Color In Visual Working Memory Research Articles

Suppression on the basis of template for rejection is reactive: Evidence from human electrophysiology.

According to most theories of attention, the selection of task-relevant visual information can be enhanced by holding them in visual working memory (VWM). However, there has been a long-standing debate concerning whether similar optimization can also be achieved for task-irrelevant information, known as a "template for rejection". The present study aimed to explore this issue by examining the consequence of cue distractors before visual search tasks. For this endeavor, we manipulated the display heterogeneity by using two distractor conditions, salient and non-salient, to explore the extent to which holding the distractor color in VWM might affect attentional selection. We measured the reaction times of participants while their EEG activity was recorded. The results showed that WM-matched distractors did not improve reaction times but rather slowed them down in both tasks. Event-related potential (ERP) results showed that the display heterogeneity had no modulatory effect on the degree of distractor suppression. Even in the salient distractor condition, the WM-matched distractor received no greater suppression. Furthermore, the WM-matched distractor but not the neutral distractor elicited an N2pc before the PD in salient distractor conditions. This suggests that the template for rejection operates reactively since suppression occurs after extra attentional processes to the distractor. Moreover, the presence of WM-matched distractors led to a reduction of P3b, indicating a competition between target processing and WM-matched distractor rejection. Our findings provide insights into the mechanisms underlying the optimization of attentional selection, and have implications for future studies aimed at understanding the role of VWM in cognition.

Comparing memory capacity across stimuli requires maximally dissimilar foils: Using deep convolutional neural networks to understand visual working memory capacity for real-world objects.

The capacity of visual working and visual long-term memory plays a critical role in theories of cognitive architecture and the relationship between memory and other cognitive systems. Here, we argue that before asking the question of how capacity varies across different stimuli or what the upper bound of capacity is for a given memory system, it is necessary to establish a methodology that allows a fair comparison between distinct stimulus sets and conditions. One of the most important factors determining performance in a memory task is target/foil dissimilarity. We argue that only by maximizing the dissimilarity of the target and foil in each stimulus set can we provide a fair basis for memory comparisons between stimuli. In the current work we focus on a way to pick such foils objectively for complex, meaningful real-world objects by using deep convolutional neural networks, and we validate this using both memory tests and similarity metrics. Using this method, we then provide evidence that there is a greater capacity for real-world objects relative to simple colors in visual working memory; critically, we also show that this difference can be reduced or eliminated when non-comparable foils are used, potentially explaining why previous work has not always found such a difference. Our study thus demonstrates that working memory capacity depends on the type of information that is remembered and that assessing capacity depends critically on foil dissimilarity, especially when comparing memory performance and other cognitive systems across different stimulus sets.

How does working memory work? The manipulation unit of visual working memory

What is the manipulation unit of visual working memory (VWM)? This is a key question to understand how the human mind updates the information absent in view to adapt to the ever-changing environment. We proposed two hypotheses: (a) the object-based hypothesis expects longer manipulating times when more objects are involved in manipulation, while (b) the Boolean-map-based hypothesis expects longer manipulating times when more Boolean maps are involved in manipulation. In Experiments 1 to 3, participants were asked to move, search, or dye a subset of stimuli (different numbers of orientations/objects, but all in one Boolean map) in VWM and then finish a change detection task. The results support the object-based hypothesis that participants’ manipulating times differed when manipulating different numbers of orientations although there was only one Boolean map all the time. In Experiment 4, two different colors linked together were presented on the same object (different Boolean maps) while two same colors were presented on different objects (same Boolean map). Participants were asked to dye a subset of stimuli into two different colors in VWM. The results showed that manipulating colors from one object (two different Boolean maps) was faster than that from two different objects (one Boolean map), supporting the object-based hypothesis. In conclusion, we adopted four novel manipulating tasks and found that objects are the elementary manipulation unit of VWM, instead of Boolean maps.

Visual working memory content influences correspondence processes.

Representing objects as continuous across time requires the establishment of correspondence, whereby current stimuli are represented as deriving from the same object as earlier stimuli. Spatiotemporal continuity and surface-feature similarity play important roles in these correspondence processes. Because objects are often represented across extended periods of time, visual working memory (VWM) content should also play a role in object correspondence. We tested this prediction using Ternus motion. Displays consisted of three-disk arrays that shifted horizontally by one position between frames. Depending on how correspondence is resolved, Ternus displays are perceived as group motion, where all three disks appear to move together, or element motion, where one disk appears to jump across the others. Reports of which motion is perceived provide an index of how correspondence was resolved. Ternus displays were adapted such that the color of some disks biased element motion while the color of others biased group motion. Maintaining one or the other of the colors in VWM for later report systematically biased which type of motion was perceived (Experiments 1 and 2). When color was incidental to the VWM task, however, it did not (Experiment 3). These results confirm that VWM content contributes to object correspondence. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

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.

The allocation of resources in visual working memory and multiple attentional templates.

In a visual search task, sensory input is matched to a representation of the search target in visual working memory (VWM). This representation is referred to as attentional template. We investigated the conditions that allow for more than a single attentional template. The attentional template of color targets was measured by means of the contingent attentional capture paradigm. We found that attentional templates did not differ between search with 1 and 2 memorized target colors, suggesting that dual target search allowed for multiple attentional templates. In the same paradigm, we asked participants to memorize target and distractor color with equal precision. Both were presented before the search task. An attentional template was set up for the target, but not for the distractor color, suggesting that keeping a color in VWM does not automatically result in the creation of multiple attentional templates. Importantly, the precision of recall of the distractor color was worse than the precision of recall of the target color, regardless of instructions, suggesting that participants always allocated fewer VWM resources to the distractor color. Thus, 2 attentional templates may be set up, but only when the 2 colors receive an equal amount of resources in VWM (i.e., in dual target search). In contrast, when 1 item is deprioritized because of task demands, it receives fewer resources in VWM and multiple attentional templates cannot be established. Thus, unequal roles in the search task prevented the simultaneous operation of multiple attentional templates in VWM. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Attentional guidance from two representations of the same or different dimensions in visual working memory

Previous studies have only focused on the interference effect induced by multiple task-irrelevant representations from the same dimensions in visual working memory (VWM). The present study reexamined the issue by not only focusing on interference effect but also facilitation effect induced by multiple task-irrelevant representations from the same dimension in VWM. Furthermore, the guidance effect of multiple task-irrelevant representations from different dimensions in VWM was also investigated. Participants were instructed to complete a gap-location search task while holding two items in VWM. In Experiment 1, one of the colors (match-1) or both colors in VWM (match-2) matched with one or two targets or distractors in the search array. No guidance effects were found for match-1 trials, but there was a reliable interference effect when both colors in VWM were presented as distractors and a facilitation effect when they matched the color of two search targets. Experiment 2 was carried out to examine the guidance effect produced by multiple task-irrelevant representations from different dimensions in VWM. Participants were required to memorize the color and direction of an arrow. Attentional guidance effects were found when each one of the VWM features matched the search target, but there was no additive facilitation effect when both features were validated in visual search. These results provide evidence that multiple items in VWM can guide the attention simultaneously, but the guidance effects are flexible and various across different types of stimuli.

Competition in saccade target selection reveals attentional guidance by simultaneously active working memory representations.

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 modulates within-object metrics of saccade landing position.

In two experiments, we examined the influence of visual working memory (VWM) on oculomotor selection, testing whether the landing positions of rapidly generated saccades are biased toward the region of an object that matches a feature held in VWM. Participants executed a saccade to the center of a single saccade target, divided into two colored regions and presented on the horizontal midline. Concurrently, participants maintained a color in VWM for an unrelated memory task. This color either matched one of the two regions or neither of the regions. Relative to the no-match baseline, the landing positions of rapidly generated saccades (mean latency < 150 ms) were biased toward the region that matched the remembered color. The results support the hypothesis that VWM modulates early, spatially organized sensory representations to bias selection toward locations with features that match VWM content. In addition, the results demonstrate that saccades to spatially extended objects are sensitive to within-object differences in salience.

In competition for the attentional template: can multiple items within visual working memory guide attention?

Recent studies have revealed that the deployment of attention can be biased by the content of visual working memory (VWM), but that stored memories do not always interact with attention. This has led to a model which proposes a division within VWM between a single active template that interacts with perception and multiple accessory representations that do not. The present study was designed to study whether multiple memory representations are able to bias attention. Participants performed a visual search task while maintaining a variable number of colors in VWM. Consistent with earlier findings, we observed increased attentional capture by memory related distractors when VWM was filled with a single item. However, memory related capture was no longer present for memory loads beyond a single item. The absence of memory related capture at higher VWM loads was independent of individual VWM capacity, nor was it attributable to weaker encoding, forgetting, or reduced precision of memory representations. When analyses were limited to those trials in which participants had a relatively precise memory, there was still no sign of attentional guidance at higher loads. However, when observers were cued toward a specific memory item after encoding, interference with search returned. These results are consistent with a distinction within VWM between representations that interact with perception and those that do not, and show that only a single VWM representation at a time can interact with visual attention.

Visual working memory modulates low-level saccade target selection: Evidence from rapidly generated saccades in the global effect paradigm

In three experiments, we examined the influence of visual working memory (VWM) on the metrics of saccade landing position in a global effect paradigm. Participants executed a saccade to the more eccentric object in an object pair appearing on the horizontal midline, to the left or right of central fixation. While completing the saccade task, participants maintained a color in VWM for an unrelated memory task. Either the color of the saccade target matched the memory color (target match), the color of the distractor matched the memory color (distractor match), or the colors of neither object matched the memory color (no match). In the no-match condition, saccades tended to land at the midpoint between the two objects: the global, or averaging, effect. However, when one of the two objects matched VWM, the distribution of landing position shifted toward the matching object, both for target match and for distractor match. VWM modulation of landing position was observed even for the fastest quartile of saccades, with a mean latency as low as 112 ms. Effects of VWM on such rapidly generated saccades, with latencies in the express-saccade range, indicate that VWM interacts with the initial sweep of visual sensory processing, modulating perceptual input to oculomotor systems and thereby biasing oculomotor selection. As a result, differences in memory match produce effects on landing position similar to the effects generated by differences in physical salience.

Metric-dependent repulsion between colors in visual working memory

Metric-dependent repulsion between colors in visual working memory