Working memory capacity and retrieval from long-term memory: the role of controlled search

In two experiments, the role of working memory capacity (WMC) in the controlled search of long-term memory was examined. Participants performed a prolonged category fluency task that required them to retrieve as many animals as possible in 5 min. The results suggested that WMC differences arose in the numbers of animals retrieved, the numbers of clusters retrieved, and the rates of the retrieval (Exp. 1). However, no differences were found in terms of how participants initiated retrieval or in the nature of the clusters generated. Furthermore, an examination of differences in retrieval strategies suggested that high-WMC individuals were more strategic than low-WMC individuals and that these differences in retrieval strategies accounted for the overall differences in the numbers of animals retrieved. Additionally, presenting participants with retrieval cues eliminated WMC differences in the numbers of animals retrieved (Exp. 2). These results suggest that low-WMC individuals are less able than high-WMC individuals to select and utilize appropriate retrieval strategies to self-generate cues to access information in long-term memory. Collectively, the results are consistent with research suggesting that WMC is important for controlled search from long-term memory.     

Variation in working memory capacity and temporal-contextual retrieval from episodic memory

Unsworth and Engle (2007) recently proposed a model of working memory capacity characterized by, among other things, the ability to conduct a strategic, cue-dependent search of long-term memory. Although this ability has been found to mediate individual variation in a number of higher order cognitive tasks, the component processes involved remain unclear. The current study was designed to investigate individual variation in successfully retrieving information from episodic memory by examining various aspects of the retrieval process. Both high- and low-working memory capacity participants were found to initiate recall in a similar fashion; however, low-working memory capacity participants did not show the classic asymmetry in their conditional-response probabilities that is typically observed. Overall, the retrieval deficits observed in low-working memory capacity individuals appear to be rooted in their inability to use the products of retrieval to further aid their search.     

How intention to retrieve a memory and expectation that a memory will come to mind influence the retrieval of autobiographical memories

While involuntary memories are retrieved with no intention and are usually unexpected (when one is not waiting for a memory to arise), voluntary memories are intended and expected (when one is searching and waiting for a memory to arise). The present study aimed to investigate the effects of retrieval intentionality (i.e. wanting to retrieve a memory) and monitoring processes (i.e. waiting for a memory to appear) during autobiographical memory retrieval. In addition, we introduced two novel laboratory conditions that have not been used in previous research on voluntary memories: in the first, participants were asked to report anything they could think of in response to each cue word; in the second, they could skip a word if nothing came to mind. These novel manipulations allowed us to differentiate between voluntary memories retrieved in response to experimenter-generated cues (when participants were forced to provide a memory or a thought for each cue) and self-selected cues (when participants were free to not answer a cue if they found it too difficult). We found that highly accessible memories were mostly experienced when retrieval was involuntary and unexpected, while memories with low accessibility were accessed through intentional retrieval and monitoring processes. Response times for memories recalled in the experimenter-generated cue conditions were longer compared to the self-selected cue conditions. This novel finding shows that experimenter-generated recall favours memories with low accessibility; it further supports the idea that, in a substantial number of trials, voluntary memories are directly rather than effortfully retrieved. The idea that the driving force behind differences between involuntary and voluntary memories is not the intention per se is further discussed.     

The role of semantic memory in short-term recall: effect of strategic retrieval ability in an elderly population

The present paper examines the relationship between two classic phenomena: semantic effects in short-term recall (STR) tasks, which are interpreted as indicating the involvement of long-term memory (LTM) in the functioning of short-term memory, on the one hand, and the existence of individual differences amongst elderly people in strategic retrieval ability (i.e., the ability to activate representations in LTM in a controlled way) on the other hand. Forty elderly participants completed a STR task under four different conditions which were thought to differentially involve LTM representations. Several executive functions, among which the strategic retrieval ability, were evaluated. The results showed that the participants who obtained the best performances in terms of strategic retrieval ability, and only in this executive ability, also exhibited better performances in the STR task, in particular when this task was performed under conditions which favored the use of LTM.     

Variation in working memory capacity and episodic recall: The contributions of strategic encoding and contextual retrieval

The present study examined the extent to which differences in strategic encoding and contextual retrieval account for the relation between individual differences in working memory capacity (WMC) and variation in episodic recall. Participants performed a continual distractor task under either incidental- or intentional-encoding conditions. High-WMC individuals outperformed low-WMC individuals across both encoding conditions and, notably, to a greater degree in the intentional-encoding condition. These results suggest that WMC differences in episodic recall are likely due to a combination of differences in both contextual-retrieval and strategic-encoding processes. These findings are consistent with prior work showing that high-WMC individuals are better at engaging in strategic-encoding processes during the presentation of items than are low-WMC individuals and are better at using contextual cues to focus the search on correct items during retrieval.     

Variation in working memory capacity and episodic memory: Examining the importance of encoding specificity

In the present study, we examined the extent to which encoding specificity influences the relation between individual differences in working memory capacity (WMC) and episodic recall. Participants performed a paired associates cued recall task in which a rhyme or a semantic judgment was made during encoding. During recall participants were presented with the cue word along with either a rhyme or semantic cue. Across both rhyme and semantic conditions, encoding and retrieval conditions either matched or mismatched. When encoding and retrieval conditions matched, high WMC individuals outperformed low WMC individuals. When encoding and retrieval conditions mismatched, high and low WMC individuals performed equivalently. Importantly, this occurred because high WMC individuals were hurt more than low WMC individuals when conditions mismatched. These results demonstrate the importance of encoding specificity in the relation between WMC and episodic recall as well as of unifying prior work that has demonstrated that high WMC individuals are hurt more in some recall conditions than are low WMC individuals.     

Individual differences in working memory capacity and search efficiency

In two experiments, we examined how various learning conditions impact the relation between working memory capacity (WMC) and memory search abilities. Experiment 1 employed a delayed free recall task with semantically related words to induce the buildup of proactive interference (PI) and revealed that the buildup of PI differentially impacted recall accuracy and recall latency for low-WMC and high-WMC individuals. Namely, the buildup of PI impaired recall accuracy and slowed recall latency for low-WMC individuals to a greater extent than what was observed for high-WMC individuals. To provide a circumstance in which previously learned information remains relevant over the course of learning, Experiment 2 required participants to complete a multitrial delayed free recall task with unrelated words. Results revealed that with increased practice with the same word list, WMC-related differences were eventually eliminated in interresponse times (IRTs) and recall accuracy, but not recall latency. Thus, despite still accumulating larger search sets, low-WMC individuals searched LTM as efficiently as high-WMC individuals. Collectively, these results are consistent with the notion that under normal free recall conditions, low-WMC individuals search LTM less efficiently than do high-WMC individuals because of their reliance on noisy temporal–contextual cues at retrieval. However, it appears that under conditions in which previously learned items remain relevant at recall, this tendency to rely on vague self-generated retrieval cues can actually facilitate the ability to accurately and quickly recall information.     

Dynamic search and working memory in social recall

What are the mechanisms underlying search in social memory (e.g., remembering the people one knows)? Do the search mechanisms involve dynamic local-to-global transitions similar to semantic search, and are these transitions governed by the general control of attention, associated with working memory span? To find out, we asked participants to recall individuals from their personal social networks and measured each participant's working memory capacity. Additionally, participants provided social-category and contact-frequency information about the recalled individuals as well as information about the social proximity among the recalled individuals. On the basis of these data, we tested various computational models of memory search regarding their ability to account for the patterns in which participants recalled from social memory. Although recall patterns showed clustering based on social categories, models assuming dynamic transitions between representations cued by social proximity and frequency information predicted participants' recall patterns best-no additional explanatory power was gained from social-category information. Moreover, individual differences in the time between transitions were positively correlated with differences in working memory capacity. These results highlight the role of social proximity in structuring social memory and elucidate the role of working memory for maintaining search criteria during search within that structure.     

Working memory and sequence learning in the Hebb Digits task: awareness is predicted by individual differences in operation span

We examined the extent to which individual differences contribute to performance in a task considered to index implicit learning, the Hebb Digits task. Although Hebb Digits learning is considered to be equivalent for those with implicit and explicit knowledge of the repeating digit pattern, this study found that participants who developed explicit knowledge showed learning, whereas those without explicit knowledge did not. Additionally, participants who developed explicit knowledge outperformed participants without explicit knowledge on working memory measures, specifically the Automated Operation Span Task total correct score and absolute score. However, no significant differences were found between those who did and who did not develop explicit knowledge on the Hopkins Verbal Learning Task-Revised, which uses delayed recall to index long-term memory. These results suggest that learning and awareness in the Hebb Digits task relies on individual differences in working memory capacity.     

The personalisation method applied to a working memory task: Evidence of long-term working memory effects

Ericsson and Kintsch (1995) proposed that, in situations of expertise, individuals can overcome working memory limitations by using long-term working memory. It allows a greater capacity than working memory thanks to long-term memory encoding and retrieving. To test this characteristic, an adaptation of Daneman and Carpenter's (1980) reading span was used. To operationalise expertise, the personalisation method (Guida & Tardieu, 2005) was employed. In Experiment 1, a personalised group, which read reading span sentences that mentioned familiar locations, was compared to a nonpersonalised group, which read sentences with unfamiliar locations. In Experiment 2, a personalised group, which read reading span sentences with neutral locations, was encouraged to mentally personalise these locations by thinking about known locations. This group was compared to a nonpersonalised group, which was encouraged to think about unknown locations. The personalised groups were expected to store and retrieve information in long-term memory via long-term working memory more easily than the nonpersonalised groups, which had to count massively on working memory. The results showed that personalisation enhanced reading span and confirmed one implication of the long-term working memory theory: high- and low-reading-span differences could also be due to long-term memory retrieval. Finally, these results are interpreted in terms of interaction between working memory size and long-term memory knowledge, showing that participants with a lower reading span benefited more from high domain knowledge than participants with a higher reading span.     

The role of working memory capacity in autobiographical retrieval: individual differences in strategic search

Remembering previous experiences from one's personal past is a principal component of psychological well-being, personality, sense of self, decision making, and planning for the future. In the current study the ability to search for autobiographical information in memory was examined by having college students recall their Facebook friends. Individual differences in working memory capacity manifested itself in the search of autobiographical memory by way of the total number of friends remembered, the number of clusters of friends, size of clusters, and the speed with which participants could output their friends' names. Although working memory capacity was related to the ability to search autobiographical memory, participants did not differ in the manner in which they approached the search and used contextual cues to help query their memories. These results corroborate recent theorising, which suggests that working memory is a necessary component of self-generating contextual cues to strategically search memory for autobiographical information.     

Working memory capacity predicts the beneficial effect of selective memory retrieval

Selective retrieval of some studied items can both impair and improve recall of the other items. This study examined the role of working memory capacity (WMC) for the two effects of memory retrieval. Participants studied an item list consisting of predefined target and nontarget items. After study of the list, half of the participants performed an imagination task supposed to induce a change in mental context, whereas the other half performed a counting task which does not induce such context change. Following presentation of a second list, memory for the original list's target items was tested, either with or without preceding retrieval of the list's nontarget items. Consistent with previous work, preceding nontarget retrieval impaired target recall in the absence of the context change, but improved target recall in its presence. In particular, there was a positive relationship between WMC and the beneficial, but not the detrimental effect of memory retrieval. On the basis of the view that the beneficial effect of memory retrieval reflects context-reactivation processes, the results indicate that individuals with higher WMC are better able to capitalise on retrieval-induced context reactivation than individuals with lower WMC.     

Remembering ads: The effects of encoding strategies,retrieval cues,and emotional response

This study uses the encoding specificity principle ( Tulving & Thomson, 1973 ) and the distinction between episodic and semantic knowledge to test predictions about the effects of processing goals and retrieval cues on memory for emotional and neutral TV commercials. Subjects viewed five emotional and five neutral ads embedded in programming. Encoding instructions asked subjects to either (a) evaluate each product or (b) “just watch” as they viewed the ads. Retrieval cues were either the opening scene of each ad (executional cue) or the product category (categorical cue). Both recall and response-time measures were used to index ad memory-trace accessibility. The results showed that when encoding and retrieval conditions were compatible (evaluation instructions with categorical cue, and just-watch instructions with executional cue) ad memory traces were retrieved more rapidly than when encoding and retrieval conditions were incompatible. In addition, subjects who “just watched” emotional ads were able to retrieve those ad memory traces more rapidly when given an executional cue compared to a categorical cue, whereas subjects who evaluated neutral ads at encoding recalled more ads, and retrieved them more rapidly, when given a categorical cue compared to an executional cue. Finally, we show that searching memory first with an executional cue and then with a product-category cue leads to an increase in ad recall for both emotional and neutral ads, whereas searching first with a categorical cue and then with an executional cue leads to a decrease in ad recall for neutral ads.     

The role of working memory capacity in autobiographical retrieval: Individual differences in strategic search

Remembering previous experiences from one's personal past is a principal component of psychological well-being, personality, sense of self, decision making, and planning for the future. In the current study the ability to search for autobiographical information in memory was examined by having college students recall their Facebook friends. Individual differences in working memory capacity manifested itself in the search of autobiographical memory by way of the total number of friends remembered, the number of clusters of friends, size of clusters, and the speed with which participants could output their friends' names. Although working memory capacity was related to the ability to search autobiographical memory, participants did not differ in the manner in which they approached the search and used contextual cues to help query their memories. These results corroborate recent theorising, which suggests that working memory is a necessary component of self-generating contextual cues to strategically search memory for autobiographical information.     

Acute pain disrupts prospective memory cue detection processes

Prospective memory refers to the planning, retention, retrieval, and execution of intentions for future behaviours and it is integral to the enterprise of daily living. Although prospective memory relies upon retrospective memory and executive processes often disrupted by pain, limited research has explored the influence of acute or chronic pain on the ability to complete prospective memory tasks. In the present study we investigated the influence of acute pain on prospective memory tasks that varied in their demands on executive processes (i.e., non-focal versus focal prospective memory cues). Complex-span working memory tasks were also administered to examine whether individual differences in working memory capacity moderated any negative impact of pain on prospective memory. Acute pain significantly impaired prospective memory performance in conditions that encouraged non-focal strategic processing of prospective memory cues, but not in conditions that encouraged more spontaneous focal processing. Individual differences in working memory capacity did not moderate the effect of acute pain on non-focal prospective memory. These findings provide new insights into prospective memory dysfunction created by painful experiences.     

Misleading postevent information and working memory capacity: an individual differences approach to eyewitness memory

The present study examines how individual differences in working memory capacity relate to the effect of misleading postevent information on memory for the original event. Participants were shown a film of a crime event and were then asked to unscramble a narrative that included misinformation regarding some of the film's details. Additionally, the working memory capacity of the participants was measured using the operation‐word span task. Finally, in a free recall test, participants recalled fewer correct details in the misinformation condition compared to the control condition. This effect was negatively correlated with working memory capacity. Copyright © 2002 John Wiley & Sons, Ltd.     

Impaired autobiographical memory in complicated grief

This study investigated the relationship between autobiographical memory and goals in complicated grief (CG). Twenty-four individuals with CG and 21 bereaved individuals without CG completed an autobiographical memory task and a personal goals task. CG participants were more likely to recall memories related to their loss, particularly in response to negative cues. There was a positive relationship between the proportion of loss-related memories recalled and the proportion of grief-related goals held by individuals after controlling for symptom level. Individuals with CG also showed impaired retrieval of specific autobiographical memories in response to both positive and negative cues. These results suggest that CG is characterised by impaired and biased retrieval of specific autobiographical memories. These patterns are consistent with propositions stemming from the self-memory models of autobiographical memory.     

部分线索对记忆提取的影响:认知抑制能力的作用

在回忆时,以刚刚学过的部分项目作为提取线索,被试的回忆成绩反而比没有任何线索时的回忆成绩差,这一现象被称为部分线索效应。该效应通常被认为是抑制执行控制过程对非线索项目记忆表征强度抑制的结果。本研究以Stroop效应量(实验1)和工作记忆容量(实验2)为指标,从个体差异角度考察了认知抑制能力对部分线索效应的影响。结果发现,Stroop效应量与部分线索效应各指标呈显著负相关,Stroop效应量越小,部分线索效应各指标的值越大;工作记忆容量与部分线索效应各指标呈显著正相关,高工作记忆容量个体的部分线索效应各指标的值也更大。结果表明,认知抑制能力越强,部分线索对回忆的破坏作用越大,研究结果支持部分线索效应的提取抑制假说。     

Disrupting attention: The need for retrieval cues in working memory theories

Sometimes in conversation, something is said that causes us to want to comment, but before our impending but implicit thoughts can be expressed, the conversation is disrupted. Later, we cannot recall what we wanted to say, but still later, we can. We used the extralist cuing task to model this phenomenon, and across experiments we varied the strength, direction, and directness of the relationship between the retrieval cues and the targeted information. Disruption was varied by switching attention to a different task before testing and by changing the testing context. Such disruptions reduced recall for the target and its implicitly activated memories. Following a disruption, stronger cues that were related to the target or to both the target and its implicit memories were more effective than those that were related to implicit memories. The findings were consistent with a model of long-term working memory that attributes forgetting to a loss of access to what has been activated, which loss is relative to the strength of the retrieval cue. Decay alone does not explain the results, indicating that many models of working memory need to be revised to take the nature of retrieval cues into account.