Accessibility of working memory representations in the focus of attention: Heightened or reduced?

Many researchers agree that information residing in the focus of attention in working memory benefits from a boost in memory strength and activation, as well as heightened accessibility. However, recent studies have questioned this heightened accessibility. More specifically, these recent studies found reduced accessibility for an item in the focus of attention compared to another item in working memory, which was referred to as an "inhibition-of-return-like" effect. Our study aimed to provide a detailed examination of the accessibility of information in the focus of attention. Across a series of experiments, varying task characteristics related to the time course of the effect (Experiments 2-3) and the potential role of response inhibition (Experiments 4a-4b), we repeatedly failed to find evidence for an inhibition-of-return-like effect. Instead, we mostly found heightened accessibility for an item in the focus of attention. Given that an inhibition-of-return-like effect seems to be limited to a very specific task condition, reduced accessibility of information in the focus of attention appears to be far from a general phenomenon. Therefore, based on our findings, we propose that information in the focus of attention generally benefits from heightened accessibility, although there may be factors, most likely unrelated to the functioning of the focus of attention, that could sometimes mask this and even result in data patterns that are consistent with reduced accessibility. The theoretical implications for the focus of attention and working memory are discussed. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Attentional switching between perception and memory: Examining asymmetrical switch costs.

Attention can be defined as a mechanism for the selection and prioritization of elements among many. When attention is directed to a specific piece of information, this information is assumed to be in the focus of attention. On a day-to-day basis, we need to rely on efficient switching between information we are holding in working memory (internal modality) and information presented in the world around us (external modality). A recent set of studies investigated between-modality attentional switches and found that there is an asymmetrical switch cost for switching between the internal and external focus of attention (Verschooren et al., 2020, Journal of Experimental Psychology: Human Perception and Performance, 46[9], 912-925; Verschooren, Liefooghe, et al., 2019a, Journal of Experimental Psychology: Human Perception and Performance, 45[10], 1399-1414). In particular, participants switched on a trial-by-trial basis between an internal task using stimuli retrieved from memory and an external task using on-screen presented stimuli. A larger cost was found when switching from the external modality towards the internal modality than the other way around. The authors found that this cost asymmetry could be best explained in terms of associative interference (i.e., differences in shielding efficiency against the memory traces from the competing task set). The present study aimed to replicate the asymmetrical switch cost (Experiment 1) and investigate whether an alternative explanation in terms of stimulus strength can account for the asymmetrical switch cost (Experiment 2). Overall, the results confirm the presence of a subtle, asymmetrical switch cost, but we observed little to no contribution of stimulus strength.

A (further) test of spontaneous serial refreshing in verbal and spatial working memory.

Working memory is the cognitive system that keeps a limited amount of information temporarily accessible for ongoing cognition. One proposed mechanism to keep information active in working memory is refreshing. Refreshing is assumed to operate serially, reactivating memory items one by one by bringing them into the focus of attention during retention. We report two experiments in which we examine evidence for the spontaneous occurrence of serial refreshing in verbal working memory (Experiment 1, using letters as memoranda) and in visuospatial working memory (Experiment 2, using locations as memoranda). Participants had to remember series of red memory items, and black probes were presented between these memory items, with each probe to be judged present in or absent from the list presented so far, as quickly as possible (i.e., the probe-span task). Response times to the probes were used to examine whether the content of the focus of attention changed over time, as would be expected if serial refreshing occurs spontaneously during interitem pauses. Contrary to this hypothesis, our results indicate that the last-presented memory item remained in the focus of attention during the interitem pauses of the probe-span tasks. These findings confirm the boundary conditions of spontaneous serial refreshing that were previously observed for verbal working memory and extend them to visuospatial working memory. Implications for working memory maintenance are discussed.

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.

Inhibition-of-return-like effects in working memory? A preregistered replication study of Johnson et al. (2013).

The present study concerns a preregistered replication of the study conducted by Johnson et al. (Johnson et al. 2013 Psychol. Sci. 24, 1104-1112 (doi:10.1177/0956797612466414)), in which they showed an inhibition-of-return-like effect in working memory. Inhibition of return is a well-known phenomenon observed in the field of perception and refers to the observation that it takes longer to look back at a location which has recently been explored than to look at an unexplored location. Working memory is a central concept in the field of cognitive psychology and refers to the capacity to process and maintain information simultaneously over short periods of time. Johnson's study applied the inhibition of return paradigm to the concept of working memory. Their results showed that it is harder to access a working memory representation that had just been thought of, i.e. refreshed, in comparison to an unrefreshed working memory representation. Contrary to this study of Johnson et al., who observed refreshing to result in inhibitory processes, most studies on refreshing have described its effect as increasing/prolonging the level of activation of the memory representations. In an attempt to integrate these opposite patterns produced by 'refreshing', we started by replicating one of the studies on the inhibition of return in working memory reported by Johnson et al.

The use of attention to maintain information in working memory: A developmental investigation of spontaneous refreshing in school-aged children.

The capacity of working memory is limited and undergoes important developmental changes during childhood. One proposed reason for the expansion of working memory capacity during childhood is the emergence and increased efficiency of active maintenance mechanisms, such as that of refreshing. Refreshing is a proposed mechanism to keep information active in working memory by bringing memory items back into the focus of attention. One prevalent view is that the spontaneous use of refreshing emerges around the age of 7 and becomes more efficient during middle childhood and beyond. Using a novel approach to examine refreshing in children in Experiment 1, we show, against common conceptions, that simply giving free time in a basic working memory task does not lead to spontaneous refreshing in 9-12-year-old children. Instead, their focus of attention appears to linger on the last-presented memory item, even when ample time for refreshing is provided. Experimentally imposing the use of refreshing in Experiment 2, however, showed that children in this age range are able to switch their focus of attention away from the last-presented item in switch to another memory item. Thus, the current study uncovers that children in middle childhood do not always spontaneously switch attention away from the last-presented memory item to refresh the entire list, even though they are able to switch attention away from the last-presented memory item when instructed to do so. The theoretical implications of these findings are discussed.

What do people typically do between list items? The nature of attention-based mnemonic activities depends on task context.

It is commonly assumed that attention-demanding postencoding processes take place during the free time immediately following encoding of each memory item in a list. These processes are thought to prevent loss of information from working memory (WM). We tested whether interitem pauses during presentation of a list are used to focus attention (a) on the last-presented memory item or (b) on all items currently in WM, and (c) whether this changes over time. Here, we presented black probe letters between to-be-remembered red letters. Participants judged whether each probe letter corresponded to the last-presented memory item (last-item match group) or to any of the memory items presented up to that point in the list (any-item match group). To examine mnemonic processing as a function of time, the delay between the to-be-remembered letter and the following probe was manipulated in three experiments. When preprobe delays and interitem intervals were relatively short (Experiment 1), recall performance was observed to be better in the last-item match group and this did not change as a function of the duration of the delay before the probe. When preprobe delays and interitem intervals were longer however (Experiment 2), this disruptive effect of Any-item match instructions was no longer observed. This pattern was found again in Experiment 3 and suggests that the nature of the attention-demanding postencoding processes taking place in between memory items depends on task context in a systematic manner. The results are discussed in terms of previously proposed attention-demanding processes; specifically, consolidation and refreshing. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

An examination of refreshing in between-category sequences.

The present study focused on refreshing within a working memory (WM) context. Refreshing refers to the mechanism that brings back information into the focus of attention in order to counteract forgetting of memory traces. Despite some research on this topic, the exact nature of refreshing remains unclear. The present study investigated refreshing by means of the cognitive load (CL) effect. This effect is typically observed in complex span tasks, which combine processing and storage demands. It refers to the observation that WM performance depends on the CL of concurrent processing, defined as the proportion of time between list items that is occupied by concurrent processing and therefore not available to refresh memory items. Traditionally, the CL effect has been demonstrated using within-category memory sequences in which all memory items are drawn from one category (e.g., all words). Here, we show that the CL effect also applies to between-category memory sequences in which memory items are drawn from different categories (e.g., words, orientations, faces, etc.). The ensemble of the results adds to the domain-generality of the CL effect. Implications concerning the specific nature of refreshing and future research directions are discussed.

Is memory better for objects than for separate single features? The temporal hypothesis.

Working memory, the system allowing for a simultaneous maintenance and processing of information, is typically conceived as a capacity limited system. A proposed method to transcend its standard maintenance capacity is to maintain multifeature objects, instead of isolated features. Several studies have shown that multifeature memory items are stored as objects instead of separate single features in working memory, this object-based maintenance being thought to result in an increase in the number of features that can be maintained. We present a series of 4 experiments that challenge the belief that object-based maintenance per se is at the origin of the better memory for features in case of multifeature item presentation. Instead, we propose an account based on the temporal parameters of the memory item's presentation, which explains memory performance in terms of the time available for encoding/consolidation per feature. (PsycINFO Database Record

Evidence for spontaneous serial refreshing in verbal working memory?

Working memory (WM) keeps information temporarily accessible for ongoing cognition. One proposed mechanism to keep information active in WM is refreshing. This mechanism is assumed to operate by bringing memory items into the focus of attention, thereby serially refreshing the content of WM. We report two experiments in which we examine evidence for the spontaneous occurrence of serial refreshing in verbal WM. Participants had to remember series of red letters, while black probe letters were presented between these memory items, with each probe to be judged present in or absent from the list presented so far, as quickly as possible (i.e., the probe-span task). Response times to the probes were used to infer the status of the representations in WM and, in particular, to examine whether the content of the focus of attention changed over time, as would be expected if serial refreshing occurs spontaneously during inter-item pauses. In sharp contrast with this hypothesis, our results indicate that the last-presented memory item remained in the focus of attention during the inter-item pauses of the probe-span task. We discuss how these findings help to define the boundary conditions of spontaneous refreshing of verbal material in WM, and discuss implications for verbal WM maintenance and forgetting.

On the sources of forgetting in working memory: The test of competing hypotheses.

Whether forgetting from working memory (WM) is only due to interference or is also caused by temporal decay is still a matter of debate. In the present study, this question was examined using complex span tasks in which each memory item was followed by a series of processing episodes, the duration and number of which were varied. It is known that recall performance in these tasks depends on the cognitive load ( CL) of concurrent processing conceived as the ratio between processing time and free time, higher CL resulting in lower spans. The decay-and-refresh hypothesis accounts for this effect by assuming that memory traces decay during processing but are refreshed during free time. This hypothesis predicts lower recall performance with longer processing episodes, but no effect of their number as long as CL remains constant. The interference-only hypothesis supposes that free time is used to alleviate the interference created by processing distractors. This hypothesis is potentially compatible with an effect of the duration of processing episodes through increased interference, but predicts a detrimental effect of their number. In three experiments, the recall pattern fitted the predictions of the decay-and-refresh hypothesis for verbal WM, but that of the interference-only hypothesis for visuospatial WM. Although the entire pattern of data is more easily accommodated by the decay-and-refresh hypothesis than by its interference-only contender, our results suggest that it is unwise to aim at identifying a unique source to a complex phenomenon like WM forgetting.

Working memory still needs verbal rehearsal.

The causal role of verbal rehearsal in working memory has recently been called into question. For example, the SOB-CS (Serial Order in a Box-Complex Span) model assumes that there is no maintenance process for the strengthening of items in working memory, but instead a process of removal of distractors that are involuntarily encoded and create interference with memory items. In the present study, we tested the idea that verbal working memory performance can be accounted for without assuming a causal role of the verbal rehearsal process. We demonstrate in two experiments using a complex span task and a Brown-Peterson paradigm that increasing the number of repetitions of the same distractor (the syllable ba that was read aloud at each of its occurrences on screen) has a detrimental effect on the concurrent maintenance of consonants whereas the maintenance of spatial locations remains unaffected. A detailed analysis of the tasks demonstrates that accounting for this effect within the SOB-CS model requires a series of unwarranted assumptions leading to undesirable further predictions contradicted by available experimental evidence. We argue that the hypothesis of a maintenance mechanism based on verbal rehearsal that is impeded by concurrent articulation still provides the simplest and most compelling account of our results.

Maintaining information in visual working memory: Memory for bindings and memory for features are equally disrupted by increased attentional demands.

This study examined the role of attention in maintaining information between visual features in visual working memory. In a change detection paradigm, two different memory conditions were created: one that required the maintenance of features and one that required the maintenance of how the features were bound together. During the short retention interval that separated the study display and test display, a tone discrimination task was to be performed. The attentional demand of the tone discrimination task was manipulated to test whether memory for binding was more disrupted than memory for features when the proportion of time during which attention is unavailable for maintenance is increased. We observed that memory for features and memory for bindings were equally disrupted by increasing the attentional demands of the tone discrimination task. This suggests that attention does not play a special role in the maintenance of feature bindings in visual working memory.

The maintenance of cross-domain associations in the episodic buffer.

The episodic buffer has been described as a structure of working memory capable of maintaining multimodal information in an integrated format. Although the role of the episodic buffer in binding features into objects has received considerable attention, several of its characteristics have remained rather underexplored. This is the case for its maintenance capacity limits and its separability from domain-specific maintenance buffers. The present study addressed these questions, making use of a complex span paradigm in which participants were asked to maintain cross-domain (i.e., verbal-spatial) associations. The 1st experiment showed that the capacity limit for these cross-domain associations proved to be lower than the capacity limit for single features, and did not exceed 3. Cross-domain associations and single features depended, however, to the same extent on attentional resources for their maintenance. The 2nd experiment showed that domain-specific (verbal or spatial) resources were not involved in the maintenance of cross-domain information, revealing a clear distinction between the episodic buffer and the domain-specific buffers. Overall, in line with the episodic buffer hypothesis, these findings support the existence of a central system of limited capacity for the maintenance of cross-domain information.

Time causes forgetting from working memory.

Although forgetting in the short term is a ubiquitous phenomenon, its exact causes remain undecided. The aim of the present study was to test the temporal decay hypothesis according to which memory traces fade away with time when attention is diverted by concurrent activities. In two experiments involving complex span tasks, adults were asked to remember series of items (either letters or spatial locations) while verifying multiplications. The duration of processing was manipulated by presenting multiplications either in word (three × four = twelve) or digit (3 × 4 = 12) format, the former taking longer to solve, while the time available to restore memory traces after each operation was kept constant across conditions. In line with the temporal decay hypothesis, the longer solution times elicited by solving word multiplications resulted in poorer recall performance. The fact that longer processing times had a comparable effect on both verbal and visuospatial memory and that the difference between conditions remained stable from the first to the last trials makes it difficult to account for these findings by assuming that forgetting is exclusively due to representation-based interference or buildup of proactive interference.