Conferences
You can see the Awh/Vogel lab’s conference presentations here:
Conference:
VSS 2026
OPAM/Psychonomics 2024
VSS 2024
VSS 2026
VSS - Talks
Electroencephalogram decoding suggests separate indexing mechanisms for attentional tracking of featureless objects and working memory storage
Henry Jones, Dawei Bai, Brian Scholl, Edward Awh
Sunday, May 17, 2026, 10:45 am – 12:30 pm, Talk Room 2
Recently, multivariate decoding of EEG data has identified a signal that scales with the number of items in working memory (WM), regardless of the specific content being maintained or the number of spatially attended locations. One possibility is that this signal reflects an abstract indexing process that binds the content of items to their context in space and time for maintenance and accessibility. To explore this possibility, we examined whether a similar load signal exists for “featureless objects”, which can only be described by their coordinates in space and time. On each trial, participants viewed a dense grid of crosses of random orientations. A moving object was implemented by having a single cross change from one random orientation to another, with changes occurring between adjacent crosses across frames. These transients yielded a persisting trackable object, even though (a) there is no constant surface feature across frames, and (b) it is impossible to identify objects on any static frame. In 2 EEG datasets, participants completed a task in which they tracked either 1 or 2 cued featureless objects, and a WM task in which they remembered either colors or the shape and location of “dot cloud” stimuli while spatial attention was controlled for. In both experiments, EEG decoding found a stable signal that scaled with the number of tracked featureless objects. However, we found no consistent evidence that the tracking load signal and the WM load signal generalized to one another. Although planned studies will examine whether this conclusion generalizes to traditional tracking tasks that may rely on other mechanisms (Lu and Sperling, 1996), these results suggest that distinct mechanisms may guide WM storage and attentional tracking.
A unique neural signature of individual differences in long-term memory from EEG inter-electrode correlation with event-related potentials
Chong Zhao, Edward K. Vogel, Monica Rosenberg
Tuesday, May 19, 2026, 10:45 am – 12:15 pm, Talk Room 1
Classic memory models suggest that the processes supporting visual working memory (VWM) play a central role in determining how effectively information is encoded into long-term memory (LTM). Consistent with this view, VWM and LTM performance are typically correlated, leaving open the question of whether LTM performance relies on neural mechanisms that are distinct from those supporting VWM encoding. To address this, we recorded EEG activity while participants performed recognition memory tasks with large set sizes (32 and 128 items), far exceeding typical VWM capacity. Using interelectrode correlation (IC) analyses, we found that IC patterns robustly predicted individual differences in LTM performance across both set sizes, indicating a stable, domain-general neural signature of LTM formation. Crucially, the predictive power of our IC model persisted even after statistically controlling for VWM capacity and attentional control, demonstrating that the model captures variance specifically related to individual differences in LTM performance rather than general cognitive performance. Temporally, IC-based predictive signals emerged shortly after stimulus onset and remained significant for approximately 500–600 ms. Distinct correlation patterns characterized early versus late encoding windows, suggesting that multiple, dynamically shifting neural processes contribute to individual differences in LTM. Together, these results identify a reliable and temporally dynamic neural signature during LTM encoding that tracks individual differences in LTM performance, independent of VWM and attentional control abilities.
The Brain Mechanisms of Attentional Lapses During Goal Competition: An EEG Study
Matthieu Chidharom, Monica Rosenberg, Edward Vogel
Sunday, May 17, 2026, 8:15 – 9:45 am, Talk Room 1
Sustained attention is the ability to maintain focus on a specific goal over time, but attentional lapses are frequent. Theories have attributed these lapses to a transient failure of cognitive control in maintaining the goal in mind. However, this proposal has been challenged by recent findings showing greater engagement of cognitive control during states more prone to lapses. To explain this result, we proposed that lapses occur when goals compete, requiring stronger cognitive control to sustain performance. We recently tested this goal-competition hypothesis with a Switch-Continuous Performance Task (CPT) in which subjects alternated task goals between blocks—either switching or holding the same goal—in an effort to manipulate periods of higher and lower competition between goals. Participants viewed a bilateral display showing a letter (vowel/consonant) and a number (even/odd) on each trial. After every 20 trials, a cue instructed participants to perform either the letter task (e.g., press for frequent vowels, not infrequent consonants) or the number task (e.g., press for frequent even, not infrequent odd, numbers). Our results showed that lapses were more frequent when competition between goals was higher during switch compared to repeat trials. Although this result has been replicated several times, the brain mechanisms by which competing goals favor lapses remain unclear. In the current study, we recorded the EEG of 30 participants during the Switch-CPT. Our ERP analysis revealed that competition between goals reduces the attention allocated to the relevant stimulus, as revealed by the lower N2pc amplitude during switch trials. Follow-up analyses showed that this effect is driven by a failure to suppress the distracting goal. A decoding analysis also revealed lower classification accuracy of task goals during switch compared to repeat trials, providing additional evidence that the relevant goal is less activated in mind during competition.
VSS - Posters
Electrophysiological evidence for dissociation between covert spatial attention and working memory gating
Brecken Marome, Henry Jones, William Thyer, Edward Vogel, Edward Awh
Sunday, May 17, 2026, 2:45 – 6:45 pm, Pavilion
To be successful at visual tasks, observers must selectively process information from cluttered environments using covert spatial attention, which selects specific regions of space, and working memory (WM) gating, which selectively encodes items into limited-capacity storage. We analyzed data from a basic change detection task, where participants encoded square target items from amongst rectangular distractors. Some trials contained 2 square targets (ss2), while others contained one target and one rectangular distractor (ss1). For ss1 trials, target/distractor similarity was manipulated such that distractors were either very dissimilar (long grey rectangles), dissimilar (long colored rectangles), or similar (squat colored rectangles). Late in the delay period, spatially-selective alpha activity showed that attention was biased towards targets over distractors. However, during the first ~600 ms after stimulus onset, spatial attention was precisely oriented towards both targets and distractors, regardless of target-distractor similarity. A WM load classifier showed that gating of distractors happened as early as 180 ms contrasting with the less selective deployment of spatial attention. In addition, the classifier showed that similar distractors were more likely to be unintentionally encoded into WM. In next steps, we are examining visually-evoked ERPs at either target or distractor locations to corroborate (or call into question) the slow time course of spatial attention that is indicated by alpha activity. Taken together, our results so far provide further evidence that covert spatial attention and WM gating represent distinct modes of attentional control.
N2pc set-size effects emerge when working memory requires flexible spatial representations
Gengshi Hu, Chong Zhao, Edward K. Vogel
Tuesday, May 19, 2026, 2:45 – 6:45 pm, Pavilion
In visual working memory (VWM) tasks the contralateral delay activity (CDA) scales with the number of items stored, while the N2pc component—reflecting attentional selection—does not vary with set size. This dissociation has been replicated many times and suggests that VWM load effects emerge mainly during maintenance, not initial selection. A notable exception is found in multiple object tracking (MOT) tasks, where the N2pc reliably increases with the number of tracked targets. Because the N2pc in MOT appears within ~250 ms of stimulus onset—well before objects begin to move—tracking cannot explain this early modulation. Instead, a key difference between MOT and standard VWM tasks is that in MOT, the target location at test differs from the object’s original position, whereas in VWM tasks, the probed item generally reappears at its initial location. To test whether expectations about future spatial transformations drive N2pc load sensitivity, subjects performed a VWM task with two block-wise conditions. In the baseline condition, the probed item appeared at the same location in which it was encoded. In the spatial-shift condition, the probe was always displaced inward within the same hemifield. Crucially, the encoding displays were physically identical between conditions, and the N2pc was measured prior to any spatial shift. Behaviorally, memory performance was equivalent across conditions. Replicating prior work, the N2pc was insensitive to set size in the baseline condition. Strikingly, in the spatial-shift condition, the N2pc showed a reliable set-size effect, with larger amplitudes for four versus two items. These findings demonstrate that the anticipatory structure of the task—specifically, whether object positions are expected to change—alters how items are individuated during selection. Expectations about future spatial uncertainty appear to recruit enhanced target individuation at encoding, revealing that attentional selection mechanisms are more flexible and forward-looking than previously assumed.
Multi-item arrays are retrieved from long-term memory into working memory as unitized chunks
Woohyeuk (Leo) Chang, Ed Awh
Sunday, May 17, 2026, 2:45 – 6:45 pm, Banyan Breezeway
Classic models propose that information retrieved from long-term memory (LTM) is reinstated into working memory (WM), engaging the same capacity-limited operations that support online storage. For example, alpha oscillations decline as a function of the number of items stored in WM, and a similar pattern is observed when observers retrieve multi-item arrays from LTM. Although this suggests that LTM retrieval mirrors WM encoding, other work indicates that alpha activity may instead reflect the spatial extent of covert attention rather than the number of WM representations per se. Thus, there is strong motivation to study reinstatement using neural signals more directly linked to WM storage and designs that de-confound spatial attention from the number of stored items. We used a sequential design in which items were separated in time rather than space, holding spatial attention constant while manipulating the number of individuated items. A multivariate decoding approach known to track WM load independently of spatial attention was used. Participants memorized LTM shape arrays containing 1 or 3 targets and then completed a sequential WM/LTM task during EEG recording. Voltage-based signatures of WM load generalized across conditions requiring the maintenance of temporal order and item identity. The key question was whether retrieving multi-item arrays from LTM would elicit a multi-item WM load signature or whether prior learning would result in unitization (i.e., chunking). Consistent with the latter, LTM retrieval elicited the same neural pattern as a WM load-1 trial, regardless of the array’s size. Alpha power was likewise insensitive to the number of retrieved items, likely because each sequence appeared at a single location. Thus, retrieval of multi-item arrays from LTM reveals a unitized representation that is insensitive to set size, providing insight into how associative learning shapes the reinstatement of multi-item LTM structures in WM.
Neural signatures of visual memorability revealed by EEG decoding
Igor Utochkin, Woohyeuk Chang, Edward Vogel, Edward Awh
Sunday, May 17, 2026, 2:45 – 6:45 pm, Banyan Breezeway
Stimulus memorability is a systematic tendency for some visual items to be remembered better than others despite variations in learning and test context. Prior studies show that memorability can be decoded from neural activity. However, the extant studies have treated memorability as a single dimension. We highlight that memorability is a compound phenomenon based on two parameters: “Hittability” (H-ability), the likelihood that a studied item will be correctly recognized, and “false-alarmability” (FA-ability), the likelihood that the same item will be erroneously recognized when not studied. Strikingly, these parameters are uncorrelated, and whether their neural bases are distinct or shared remains unclear. Using multivariate decoding of EEG, we show that both H-ability and FA-ability can be robustly decoded from neural activity. Importantly, these signatures are evident not only during the test phase, where retrieval success might drive decoding, but also during study. Neural patterns associated with each parameter generalize across study and test, indicating that their representational bases are not contingent on explicit memory judgments. We next asked whether decoding of H-ability and FA-ability reflects movement along a shared representational dimension. Despite their behavioral independence, cross-decoding revealed strong generalization: classifiers trained to decode H-ability reliably decoded FA-ability, and vice versa. Thus, these parameters share a common dimension in neural state space. A natural hypothesis is that this dimension reflects item familiarity. Contrary to this prediction, neural patterns associated with high H-ability aligned with those associated with low FA-ability. This inversion rules out a simple familiarity account and instead suggests that neural signatures of memorability track systematic biases in decision efficacy based on relative familiarity. Presumably, stimuli with high H-ability and low FA-ability are easier to endorse or reject based on mnemonic status, whereas those with low H-ability and high FA-ability make these decisions more difficult.
Stimulus-specific memorability effects go beyond memory
Darius Suplica, Igor Utochkin, Edward Awh
Tuesday, May 19, 2026, 2:45 – 6:45 pm, Banyan Breezeway
Stimulus-specific memorability refers to the finding that recognition memory performance is enhanced for specific items, independent of study and retrieval context. Nevertheless, recent work has raised the possibility that memorability effects are not specific to memory, per se. For instance, the efficiency of low-level perceptual discriminations – in the absence of memory demands – is higher for memorable stimuli (Deng et al., 2024). Following this thread, we investigated whether memorability affects visual search performance when recognition memory is not a limiting factor. Critically, memorability appears to have two distinct facets: “Hittability” and “false-alarmability” refer to the probability of correctly recognizing previously studied items, or falsely recognizing unstudied items, respectively. While both facets can strongly impact memory performance, they are virtually uncorrelated at the item level. Thus, we independently manipulated the hittability and fa-ability of targets and distractors in four separate samples. Visual search performance was strongly affected by both factors. Subjects were faster to find more hittable (rm-ANOVA, p = 1 x 10-11) and less fa-able targets (p = 6.9 x 10-10), with no effect of distractor memorability (hittability p=0.18, fa-ability p=0.08). Experiment 2 replicated these findings while employing a continuous manipulation of hittability and fa-ability within a single set of stimuli. Once again, subjects were faster to recognize more hittable and less fa-able targets (linear mixed-effects model, hittability p=7x10-17, fa-ability p=1.2x10-6), with a significant (p=2x10-19) negative interaction between the two. In line with the argument that hittability and fa-ability are distinct aspects of memorability, search performance was better explained by keeping hittability and fa-ability as independent factors, rather than combining them into single d-prime measure (WAIC=-2954 vs -3048). Therefore, stimulus-specific memorability powerfully affects performance in tasks that do not require recognition memory, motivating further work on precisely which computations are impacted by memorability.
Changes in the absolute position of attentionally tracked targets trigger a hemispheric exchange as items move between visual fields
Huiqin Chen, Piotr Styrkowiec, Edward K. Vogel
Tuesday, May 19, 2026, 8:30 am – 12:30 pm, Pavilion
Tracking objects that move between visual fields requires coordination between the two hemispheres. The CDA is a sustained negative EEG voltage over the hemisphere contralateral to the positions of the tracked targets. When targets cross the vertical midline, the CDA “flips” in polarity, revealing a handoff of information between the hemispheres (Drew et al., 2014). More recent work has shown that this CDA flip reflects the immediate demands of tracking the target position rather than reflecting prospective allocation of attention to the new region because it still occurs even when the target is expected to return to its original hemifield (Chen et al., VSS 2025). However, it is unclear which aspect of the immediate tracking demands triggered this hemispheric handoff because, during the crossing there was both movement of the target’s absolute position in space as well as relative movement between the positions of the target and its accompanying distractor. Here, we tested whether the change in absolute position on its own was sufficient to trigger the CDA flip even in the absence of relative changes in the positions of the target and distractor during the crossing. In a condition with both types of motion, we replicated the CDA flip as the target moved between fields and then “flipped back” as it returned to its original field. We compared this to a “no relative motion” condition in which the relative positions of the target and distractor were “frozen” as the items moved between visual fields. The CDA flip still occurred as the target crossed visual fields suggesting that this interhemispheric exchange did not depend on resolving the relative positions of the target and distractor. Thus, the need to track changes in the absolute position of the target appears to be the critical feature for triggering the handoff between hemispheres.
Working Memory Capacity Modulates the Link Between Lapses and Voluntary Switching
Hyung-Bum Park, Monica Rosenberg, Edward Vogel
Sunday, May 17, 2026, 2:45 – 6:45 pm, Pavilion
Attentional lapses are often interpreted as uniform failures of control, yet emerging accounts propose that they reflect competition among concurrently active goals. If lapses signal goal competition, they should prospectively predict voluntary task switches, and this relationship may depend on individual differences in working memory (WM) capacity. We tested this idea using a modified continuous performance task with bilateral face and scene stimuli. Participants freely chose whether to perform the face or scene task after each block, with the constraint that all 25 blocks of each task type had to be completed. Lapses in block n predicted the task chosen on block n+1, and this prospective link depended strongly on WM capacity. Individuals with lower WM capacity were more likely to switch after lapse-prone blocks, whereas individuals with higher WM capacity tended to switch after successful blocks. Eye-tracking revealed matching patterns, with low-capacity participants directing early saccades toward the irrelevant distractor before switches and high-capacity participants showing the opposite tendency. Pupil dilation was elevated early in pre-switch blocks for low-capacity participants, consistent with heightened internal competition. In a forced-choice control session, externally imposed task sequences selectively reduced lapse rates for low-capacity individuals while leaving high-capacity performance unchanged. These findings indicate that lapses do not uniformly reflect disengagement or a single type of control failure. Instead, the relationship between lapses and voluntary switching depends on WM capacity, and is consistent with a goal-competition framework in which lapses mark dynamic shifts in the balance between competing goals.
OPAM/Psychonomics 2024
OPAM - Talks
Reconciling Meaningful Object Benefit in Visual Working Memory: The Role of Proactive Interference
Hyung-Bum Park & Edward Awh
Thursday, November 21, 3:40 - 4:40pm (Talk Session 4)
Visual working memory (VWM) capacity is often reported higher for meaningful objects due to their rich representations. However, previous work has confounded meaningfulness with the strength of proactive interference (PI) between stimulus types. By manipulating stimulus type and repetition in a recognition task, we found the VWM benefit for meaningful objects appeared only in the trial-unique condition due to lower false-alarm rates. Mouse trajectory analysis highlighted robust PI effects during initial movements in trial-repeated conditions. Dual-process modeling indicated the benefit was driven by global familiarity, not recollection. These results highlight the role of long-term memory, through PI, in shaping VWM capacity estimates.
Keynote Address: Working memory storage depends on content-independent pointers
Edward Awh
Thursday, November 21, 4:50-5:45pm
Working memory theorists have often highlighted the links between voluntary attentional control and the intentional storage of information in working memory (WM). For example, my early work provided initial evidence that covert spatial attention is oriented towards positions held in spatial WM, yielding faster behavioral responses and enhanced visually-evoked neural activity at memorized locations. Twenty-five years later, temporally resolved EEG measures of covert attention provide even clearer evidence for the parallel deployment of covert spatial attention during visual working memory tasks, even when location is irrelevant to the task. Nevertheless, here I will show that while spatial attention is a persistent partner of visual working memory, the deployment of spatial attention can be functionally dissociated from encoding into visual working memory. Specifically, WM storage recruits a content-independent indexing operation that tracks the number of items currently stored in WM, independent of the features contained in those items. Our hypothesis is that this content-independent load signal reflects the deployment of “pointers” that enables the binding of items to the surrounding context. Critically, I’ll present direct evidence that observers can spatially attend and categorize items without encoding those items into working memory. Thus, spatial attention and pointer deployment reflect dissociable aspects of voluntary attentional control, a distinction that may enrich our understanding of a range of major attentional phenomena.
OPAM - Posters
The brain knows more is stored in visual long-term memory than we can report
Chong Zhao, Keisuke Fukuda & Geoffrey F. Woodman
Thursday November 21, 11:30am-12:30pm (Poster Session 1)
When we attempt to recall a representation from visual long-term memory, there is a possibility that we might not succeed in retrieving it even though it exists in our brain. This study reveals that while explicit memory retrieval mechanisms sometimes fail to access these stored memories, executive control mechanisms can swiftly query the memory to confirm the presence of a representation. Our findings suggest that much of the memory typically accessed implicitly is, in fact, directly accessible by the brain’s higher-level control processes.
Psychonomics - Talks
Neural evidence for modality-general indexing in working memory
Henry Jones, Darius Suplica, William Thyer, Edward Awh
Friday, November 22, 10:40-11:00am (Visual Working Memory II)
Neural studies of working memory (WM) have strongly focused on the stimulus-specific neural patterns that track the stored content. By contrast, we highlight a distinct class of neural signals that appears to track the number of individuated items stored in a content-independent fashion. We propose that these load signals track the deployment of spatiotemporal pointers that bind stored items to the surrounding context. We provide support for this theory in 2 EEG experiments. First, we show that the multivariate signature of these pointers generalizes across color and motion stimuli, despite the cortically disparate representations of these features (Experiment 1). Moreover, representational similarity analysis (RSA) reveals a pointer signal that generalizes across visual and auditory sensory modalities, while also providing evidence for distinct signals reflecting spatial attention and feature load (Experiment 2). These results support the abstract indexing of individuated memory representations as a core component of WM storage and may provide ins
Recognition-memory asymmetries predicted from item memorability
Igor Utochkin, Nicholas Chiang, & Wilma Bainbridge
Friday, November 22, 4:50-5:10pm (Recognition I)
In two-alternative forced-choice (2-AFC) memory tests, target-foil similarity is a strong determinant of confusions. We hypothesize that confusions can be driven by intrinsic memorability properties of test items, the likelihood for each item to be correctly or falsely recognized individually. We tested old-new recognition for 240 images in two groups of 100 observers swapping target-foil roles between the groups, which yielded hit (H) and false alarm (FA) rates for each image. We z-transformed H and FA to locate both roles of all items in a signal-detection “memorability space” and predicted 2-AFC discriminability (d’) between arbitrary targets and foils. Critically, for some 2-AFC pairs we predicted strong d’ asymmetries when items swap their target-foil roles. These predictions were confirmed in a 2-AFC experiment with the same set of images and two new groups of observers studying either one or another set of targets but tested on the same target-foil pairs. The d’ asymmetries between identical pairs with swapped roles highly correlated with the asymmetries predicted by our model (rho=.73). These asymmetries cannot be explained by simple inter-item similarity and require incorporating memorability to the existing models.
Psychonomics - Posters
Characterizing individual differences in sustained attention, attentional control, and long-term memory
Chong Zhao, Anna Corriveau, Jin Ke, Edward K. Vogel, Monica Rosenberg
Friday, November 22, 7:45-9:15pm (Poster Session IV)
Individuals differ in their ability to sustain attention. However, whether differences in sustained attention reflect differences in attentional control (AC) and long-term memory (LTM) or whether these abilities comprise largely separable processes remains unknown. We conducted an online study measuring participants’ sustained attention, AC, and LTM. We measured sustained attention with an audio-visual continuous performance task (avCPT) in which participants responded to visual or auditory stimuli while inhibiting responses to infrequent targets, AC with Square tasks, and LTM with recognition and source memory tests. An exploratory factor analysis revealed that sustained attention formed a distinct factor (eigenvalue = 4.71) that loaded positively onto LTM, and, to a lesser extent, AC factors. To test how neural signatures of sustained attention related to AC and LTM, we analyzed fMRI functional connectivity patterns collected as 20 participants performed the avCPT. A pre-trained connectome-based model of sustained attention predicted participants’ performance on out-of-scanner LTM, but not AC, tasks. Together this suggests that differences in sustained attention, although correlated with AC, are more closely related to LTM.
Improving sustained attention with real-time monitoring of attentional lapses
Matthieu Chidharom, Monica D. Rosenberg, Edward K. Vogel
Saturday, November 23, 7:45-9:15pm (Poster Session VII)
Lapses in attention are common in everyday life, increasing the risk of errors such as missing a highway exit. In this study, we examined participants’ ability to externally monitor their attentional lapses in real-time to prevent behavioral errors before they occur. Thirty participants performed a go/no-go task in which they were instructed to respond to frequent-category images (e.g., indoor scenes) and withhold response to infrequent-category images (e.g., outdoor scenes). Fast reaction times, previously identified as strong predictors of no-go trial errors, were measured during task performance and used to track periods of inattention. During the intertrial-interval, a white fixation cross turned red whenever an error-prone period of fast responding was detected. A generalized mixed model showed that participants could reduce errors by monitoring their lapse states, compared to blocks where the red-cross appeared randomly. Notably, individuals with better performance overall were more likely to benefit from external monitoring.
VSS 2024
Talks
Storage in working memory recruits a modality-independent pointer system
Henry Jones (henryjones@uchicago.edu), Darius Suplica, William Thyer, Edward Awh
Sunday, May 19, 11:30am (Talk Room 1)
Prominent theories of working memory (WM) have proposed that distinct working memory systems may support the storage of different types of information. For example, distinct dorsal and ventral stream brain regions are activated during the storage of spatial and object information in visual WM. Although feature-specific activity is likely critical to WM storage, we hypothesize that a content-independent indexing process may also play a role. Specifically, spatiotemporal pointers may be required for the sustained indexing and tracking of items in space and time, even while features change, within an unfolding event. Past evidence for such a content-independent pointer operation includes the finding that signals tracking the number of individuated representations in WM (load) generalize across colors, orientations and conjunctions of those features. However, overlapping orientation and color codes in early visual cortices may mimic a generalizable signal. Here, we provide a stronger demonstration of content-independence by using pairs of features that are as cortically disparate as possible. Study 1 (n=16) used color and motion coherence stimuli, and showed that load decoding models generalized across these disparate features. In addition, we used representational similarity analysis (RSA) to document “pure” load signals that tracked the number of items stored regardless of attended feature, while simultaneously documenting and controlling for feature-specific neural activity. Extending these observations, in Study 2 (n=24; n=16) we applied similar analytic approaches to demonstrate a common load signature between auditory and visual sensory modalities, while controlling for modality-specific neural activity and the spatial extent of covert attention. Our findings suggest that content-independent pointers may play a fundamental role in the storage of information in working memory, and may contribute to its overall limited capacity.
Piotr Styrkowiec, William Ngiam, Will Epstein, Ron Gneezy, Edward Awh, Edward Vogel
Sunday, May 19, 2:30pm (Talk Room 1)
Recent work has suggested that storage in visual working memory (VWM) occurs through the assignment of spatiotemporal pointers to the to-be-remembered items (Thyer et al., 2022). Thus, VWM capacity limits may not be set by the stimulus content exactly, but rather by attentional processes that define the spatiotemporal pointers for item-based storage. We examined whether this is the case in the contralateral delay activity (CDA), an event-related potential long known to track VWM load. The CDA has been shown to track the number of targets in multiple-object tracking (Drew and Vogel, 2008), but also the number of to-be-remembered colors (Vogel and Machizawa, 2004). To directly contrast the effects of attentional tracking load and stimulus content load on working memory, we developed a novel dual-task paradigm. Participants track either one or two moving discs (attentional tracking load), with either two or four colors displayed across each of the discs (working memory load). Participants completed a ‘tracking only’ condition, where they would need to monitor the moving target discs like in a multiple-object tracking task, and a ‘tracking plus memory’ condition, where they would track the discs and remember all displayed colors like in a multiple-identity tracking task. The key question was whether or not CDA amplitude would be determined by the number of individuated items tracked, or by the number of distinct colors associated with the currently tracked items. Strikingly, CDA amplitude was determined almost entirely by the number of items tracked, with no reliable effect of variations in the number of colors per tracked item. These findings suggest the CDA largely reflects the maintenance of spatiotemporal pointers for moving objects, not the number of feature values associated with those objects.
Associative learning changes multivariate neural signatures of visual working memory
William Ngiam, William Thyer, Henry Jones, Darius Suplica, Will Epstein, Edward Awh
Tuesday, May 21, 3:30pm (Talk Room 1)
A hallmark of visual working memory is its sharp capacity limit, though this limit can be circumvented using learned knowledge. For example, when arrays of to-be-remembered items contain statistical regularities, people can learn the associations between items and recall more information overall (Brady et al., 2009; Ngiam et al., 2019). One proposed mechanism for how this recall benefit is achieved is through ‘memory compression’ – redundancies introduce a reduction of information per item, enabling more items to be stored online. Another proposed mechanism is that pointers are efficiently allocated to each ‘chunk’ with the benefit coming from long-term memory retrieval rather than changes to working memory itself. In an attempt to distinguish between these possibilities, we turned to an EEG measure that tracks the number of individuated items stored in working memory (mvLoad; Thyer et al., 2022). The memory compression account predicts an overall increase in the number of items stored online, whereas the long-term memory retrieval account predicts a reduction in working memory load. Subjects completed a training session where they learned specific color-color pairs. In a subsequent EEG session, subjects completed a recall task with 2 random colors, 4 random colors, or 2 learned color pairs. mvLoad analysis showed a reduction in working memory load for the 2 learned pairs condition (from 4 towards 2), consistent with the notion that an item-based pointer is assigned to each chunk. Moreover, multidimensional scaling shows an additional independent signal that distinguishes the 2 learned pairs condition from the other conditions. We propose that this additional signal reflects the involvement of long-term memory, consistent with the notion that the learned association is being relied upon to maintain the information.
The effects of visual encoding speed on ERP markers of subsequent retrieval
Igor Utochkin, Chong Zhao, Edward Vogel
Wednesday, May 22, 8:15am (Talk Room 2)
Our memory for meaningful visual stimuli is remarkable: Even when we see thousands of images, each presented for a few seconds, we can later recognize them among new images with high accuracy and in detail (Standing et al., 1973; Brady et al., 2008). However, recognition suffers if the images are encoded at a speed of 2 images per second or faster (Intraub, 1980; Potter, 1976; Potter et al., 2002). Presumably, this happens because the encoding of each new rapidly presented image disrupts relatively slow short-term memory consolidation which is essential for the instantiation of subsequent long-lasting episodic memory. Here, we studied how encoding speed impacts EEG markers of subsequent recognition, namely, ERP Old/New effects, that is, differences between ERP responses to earlier presented (old) and never presented (new) stimuli. In each block, participants memorized sequences of 20 real-world object images at a slow or fast rate (one image each 1,750 ms or 250 ms, respectively). Their memory was then tested with an “old/new” recognition task combined with EEG recording. Our analysis focused on two ERP Old/New components typically distinguished in the literature (Curran, 2000; Paller et al., 2007; Rugg & Curran, 2007): earlier frontal, FN400, and later parietal, LPC. Although observers showed significantly worse recognition at the fast compared to the slow encoding condition, we found almost equally pronounced FN400 in both conditions. In contrast, the LPC was much larger in amplitude in the slow than in the fast encoding blocks. One interpretation of this dissociation can be that fast encoding speed selectively impairs recollection-based memory (which reflects in reduced LPE) but not familiarity-based memory (little effect on FN400). However, other interpretations (e.g., that slower encoding speed causes a stronger confidence signal reflected in LPE) can also be discussed.
Posters
Reaction Time Variability and Mind-Wandering Provide Complementary Insights
Matthieu Chidharom, Edward Vogel, Monica Rosenberg
Saturday, May 18m 8:30am (Pavilion)
Sustained attention refers to the ability to maintain focus on a task over an extended period of time. However, sustaining attention is challenging, as there are inherent fluctuations between periods of good attention (stable and less error-prone) and poor attention (unstable and error-prone). Two main methodologies have been used to isolate these attentional fluctuations in visual attention tasks: objective and subjective approaches. The objective methodology analyzes intraindividual reaction time (RT) variability. For example, Esterman et al. (2013) revealed higher errors during periods of high RT variability (out-of-the-zone state) compared to periods of low variability (in-the-zone state). The subjective methodology uses thought probes to identify mind-wandering episodes (task-unrelated thoughts), that can be either intentional (i.e., deliberate) or unintentional (Seli, 2016). Although previous studies revealed higher error rates during out-of-the-zone and mind-wandering states, it is unclear whether those two methodologies isolate the same or different type of attentional fluctuations. This study compared the two approaches in a single Go/NoGo sustained attention task (N=38), objectively measuring attention via RT variability, and subjectively via intermittent thought probes administered every 30 trials. The entire task lasted approximately 40 minutes. If both methods isolate similar fluctuations, we hypothesize that the time spent out-of-the-zone should be higher during mind-wandering than during on-task periods. Our results revealed significantly higher time out-of-the-zone during mind-wandering (52.1%) compared to on-task periods (47.8%), suggesting the methods isolate, to some extent, similar aspects of fluctuations. However, time out-of-the-zone was significantly higher during intentional (57.7%) versus unintentional mind-wandering (49.7%), indicating higher overlap between the objective and subjective methods for deliberate mind-wandering rather that spontaneous. These findings suggest the two methods capture complementary information about attentional fluctuations and highlights the utility of combining objective and subjective methods to gain a comprehensive understanding of sustained attention and its lapses.
A Change Localization Benefit for Mixed Arrays Over Uniform Arrays
Temilade Adekoya, Chong Zhao, Edward Vogel, Edward Awh
Sunday, May 19, 2:45pm (Pavilion)
Given relatively sharp capacity limits in visual working memory (WM), there has been sustained interest in whether these limits are based on the number of individuated items stored, or based on interference that varies as a function of inter-item similarity. Object-based models predict that the costs of concurrent storage will be determined only by the total number of items stored, while feature-based models of capacity often argue that competition for feature-specific resources is the key limiting factor. To examine this question we manipulated both the number of stimuli within each memory array, as well as the similarity between those items. Thus, we measured visual WM performance with uniform arrays with only one type of feature (e.g. color), or mixed arrays with two feature-types (e.g. color and orientation). Consistent with object-based models, we observed a significant cost of increasing load in both the mixed and uniform conditions. However, we also saw evidence for a modest advantage in the mixed array conditions, a difference that is not predicted by pure object-based models. Our follow-up work examined whether the advantage in the mixed condition reflects differences in whether items are stored, or differences in memory fidelity. We found that this advantage indeed reflected a change in memory fidelity, specifically a better precision in memory of items in the mixed arrays than in uniform arrays. Additionally, there was no evidence that participants were storing a larger number of items in the mixed condition. These results suggest that working memory performance is subject to item-based limits independent of item similarity, but the fidelity of those memories can be shaped by inter-item similarity.
Visual working memory load persists during the comparison phase
Chong Zhao, Temilade Adekoya, Sintra Horwitz, Edward Awh, Edward Vogel
Sunday, May 19, 2:45pm (Pavilion)
Working memory is often measured by presenting arrays of visual items to be remembered over a short delay that must be compared with a test display. Extensive work has elucidated the neural mechanisms that support the encoding and maintenance periods of these tasks. Though, little is still understood about the comparison process itself. For example, the contralateral delay activity (CDA) is a sustained EEG component that provides a sensitive measure of the current working memory load during the retention period. However, it is not clear whether this activity continues to track the full working memory load during the comparison phase of the task or if it is reduced to just the one item from the array that is being tested. In Experiment 1, we used a change localization task with 2-item and 4-item arrays of colors. At test, subjects had to report which item changed. We observed that the response-phase CDA for set size 4 was significantly larger than the CDA for set size 2. In Experiment 2 we used a single-probe change detection design, in which only a single item from the original array was shown at test. Despite only a single item shown on the screen, we again observed that the response-phase CDA for set size 4 was still significantly larger than the CDA for set size 2. Our results suggest that the working memory load during test reflects the load from all of the items from the array that were stored.
Crossing category boundaries: Perceptual hysteresis for scenes even with endpoint preview
Huiqin Chen, Mei Yang, Gaeun Son, Dirk Bernhardt-Walther
Monday, May 20, 8:30am (Pavilion)
n dynamically changing environments, how does our visual system make quick perceptual decisions based on information that is actively changing? The hysteresis effect suggests that when resolving perceptual ambiguity, people tend to stick with their current interpretation of sensory information and find it difficult to change their perception until there is a noticeable and significant change in input. We here demonstrate this effect for dynamically changing scenes. We further explored how prior exposure to target scene would affect the hysteresis effect. We used indoor scene images generated with a Generative Adversarial Network to create smooth yet realistic transitions between scene categories. Participants were asked to report when they perceived a shift in category during these transitions. Before each trial, participants were provided with information about the scene category at the end of the transition, either in the form of words, images, or both. Each transition was repeated in both directions (A to B and B to A), and the differences in responses between the two opposite directions were analyzed. Our findings indicated that exposure to words or images had no effect on perceptual hysteresis. Even when participants had knowledge of the target category, their perception of the image categories was still biased towards the initial category. This result suggests that neither semantic knowledge nor visual representation of the future can influence the hysteresis effect. The top-down knowledge of the future direction does not impact or eliminate the conservatism of the visual system. This has important implications, indicating that hysteresis is an innate characteristic of the visual system and is not easily influenced by higher-level control. Thus, perceptual conservatism is likely instrumental for the apparent stability of visual perception in most real-world settings.
Unfolding Serial Dependence Across Perception, Working Memory Consolidation and Retrieval
Hyung-Bum Park (hbpark@uchicago.edu), Edward Awh
Tuesday, May 21, 8:30am (Banyan Breezeway)
Abstract
The debate on serial dependence questions its origin in perceptual versus post-perceptual working memory (WM) components, with mixed findings on whether perceptual decisions exhibit attractive serial dependence toward previous target or repulsive bias linked to sensory adaptation. The present study aims to examine the dynamics of serial biases across perception and WM processes at consolidation and retrieval. Participant performed a two-part experiment, with the first part involved immediate continuous estimations of color on color-wheel within view (perceptual report). The second part involved WM recall with dual-response. A memory color followed by masks was reported after stimulus offset (consolidation report), and the same item was reported again after delay on another color-wheel (retrieval report). Mouse trajectories for all responses were recorded to index direction and magnitude of serial bias. Behavioral reports showed a gradual evolution of serial bias across opposite directions: repulsion in perceptual reports, moderate attraction in consolidation, and stronger attraction in retrieval. Critically, we found a unique mouse trajectory pattern in consolidation reports, with a repulsive curvature from the previous target appearing on the color-wheel, while the overall trajectory exhibited attraction bias. Further examination of moment-by-moment trajectories, coupled with a median-split of movement onset latency, captured a ‘repulsion-to-attraction’ transition in consolidation reports, with early repulsion evolving into attraction as movements progressed. Moreover, the median-split analysis revealed a magnification of bias from early-onset to late-onset trials within their directions (stronger repulsion vs. attraction in perceptual and WM reports, respectively). These suggest that changes in serial biases across processes are not solely time-dependent, but originate from distinct perceptual and WM mechanisms. The repulsion-to-attraction transition during the WM consolidation phase offers an intermediate window into the interplay between sensory adaptation and serial dependence, jointly shaping serial bias in behavioral reports. Together, our study provides evidence supporting the mnemonic origin of serial dependence.
Investigating Meaningfulness in Visual Working Memory
Leo Chang (woohyeukchang@uchicago.edu), William Ngiam, Edward Awh
Tuesday, May 21, 2:45pm (Banyan Breezeway) (Pre-data Poster!)
There has been a growing body of work in Visual Working Memory (VWM), where researchers are utilizing the real-world objects as test stimuli, instead of simple colored shapes and orientations, that are more meaningful. In addition, there are findings that show advantage in VWM capacity for real-world objects, suggesting that the meaningfulness is contributing to our visual cognition, possibly through the involvement of our episodic Long Term Memory (LTM) system. However, the concept of meaningfulness has not been defined nor tested thoroughly. To understand how such concept affects our VWM, we propose the usage of words that clearly have associated meanings and are prevalent in our daily lives, just like real-world objects. Before investigating the effect of meaningfulness in words on VWM, we will run a scalp EEG replication study with a slight modification, where we present words in CDA design with place holders. This would allow us to perform multivariate load analysis and further confirm that words do undergo similar VWM processing as simple colored stimuli. Next, we will run a more canonical working memory paradigms using words with a manipulation of meaningfulness (e.g., word frequency, emotion, semantics) and see if we observe different patterns in both behavior and neural responses in scalp EEG recordings as a function of meaningfulness in words. This dataset will not only create an opportunity for better understanding in how meaningfulness influence VWM but also allow us to directly investigate the interaction between VWM and LTM.
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