Contents Of Visual Working Memory Research Articles

The Case of the Cognitive (Opti)miser: Electrophysiological Correlates of Working Memory Maintenance Predict Demand Avoidance.

People are often considered cognitive misers. When given a free choice between two tasks, people tend to choose tasks requiring less cognitive effort. Such demand avoidance (DA) is associated with cognitive control, but it is still not clear to what extent individual differences in cognitive control can account for variations in DA. We sought to elucidate the relation between cognitive control and cognitive effort preferences by investigating the extent to which sustained neural activity in a task requiring cognitive control is correlated with DA. We hypothesized that neural measures of efficient filtering will predict individual variations in demand preferences. To test this hypothesis, we had participants perform a delayed-match-to-sample paradigm with their ERPs recorded, as well as a separate behavioral demand-selection task. We focused on the ERP correlates of cognitive filtering efficiency (CFE)-the ability to ignore task-irrelevant distractors during working memory maintenance-as it manifests in a modulation of the contralateral delay activity, an ERP correlate of cognitive control. As predicted, we found a significant positive correlation between CFE and DA. Individuals with high CFE tended to be significantly more demand avoidant than their low-CFE counterparts. Low-CFE individuals, in comparison, did not form distinct cognitive effort preferences. Overall, our results suggest that cognitive control over the contents of visual working memory contribute to individual differences in the expression of cognitive effort preferences. This further implies that these observed preferences are the product of sensitivity to cognitive task demands.

Tracking stimulus representation across a 2-back visual working memory task.

How does the neural representation of visual working memory content vary with behavioural priority? To address this, we recorded electroencephalography (EEG) while subjects performed a continuous-performance 2-back working memory task with oriented-grating stimuli. We tracked the transition of the neural representation of an item (n) from its initial encoding, to the status of ‘unprioritized memory item' (UMI), and back to ‘prioritized memory item', with multivariate inverted encoding modelling. Results showed that the representational format was remapped from its initially encoded format into a distinctive ‘opposite' representational format when it became a UMI and then mapped back into its initial format when subsequently prioritized in anticipation of its comparison with item n + 2. Thus, contrary to the default assumption that the activity representing an item in working memory might simply get weaker when it is deprioritized, it may be that a process of priority-based remapping helps to protect remembered information when it is not in the focus of attention.

Age-related decline in visual working memory: The effect of nontarget objects during a delayed estimation task.

Visual working memory (VWM) is an essential aspect of cognitive functioning that becomes compromised in older adults. A canonical probe of VWM is the change detection task in which participants compare a visually presented stimulus with items being maintained in VWM. Older adults show a decreased ability to detect changes between a stimulus and the contents of VWM compared with younger adults. Previously, we used a dynamic neural field (DNF) model to explore changes in neural connectivity that can explain this pattern of decline in performance. These simulations suggest that older adults have cortical interactions that are more diffuse compared to younger adults. In the current article, we examined the precision of representations in VWM using the delayed-estimation task. Participants are first presented with a memory array. After a delay, a location is cued, and participants click on a color wheel to indicate which color was at that location. The model predicted that older adults should show increased guessing rates and decreased precision (defined as the variability of color responses around the target location) relative to younger adults. The model also predicted that presenting the nontarget items during test should improve the precision of responses for older adults but not for younger adults. Results from two experiments supported these predictions of the model. These findings further advance an emerging theory of the neurocognitive decline of VWM and illustrate how older adults' VWM representations are influenced by the context in which information is being recalled. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

No evidence for mnemonic modulation of interocularly suppressed visual input

Visual working memory (VWM) allows for keeping visual information available for upcoming goal-directed behavior, while new visual input is processed concurrently. Interactions between the mnemonic and perceptual systems cause VWM to affect the processing of visual input in a content-specific manner: visual input that is initially suppressed from consciousness is detected faster when it matches rather than mismatches the content of VWM. It is currently under debate whether such mnemonic influences on perception occur prior to or after conscious access. To address this issue, we investigated whether VWM content modulates the neural response to visual input that remains suppressed from consciousness. We measured fMRI responses to interocularly suppressed stimuli in 20 human participants performing a delayed match-to-sample task: Participants were retro-cued to memorize one of two geometrical shapes for subsequent recognition. During retention, an interocularly suppressed peripheral stimulus (the probe) was briefly presented, which was either of the cued (memorized) or uncued (not memorized) shape category. We found no evidence that VWM content modulated the neural response to the probe. Substantial evidence for the absence of this modulation was found despite leveraging a highly liberal analysis approach: (1) selecting regions of interest that were particularly prone to detecting said modulation, and (2) using directional Bayesian tests favoring the presence of the hypothesized modulation. We did observe faster detection of memory-matching compared to memory-mismatching probes in a behavioral control experiment, thus validating the stimulus set. We conclude that VWM impacts the processing of visual input only once suppression is mostly alleviated.

Limitations of concurrently representing objects within view and in visual working memory

Representing visibly present stimuli is as limited in capacity as representing invisible stimuli in visual working memory (WM). In this study, we explored whether concurrently representing stimuli within view affects representing objects in visual WM, and if so, whether this effect is modulated by the storage states (active and silent state) of memory contents? In experiment 1, participants were asked to perform the change-detect task in a simultaneous-representing condition in which WM content and the continuously-visible stimuli in view were simultaneously represented, as well as a baseline condition in which only the representations of visual WM content were maintained. The results showed that the representations in visual WM would be impaired when the continuously-visible stimuli in view were concurrently represented, revealed by the reduced CDA amplitude and the lower behavior performance. In experiment 2, a dual-serial retro-cue paradigm was adopted to guide participants to maintain memory items in two different storage states, and the results revealed that simultaneously representing the continuously-visible stimuli and the WM content would only impair the WM representations in the active state. These evidences demonstrated that only the visual WM representations that were maintained in the active state would definitely share the limited resources with the representations of continuously-visible information, and further supported the dissociation between the active state and silent state of visual WM storage.

The pupillary light response reflects visual working memory content.

Recent studies have shown that the pupillary light response (PLR) is modulated by higher cognitive functions, presumably through activity in visual sensory brain areas. Here we use the PLR to test the involvement of sensory areas in visual working memory (VWM). In two experiments, participants memorized either bright or dark stimuli. We found that pupils were smaller when a prestimulus cue indicated that a bright stimulus should be memorized; this reflects a covert shift of attention during encoding of items into VWM. Crucially, we obtained the same result with a poststimulus cue, which shows that internal shifts of attention within VWM affect pupil size as well. Strikingly, the effect of VWM content on pupil size was most pronounced immediately after the poststimulus cue, and then dissipated. This suggests that a shift of attention within VWM momentarily activates an "active" memory representation, but that this representation quickly transforms into a "hidden" state that does not rely on sensory areas. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Modulation of the pupillary response by the content of visual working memory

Studies of selective attention during perception have revealed modulation of the pupillary response according to the brightness of task-relevant (attended) vs. -irrelevant (unattended) stimuli within a visual display. As a strong test of top-down modulation of the pupil response by selective attention, we asked whether changes in pupil diameter follow internal shifts of attention to memoranda of visual stimuli of different brightness maintained in working memory, in the absence of any visual stimulation. Across 3 studies, we reveal dilation of the pupil when participants orient attention to the memorandum of a dark grating relative to that of a bright grating. The effect occurs even when the attention-orienting cue is independent of stimulus brightness, and even when stimulus brightness is merely incidental and not required for the working-memory task of judging stimulus orientation. Furthermore, relative dilation and constriction of the pupil occurred dynamically and followed the changing temporal expectation that 1 or the other stimulus would be probed across the retention delay. The results provide surprising and consistent evidence that pupil responses are under top-down control by cognitive factors, even when there is no direct adaptive gain for such modulation, since no visual stimuli were presented or anticipated. The results also strengthen the view of sensory recruitment during working memory, suggesting even activation of sensory receptors. The thought-provoking corollary to our findings is that the pupils provide a reliable measure of what is in the focus of mind, thus giving a different meaning to old proverbs about the eyes being a window to the mind.

The contents of visual working memory delay the perceived offset of matching visual stimuli

Previous research suggests that the perception of stimulus onset can be accelerated by a match between the contents of visual working memory and the stimulus presented alone in the peripheral visual field. This onset acceleration effect might contribute to previously reported effects of working memory on perceived stimulus duration. However, it remains possible that the contents of visual working memory may also modulate the offset perception of matching visual stimuli, thereby contributing to the modulation of duration perception by working memory. The present study directly tested this possibility by using a simple reaction time task to assess the effect of visual working memory on perceived stimulus offset. Participants were asked to maintain a sample stimulus in working memory and subsequently had to respond to the offset of a single visual target. Across three experiments, we showed that the offset response was reliably slower when the target matched the sample held in visual working memory, as compared with when the target did not. This effect was not likely attributed to the mechanism of repetition priming from the presentation of the sample, because we failed to observe a priming effect either when the sample was only passively viewed without working memory demands or when the sample was initially encoded into memory but did not need to be actively maintained in mind by the time the offset target appeared. The findings provide direct evidence indicating that active maintenance of information in visual working memory delays the perceived offset of matching visual stimuli.

The content of visual working memory regulates the priority to access visual awareness, including bound memoranda with multiple features

The content of visual working memory regulates the priority to access visual awareness, including bound memoranda with multiple features

Selection of Visual Objects in Perception and Working Memory One at a Time

How does the content of visual working memory influence the way we process the visual environment? We addressed this question using the steady-state visual evoked potential (SSVEP), which provides a discernible measure of visuocortical activation to multiple stimuli simultaneously. Fifty-six adults were asked to remember a set of two oriented gratings. During the retention interval, two frequency-tagged oriented gratings were presented to probe the visuocortical processing of matching versus mismatching orientations relative to the memory set. Matching probes prompted an increased visuocortical response, whereas mismatching stimuli were suppressed. This suggests that the visual cortex prioritizes attentional selection of memory-relevant features at the expense of non-memory-relevant features. When two memory items were probed simultaneously, visuocortical amplification alternated between the two stimuli at a rate of 3 Hz to 4 Hz, consistent with the rate of attentional sampling of sensory events from the external world. These results suggest a serial, single-item attentional sampling of remembered features.

Can you have multiple attentional templates? Large-scale replications of Van Moorselaar, Theeuwes, and Olivers (2014) and Hollingworth and Beck (2016)

Stimuli that resemble the content of visual working memory (VWM) capture attention. However, theories disagree on how many VWM items can bias attention simultaneously. According to some theories, there is a distinction between active and passive states in VWM, such that only items held in an active state can bias attention. The single-item-template hypothesis holds that only one item can be in an active state and thus can bias attention. In contrast, the multiple-item-template hypothesis posits that multiple VWM items can be in an activate state simultaneously, and thus can bias attention. Recently, Van Moorselaar, Theeuwes, and Olivers (Journal of Experimental Psychology: Human Perception and Performance, 40(4):1450, 2014) and Hollingworth and Beck (Journal of Experimental Psychology: Human Perception and Performance, 42(7):911–917, 2016) tested these accounts, but obtained seemingly contradictory results. Van Moorselaar et al. (2014) found that a distractor in a visual-search task captured attention more when it matched the content of VWM (memory-driven capture). Crucially, memory-driven capture disappeared when more than one item was held in VWM, in line with the single-item-template hypothesis. In contrast, Hollingworth and Beck (2016) found memory-driven capture even when multiple items were kept in VWM, in line with the multiple-item-template hypothesis. Considering these mixed results, we replicated both studies with a larger sample, and found that all key results are reliable. It is unclear to what extent these divergent results are due to paradigm differences between the studies. We conclude that is crucial to our understanding of VWM to determine the boundary conditions under which memory-driven capture occurs.

How robust and rapid can the memory-driven attentional capture be?

Previous research has indicated that visual attention can be automatically captured by sensory inputs that match the contents of visual working memory. Furthermore, the information in visual working memory can be used as a template of memory guidance for either the selection or rejection of visual attention. The current study investigated the memory-driven attentional processes in four experiments which extend and complement previous research. Participants performed a visual search task while maintaining items in visual working memory. Experiment 1 used an arrow as a pre-cue indicating which side of the screen the search target would appear on. Experiment 2 used two circles as pre-cues for the right-up/down location of the search target. Experiment 3 presented a memory-matching distractor for 300 ms followed by a blank screen. Experiment 4 presented a memory-matching distractor for 150 ms followed by the visual search task. All experiments resulted in significantly slower visual search reaction times (RTs) for the invalid condition (memory-matching distractor) compared to the neutral condition but with no significant differences in memory performance. This result suggests that the contents of working memory affect the deployment of attention in visual search. Our findings show that attentional capture occurs even within short periods of 150 ms, which demonstrates the robustness and speed of memory-driven attentional processes. Consequently, attentional capture appears to be initiated at an early phase of visual processing but can be strategically inhibited through cognitive control at later stages of analysis.

What can half a million change detection trials tell us about visual working memory?

Visual working memory (VWM) represents the surrounding world in an active and accessible state, but its capacity is severely limited. To better understand VWM and its limits, we collected data from over 3,800 participants in the canonical change detection task. This unique population-level data-set sheds new light on classic debates regarding VWM capacity. First, the result supported a view of VWM as an active process, as manifested by the fact that capacity estimates were not stable across set-sizes, but rather lower for the larger set-size. Another support for this notion came from the tight connection capacity estimates had with a measure of attentional control. Together, the data suggested that individual differences in capacity do not reflect only differences in storage-size, but differences in the efficiency of using this storage. Second, we found a response bias such that subjects are more likely to respond that the probed item changed, and this criterion bias was further shifted as the set-size increased. These findings are naturally explained by a slot-like theory arguing that when load exceeds capacity, certain items remain completely outside of VWM (instead of all items being represented in lower resolution), therefore causing subjects to perceive them as different from VWM contents even when they are unchanged. Additionally, we found that the pattern of d' also confirmed the predictions of a slot-like view of VWM, such that some items are represented with high fixed resolution and others are not represented at all, although this finding is based on two measures with very different underlying assumptions. We also discuss how flexible-resource views can accommodate these results. Moreover, comparing performance between the first and last trials demonstrated no evidence for proactive interference as the driving factor of capacity limitations. We provide further details regarding the distribution of individual capacity, the relations between capacity and demographic variables, and the spatial prioritization of the items.

Feature-based guidance of attention by visual working memory is applied independently of remembered object location.

Visual working memory (VWM) has been implicated both in the online representation of object tokens (in the object-file framework) and in the top-down guidance of attention during visual search, implementing a feature template. It is well established that object representations in VWM are structured by location, with access to the content of VWM modulated by position consistency. In the present study, we examined whether this property generalizes to the guidance of attention. Specifically, in two experiments, we probed whether the guidance of spatial attention from features in VWM is modulated by the position of the object from which these features were encoded. Participants remembered an object with an incidental color. Items in a subsequent search array could match either the color of the remembered object, the location, or both. Robust benefits of color match (when the matching item was the target) and costs (when the matching items was a distractor) were observed. Critically, the magnitude of neither effect was influenced by spatial correspondence. The results demonstrate that features in VWM influence attentional priority maps in a manner that does not necessarily inherit the spatial structure of the object representations in which those features are maintained.

Oculomotor capture reveals trial-by-trial neural correlates of attentional guidance by contents of visual working memory

Evidence from attentional and oculomotor capture, contingent capture, and other paradigms suggests that mechanisms supporting human visual working memory (VWM) and visual attention are intertwined. Features held in VWM bias guidance toward matching items even when those features are task irrelevant. However, the neural basis of this interaction is underspecified. Prior examinations using fMRI have primarily relied on coarse comparisons across experimental conditions that produce varying amounts of capture. To examine the neural dynamics of attentional capture on a trial-by-trial basis, we applied an oculomotor paradigm that produced discrete measures of capture. On each trial, subjects were shown a memory item, followed by a blank retention interval, then a saccade target that appeared to the left or right. On some trials, an irrelevant distractor appeared above or below fixation. Once the saccade target was fixated, subjects completed a forced-choice memory test. Critically, either the target or distractor could match the feature held in VWM. Although task irrelevant, this manipulation produced differences in behavior: participants were more likely to saccade first to an irrelevant VWM-matching distractor compared with a non-matching distractor – providing a discrete measure of capture. We replicated this finding while recording eye movements and scanning participants' brains using fMRI. To examine the neural basis of oculomotor capture, we separately modeled the retention interval for capture and non-capture trials within the distractor-match condition. We found that frontal activity, including anterior cingulate cortex and superior frontal gyrus regions, differentially predicted subsequent oculomotor capture by a memory-matching distractor. Other regions previously implicated as involved in attentional capture by VWM-matching items showed no differential activity across capture and non-capture trials, even at a liberal threshold. Our findings demonstrate the power of trial-by-trial analyses of oculomotor capture as a means to examine the underlying relationship between VWM and attentional guidance systems.

Alpha-band activity tracks dynamic changes in the contents of visual working memory.

Alpha-band activity tracks dynamic changes in the contents of visual working memory.

The neural mechanisms underlying the maintenance of visual working memory contents

Visual working memory (WM) refers to the maintenance and manipulation of visual information that is not in the visual field. Visual WM provides an essential connection between perception and higher cognitive functions. Previous fMRI studies with classification methods showed that early visual cortex could retain information of visual features maintained in WM. However, we still know little about the neural mechanisms of visual WM during maintenance period in higher visual cortex and the influence of memory load on such mechanisms. Therefore, the present study utilized a modified delayed match-to-sample paradigm to investigate the visual WM performance. Participants were required to maintain one or two target items (face or house) for 11s. At the same time, function magnetic resonance imaging (fMRI) was applied to acquire the neural activities in visual cortical areas. Behavioral results showed that memory load but not stimuli significantly affected the accuracy of memory. Next, the amplitude of the neural activity during maintenance in each area was extracted. In order to reveal the areas sensitive to mnemonic stimuli, we compared the activity induced by face and house WM. The results showed that parahippocampal place area (PPA) and intra-parietal sulcus (IPS) were activated differently to different stimuli. Specifically, the neural response was stronger when house relative to face was held in memory. To further investigate whether other areas also retained visual information in WM, activation pattern analysis with decoding method was applied to the neural response in each area. The results demonstrated decoding performance in face selective areas including superior temporal sulcus (STS), FFA and V4. Taken together, these results indicated that higher visual cortex could retain visual information held in WM. Specifically, PPA and IPS showed general stronger responses to mnemonic houses than mnemonic faces, while FFA, STS, and V4 contained different detailed representations of mnemonic faces and mnemonic houses. These findings were consistent with previous findings concerning visual features, and supported the view that the contents in visual working memory are represented in visual cortex. Notably, we did not find any effects of memory load on the neural activity in PPA and IPS. However, the activity pattern analysis about other areas showed significant effects only in high memory load condition, suggesting that high memory load might refine the representations in face selective areas without boosting the average activation level. In order to find the cortical areas of which responses were significantly modulated by memory load, we further performed a voxel-based whole brain analysis. Specifically, a 2 (stimuli: face, house) * 2 (memory load: 1 item, 2 items) repeated measures ANOVA was performed for each voxel on the neural response during the maintenance. No interaction was observed in each voxel. Interestingly, the main effect for memory load was significant in bilateral putamen. In summary, our findings revealed the crucial role of higher visual cortex in maintaining visual information in WM and the important role of putamen in modulating memory load.

Effect of visual working memory contents on visual function and fluid intelligence

Objective To explore the influence of visual working memory contents on visual function and fluid intelligence. Methods 42 subjects were randomly divided into three groups: controll group including 17 people who had no training, working memory based on Gabor vision group including 13 people and standard working memory group including 12 people who received the N-back working memory training for 15 days, and lasted half an hour in every day.The contrast sensitivity was recorded and measured using OPTEC6500, and the fluid intelligence was measured with the Raven's advanced progressive matrices before and after training. Results In the Gabor working memory group, there were salient gains in contrast sensitivity(respectively(1.48±0.26)log, (1.87±0.13)log, P 0.05), the fluid intelligence increased significantly(respectively(11.25±1.91), (13.00±1.86), P 0.05)and in fluid intelligence(respectively(11.41±1.87), (11.58±1.94), P>0.05) between pre- and post-test. Conclusion Working memory training based on Gabor vision can enhance the subjective perception of visual stimuli and improve the behavioral effect of visual contrast sensitivity, but the visual working memory contents do not affect the migration effect of working memory training on fluid intelligence. Key words: Visual working memory contents; Visual function; Fluid intelligence; Visual contrast sensitivity

Separate and combined effects of action relevance and motivational value on visual working memory.

Visual working memory contents can be selectively weighted according to differences in their task-relevance. In the present study, we examined the influence of two more indirect selection biases established by a concurrent task or learned reward associations: action relevance and motivational value. In three experiments, memory performance was assessed with the same color change detection task. Potential action relevance and motivational value were each determined by a specific feature of the memory items (location or shape, respectively) and manipulated orthogonally. Investigated separately (Experiments 1A and 1B), both selection biases modulated visual working memory. In combination (Experiment 2), action relevance and motivational value still each exerted an influence, but not in a fully independent and additive manner. While action relevance impacted performance irrespective of the reward associated with the items, an effect of motivational value was only observed for action-relevant items. These results support the notion that visual working memory is automatically biased as an inherent part of action planning. More generally, these findings highlight the versatile nature of visual working memory: Contents can be flexibly weighted to reflect differences in their importance, taking into account several sources of information.

Flexible Coding of Visual Working Memory Representations during Distraction.

Visual working memory (VWM) recruits a broad network of brain regions, including prefrontal, parietal, and visual cortices. Recent evidence supports a "sensory recruitment" model of VWM, whereby precise visual details are maintained in the same stimulus-selective regions responsible for perception. A key question in evaluating the sensory recruitment model is how VWM representations persist through distracting visual input, given that the early visual areas that putatively represent VWM content are susceptible to interference from visual stimulation.To address this question, we used a functional magnetic resonance imaging inverted encoding model approach to quantitatively assess the effect of distractors on VWM representations in early visual cortex and the intraparietal sulcus (IPS), another region previously implicated in the storage of VWM information. This approach allowed us to reconstruct VWM representations for orientation, both before and after visual interference, and to examine whether oriented distractors systematically biased these representations. In our human participants (both male and female), we found that orientation information was maintained simultaneously in early visual areas and IPS in anticipation of possible distraction, and these representations persisted in the absence of distraction. Importantly, early visual representations were susceptible to interference; VWM orientations reconstructed from visual cortex were significantly biased toward distractors, corresponding to a small attractive bias in behavior. In contrast, IPS representations did not show such a bias. These results provide quantitative insight into the effect of interference on VWM representations, and they suggest a dynamic tradeoff between visual and parietal regions that allows flexible adaptation to task demands in service of VWM.SIGNIFICANCE STATEMENT Despite considerable evidence that stimulus-selective visual regions maintain precise visual information in working memory, it remains unclear how these representations persist through subsequent input. Here, we used quantitative model-based fMRI analyses to reconstruct the contents of working memory and examine the effects of distracting input. Although representations in the early visual areas were systematically biased by distractors, those in the intraparietal sulcus appeared distractor-resistant. In contrast, early visual representations were most reliable in the absence of distraction. These results demonstrate the dynamic, adaptive nature of visual working memory processes, and provide quantitative insight into the ways in which representations can be affected by interference. Further, they suggest that current models of working memory should be revised to incorporate this flexibility.