate a role for forgetting in overcoming fixation in creative problem solving.

ADHD and retrieval-induced forgetting: Evidence for a deficit in the inhibitory control of memory

Research on retrieval-induced forgetting has shown that the selective retrieval of some information can cause the forgetting of other information. Such forgetting is believed to result from inhibitory processes that function to resolve interference during retrieval. The current study examined whether individuals with ADHD demonstrate normal levels of retrieval-induced forgetting. A total of 40 adults with ADHD and 40 adults without ADHD participated in a standard retrieval-induced forgetting experiment. Critically, half of the items were tested using category cues and the other half of the items were tested using category-plus-one-letter-stem cues. Whereas both ADHD and non-ADHD participants demonstrated retrieval-induced forgetting on the final category-cued recall test, only non-ADHD participants demonstrated retrieval-induced forgetting on the final category-plus-stem-cued recall test. These results suggest that individuals with ADHD do have a deficit in the inhibitory control of memory, but that this deficit may only be apparent when output interference is adequately controlled on the final test.

Successful inhibition, unsuccessful retrieval: manipulating time and success during retrieval practice.

Retrieving an item or set of items from memory can cause the forgetting of other related items in memory; a phenomenon known as retrieval-induced forgetting. According to the inhibitory account of retrieval-induced forgetting, in searching for a particular item, other items that are related but incorrect can vie for access. Inhibition functions to decrease the accessibility of such interfering items, thereby facilitating access to the target item. Experiments 1 and 2 replicated recent work suggesting that retrieval success is not a necessary condition for retrieval-induced forgetting to occur. Interfering items were forgotten even when retrieval practice was designed to be impossible. Experiments 3 and 4 employed the impossible retrieval practice procedure to examine the time-course of forgetting across a single retrieval practice trial. Results support the inhibitory account of retrieval-induced forgetting and offer insight into the dynamics of how and when inhibition plays a role in retrieval.