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 episodic retrieval: examining the dynamics of delayed and continuous distractor free recall

Two experiments explored the possibility that individual differences in working memory capacity (WMC) partially reflect differences in the size of the search set from which items are retrieved. High- and low-WMC individuals were tested in delayed (Experiment 1) and continuous distractor (Experiment 2) free recall with varying list lengths. Across both experiments low-WMC individuals recalled fewer items than high-WMC individuals, recalled more previous list intrusions than high-WMC individuals, and recalled at a slower rate than high-WMC individuals. It is argued that low-WMC individuals' episodic retrieval deficits are partially due to the fact that these individuals search through a larger set of items than high-WMC individuals. Simulations based on a random search model were consistent with these general conclusions.     

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.     

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.     

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.     

Variation in working memory capacity and intrusions: Differences in generation or editing?

The current study explored the reason for the relation between individual differences in working memory capacity (WMC) and intrusions in free recall. High and low WMC individuals were tested in standard delayed free recall and externalised free recall in which participants recalled everything that came to mind. Additionally, in externalised free recall participants were instructed to press a key for each item that they knew was an intrusion. In delayed free recall, low WMC individuals recalled fewer correct items and more previous list and extralist intrusions than high WMC individuals. In externalised free recall, differences only arose in previous list intrusions. Furthermore, in externalised free recall it was found that low WMC were less likely to identify both types of intrusions than high WMC individuals. It is argued that the reason low WMC individuals recall more intrusions than high WMC in free recall is due to differences in both generation and editing abilities.     

Order information and retrieval distinctiveness: recall of common versus bizarre material

The order-encoding hypothesis (E. L. DeLosh & M. A. McDaniel, 1996) assumes that serial-order information contributes to the retrieval of list items and that serial-order encoding is better for common items than bizarre items. In line with this account, Experiment 1 revealed better free recall and serial-order memory for common than for bizarre items in pure lists, and Experiment 2 showed that recall for bizarre items increased and the recall advantage of common items was eliminated when serial-order encoding for bizarre items was increased to the level of common items. However, inconsistent with a second assumption that bizarre-item advantages in mixed lists reflect better individual-item encoding for bizarre items, Experiments 3 and 4 showed that the bizarreness effect in mixed lists is eliminated when alternative retrieval strategies are encouraged. This set of findings is better explained by the differential-retrieval-process framework, which proposes that contextual factors (e.g., list composition) influence the extent to which various types of information are used at retrieval, with the bizarreness advantage in mixed lists dependent on a distinctiveness-based retrieval process.     

Variation in working memory capacity and cognitive control: goal maintenance and microadjustments of control

Variation in working memory capacity (WMC) and cognitive control was examined in four experiments. In the experiments high- and low-WMC individuals performed a choice reaction time task (Experiment 1), a version of the antisaccade task (Experiment 2), a version of the Stroop task (Experiment 3), and an arrow version of the flanker task (Experiment 4). An examination of response time distributions suggested that high- and low-WMC individuals primarily differed in the slowest responses in each experiment, consistent with the notion that WMC is related to active maintenance abilities. Examination of two indicators of microadjustments of control (posterror slowing and conflict adaptation effects) suggested no differences between high- and low-WMC individuals. Collectively these results suggest that variation in WMC is related to some, but not all, cognitive control operations. The results are interpreted within the executive attention theory of WMC.     

The role of integration in recognition failure and action memory

In three experiments, we studied memory for action events with respect to exceptions from the Tulving-Wiseman function demonstrated in experiments on recognition failure of recallable words. In Experiment 1, we examined exceptions of poor integration in a regular recognition failure condition (i.e., recognition of targets without contextual cues, followed by recall of targets in the presence of contextual cues). In Experiment 2, we examined exceptions of cue overlap in which subjects also had access to the information of contextual cues at recognition test. In Experiment 3, we attempted to equate the levels of recognition across the action and verbal encoding. In addition, the cue overlap and no-cue overlap conditions were studied in a within-subjects design. Results from the three experiments indicated that encoding enactment (episodic integration) and conceptual integration (semantic integration) are related to each other. As a consequence of this relationship, there is a larger independence between recognition and recall of well-integrated items with encoding enactment. On the other hand, for the poorly integrated items without encoding enactment, there is a larger dependence between recognition and recall. Even in the cue overlap condition, where there is a case of large dependence between recognition and recall, the same pattern of data was observed. The results are discussed in terms of an episodic integration view of encoding enactment.     

Collaborative memory and part-set cueing impairments: the role of executive depletion in modulating retrieval disruption

When people are exposed to a subset of previously studied list items they recall fewer of the remaining items compared to a condition where none of the studied items is provided during recall. This occurs both when the subset of items is provided by the experimenter (i.e., the part-set cueing deficit in individual recall) and when they are provided during the course of a collaborative discussion (i.e., the collaborative inhibition effect in group recall). Previous research has identified retrieval disruption as a common mechanism underlying both effects; however, less is known about the factors that may make individuals susceptible to such retrieval disruption. In the current studies we tested one candidate factor: executive control. Using an executive depletion paradigm we directly manipulated an individual's level of executive control during retrieval. Results revealed no direct role of executive depletion in modulating retrieval disruption. In contrast, executive control abilities were indirectly related to retrieval disruption through their influence at encoding. Together these results suggest that executive control des not directly affect retrieval disruption at the retrieval stage, and that the role of this putative mechanism may be limited to the encoding stage.     

Age- and performance-related differences in encoding during early childhood: insights from event-related potentials

Previous studies have found that children show rapid and significant improvements in their ability to remember individual items and the contextual details that surround these items (i.e., episodic memory) during early childhood. Encoding processes have been suggested to contribute to the development of episodic memory; however, few studies have investigated encoding processes. The goal of the current study was to examine age- and performance-related effects on encoding in children between 4 and 8 years of age using event-related potentials (ERPs). Results revealed effects of both age and performance on encoding, as indexed by the ERPs response. However, the nature of these effects differed between subsequent recognition and subsequent recollection, as well as for the two ERP components (i.e., Nc and LSW) examined. These findings are important as they contribute empirical evidence that encoding processes show developmental change across early childhood. In addition, these findings highlight the importance of controlling for performance differences in future studies examining developmental changes in episodic memory.     

The influence of levels of processing on recall from working memory and delayed recall tasks

Recent research in working memory has highlighted the similarities involved in retrieval from complex span tasks and episodic memory tasks, suggesting that these tasks are influenced by similar memory processes. In the present article, the authors manipulated the level of processing engaged when studying to-be-remembered words during a reading span task (Experiment 1) and an operation span task (Experiment 2) in order to assess the role of retrieval from secondary memory during complex span tasks. Immediate recall from both span tasks was greater for items studied under deep processing instructions compared with items studied under shallow processing instructions regardless of trial length. Recall was better for deep than for shallow levels of processing on delayed recall tests as well. These data are consistent with the primary-secondary memory framework, which suggests that to-be-remembered items are displaced from primary memory (i.e., the focus of attention) during the processing phases of complex span tasks and therefore must be retrieved from secondary memory.     

Collaborative memory and part-set cueing impairments: The role of executive depletion in modulating retrieval disruption

When people are exposed to a subset of previously studied list items they recall fewer of the remaining items compared to a condition where none of the studied items is provided during recall. This occurs both when the subset of items is provided by the experimenter (i.e., the part-set cueing deficit in individual recall) and when they are provided during the course of a collaborative discussion (i.e., the collaborative inhibition effect in group recall). Previous research has identified retrieval disruption as a common mechanism underlying both effects; however, less is known about the factors that may make individuals susceptible to such retrieval disruption. In the current studies we tested one candidate factor: executive control. Using an executive depletion paradigm we directly manipulated an individual's level of executive control during retrieval. Results revealed no direct role of executive depletion in modulating retrieval disruption. In contrast, executive control abilities were indirectly related to retrieval disruption through their influence at encoding. Together these results suggest that executive control des not directly affect retrieval disruption at the retrieval stage, and that the role of this putative mechanism may be limited to the encoding stage.     

Dissociative effects of true and false recall as a function of different encoding strategies

Goodwin, Meissner, and Ericsson (2001) proposed a path model in which elaborative encoding predicted the likelihood of verbalisation of critical, nonpresented words at encoding, which in turn predicted the likelihood of false recall. The present study tested this model of false recall experimentally with a manipulation of encoding strategy and the implementation of the process-tracing technique of protocol analysis. Findings indicated that elaborative encoding led to more verbalisations of critical items during encoding than rote rehearsal of list items, but false recall rates were reduced under elaboration conditions (Experiment 2). Interestingly, false recall was more likely to occur when items were verbalised during encoding than not verbalised (Experiment 1), and participants tended to reinstate their encoding strategies during recall, particularly after elaborative encoding (Experiment 1). Theoretical implications for the interplay of encoding and retrieval processes of false recall are discussed.     

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。     

Hippocampal Activations during Repetitive Learning and Recall of Geometric Patterns

Hippocampal activation is required for episodic memory. Encoding and retrieval of novel and memorable items have been related to different locations in the hippocampus; however, the data remain ambiguous. The application of a newly designed keyboard allowed investigation of brain activation during encoding and free immediate and delayed recall with functional magnetic resonance imaging (fMRI) in young healthy controls (n=12). Because of the repetitive learning and recall conditions, an individual learning gradient was used to contrast neural activity at different individual levels of novelty. During learning, subjects were asked to memorize 10 geometric patterns requiring the establishment of intra-item associations for memorization. After learning, subjects were asked to recall the items actively via the keyboard. Learning and recall were alternated five times. Delayed recall was scanned about 15 min after the fifth immediate recall condition without subjects having seen the items again. Left-sided anterior hippocampal activity was observed during conditions of initial learning as well as maximum recall. Neural activity during delayed recall did not reveal hippocampal responses and was characterized by a transition of neural activity from occipitoparietal regions to bilateral temporal cortices. We conclude that both lateralization and segregation depend on the specific relational characteristics of the stimuli requiring establishment of intra-item associations for encoding as well as retrieval. The absence of hippocampal activation during delayed recall together with the increase of lateral temporal involvement possibly corresponds with an emerging transition from episodic to long-term memory.     

Distinct episodic contexts enhance retrieval-based learning

Spaced retrieval practice results in better long-term retention than massed retrieval practice. The episodic context account of this effect suggests that updated representations of the more distinct temporal contexts associated with spaced retrievals facilitate later recall. We examined whether environmental context, in addition to temporal context, may also play a role in retrieval-based learning. Participants studied and then attempted to retrieve the English translations of Swahili words during four acquisition blocks of trials. They were then randomly assigned to practice retrieving items three more times in one of the following conditions: massed practice with the same environmental context scene; massed practice with different environmental context scenes; spaced practice with the same environmental context scene; or spaced practice with different environmental context scenes. After a one-week delay, measures of recall, forgetting, and the joint probabilities between study session recall and final recall performance all indicated enhanced retention for both the spaced and different environmental context conditions. Indeed, after retrieving items in the study session, forgetting them during final recall was 371% more likely in the same context than in the different context conditions. These findings redefine and refine previous accounts of the episodic context model of retrieval-based learning.     

Item-specific and relational encoding effects in children's recall and recognition memory for words

This study tests the hypothesis that children's deficiency in encoding itemspecific and relational information in episodic events contributes to age differences in recall and recognition. In two experiments, grade school children and college adults were presented with word triplets varying in categorical relatedness. The processing of the item-specific and relational information in the triplets was independently manipulated. Experiment 1 assessed cued recall, and Experiment 2 assessed recognition of both the central target and incidental contextual members of each triplet. The results showed that the processing manipulations had independent and different effects on recall and recognition, on memory for the members of the different kinds of triplets, on the use of the retrieval cues, and on memory for target and incidental words. Developmental differences were found in both recall and recognition, and of both target and incidental words, that varied with triplet type and the processing manipulations and that were attributable to differences in the encoding of item-specific and relational information in the triplets. The discussion contrasts alternative accounts of children's encoding deficiency, and suggests that the distinction between automatic, age-invariant, and strategic age-sensitive encoding processes needs to be redrawn.     

The temporal contiguity effect predicts episodic memory performance

One way to study the associative processes at work during episodic memory is to examine the order of participant responses, which reveal the strong tendency to transition between temporally contiguous or semantically proximal items on the study list. Here, we assessed the correlation between participants’ recall performance and their use of semantic and temporal associations to guide retrieval across nine delayed free recall studies. The size of the participants’ temporal contiguity effects predicted their recall performance. When interpreted in terms of two models of episodic memory, these results suggest that participants who more effectively form and retrieve associations between items that occur nearby in time perform better on episodic recall tasks. Sample code may be downloaded as a supplement for this article from http://mc.psychonomic-journals.org/content/ supplemental.     

The effects of gender on the retrieval of episodic and semantic components of autobiographical memory

Despite consistent evidence that women exhibit greater episodic memory specificity than men, little attention has been paid to gender differences in the production of episodic details during autobiographical recall under conditions of high and low retrieval support. Similarly the role of gender on the production of semantic details used to support autobiographical memory recollections of specific events has been largely unexplored. In the present study an undergraduate sample of 50 men and 50 women were assessed using the Autobiographical Interview (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002). Women recalled more episodic information compared to men in the high retrieval support condition, whereas no gender differences were found in the low retrieval support condition. In addition, women produced more repetitions compared to men in the high retrieval support condition. No gender differences were found in the production of semantic details. These results are interpreted in terms of gender differences in encoding and reminiscence practices. This research adds to the literature on gender differences in memory recall and suggests that gender is an important variable in explaining individual differences in AM recall.