Visual Working Memory Load Research Articles

I can look for it! Modulation of a concurrent Visual Working Memory task in Visual Search in development.

Daily classroom activities that require children to perform visual search (VS) tasks are common across all educational levels: from searching for a missing piece of a puzzle in kindergarten to solving equations in college. However, VS tasks are often not performed in isolation, but rather students are maintaining information related to an ongoing task that loads working memory (WM). Unfortunately, it is still unclear how these processes interact and evolve in development. The present work aims to study how a concurrent visual WM (VWM) load can modulate VS performance based on the Developmental Model of Endogenous Mental Attention (Pascual-Leone and Johnson, 1999, 2005, 2021). A sample of kindergarten, elementary (2nd and 4th grades), middle school (6th grade), and college students looked for real-world photorealistic targets while maintaining similar objects in VWM in a dual-task paradigm. VWM load was manipulated using high and low memory load conditions. Additionally, looking for potential modulations related to individual differences, we studied the relationship between IQ, VWM span, and executive functions with VS efficiency. Finally, we also registered reported measures of potential strategies employed during the VS task. The results from a large sample of 147 participants between 5 and 25 years old revealed that even the youngest children could efficiently perform a VS task with a concurrent VWM load, replicating previous results found in adulthood. However, we found a slight increase in false alarms and commission errors when memory was highly loaded for all the participants regardless of age. As expected, we found positive correlations between VS efficiency and IQ and VWM span measures. Interestingly, the proportion of participants who used tracking organization strategies increased with age in all cases. However, although cognitive strategies to remember the target became more complex as age increased, it was only significant under the low VWM load conditions. The results seem relevant to understanding the development of VS based on the Model of Endogenous Mental Attention and the design of training programs to improve attention. The implications in educational contexts are discussed and are especially relevant for students with learning disabilities or attention problems.

Dissociable causal roles of the frontal and parietal cortices in the effect of object location on object identity detection: a TMS study.

According to the spatial congruency advantage, individuals exhibit higher accuracy and shorter reaction times during the visual working memory (VWM) task when VWM test stimuli appear in spatially congruent locations, relative to spatially incongruent locations, during the encoding phase. Functional magnetic resonance imaging studies have revealed changes in right inferior frontal gyrus (rIFG) and right supra-marginal gyrus (rSMG) activity as a function of object location stability. Nevertheless, it remains unclear whether these regions play a role in active object location repositioning or passive early perception of object location stability, and demonstrations of causality are lacking. In this study, we adopted an object identity change-detection task, involving a short train of 10-Hz online repetitive transcranial magnetic stimulations (rTMS) applied at the rIFG or rSMG concurrently with the onset of VWM test stimuli. In two experimental cohorts, we observed an improved accuracy in spatially incongruent high VWM load conditions when the 10Hz-rTMS was applied at the rIFG compared with that in TMS control conditions, whereas these modulatory effects were not observed for the rSMG. Our results suggest that the rIFG and rSMG play dissociable roles in the spatial congruency effect, whereby the rIFG is engaged in active object location repositioning, while the rSMG is engaged in passive early perception of object location stability.

How is the visual working memory load of driver influenced by information density of traffic signs?

The rapid development of urban roads has resulted in an increase in the amount of information that needs to be displayed on traffic signs. The overloading of information on traffic signs may increase drivers’ visual cognition burden and cause driving errors. It could be an important factor affecting driving safety and result in accidents. To enable drivers to cognize traffic signs, the information density that they could endure under reasonable workload levels should be determined. In this study, we designed and implemented trials to analyze drivers’ visual working memory load (VWML) caused by different information densities (including stimulus intensity (SI) and interval time of stimulus (IS)) of traffic signs. Twenty-four paid participants (12 females) with a mean age of 23.38 years (SD = 1.38) participated in laboratory simulation trials based on the memory retrieval approach. Subjective ratings (rating scale mental effort (RSME)), and performance measurement based on reaction time and accuracy of information-matching task were measured to reflect drivers’ VWML at different information densities. The results show that information density is an important factor affecting drivers’ VWML. The following are the significant observations of the study: (1) The subjective ratings on mental effort increased with increase in the SI. Meanwhile, it first decreased and then increased with increase in the IS. (2) The response accuracy results show that a high accuracy (≥0.7) was achieved by drivers in an IS of 15 s when the SI was at most 14.16 bit/m2. Correspondingly, the drivers underwent less mental workload as a result of their better short-term memory characteristic. (3) The mean reaction time was over 1800 ms when the SI was over 14.16 bit/m2. This indicated a reduction in the information-processing capability of the drivers. The results indicate that cognition of information of unreasonable density on traffic signs would increase drivers’ VWML. This would, in turn, result in an increase in their reaction time and decrease in accuracy. The threshold of information density was also determined through the experiment. It would satisfy the information demand of drivers and prevent information redundancy. The results contribute to an understanding of drivers’ VWML while cognizing traffic signs with different information densities and provide safety, effectiveness, and information continuity considerations for the design and setting of traffic signs.

Inhibition continues to guide search under concurrent visual working memory load.

It is well known that attention can be automatically attracted to salient items. However, recent studies show that it is possible to avoid distraction by a salient item (with a known feature), leading to facilitated search. This article tests a proposed mechanism for distractor inhibition: that a mental representation of the distractor feature held in visual working memory (VWM) allows attention to be guided away from the distractor. We tested this explanation by examining color-based inhibition in visual search for a shape target with and without VWM load. In Experiment 1 the presence of a distractor facilitated visual search under low and high VWM loads, as reflected in faster response times when the distractor was present (compared to absent), and in fewer eye movements to the salient distractor than the non-target items. However, the eye movement inhibition effect was noticeably weakened in the load conditions. Experiment 2 explored further, to distinguish between inhibition of the distractor color and activation of the (irrelevant) target color. Intermittently presenting single-color search trials that contained only either a target, distractor or a neutral-colored singleton revealed that the distractor color attracted attention less than the neutral color with and without VWM load. The target color, however, only attracted attention more than neutral colors under no load, whereas a VWM load completely eliminated this effect. This suggests that although VWM plays a role in guiding attention to the (irrelevant) target color, distractor-feature inhibition can operate independently.

Are all real-world objects created equal? Estimating the "set-size" of the search target in visual working memory.

Are all real-world objects created equal? Visual search difficulty increases with the number of targets and as target-related visual working memory (VWM) load increases. Our goal was to investigate the load imposed by individual real-world objects held in VWM in the context of search. Measures of visual clutter attempt to quantify real-world set-size in the context of scenes. We applied one of these measures, the number of proto-objects, to individual real-world objects and used contralateral delay activity (CDA) to measure the resulting VWM load. The current study presented a real-world object as a target cue, followed by a delay where CDA was measured. This was followed by a four-object search array. We compared CDA and later search performance from target cues containing a high or low number of proto-objects. High proto-object target cues resulted in greater CDA, longer search RTs, target dwell times, and reduced search guidance, relative to low proto-object targets. These findings demonstrate that targets with more proto-objects result in a higher VWM load and reduced search performance. This shows that the number of proto-objects contained within individual objects produce set-size like effects in VWM and suggests proto-objects may be a viable unit of measure of real-world VWM load. Importantly, this demonstrates that not all real-world objects are created equal.

Visual working memory impairs visual detection: A function of working memory load or sensory load?

Researchers have explored the influence of visual working memory (VWM) load on visual perception in the past decade. One of their key findings is that a high VWM load leads to reduced visual detection sensitivity to incoming visual stimuli. However, recent studies imply that persistent sensory processing continues after the memory array is offset. It is possible that the impaired visual detection is due to the sensory load of the residual sensory processing of the memory array (sensory load account) rather than the working memory load of the VWM task (VWM load account). We performed four experiments to examine the impacts on visual detection. Experiment 1 manipulated the retention time of the memory array while keeping the VWM load constant, revealing reduced visual detection along with retention time. Experiments 2 and 3 manipulated the VWM load while maintaining a constant sensory load, and visual detection was not affected. Experiment 4 affirmed that the findings in Experiments 1-3 were reliable. Together, the results of the current study suggest that the residual sensory load, rather than the VWM load of the VWM task, impairs visual detection. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Shared resources between visual attention and visual working memory are allocated through rhythmic sampling.

Attention and visual working memory (VWM) are among the most theoretically detailed and empirically tested constructs in human cognition. Nevertheless, the nature of the interrelation between selective attention and VWM still presents a fundamental controversy: Do they rely on the same cognitive resources or not? The present study aims at disentangling this issue by capitalizing on recent evidence showing that attention is a rhythmic phenomenon, oscillating over short time windows. Using a dual-task approach, we combined a classic VWM task with a visual detection task in which we densely sampled detection performance during the time between the memory and the test array. Our results show that an increment in VWM load was related to reduced detection of near-threshold visual stimuli. Importantly, we observed an oscillatory pattern in detection at ~7.5Hz in the low VWM load conditions, which decreased towards ~5Hz in the high VWM load condition. These findings suggest that the frequency of this sampling rhythm changes according to the allocation of attentional resources to either the VWM or the detection task. This pattern of results is consistent with a central sampling attentional rhythm which allocates shared attentional resources both to the flow of external visual stimulation and to the internal maintenance of visual information.

Visual working memory load plays limited, to no role in encoding distractor objects during visual search

ABSTRACT Previous research raised the counterintuitive hypothesis that searching for multiple potential targets leads to increased incidental encoding of distractors. Are these previously reported findings due to increased visual working memory (VWM) engagement, or less precise target templates? In four experiments, we examined the effect of VWM load during visual search on incidental encoding of distractors. Consecutive target repetitions indirectly reduce template-related VWM demands but failed to reduce recognition for distractors relative to conditions where the targets were novel. Distractors that were subsequently recognized attracted longer cumulative dwell time, regardless of search condition. When placed in a dual-task situation where search was performed while holding a working memory load, recognition for distractors was marginally improved relative to a search task without additional VWM demands. We ruled out the possibility that the dual-task was not sufficiently difficult to trigger the scrutiny of distractors required for significant encoding benefits by showing a decrement to encoding when search time was limited. This suggests that widening the attentional set is the crucial factor in improved incidental encoding given that observers can assign differential status to various contents of VWM. Thus, utilizing VWM resources in general appears insufficient to meaningfully improve incidental memory.

Disgust face captures more attention in individuals with high social anxiety when cognitive resources are abundant: Evidence from N2pc

There is a debate about the relative contributions of top-down and bottom-up attention to the threat-related attentional bias. In this study we investigated the attentional bias in individuals with social anxiety under conditions of no, low and high visual working memory (WM) load. Event-related potential (ERP) and response time (RT) data were recorded while participants performed the dot-probe task and a concurrent change-detection task. The ERP results revealed that the maximum N2pc effect emerged in no visual WM load condition in individuals with social anxiety. The difference of N2pc effect between high socially anxious (HSA) and low socially anxious (LSA) groups was observed in no visual WM load condition, whereas this difference was eliminated under low and high load conditions. However, no significant main effects or interactions were observed in the behavioral index (reflected by Trial Level-Bias Score variability). Overall, the findings indicate the critical role of top-down attention on social anxiety-related attentional bias, which have important implication for attentional bias modification.

Distinguishing the neural mechanism of attentional control and working memory in feature-based attentive tracking.

Surface features are an important component in attentive tracking. However, the neural mechanisms underlying how features affect attentive tracking remain unknown. The present fMRI study addressed this issue by manipulating the intragroup feature complexity and intergroup feature similarity. In particular, this study distinguished the different neural mechanisms of intragroup feature complexity and intergroup feature similarity by investigating the roles of attentional control and working memory in dynamic feature-based attentive tracking. Behavioral and neuroimaging evidence showed that when targets are distinct from distractors, the intragroup feature complexity of the targets, rather than that of the distractors, mainly increases the visual working memory load and significantly activates the frontoparietal cortical circuit. Thus, the involvement of working memory in feature-based attentive tracking is modulated by goal-directed attention control. In addition, when targets are similar to distractors, the intergroup feature similarity (i.e., target-distractor similarity) mainly affects the allocation of attention. Specifically, target-distractor similarity affects the goal-directed attention toward the targets in a stimulus-driven way and induces an interaction between the ventral and dorsal attention networks.

Neural correlates of task-related refixation behavior

Eye movement research has shown that attention shifts from the currently fixated location to the next before a saccade is executed. We investigated whether the cost of the attention shift depends on higher-order processing at the time of fixation, in particular on visual working memory load differences between fixations and refixations on task-relevant items. The attention shift is reflected in EEG activity in the saccade-related potential (SRP). In a free viewing task involving visual search and memorization of multiple targets amongst distractors, we compared the SRP in first fixations versus refixations on targets and distractors. The task-relevance of targets implies that more information will be loaded in memory (e.g. both identity and location) than for distractors (e.g. location only). First fixations will involve greater memory load than refixations, since first fixations involve loading of new items, while refixations involve rehearsal of previously visited items. The SRP in the interval preceding the saccade away from a target or distractor revealed that saccade preparation is affected by task-relevance and refixation behavior. For task-relevant items only, we found longer fixation duration and higher SRP amplitudes for first fixations than for refixations over the occipital region and the opposite effect over the frontal region. Our findings provide first neurophysiological evidence that working memory loading of task-relevant information at fixation affects saccade planning.

Tracking visual search demands and memory load through pupil dilation

Continuously tracking cognitive demands via pupil dilation is a desirable goal for the monitoring and investigation of cognitive performance in applied settings where the exact time point of mental engagement in a task is often unknown. Yet, hitherto no experimentally validated algorithm exists for continuously estimating cognitive demands based on pupil size. Here, we evaluated the performance of a continuously operating algorithm that is agnostic of the onset of the stimuli and derives them by way of retrospectively modeling attentional pulses (i.e., onsets of processing). We compared the performance of this algorithm to a standard analysis of stimulus-locked pupil data. The pupil data were obtained while participants performed visual search (VS) and visual working memory (VWM) tasks with varying cognitive demands. In Experiment 1, VS was performed during the retention interval of the VWM task to assess interactive effects between search and memory load on pupil dilation. In Experiment 2, the tasks were performed separately. The results of the stimulus-locked pupil data demonstrated reliable increases in pupil dilation due to high VWM load. VS difficulty only affected pupil dilation when simultaneous memory demands were low. In the single task condition, increased VS difficulty resulted in increased pupil dilation. Importantly, online modeling of pupil responses was successful on three points. First, there was good correspondence between the modeled and stimulus locked pupil dilations. Second, stimulus onsets could be approximated from the derived attentional pulses to a reasonable extent. Third, cognitive demands could be classified above chance level from the modeled pupil traces in both tasks.

Visual and verbal working memory loads interfere with scene-viewing.

Working memory is thought to be divided into distinct visual and verbal subsystems. Studies of visual working memory frequently use verbal working memory tasks as control conditions and/or use articulatory suppression to ensure that visual load is not transferred to verbal working memory. Using these verbal tasks relies on the assumption that the verbal working memory load will not interfere with the same processes as visual working memory. In the present study, participants maintained a visual or verbal working memory load as they simultaneously viewed scenes while their eye movements were recorded. Because eye movements and visual working memory are closely linked, we anticipated the visual load would interfere with scene-viewing (and vice versa), while the verbal load would not. Surprisingly, both visual and verbal memory loads interfered with scene-viewing behavior, while eye movements during scene-viewing did not significantly interfere with performance on either memory task. These results suggest that a verbal working memory load can interfere with eye movements in a visual task.

Visual working-memory capacity load does not modulate distractor processing.

Over the last decade, researchers have explored the influence of visual working-memory (WM) load on selective attention in general, by focusing on the modulation of visual WM load on distractor processing in perception. However, there were three distinct hypotheses (perceptual-load hypothesis, resolution hypothesis, and domain-specific hypothesis) with different predictions. While the perceptual-load hypothesis suggests that visual WM capacity load serves as a type of perceptual load, the latter two hypotheses consider visual WM capacity load acting as a type of central executive load, with a constraint that the domain-specific hypothesis claimed that only a content overlap existed between WM load and the perceptual task. By adding a flanker task into the maintenance phase of visual WM, here we attempted to understand the influence of visual WM load on distractor processing. We systematically manipulated the parameters of the task setting between WM and flanker tasks (Experiments 1-4), the perceptual load of flanker task (Experiment 5), the settings of the flanker stimuli and the WM load (Experiment 6), and the content overlap between WM task and flanker task and the exposure time of flanker task (Experiments 7, 8, and 9). However, in 11 out of 12 sub-experiments we consistently found that the visual WM load did not modulate the distractor processing. The implications of these findings are discussed.

Separating the effects of visual working memory load and attentional zoom on selective attention.

Selecting relevant information while ignoring irrelevant distractors is critical for every cognitive function. Visual working memory (VWM) load is 1 factor that can modulate attentional selection; however, previous studies yielded inconsistent results concerning whether VWM load increases or decreases attentional selection. In the current study, we manipulated VWM load while controlling the size of attentional zoom, which could have influenced distractor interference in prior studies. We found that increasing the size of attentional zoom resulted in greater distractor interference; however, increasing VWM load did not modulate attentional selection when attentional zoom was held narrow. The current findings suggest that the interaction between selective attention and VWM can be better understood by dissociating the size of attentional focus and VWM load. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Visual working memory load does not affect the overall stimulus processing time in visual search.

The dual-task paradigm is widely used in studying the interaction between visual search and working memory. A number of studies showed that holding items in working memory delays the overall response time (RT) in visual search, but it does not affect the efficiency of search (i.e., the slope of the RT × set size function). Why the memory load merely affects the overall RT? Some researchers proposed that this load-effect on overall RT may be caused by factors that only affect response selection processes, while others argued that it may reflect the effect of visual working memory load on visual search. This study investigated the two competing hypotheses by measuring the threshold stimulus exposure duration (TSED) for successfully fulfilling a search task. Experiment 1 replicated the large overall RT difference with the RT method but only found a small though reliable overall TSED difference with the TSED method. Experiment 2, with better controls, found no TSED difference by manipulating the visual working memory load. Experiment 3 showed that the TSED is not influenced by processes in the response selection stage. The present findings suggest that the overall stimulus processing time in visual search is not affected by visual working memory load and that the effect of memory load on overall RT is largely due to factors affecting response selection alone.

Visual working memory load induces similar representational structures in a distributed cortical network

Visual working memory load induces similar representational structures in a distributed cortical network

Visual working memory load induces similar representational structures in a distributed cortical network

Visual working memory load induces similar representational structures in a distributed cortical network

Visual working memory load does not eliminate visuomotor repetition effects.

When we respond to a stimulus, our ability to quickly execute this response depends on how combinations of stimulus and response features match to previous combinations of stimulus and response features. Some kind of memory representations must be underlying these visuomotor repetition effects. In this paper, we tested the hypothesis that visual working memory stores the stimulus information that gives rise to these effects. Participants discriminated the colors of successive stimuli while holding either three locations or colors in visual working memory. If visual working memory maintains the information about a previous event that leads to visuomotor repetition effects, then occupying working memory with colors or locations should selectively disrupt color-response and location-response repetition effects. The results of two experiments showed that neither color nor spatial memory load eliminated visuomotor repetition effects. Since working memory load did not disrupt repetition effects, it is unlikely that visual working memory resources are used to store the information that underlies visuomotor repetitions effects. Instead, these results are consistent with the view that visuomotor repetition effects stem from automatic long-term memory retrieval, but can also be accommodated by supposing separate buffers for visual working memory and response selection.

Visual working memory load constrains language non-selective activation under task-demands

Abstract Visual world studies with bilinguals have demonstrated spontaneous cross-linguistic activations. In two experiments, we examined whether concurrent visual working memory (VWM) load constrains bilingual parallel activation during spoken word comprehension. Hindi-English bilinguals heard a spoken word in Hindi (L1) or English (L2) and saw a display containing the spoken word-referent, a phonological cohort of the spoken word’s translation and two unrelated objects. Participants completed a concurrent WM task of remembering an array of five coloured squares and judging its similarity with a test array. Participants were asked to click on the spoken word-referent in Experiment 1 but not in Experiment 2. Reduced parallel activation and enhanced target activation was observed under the load for L2 spoken words in Experiment 1 (where the task-demands were high). The findings suggest that a VWM load can constrain the spontaneous activation of an irrelevant lexicon, under certain conditions.