Time limits during visual foraging reveal flexible working memory templates.

Working memory (WM) is limited in capacity, but it is controversial whether these capacity limitations are domain-general or are generated independently within separate modality-specific memory systems. These alternative accounts were tested in bimodal visual/tactile WM tasks. In Experiment 1, participants memorized the locations of simultaneously presented task-relevant visual and tactile stimuli. Visual and tactile WM load was manipulated independently (one, two, or three items per modality), and one modality was unpredictably tested after each trial. To track the activation of visual and tactile WM representations during the retention interval, the visual contralateral delay activity (CDA) and tactile CDA (tCDA) were measured over visual and somatosensory cortex, respectively. CDA and tCDA amplitudes were selectively affected by WM load in the corresponding (tactile or visual) modality. The CDA parametrically increased when visual load increased from one to two and to three items. The tCDA was enhanced when tactile load increased from one to two items and showed no further enhancement for three tactile items. Critically, these load effects were strictly modality-specific, as substantiated by Bayesian statistics. Increasing tactile load did not affect the visual CDA, and increasing visual load did not modulate the tCDA. Task performance at memory test was also unaffected by WM load in the other (untested) modality. This was confirmed in a second behavioral experiment where tactile and visual loads were either two or four items, unimodal baseline conditions were included, and participants performed a color change detection task in the visual modality. These results show that WM capacity is not limited by a domain-general mechanism that operates across sensory modalities. They suggest instead that WM storage is mediated by distributed modality-specific control mechanisms that are activated independently and in parallel during multisensory WM.

Precision requirements do not affect the allocation of visual working memory capacity

Visual working memory (VWM) capacity has been studied extensively in adults, and methodological advances have enabled researchers to probe capacity limits in infancy using a preferential looking paradigm. Evidence suggests that capacity increases rapidly between 6 and 10 months of age. To understand how the VWM system develops, we must understand the relationship between the looking behavior used to study VWM and underlying cognitive processes. We present a dynamic neural field model that captures both real-time and developmental processes underlying performance. Three simulation experiments show how looking is linked to VWM processes during infancy and how developmental changes in performance could arise through increasing neural connectivity. These results provide insight into the sources of capacity limits and VWM development more generally.

Manipulations of attention dissociate fragile visual short-term memory from visual working memory

Contralateral delay activity does not reflect behavioral feature load in visual working memory

Despite increasing recognition of the significance of mild traumatic brain injury (mTBI), the long-term cognitive consequences of the injury remain unclear. More sensitive measures that can detect subtle cognitive changes and consideration of individual variability are needed to properly characterise cognitive outcomes following mTBI. Here, we used complex behavioural tasks, individual differences approaches, and electrophysiology to investigate the long-term cognitive effects of a history of mTBI. In Experiment 1, participants with self-reported mTBI history (n=82) showed poorer verbal working memory performance on the operation span task compared to control participants (n=88), but there were no group differences in visual working memory, multitasking, cognitive flexibility, attentional control, visuospatial ability, or information processing speed. Individual differences analyses revealed that time since injury and presence of memory loss predicted visual working memory capacity and visuospatial ability, respectively, in those with mTBI history. In Experiment 2, participants with mTBI history (n=20) again demonstrated poorer verbal working memory on the operation span task compared to control participants (n=38), but no group differences were revealed on a visuospatial complex span task or simpler visual working memory measures. We also explored the electrophysiological indices of visual working memory using EEG during a change detection task. No differences were observed in early sensory event-related potentials (P1, N1) or the later negative slow wave associated with visual working memory capacity. Together, these findings suggest that mTBI history may be associated with a lasting, isolated disruption in the subsystem underlying verbal working memory storage. The results emphasise the importance of sensitive cognitive measures and accounting for individual variability in injury characteristics when assessing mTBI outcomes.

Background and purposeWorking memory is critical for individuals and has been found to be improved by electrical stimulation of the left dorsolateral prefrontal cortex (DLPFC). However, the effects of different types of transcranial electrical stimulation on working memory are controversial, and the underlying mechanism remains uncertain. In this study, high-definition transcranial direct current stimulation (HD-tDCS) and high-definition transcranial random noise stimulation (HD-tRNS) were applied to the DLPFC to observe the different effects on visual working memory (VWM). The aim was to explore the causal relationship between the electrical activity of the DLPFC and the posterior parietal cortex (PPC) electrical activity and the contralateral delayed activity (CDA).MethodsThirty-three healthy subjects received HD-tDCS, HD-tRNS and sham stimulation in a random order. Stimulation was applied to the left DLPFC for 20 min. The subjects underwent a color change-detection task as our VWM task and an auditory digit span test (DST) immediately after stimulation. Event-related potential (ERP) data were collected during the VWM task.ResultsThe results revealed significant differences between the different types of HD-tES. There was a remarkable increase in VWM capacity following HD-tDCS compared with both HD-tRNS (pa = 0.038) and sham stimulation (pa = 0.038). Additionally, the CDA from the PPC differed after stimulation of the DLPFC. Both HD-tDCS and HD-tRNS expanded the maximum CDA amplitude from set size of 4 to 6, whereas after sham stimulation, the maximum CDA was maintained at a set size of 4. Compared with the sham condition, only HD-tDCS induced a noteworthy increase in CDA amplitude (pa = 0.012). Notably, a significant correlation emerged between the mean CDA amplitude and VWM capacity (p < 0.001, r = − 0.402).ConclusionThese findings underscore the ability of HD-tDCS to target the DLPFC to augment working memory capacity while concurrently amplifying CDA amplitudes in the PPC through the frontoparietal network.Trial registration ChiCTR2300074898.

Maintaining visual working memory (VWM) representations recruits a network of brain regions, including the frontal, posterior parietal, and occipital cortices; however, it is unclear to what extent the occipital cortex is engaged in VWM after sensory encoding is completed. Noninvasive brain stimulation data show that stimulation of this region can affect working memory (WM) during the early consolidation time period, but it remains unclear whether it does so by influencing the number of items that are stored or their precision. In this study, we investigated whether single-pulse transcranial magnetic stimulation (spTMS) to the occipital cortex during VWM consolidation affects the quantity or quality of VWM representations. In three experiments, we disrupted VWM consolidation with either a visual mask or spTMS to retinotopic early visual cortex. We found robust masking effects on the quantity of VWM representations up to 200 msec poststimulus offset and smaller, more variable effects on WM quality. Similarly, spTMS decreased the quantity of VWM representations, but only when it was applied immediately following stimulus offset. Like visual masks, spTMS also produced small and variable effects on WM precision. The disruptive effects of both masks and TMS were greatly reduced or entirely absent within 200 msec of stimulus offset. However, there was a reduction in swap rate across all time intervals, which may indicate a sustained role of the early visual cortex in maintaining spatial information.

Event Abstract Back to Event Visual working memory in people with stuttering: ERP study Maria Pyasik1*, Stanislav Kozlovskiy1, Alexander Vartanov1 and Janna Glozman1 1 Lomonosov Moscow State University, Psychology, Russia Recent studies show, that working memory functioning is impaired in people with stuttering (Bajaj, 2007; Kaganovich et al. 2010). However, there is still no certain neurophysiological explanation of this fact. Participants in the study were 10 people with stuttering and 10 people without any speech impairments (8 men and 2 women in each subject group, mean age - 25,3±4,8 years old). We performed computer neuropsychological testing of visual working memory capacity. Subjects’ goal was to remember three simultaneously presented for 1000 ms visual stimuli and then find them in the same sequence among 16-20 similar stimuli after a 1200 ms delay. The test consisted of two series, which differed in stimuli type - complex geometric figures and words; the stimuli were based on A.R. Luria’s neuropsychological assessment materials. During the computer test event-related potentials were registered for the stimuli presentation. We compared the percentage of correct answers in the test between subject groups; event-related potentials were averaged for each part of the test and also compared between subject groups (the significance of the differences in ERP amplitudes was evaluated with Student’s t-test). According to the results of the test, visual working memory capacity in stuttering is significantly lower in comparison to the control subjects for memorizing complex geometric figures, while memorizing words did not reveal any significant differences. ERP amplitudes differ significantly between subject groups on the 400-600 ms interval post-stimulus for the ‘geometric figures’ part of the test; for the second part of the test there were no significant differences in ERP amplitudes. Furthermore, the coordinates of electrical activity dipole sources for 400-600 ms interval were calculated with BrainLoc 6.0 program (dipole coefficient > 0.95). For both parts of the test and both subject groups activation of orbitofrontal cortex and occipital lobe was revealed. However, the activation of orbitofrontal cortex in control subjects was stronger during more difficult part of the test than during the easier one, whereas in stuttering this activation was weaker (smaller amount of dipoles were revealed) regardless of the task difficulty. It can be speculated, that the resources of the central executive of working memory are limited in stuttering, which does not affect the performance in simple tasks but causes trouble during the difficult ones. Acknowledgements This study was supported by Russian Humanitarian Science Foundation (RHSF) project # 13-06-00570. Keywords: visual working memory, Stuttering, orbitofrontal cortex, Event-related potentials, source localization Conference: ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013. Presentation Type: Oral Topic: Memory Citation: Pyasik M, Kozlovskiy S, Vartanov A and Glozman J (2013). Visual working memory in people with stuttering: ERP study. Conference Abstract: ACNS-2013 Australasian Cognitive Neuroscience Society Conference. doi: 10.3389/conf.fnhum.2013.212.00174 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 15 Oct 2013; Published Online: 25 Nov 2013. * Correspondence: Ms. Maria Pyasik, Lomonosov Moscow State University, Psychology, Moscow, Russia, maria.pyasik@unito.it Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Maria Pyasik Stanislav Kozlovskiy Alexander Vartanov Janna Glozman Google Maria Pyasik Stanislav Kozlovskiy Alexander Vartanov Janna Glozman Google Scholar Maria Pyasik Stanislav Kozlovskiy Alexander Vartanov Janna Glozman PubMed Maria Pyasik Stanislav Kozlovskiy Alexander Vartanov Janna Glozman Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The study of working memory capacity is of outmost importance in cognitive psychology as working memory is at the basis of general cognitive function. Although the working memory capacity limit has been thoroughly studied, its origin still remains a matter of strong debate. Only recently has the role of visual saliency in modulating working memory storage capacity been assessed experimentally and proved to provide valuable insights into working memory function. In the computational arena, attractor networks have successfully accounted for psychophysical and neurophysiological data in numerous working memory tasks given their ability to produce a sustained elevated firing rate during a delay period. Here we investigate the mechanisms underlying working memory capacity by means of a biophysically-realistic attractor network with spiking neurons while accounting for two recent experimental observations: 1) the presence of a visually salient item reduces the number of items that can be held in working memory, and 2) visually salient items are commonly kept in memory at the cost of not keeping as many non-salient items.Our model suggests that working memory capacity is determined by two fundamental processes: encoding of visual items into working memory and maintenance of the encoded items upon their removal from the visual display. While maintenance critically depends on the constraints that lateral inhibition imposes to the mnemonic activity, encoding is limited by the ability of the stimulated neural assemblies to reach a sufficiently high level of excitation, a process governed by the dynamics of competition and cooperation among neuronal pools. Encoding is therefore contingent upon the visual working memory task and has led us to introduce the concept of effective working memory capacity (eWMC) in contrast to the maximal upper capacity limit only reached under ideal conditions.

Two hypotheses have been proposed to explain the formation manner for visual working memory (VWM) representations during the consolidation process: an all-or-none process hypothesis and a coarse-to-fine process hypothesis. However, neither the all-or-none process hypothesis nor the coarse-to-fine process hypothesis can stipulate clearly how VWM representations are formed during the consolidation process. In the current study, we propose a two-stage process hypothesis to reconcile these hypotheses. The two-stage process hypothesis suggests that the consolidation of coarse information is an all-or-none process in the early consolidation stage, while the consolidation of detailed information is a coarse-to-fine process in the late consolidation stage. By systematically manipulating the encoding time of memory stimuli, we asked participants to memorize one (Experiment 1) or two (Experiment 2) orientations in different encoding time intervals. We found that the memory rate increased linearly as the encoding time increased. More importantly, VWM precision remained constant when the encoding time was short, while the precision increased linearly as the encoding time increased when the encoding time was sufficient. These results supported the two-stage process hypothesis, which reconciles previous conflicting findings in the literature.

As of yet, visual working memory (WM) training has failed to yield consistent cognitive benefits to performance in untrained tasks, despite large improvements in trained tasks. Investigating the mechanisms underlying training effects can help explain these inconsistencies. In this pre-registered, pre-test/post-test online training study, we examined how training affects the quantity and quality of representations in visual WM using continuous-reproduction tasks. N = 64 young healthy adults were randomly assigned to an experimental group or an active control group to complete four training sessions of practce in an orientation-reproduction or a visual search task, respectively. We observed that, in the trained task, only the quality, but not the quantity, of visual WM representations significantly increased in the experimental group relative to the control group. These improvements did not generalise to untrained stimuli or paradigms. Therefore, our findings suggest that training gains are not driven by enhanced capacity. Instead, gains in the quality of visual WM representations that are tied to specific stimuli and paradigms may reflect enhanced efficiency in using the existing visual WM capacity.

Visual working memory (WM) can hold a limited amount of information for a short interval. The current study investigated whether the features of the objects maintained in WM are represented in a dependent or independent manner. Across five experiments, we presented multifeature objects (color and shape) and investigated whether remembering one feature is correlated with remembering the other feature. To answer this question, we divided the continuous response distribution into five quintiles according to the accuracy performance, then computed the area under the curve of the continuous response of the other feature, thus calculating the area under the curve for a given feature for each quintile of the other feature. A dependent object representation predicts a correlation between these measures, indicating that remembering one feature is correlated with remembering the other feature. In all five experiments, in which we used different stimuli (triangles or polygons), different memory exposure intervals (1,200 or 300 ms), and different response procedures (sequential or simultaneous responses), we found strong evidence for a dependency between the object's features. We conclude that this current analysis was able to reveal strong feature dependency in WM. These findings support the conclusion that visual WM relies on object-based representations and that all the objects' features are represented in a dependent manner. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

The content of visual working memory (VWM) guides attention, but whether this interaction is limited to a single VWM representation or functional for multiple VWM representations is under debate. To test this issue, we developed a gaze-contingent search paradigm to directly manipulate selection history and examine the competition between multiple cue-matching saccade target objects. Participants first saw a dual-color cue followed by two pairs of colored objects presented sequentially. For each pair, participants selectively fixated an object that matched one of the cued colors. Critically, for the second pair, the cued color from the first pair was presented either with a new distractor color or with the second cued color. In the latter case, if two cued colors in VWM interact with selection simultaneously, we expected the second cued color object to generate substantial competition for selection, even though the first cued color was used to guide attention in the immediately previous pair. Indeed, in the second pair, selection probability of the first cued color was substantially reduced in the presence of the second cued color. This competition between cue-matching objects provides strong evidence that both VWM representations interacted simultaneously with selection. (PsycINFO Database Record

Visual working memory (WM) capacity has been claimed to be larger for meaningful objects than for simple features, possibly because richer semantic representations enhance the distinctiveness of stored items. However, prior demonstrations typically compared trial-unique meaningful objects with a small set of repeated simple features. This design confounds meaningfulness with proactive interference (PI), such that PI is minimal for trial-unique objects but substantial for repeated features. As a result, superior performance for meaningful objects may reflect contributions from episodic long-term memory (LTM) rather than expanded WM capacity. To test this, Experiment 1 measured WM for repeated colors, repeated meaningful objects, and trial-unique meaningful objects. The advantage for objects over colors was replicated in the trial-unique condition, but eliminated for repeated objects that equated PI across stimulus types. Hierarchical Bayesian dual-process modeling revealed that the trial-unique advantage reflected stronger familiarity signals, whereas recollection remained stable across stimulus types. Experiment 2 assessed WM storage directly using contralateral delay activity (CDA), an electrophysiological marker of the number of items stored. Although trial-unique objects again yielded behavioral advantages, CDA activity across increasing set sizes revealed a common slope and plateau for trial-unique meaningful objects and repeated colors. The CDA difference between stimulus types was additive and did not vary with set size, providing no evidence for an increased number of stored items. These findings demonstrate that previously reported advantages for meaningful objects primarily reflect reduced PI and enhanced LTM familiarity. When PI is equated, WM storage limits for simple and meaningful stimuli are equivalent.