无关长时记忆表征能否引导视觉注意选择?

与任务相关的长时记忆表征在引导视觉注意选择的过程中扮演着重要的角色,它可以使人们在熟悉的视觉情境中快速搜索目标刺激,并偏离干扰刺激。但当长时记忆表征与任务无关时,还能否引导视觉注意选择?目前还不清楚。实验1采用眼动追踪技术直接比较无关工作记忆表征与无关长时记忆表征在视觉搜索阶段对视觉注意的捕获效应,行为反应时与首次注视点百分率的结果都发现,当无关工作记忆表征在视觉搜索中再次出现时能引导视觉注意偏向到与之匹配的干扰刺激,但无关长时记忆表征并没有表现出类似的注意引导效应;实验2探讨记忆表征由工作记忆系统转移到长时记忆系统的过程中对视觉注意的引导效应,结果发现,随着记忆表征的转移,注意引导效应消失了,实验3排除工作记忆表征的干扰后,依然没有发现无关长时记忆表征对注意的引导效应。以上结果表明,无关长时记忆表征并不能像工作记忆表征一样引导视觉注意选择,工作记忆表征和长时记忆表征对视觉注意的引导属于两个不同的认知过程。     

Selective interference with image retention and generation: Evidence for the workspace model

We address three types of model of the relationship between working memory (WM) and long-term memory (LTM): (a) the gateway model, in which WM acts as a gateway between perceptual input and LTM; (b) the unitary model, in which WM is seen as the currently activated areas of LTM; and (c) the workspace model, in which perceptual input activates LTM, and WM acts as a separate workspace for processing and temporary retention of these activated traces. Predictions of these models were tested, focusing on visuospatial working memory and using dual-task methodology to combine two main tasks (visual short-term retention and image generation) with two interference tasks (irrelevant pictures and spatial tapping). The pictures selectively disrupted performance on the generation task, whereas the tapping selectively interfered with the retention task. Results are consistent with the predictions of the workspace model.     

Working memory retrieval differences between medial temporal lobe epilepsy patients and controls: A three memory layer approach

Multi-store models of working memory (WM) have given way to more dynamic approaches that conceive WM as an activated subset of long-term memory (LTM). The resulting framework considers that memory representations are governed by a hierarchy of accessibility. The activated part of LTM holds representations in a heightened state of activation, some of which can reach a state of immediate accessibility according to task demands. Recent neuroimaging studies have studied the neural basis of retrieval information with different states of accessibility. It was found that the medial temporal lobe (MTL) was involved in retrieving information within immediate access store and outside this privileged zone. In the current study we further explored the contribution of MTL to WM retrieval by analyzing the consequences of MTL damage to this process considering the state of accessibility of memory representations. The performance of a group of epilepsy patients with left hippocampal sclerosis in a 12-item recognition task was compared with that of a healthy control group. We adopted an embedded model of WM that distinguishes three components: the activated LTM, the region of direct access, and a single-item focus of attention. Groups did not differ when retrieving information from single-item focus, but patients were less accurate retrieving information outside focal attention, either items from LTM or items expected to be in the WM range. Analyses focused on items held in the direct access buffer showed that consequences of MTL damage were modulated by the level of accessibility of memory representations, producing a reduced capacity.     

Why do we move our eyes while trying to remember? The relationship between non-visual gaze patterns and memory

Non-visual gaze patterns (NVGPs) involve saccades and fixations that spontaneously occur in cognitive activities that are not ostensibly visual. While reasons for their appearance remain obscure, convergent empirical evidence suggests that NVGPs change according to processing requirements of tasks. We examined NVPGs in tasks with long-term memory (LTM) and working memory (WM) requirements. Experiment 1 yielded significantly higher eye movement rate (EMR) in tasks requiring LTM search than in a WM task requiring maintenance of information. Experiment 2 manipulated accessibility of items in study-test episodic tasks using the levels of processing paradigm. EMR was high in episodic recall irrespective of item accessibility. Experiment 3 examined functional significance of saccades in LTM tasks. Voluntary saccadic suppression produced no evidence that saccades contribute to task performance. We discuss the apparent epiphenomenal nature of spontaneous saccades from an evolutionary perspective and outline a neuroanatomical model of the link between the saccadic and memory system.     

Neural substrates of successful working memory and long-term memory formation in a relational spatial memory task

Working memory (WM) tasks may involve brain activation actually implicated in long-term memory (LTM). In order to disentangle these two memory systems, we employed a combined WM/LTM task, using a spatial relational (object-location) memory paradigm and analyzed which brain areas were associated with successful performance for either task using fMRI. Critically, we corrected for the performance on the respective memory task when analyzing subsequent memory effects. The WM task consisted of a delayed-match-to-sample task assessed in an MRI scanner. Each trial consisted of an indoor or outdoor scene in which the exact configuration of four objects had to be remembered. After a short delay (7–13 s), the scene was presented from a different angle and spatial recognition for two objects was tested. After scanning, participants received an unexpected subsequent recognition memory (LTM) task, where the two previously unprobed objects were tested. Brain activity during encoding, delay phase and probe phase was analyzed based on WM and LTM performance. Results showed that successful WM performance, when corrected for LTM performance, was associated with greater activation in the inferior frontal gyrus and left fusiform gyrus during the early stage of the maintenance phase. A correct decision during the WM probe was accompanied by greater activation in a wide network, including bilateral hippocampus, right superior parietal gyrus and bilateral insula. No voxels exhibited supra-threshold activity during the encoding phase, and we did not find any differential activity for correct versus incorrect trials in the WM task when comparing LTM correct versus LTM incorrect trials.     

Control of the contents of working memory--a comparison of two paradigms and two age groups

Two experiments investigated whether young and old adults can temporarily remove information from a capacity-limited central component of working memory (WM) into another component, the activated part of long-term memory (LTM). Experiment 1 used a modified Sternberg recognition task (S. Sternberg, 1969); Experiment 2 used an arithmetic memory-updating task. In both paradigms, participants memorized 2 lists, one of which was cued as temporarily irrelevant. Removal of the irrelevant list from capacity-limited WM was indexed by the disappearance of list-length effects of that list on latencies for concurrent processing tasks. Young adults could outsource the irrelevant list within 2-3 s and retrieve it back into the central part of WM later. Old adults showed the same flexibility in the arithmetic updating task but seemed somewhat less able or inclined to temporarily move information into the activated part of LTM in the modified Sternberg task.     

Media multitasking and memory: Differences in working memory and long-term memory

Increasing access to media in the 21st century has led to a rapid rise in the prevalence of media multitasking (simultaneous use of multiple media streams). Such behavior is associated with various cognitive differences, such as difficulty filtering distracting information and increased trait impulsivity. Given the rise in media multitasking by children, adolescents, and adults, a full understanding of the cognitive profile of media multitaskers is imperative. Here we investigated the relationship between chronic media multitasking and working memory (WM) and long-term memory (LTM) performance. Four key findings are reported (1) heavy media multitaskers (HMMs) exhibited lower WM performance, regardless of whether external distraction was present or absent; (2) lower performance on multiple WM tasks predicted lower LTM performance; (3) media multitasking-related differences in memory reflected differences in discriminability rather than decision bias; and (4) attentional impulsivity correlated with media multitasking behavior and reduced WM performance. These findings suggest that chronic media multitasking is associated with a wider attentional scope/higher attentional impulsivity, which may allow goal-irrelevant information to compete with goal-relevant information. As a consequence, heavy media multitaskers are able to hold fewer or less precise goal-relevant representations in WM. HMMs’ wider attentional scope, combined with their diminished WM performance, propagates forward to yield lower LTM performance. As such, chronic media multitasking is associated with a reduced ability to draw on the past—be it very recent or more remote—to inform present behavior.     

Memory guidance in distractor suppression is governed by the availability of cognitive control

Information stored in the memory systems can affect visual search. Previous studies have shown that holding the to-be-ignored features of distractors in working memory (WM) could accelerate target selection. However, such facilitation effect was only observed when the cued to-be-ignored features remained unchanged within an experimental block (i.e., the fixed cue condition). No search benefit was obtained if the to-be-ignored features varied from trial to trial (i.e., the varied cue condition). In the present study, we conducted three behavioral experiments to investigate whether the WM and long-term memory (LTM) representations of the to-be-ignored features could facilitate visual search in the fixed cue (Experiment 1) and varied cue (Experiments 2 and 3) conditions. Given the importance of the processing time of cognitive control in distractor suppression, we divided visual search trials into five quintiles based on their reaction times (RTs) and examined the temporal characteristics of the suppression effect. Results showed that both the WM and LTM representations of the to-be-ignored features could facilitate distractor suppression in the fixed cue condition, and the facilitation effects were evident across the quintiles in the RT distribution. However, in the varied cue condition, the RT benefits of the WM-matched distractors occurred only in the trials with the longest RTs, whereas no advantage of the LTM-matched distractors was observed. These results suggest that the effective WM-guided distractor suppression depends on the availability of cognitive control and the LTM-guided suppression occurs only if sufficient WM resource is accessible by LTM reactivation.     

Interference with prior knowledge while writing from sources: Effects of working memory capacity

Writing from sources requires the processing of both external (documentary) and internal (long-term memory; LTM) sources of information, which can sometimes interfere with each other. We hypothesised that writers with high working memory (WM) capacity would resolve interference faster than those with low-capacity WM. However, results showed that writing pause duration was shorter for low-capacity writers. This result suggests that when WM resources are limited, access to domain knowledge in LTM is restricted, thereby avoiding interference between the two sources. Results are discussed within the broader context of text composition from sources and individual differences.     

The amygdala is involved in the modulation of long-term memory, but not in working or short-term memory

Rats with cannulae implanted in the junction between the central and the basolateral nuclei of the amygdala were trained in one-trial step-down inhibitory avoidance and tested at 3 s for working memory (WM) or 1.5 or 24 h later for short-term memory (STM) and long-term memory (LTM), respectively. Several drugs were infused 6 min prior to training in the animals in which WM was measured or 0 min posttraining in those in which STM and LTM were measured: the glutamate receptor antagonists CNQX (0.5 microg) and AP5 (5.0 microg), the indirect GABA A receptor antagonist picrotoxin (0.08 microg), the cholinergic muscarinic receptor blocker scopolamine (2. 0 microg), norepinephrine (0.3 microg), the protein kinase C inhibitor staurosporin (1.0 microg), or the calcium/calmodulin dependent protein kinase II inhibitor Kn-62 (3.5 ng). None of the drugs had any effect on either WM or STM. All had, as previously shown, strong effects on LTM: picrotoxin and norepinephrine enhanced it, and CNQX, AP5, scopolamine, Kn-62, and staurosporin inhibited it. The results do not support the idea that memory of this task is formed in the amygdala; they indicate that the amygdala is not involved in WM or STM processing and support the idea that the amygdala modulates LTM storage processes carried out elsewhere.     

Working memory maintenance contributes to long-term memory formation: Evidence from slow event-related brain potentials

Behavioral research has led to conflicting views regarding the relationship between working memory (WM) maintenance and long-term memory (LTM) formation. We used slow event-related brain potentials to investigate the degree to which neural activity during WM maintenance is associated with successful LTM formation. Participants performed a WM task with objects and letter strings, followed by a surprise LTM test. Slow potentials were found to be more negative over the parietal and occipital cortex for objects and over the left frontal cortex for letter strings during WM maintenance. Within each category, they were enhanced for items that were subsequently successfully remembered. These effects were topographically distinct, with maximum effects at those electrodes that showed the maximum negativity during WM maintenance in general. Together, these results are strongly consistent with the ideas that WM maintenance contributes to LTM formation and that this may occur through strengthening of stimulus-specific cortical memory traces.     

工作记忆和长时记忆共享信息表征的ERP证据

工作记忆和长时记忆共享记忆系统的信息表征网络, 关系密切。实验采用事件相关电位技术记录长时记忆信息对工作记忆的长时语义启动和工作记忆对相关长时记忆信息的长时语义启动。结果显示：与新项目相比, 学习项(即长时记忆信息)对工作记忆的目标信息产生了明显的行为启动效应, N2潜伏期、波幅和P3潜伏期也表现出明显的神经启动效应, 即, 学习项比新项目的反应时更短、N2和P3的潜伏期更短、N2更正, 但学习对非记忆项的影响不大; 工作记忆对相关的长时记忆信息也产生了神经启动, 表现在类别比较任务中记忆类信息比其他信息(即, 与工作记忆任务中的信息无关的内容)的N400更正。而且, 这种神经启动也会因刺激重复次数的增多而降低：与新项目相比, 学习项会使与之语义类似信息的N400更负。上述两种长时语义启动的存在及其ERPs的神经启动均为长时记忆和工作记忆使用共同信息表征的观点提供了证据支持。证据还表明, 在工作记忆和长时记忆的相互作用中注意是关键的调节因素。     

A bilateral advantage for storage in visual working memory

Various studies have demonstrated enhanced visual processing when information is presented across both visual hemifields rather than in a single hemifield (the bilateral advantage). For example, Alvarez and Cavanagh (2005) reported that observers were able to track twice as many moving visual stimuli when the tracked items were presented bilaterally rather than unilaterally, suggesting that independent resources enable tracking in the two visual fields. Motivated by similarities in the apparent capacity and neural substrates that mediate tracking and visual working memory (WM), the present work examined whether or not a bilateral advantage also arises during storage in visual WM. Using a recall procedure to assess working memory for orientation information, we found a reliable bilateral advantage; recall error was smaller with bilateral sample displays than with unilateral displays. To demonstrate that the bilateral advantage influenced storage per se rather than just encoding efficiency, we replicated the observed bilateral advantage using sequentially presented stimuli. Finally, to further characterize how bilateral presentations enhanced storage in working memory, we measured both the number and the resolution of the stored items and found that bilateral presentations lead to an increased probability of storage, rather than enhanced mnemonic resolution. Thus, the bilateral advantage extends beyond the initial selection and encoding of visual information to influence online maintenance in visual working memory.     

Modulation of working, short- and long-term memory by nicotinic receptors in the basolateral amygdala in rats

Male Wistar rats were exposed to one-trial step-down inhibitory avoidance training using a 0.5 mA footshock. Through bilaterally implanted indwelling cannulae, they received bilateral 0.5 microL infusions of saline, mecamylamine (1.0 or 10.0 microg/side), or nicotine (0.6 or 3.0 microg/side) into the basolateral complex of the amygdaloid nucleus (BLA). Infusions were either 10 min before training (Experiment 1) or 4 min after training (Experiment 2). In Experiment 1, the animals were tested three times: first for working memory (WM) 5 s after training, then for short-term memory (STM) 90 min later, and finally for long-term memory (LTM) 24 h later. Mecamylamine depressed and nicotine enhanced WM, STM, and LTM. In Experiment 2, the treatments were given after WM was presumably over. Again, mecamylamine inhibited and nicotine enhanced STM and LTM. The results indicate that nAChRs in BLA participate in the regulation of WM formation and STM and LTM acquisition and consolidation.     

A processing approach to the working memory/long-term memory distinction: evidence from the levels-of-processing span task

Recent theories suggest that performance on working memory (WM) tasks involves retrieval from long-term memory (LTM). To examine whether WM and LTM tests have common principles, Craik and Tulving's (1975) levels-of-processing paradigm, which is known to affect LTM, was administered as a WM task: Participants made uppercase, rhyme, or category-membership judgments about words, and immediate recall of the words was required after every 3 or 8 processing judgments. In Experiment 1, immediate recall did not demonstrate a levels-of-processing effect, but a subsequent LTM test (delayed recognition) of the same words did show a benefit of deeper processing. Experiment 2 showed that surprise immediate recall of 8-item lists did demonstrate a levels-of-processing effect, however. A processing account of the conditions in which levels-of-processing effects are and are not found in WM tasks was advanced, suggesting that the extent to which levels-of-processing effects are similar between WM and LTM tests largely depends on the amount of disruption to active maintenance processes.     

Short-term retention of a single word relies on retrieval from long-term memory when both rehearsal and refreshing are disrupted

Many working memory (WM) models propose that the focus of attention (or primary memory) has a capacity limit of one to four items, and therefore, that performance on WM tasks involves retrieving some items from long-term (or secondary) memory (LTM). In the present study, we present evidence suggesting that recall of even one item on a WM task can involve retrieving it from LTM. The WM task required participants to make a deep (living/nonliving) or shallow (“e”/no “e”) level-of-processing (LOP) judgment on one word and to recall the word after a 10-s delay on each trial. During the delay, participants either rehearsed the word or performed an easy or a hard math task. When the to-be-remembered item could be rehearsed, recall was fast and accurate. When it was followed by a math task, recall was slower, error-prone, and benefited from a deeper LOP at encoding, especially for the hard math condition. The authors suggest that a covert-retrieval mechanism may have refreshed the item during easy math, and that the hard math condition shows that even a single item cannot be reliably held in WM during a sufficiently distracting task—therefore, recalling the item involved retrieving it from LTM. Additionally, performance on a final free recall (LTM) test was better for items recalled following math than following rehearsal, suggesting that initial recall following math involved elaborative retrieval from LTM, whereas rehearsal did not. The authors suggest that the extent to which performance on WM tasks involves retrieval from LTM depends on the amounts of disruption to both rehearsal and covert-retrieval/refreshing maintenance mechanisms.     

On the division of working memory and long-term memory and their relation to intelligence: A latent variable approach

The present study examined the extent to which working (WM) and long-term memory (LTM) reflect the same, related, or completely different constructs and how they relate to other cognitive ability constructs. Participants performed various WM, recall, recognition, general fluid (gF) and general crystallized intelligence (gC) measures. Confirmatory factor analyses suggested that the memory measures could be grouped into three separate yet correlated factors (WM, recall, and recognition) and that these factors were strongly related to gF, but were related less so with gC. Furthermore, it was found that the common variance from the three memory factors could be accounted for by a higher-order memory factor which was strongly related to gF, but less so with gC. Finally, structural equation modeling suggested that both the variance common to the WM tasks and the variance common to all the memory tasks accounted for a unique variance in gF. These results are interpreted within an embedded process model of memory and suggest that WM and LTM tasks measure both shared and unique processes, which are important for intelligence.     

Familiarity increases the number of remembered Pokémon in visual short-term memory

Long-term memory (LTM) can influence many aspects of short-term memory (STM), including increased STM span. However, it is unclear whether LTM enhances the quantitative or qualitative aspect of STM. That is, do we retain a larger number of representations or more precise representations in STM for familiar stimuli than unfamiliar stimuli? This study took advantage of participants’ prior rich multimedia experience with Pokémon, without investing on laboratory training to examine how prior LTM influenced visual STM. In a Pokémon visual STM change detection task, participants remembered more first-generation Pokémon characters that they were more familiar with than recent-generation Pokémon characters that they were less familiar with. No significant difference in memory quality was found when quantitative and qualitative effects of LTM were isolated using receiver operating characteristic (ROC) analyses. Critically, these effects were absent in participants who were unfamiliar with first-generation Pokémon. Furthermore, several alternative interpretations were ruled out, including general video-gaming experience, subjective Pokémon preference, and verbal encoding. Together, these results demonstrated a strong link between prior stimulus familiarity in LTM and visual STM storage capacity.     

What happens to an individual visual working memory representation when it is interrupted?

This study tested the hypothesis that even the simplest cognitive tasks require the storage of information in working memory (WM), distorting any information that was previously stored in WM. Experiment 1 tested this hypothesis by requiring observers to perform a simple letter discrimination task while they were holding a single orientation in WM. We predicted that performing the task on the interposed letter stimulus would cause the orientation memory to become less precise and more categorical compared to when the letter was absent or when it was present but could be ignored. This prediction was confirmed. Experiment 2 tested the modality specificity of this effect by replacing the visual letter discrimination task with an auditory pitch discrimination task. Unlike the interposed visual stimulus, the interposed auditory stimulus produced little or no disruption of WM, consistent with the use of modality‐specific representations. Thus, performing a simple visual discrimination task, but not a simple auditory discrimination task, distorts information about a single feature being maintained in visual WM. We suggest that the interposed task eliminates information stored within the focus of attention, leaving behind a WM representation outside the focus of attention that is relatively imprecise and categorical.     

A secondary task is not always costly: Context‐based guidance of visual search survives interference from a demanding working memory task

Repeatedly encountering a visual search display with the target located at a fixed position relative to the distractors facilitates target detection, relative to novel displays – which is attributed to search guidance by (acquired) long‐term memory (LTM) of the distractor ‘context’ of the target. Previous research has shown that this ‘contextual cueing’ effect is severely impeded during learning when participants have to perform a demanding spatial working memory (WM) task concurrently with the search task, though it does become manifest when the WM task is removed. This has led to the proposal that search guidance by LT context memories critically depends on spatial WM to become ‘expressed’ in behaviour. On this background, this study, of two experiments, asked: (1) Would contextual cueing eventually emerge under dual‐task learning conditions if the practice on the task(s) is extended beyond the short training implemented in previous studies? and given sufficient practice, (2) Would performing the search under dual‐task conditions actually lead to an increased cueing effect compared to performing the visual search task alone? The answer is affirmative to both questions. In particular, Experiment 1 showed that a robust contextual cueing effect emerges within 360–720 dual‐task trials as compared to some 240 single‐task trials. Further, Experiment 2 showed that when dual‐ and single‐task conditions are performed in alternating trials blocks, the cueing effect for the very same set of repeated displays is significantly larger in dual‐task blocks than in single‐task blocks. This pattern of effects suggests that dual‐task practice eventually leads to direct, or ‘automatic’, guidance of visual search by learnt spatial LTM representations, bypassing WM processes. These processes are normally engaged in single‐task performance might actually interfere with direct LTM‐based search guidance.