Towards theoretically understanding how long-term memory semantics can support working memory performance

Working memory is the system that supports the temporary storage and processing of information. It is generally agreed that working memory is a mental workspace, with a combination of resources operating together to maintain information in mind for potential use in thought and action. Theories typically acknowledge the contributions of long-term memory to this system. One particular aspect of long-term memory, namely semantic long-term memory, can effectively supplement or "boost" working memory performance. This may be a relatively automatic process via the semantic properties of the stimuli or more active via strategy development and implementation. However, the precise mechanisms require greater theoretical understanding. In this review of the literature, we critically discuss theoretical models of working memory and their proposed links with long-term memory. We also explore empirical research that contributes to our understanding of the ways in which semantics can support performance of both verbal and visuospatial working memory tasks, with a view to potential intervention development. This includes the possibility of training people with lower performance (e.g., older adults) to use semantics during working memory tasks. We conclude that semantics may offer an opportunity to maximise working memory performance. However, to realise this potential, more research is needed, particularly in the visuospatial domain.

The multicomponent model of working memory fifty years on

We provide a broad overview of our original investigation of working memory; how the multicomponent model followed from our use of a dissociative methodology; and our intention that it should be simple, robust, and applicable. We describe how subsequent development of the model has increased its scope, depth, and applications while at the same time retaining its core features. Comparisons with the growing number of alternative models suggest agreement on the basic phenomena to be explained and more similarities than differences. While differences between models attract interest, we caution that they do not necessarily reflect the most important issues for future research, which we suggest relate principally to the nature of executive control. The longevity of the multicomponent model reflects not only the importance of working memory in cognition but also the usefulness of a simple, robust framework for further theoretical development and applications.

Navigating the mind's eye: Understanding gaze shifts in visuospatial bootstrapping

Visuospatial bootstrapping refers to the well-replicated phenomena in which serial recall in a purely verbal task is boosted by presenting digits within the familiar spatial layout of a typical telephone keypad. The visuospatial bootstrapping phenomena indicates that additional support comes from long-term knowledge of a fixed spatial pattern, and prior experimentation supports the idea that access to this benefit depends on the availability of the visuospatial motor system. We investigate this by tracking participants' eye movements during encoding and retention of verbal lists to learn whether gaze patterns support verbal memory differently when verbal information is presented in the familiar visual layout. Participants' gaze was recorded during attempts to recall lists of seven digits in three formats: centre of the screen, typical telephone keypad, or a spatially identical layout with randomised number placement. Performance was better with the typical than with the novel layout. Our data show that eye movements differ when encoding and retaining verbal information that has a familiar layout compared with the same verbal information presented in a novel layout, suggesting recruitment of different spatial rehearsal strategies. However, no clear link between gaze pattern and recall accuracy was observed, which suggests that gazes play a limited role in retention, at best.

Hanging on the telephone: Maintaining visuospatial bootstrapping over time in working memory

Visuospatial bootstrapping (VSB) refers to the phenomenon in which performance on a verbal working memory task can be enhanced by presenting the verbal material within a familiar visuospatial configuration. This effect is part of a broader literature concerning how working memory is influenced by use of multimodal codes and contributions from long-term memory. The present study aimed to establish whether the VSB effect extends over a brief (5-s) delay period, and to explore the possible mechanisms operating during retention. The VSB effect, as indicated by a verbal recall advantage for digit sequences presented within a familiar visuospatial configuration (modelled on the T-9 keypad) relative to a single-location display, was observed across four experiments. The presence and size of this effect changed with the type of concurrent task activity applied during the delay. Articulatory suppression (Experiment 1) increased the visuospatial display advantage, while spatial tapping (Experiment 2) and a visuospatial judgment task (Experiment 3) both removed it. Finally, manipulation of the attentional demands placed by a verbal task also reduced (but did not abolish) this effect (Experiment 4). This pattern of findings demonstrates how provision of familiar visuospatial information at encoding can continue to support verbal working memory over time, with varying demands on modality-specific and general processing resources.

Autistic traits are associated with enhanced working memory capacity for abstract visual stimuli

We tested whether the association between autistic traits and enhanced performance in visual-perceptual tasks extends to visual working memory capacity. We predicted that any positive effect of autistic traits on visual working memory performance would be greatest during domain-specific tasks, in which visual resources must be relied upon. We used a visual 'matrix' task, involving recall of black-and-white chequered patterns which increased in size, to establish participants' capacity (span). We assessed 144 young adults' (M = 22.0 years, SD = 2.5) performance on abstract, 'low semantic' versus 'high semantic' task versions. The latter offered multimodal coding due to the availability of long-term memory resources that could supplement visual working memory. Participants also completed measures of autistic traits and trait anxiety. Autistic traits, especially Attention to Detail, Attention Switching, and Communication, positively predicted visual working memory capacity, specifically in the low semantic task, which relies on visual working memory resources. Autistic traits are therefore associated with enhanced processing and recall of visual information. The benefit is removed, however, when multimodal coding may be incorporated, emphasising the visual nature of the benefit. Strengths in focused attention to detail therefore appear to benefit domain-specific visual working memory task performance.

Leveraging Prior Knowledge to Support Short-term Memory: Exploring the Role of the Ventromedial Prefrontal Cortex

It is well established that the ventromedial prefrontal cortex (vmPFC) plays a critical role in memory consolidation and the retrieval of remote long-term memories. Recent evidence suggests that the vmPFC also supports rapid neocortical learning and consolidation over shorter timescales, particularly when novel events align with stored knowledge. One mechanism by which the vmPFC has been proposed to support this learning is by integrating congruent information into existing neocortical knowledge during memory encoding. An important outstanding question is whether the vmPFC also plays a critical role in linking congruent information with existing knowledge before storage in long-term memory. The current study investigated this question by testing whether lesions to the vmPFC disrupt the ability to leverage stored knowledge in support of short-term memory. Specifically, we investigated the visuospatial bootstrapping effect, the phenomenon whereby immediate verbal recall of visually presented stimuli is better when stimuli appear in a familiar visuospatial array that is congruent with prior knowledge compared with an unfamiliar visuospatial array. We found that the overall magnitude of the bootstrapping effect did not differ between patients with vmPFC lesions and controls. However, a reliable bootstrapping effect was not present in the patient group alone. Post hoc analysis of individual patient performance revealed that the bootstrapping effect did not differ from controls in nine patients but was reduced in two patients. Although mixed, these results suggest that vmPFC lesions do not uniformly disrupt the ability to leverage stored knowledge in support of short-term memory.

Intentional and incidental odour-colour binding in working memory

The question of how features are bound together in working memory has become a topic of much research in recent years. However, this is typically focused on visual and/or auditory stimuli. The purpose of this study is to apply established feature binding procedures to investigate odour binding in working memory. Across three experiments, memory for intentionally and incidentally formed odour-colour pairings was tested. Experiment 1 showed that following explicit instruction to remember the odour-colour combinations, young adults can recall lists of 3-pairings at levels above that of chance and exhibit a recency advantage for the last pairing. In Experiment 2 participants were asked to prioritise the first pairing in the list or treat all pairings equally. We observed only limited evidence of prioritisation affecting the serial position function. Experiment 3 explored incidental odour-colour binding. Using a yes/no recognition procedure, accuracy did not differ for positive test probes presented in the same (bound) or different (unbound) colour to encoding. This study is one of the first to examine odour-colour binding in working memory and, taking the evidence together, suggests that odour-colour bindings can be formed in working memory; however, functionality may be limited compared to that of visual feature binding.

Encode a Letter and Get Its Location for Free? Assessing Incidental Binding of Verbal and Spatial Features

Previous studies have demonstrated that when presented with a display of spatially arranged letters, participants seem to remember the letters’ locations when letters are the focus of a recognition test, but do not remember letters’ identity when locations are tested. This strong binding asymmetry suggests that encoding location may be obligatory when remembering letters, which requires explanation within theories of working memory. We report two studies in which participants focused either on remembering letters or locations for a short interval. At test, positive probes were either intact letter–location combinations or recombinations of an observed letter and another previously occupied location. Incidental binding is observed when intact probes are recognized more accurately or faster than recombined probes. Here, however, we observed no evidence of incidental binding of location to letter in either experiment, neither under conditions where participants focused on one feature exclusively for a block, nor where the to-be-remembered feature was revealed prior to encoding with a changing pre-cue, nor where the to-be-remembered feature was retro-cued and therefore unknown during encoding. Our results call into question the robustness of a strong, consistent binding asymmetry. They suggest that while incidental location-to-letter binding may sometimes occur, it is not obligatory.

Improving older adults' ability to follow instructions: benefits of actions at encoding and retrieval in working memory

The ability to follow instructions is critical for learning new skills and may support successful aging. Recent evidence indicates a close link between following instructions and working memory, and that action-based processing at encoding and retrieval can improve this ability. In this study, we examined the ability to follow instructions and the benefits of action-based processing in young and older adults. In Experiment 1, participants were presented with spoken or silent demonstrated instructions, then recalled them by oral repetition or physical enactment. Older adults produced fewer correct responses in all conditions. Both age groups were better at recalling demonstrated than spoken instructions in the verbal but not the enacted recall condition. Older adults also benefited from enacted recall relative to verbal recall, but to a smaller extent than younger adults. In Experiment 2, the additional benefit of dual modalities (spoken instructions with simultaneous demonstration) relative to single modality presentation (spoken instructions, or silent demonstration) was examined. Both age groups showed superior performance in dual modality conditions relative to spoken instructions when using verbal recall. These findings suggest that although following instruction ability appears to decline with age, older adults can still benefit from action at encoding and retrieval.

Fractionating the episodic buffer

The episodic buffer is a putative component of working memory proposed to account for several short-term memory functions, including unexpectedly preserved immediate prose recall by amnesic patients. Over the course of time, this component has increasingly become associated with binding functions. Considering recent findings regarding the performance of both memory-impaired and healthy individuals on the range of tasks purported to require the contribution of the episodic buffer, we suggest that it should be fractionated into two functional systems. One is a schematic store instantiated in brain areas responsible for conceptual and schema representations, which is likely to be hippocampus-independent, and preserved in the face of amnesia. In contrast, short-term maintenance of novel associative binding is likely to require the contribution of the hippocampus and may therefore not be functionally dissociable from long-term memory.

Using space to remember: Short-term spatial structure spontaneously improves working memory

Spatial information plays an important role in how we remember. In general, there are two (non mutually exclusive) views regarding the role that space plays in memory. One view is that objects overlapping in space interfere with each other in memory. For example, objects presented in the same location (at different points in time) are more frequently confused with one another than objects that are not. Another view is that spatial information can 'bootstrap' other kinds of information. For example, remembering a phone number is easier one can see the arrangement of a keypad. Here, building on both perspectives, we test the hypothesis that task-irrelevant spatial structure (i.e., objects appearing in stable locations over repeated iterations) improves working memory. Across 7 experiments, we demonstrate that (1) irrelevant spatial structure improves memory for sequences of objects; (2) this effect does not depend on long-term spatial associations; (3) this effect is unique to space (as opposed to features like color); and (4) spatial structure can be teased apart from spatial interference, and the former drives memory improvement. We discuss how these findings relate to and challenge 'spatial interference' accounts as well as 'visuospatial bootstrapping'.

Bootstrapping the visuospatial bootstrapping effect and testing its spatialisation

When sequences of digits are visually presented within a numerical keypad on a screen, memory span increases, this effect was named visuospatial bootstrapping. The aim of the first experiment was to know if this effect could emerge without presenting a keypad on the screen. For this purpose, a three-phase experiment was designed. During phase 1, the immediate serial recall of two groups of participants was compared (pre-training): the first group saw sequences of one-digit numbers displayed on a screen within a keypad (the keypad group) whereas the second group heard the (same) sequences (the auditive group). During phase 2, all participants underwent a training session to help them visualise in their mind a keypad. Finally, in the third phase, participants were tested again with an immediate serial recall task (post-training). Results showed that both groups had comparable performance in post-training indicating that the visuospatial bootstrapping could be obtained without displaying a numerical keypad. The second experiment also involved a keypad group and an auditive group and was designed to investigate their spatial representation. Results showed that both groups spatialised the digits following the keypad spatial configuration: digits 1-4-7 were associated to left, 2-5-8 to middle and 3-6-9 to right.

The development of working memory spatialization revealed by using the cave paradigm in a two-alternative spatial choice

When Western participants are asked to keep in mind a sequence of verbal items, they tend to associate the first items to the left and the last items to the right. This phenomenon, known as the spatial-positional association response codes effect, has been interpreted as showing that individuals spatialize the memoranda by creating a left-to-right mental line with them. One important gap in our knowledge concerns the development of this phenomenon: when do Western individuals start organizing their thought from left to right? To answer this question, 274 participants in seven age groups were tested (kindergarten, Grades 1, 2, 3, 4, and 5, and adults). We used a new protocol meant to be child-friendly, which involves associating two caves with two animals using a two-alternative spatial forced choice. Participants had to guess in which cave a specific animal could be hidden. Results showed that it is from Grade 3 on that participants spatialize information in working memory in a left-to-right fashion like adults.

The spatial coding mechanism of ordinal symbols: a study based on the ordinal position effect

The ordinal position effect refers to a phenomenon in which items positioned early in an ordinal sequence receive a faster response with the left key than with the right key, and the opposite response pattern occurs when items are positioned later in an ordinal sequence. Previous studies have suggested that ordinal symbols are spatially represented from left to right, thus leading to the ordinal position effect; however, the spatial coding mechanism of ordinal symbols remains unclear. Therefore, the present study explored the ordinal position effect as an index to judge the spatial coding of ordinal symbols, and three experiments were performed to investigate the spatial coding mechanism of ordinal symbols. In particular, a novel transitory ordinal sequence was induced by presenting successive dots of different colors centrally (Experiment 1), from left to right or from right to left (Experiments 2 and 3), and participants were asked to memorize the successive dots in the correct order. Then, the participants were asked to press a key to provide a response corresponding to a probe dot's ordinal position (Experiments 1 and 2) or its spatial location (Experiment 3). The following results were identified: (1) The ordinal position effect occurred when responses were based on the ordinal position regardless of the presentation direction, and (2) the ordinal position effect was overridden when responses were based on the spatial locations of the ordinal symbols. From these results, we concluded that the spatial coding of ordinal symbols is flexible and that ordinal symbols are encoded depending on the specific experimental context.

From short-term store to multicomponent working memory: The role of the modal model

The term "modal model" reflects the importance of Atkinson and Shiffrin's paper in capturing the major developments in the cognitive psychology of memory that were achieved over the previous decade, providing an integrated framework that has formed the basis for many future developments. The fact that it is still the most cited model from that period some 50 years later has, we suggest, implications for the model itself and for theorising in psychology more generally. We review the essential foundations of the model before going on to discuss briefly the way in which one of its components, the short-term store, had influenced our own concept of a multicomponent working memory. This is followed by a discussion of recent claims that the concept of a short-term store be replaced by an interpretation in terms of activated long-term memory. We present several reasons to question these proposals. We conclude with a brief discussion of the implications of the longevity of the modal model for styles of theorising in cognitive psychology.

No Effect of Cue Format on Automation Dependence in an Aided Signal Detection Task

OBJECTIVE

To investigate whether manipulating the format of an automated decision aid's cues can improve participants' information integration strategies in a signal detection task.

BACKGROUND

Automation-aided decision making is often suboptimal, falling well short of statistically ideal levels. The choice of format in which the cues from the aid are displayed may help users to better understand and integrate the aid's judgments with their own.

METHOD

Participants performed a signal detection task that asked them to classify random dot images as either blue or orange dominant. They made their judgments either unaided or with assistance from a 93% reliable automated decision aid. The aid provided a binary judgment, along with an estimate of signal strength in the form of either a raw value, a likelihood ratio, or a confidence rating (Experiments 1 and 2) or a binary judgment along with either a verbal or verbal-visuospatial expression of confidence (Experiment 3). Aided sensitivity was benchmarked to the predictions of various statistical models of collaborative decision making.

RESULTS AND CONCLUSION

Aided performance was suboptimal, matching the predictions of some of the least efficient models. Most importantly, performance was similar across cue formats.

APPLICATION

Results indicate that changes to the format in which cues from a signal detection aid are rendered are unlikely to dramatically improve the efficiency of automation-aided decision making.

Mechanism of the SNARC Effect in Numerical Magnitude, Time Sequence, and Spatial Sequence Tasks: Involvement of LTM and WM

The spatial-numerical association of response codes (SNARC) effect refers to the phenomenon that responses involving small numbers are faster with the left hand and responses involving large numbers are faster with the right hand. Previous studies have investigated the mechanism of the SNARC effect only when the time sequence is induced by centrally presented successive numbers. No study has investigated the mechanism of the SNARC effect when the spatial sequence is induced. Given that the induction of a spatial sequence together with a time sequence provides a new temporary reference for the serial order to be coded in working memory (WM), it would be interesting to examine the SNARC effect when both the time sequence and spatial sequence are induced. Therefore, a novel priming paradigm that simultaneously induced the time sequence and spatial sequence was employed in the present study to investigate the mechanism of the SNARC effect. Specifically, the time sequence and spatial sequence were induced by presenting a series of self-paced successive numbers, centrally or in a left-to-right or right-to-left direction, on the screen. Following the presentation of successive numbers, the probe number was centrally presented on the screen and university students were asked to distinguish to which time sequence or spatial sequence the probe number belonged by pressing a specified key of a qwerty keyboard. The results indicated that (1) the SNARC effect simultaneously appeared in the processing of the number magnitude and time sequence when only the time sequence was induced. (2) The SNARC effect disappeared in the processing of the time sequence; however, the SNARC effect coexisted in the processing of the numerical magnitude and spatial sequence when the spatial sequence was induced and participants performed a time sequence relevant task. (3) The SNARC effect coexisted in the processing of the numerical magnitude, time sequence, and spatial sequence when the spatial sequence was induced and participants performed a spatial sequence relevant task. Based on these results, we conclude that whether the SNARC effect coexists in the processing of the numerical magnitude, the time sequence and spatial sequence were influenced by the spatial sequence and relevant task. The results further support the mental whiteboard hypothesis and extended the WM account. Implications for theories on the SNARC effect were discussed.

Visuospatial bootstrapping: Binding useful visuospatial information during verbal working memory encoding does not require set-shifting executive resources

Immediate serial recall of digits is better when the digits are shown by highlighting them in a familiar array, such as a phone keypad, compared with presenting them serially in a single location, a pattern referred to as "visuospatial bootstrapping." This pattern implies the establishment of temporary links between verbal and spatial working memory, alongside access to information in long-term memory. However, the role of working memory control processes like those implied by the "Central Executive" in bootstrapping has not been directly investigated. Here, we report a study addressing this issue, focusing on executive processes of attentional shifting. Tasks in which information has to be sequenced are thought to be heavily dependent on shifting. Memory for digits presented in keypads versus single locations was assessed under two secondary task load conditions, one with and one without a sequencing requirement, and hence differing in the degree to which they invoke shifting. Results provided clear evidence that multimodal binding (visuospatial bootstrapping) can operate independently of this form of executive control process.

Classic and recent advances in understanding amnesia

Neurological amnesia has been and remains the focus of intense study, motivated by the drive to understand typical and atypical memory function and the underlying brain basis that is involved. There is now a consensus that amnesia associated with hippocampal (and, in many cases, broader medial temporal lobe) damage results in deficits in episodic memory, delayed recall, and recollective experience. However, debate continues regarding the patterns of preservation and impairment across a range of abilities, including semantic memory and learning, delayed recognition, working memory, and imagination. This brief review highlights some of the influential and recent advances in these debates and what they may tell us about the amnesic condition and hippocampal function.

Exploring the sentence advantage in working memory: Insights from serial recall and recognition

Immediate serial recall of sentences has been shown to be superior to that of unrelated words. This study was designed to further explore how this effect might emerge in recall and to establish whether it also extends to serial recognition, a different form of response task that has relatively reduced output requirements. Using auditory or visual presentation of sequences, we found a substantial advantage for sentences over lists in serial recall, an effect shown on measures of recall accuracy, order, intrusion, and omission errors and reflected in transposition gradients. In contrast however, recognition memory based on a standard change detection paradigm gave only weak and inconsistent evidence for a sentence superiority effect. However, when a more sensitive staircase procedure imported from psychophysics was used, a clear sentence advantage was found although the effect sizes were smaller than those observed in serial recall. These findings suggest that sentence recall benefits from automatic processes that utilise long-term knowledge across encoding, storage, and retrieval.