Biology subjects

van Moorselaar, D.

Publications and source records attributed to van Moorselaar, D..

15 recordsLinked to original sources

bioRxiv2025

The neural correlates of parallel and serial search

For almost half a century, target-distractor similarity has been known to induce different visual search modes. When a target is highly salient, it can pop out, suggesting parallel processing of all items irrespective of set size. By contrast, high similarity among items requires item-by-item comparison with an attentional template, a characteristic of serial search. Despite this long-standing distinction, little is known about the neural correlates of search modes, as typical differences in visual displays confound interpretation. Here, we contrasted the neural correlates of serial and parallel search under visually identical displays. Across distinct blocks, we biased 24 participants (21 female) toward parallel or serial search by varying target-distractor similarity, thereby directing attentional focus toward a single feature or conjunction. Embedded among inducer trials, test trials were visually identical across all blocks and afforded both parallel and serial search. Behavioral analyses confirmed successful induction of distinct search modes during test trials. EEG decoding reliably discriminated search modes and these neural patterns generalized across inducer and test trials. Attentional deployment toward the target differed across search modes, revealing topographical differences in target location representations. The strength of target-location representations correlated with response times, indicating that during parallel test trials participants switched search strategies when the target was not detected early. Moreover, target representations diverged between search modes: a temporally stable pattern emerged during serial search, suggesting reliance on working memory, whereas parallel search was characterized by more dynamic representations, likely reflecting prioritization of the relevant feature. These findings demonstrate that search history shapes search mode, giving rise to clearly distinct neural dynamics even under visually identical stimulation.

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bioRxiv2025

Boosting the signal: Expectation-driven gain modulation of preparatory spatial attention

The visual system can flexibly adjust attentional deployment to match task demands, but whether observers can proactively modulate the spatial scope of attention based on expectations about upcoming search difficulty remains unclear. According to the zoom lens model, attention can narrow or broaden its spatial extent, with narrower focus enhancing processing efficiency, a mechanism that would benefit target discrimination in crowded displays. We tested whether observers adjust attentional scope when expecting sparse versus dense search arrays by combining spatial cueing with block-wise manipulations of display density expectations. Participants performed a visual search task in which endogenous cues predicted target location, while blocks predominantly contained either sparse (1 target, 3 distractors) or dense (1 target, 7 distractors) displays. We applied inverted encoding models to broadband EEG data to reconstruct spatial channel tuning functions, enabling precise characterization of both the locus and breadth of attentional deployment. Behaviorally, expecting difficult searches selectively improved accuracy at cued locations without costs elsewhere. Consistent with this selective benefit, neural measurements revealed that expectancy enhanced the amplitude of spatially selective responses at the attended location but did not alter tuning width. These findings demonstrate that expectations about search difficulty modulate attention through gain-based signal enhancement rather than adjustments to spatial scope, revealing that preparatory attentional control operates via amplitude modulation within a stable spatial focus. This mechanism complements reactive attentional adjustments and provides an efficient means for the visual system to optimize processing under predictable task demands.

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bioRxiv2024

The spatial reference frame of history-driven distractor suppression and target enhancement

The world around us is inherently structured and often repetitive. Research has shown that we can implicitly learn to prioritize relevant objects and locations while filtering out distracting information, creating an integrated priority map for attention allocation. The current study examines whether providing an object-like reference frame would induce an object-centered attentional bias or whether the bias would remain in egocentric (viewpoint-centered) coordinates. The search display consisted of six stimuli that were surrounded by a wheel and square frame. In two experiments, either a distractor or a target appeared more frequently in one location, leading to the suppression or enhancement of that location, respectively. Learning blocks were followed by test blocks, where the frame rotated, creating egocentric-matching and object-centered locations. These experiments showed that both target and distractor learning relied on an egocentric reference frame only. In follow-up experiments, the likely target and distractor location rotated dynamically with the frame during learning. This revealed that participants can learn to enhance a likely target location in an object-centered manner. We hypothesized that while space-based learning feeds into a priority map reliant on an egocentric reference frame, object-based learning allows for implicit prioritization of subparts of objects independent of their spatial orientation. Public significance statementOur brains cannot process the overwhelming amount of visual information we encounter daily. Fortunately, the world is inherently structured and has patterns we can learn, helping us to selectively focus on whats important and ignore distractions. This study examines how we use these patterns in dynamic, ever-changing environments. The findings show that when regularities are learned in static settings, our learned attentional biases remain tied to our static viewpoints. But in dynamic environments, attentional priorities can be tied to objects, irrespective of the objects orientation, while suppressed distractor locations remain tied to specific viewpoints. This discovery helps us understand how our brain adapts to complex, real-world situations.

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bioRxiv2024

Pinging the Hidden Attentional Priority Map: Suppression Needs Attention

Attentional capture by an irrelevant salient distractor is attenuated when the distractor is presented more frequently in one location compared to other locations, suggesting that people learn to suppress an irrelevant salient location. However, to date it is unclear whether this suppression is proactive, applied before attention has been directed to the distractor location, or reactive, occurring after attention has been directed to that specific location. The aim of the present study is to investigate how suppression is accomplished by using the pinging technique, which allows one to probe how attention is distributed across the visual field prior to the presentation of the search display. In an EEG experiment, participants performed a visual search task wherein they were tasked with identifying a shape singleton in the presence of an irrelevant color singleton. Compared to all other locations, this color singleton appeared more frequently at a specific location, which was termed the high-probability location. Prior to the search task, we introduced a continuous recall spatial memory task to reveal the hidden attentional priority map. Participants had to memorize the location of a memory cue continuously and report this location after the visual search task. Critically, after the presentation of the memory cue but before the onset of the search display, a neutral placeholder display was presented to probe how the hidden priority map is reconfigured by the learned distractor suppression. Behaviorally, there was clear evidence that the high-probability location was suppressed, as search was more efficient when the distractor appeared at this location. To examine the priority map prior to search, we adopted an inverted encoding approach to reconstruct the tuning profile of the memorized position in the spatial memory task. Inverted modeling resulted in reliable tuning profiles during memory maintenance that gradually decayed and that were revived again by the onset of a neutral placeholder display preceding search. After the onset of the placeholders, the tuning profile observed was characterized by a spatial gradient centered over the high-probability location, with tuning being most pronounced at the-to-be suppressed location. This finding suggests that while learned suppression is initiated prior to search display onset, it is preceded by an initial phase of spatial selection, which is in line with a reactive suppression account. Together these results further our understanding of the mechanism of spatial distractor suppression.

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bioRxiv2024

Proactive distractor suppression in early visual cortex

Avoiding distraction by salient yet irrelevant stimuli is critical when accomplishing daily tasks. One possible mechanism to accomplish this is by suppressing stimuli that may be distracting such that they no longer compete for attention. While the behavioral benefits of distractor suppression are well-established, its neural underpinnings are not yet fully understood. In an fMRI study, we examined whether and how sensory responses in early visual areas show signs of distractor suppression after incidental learning of spatial statistical regularities. Participants were exposed to an additional singleton task where, unbeknownst to them, one location more frequently contained a salient distractor. We analyzed whether visual responses in terms of fMRI BOLD were modulated by this distractor predictability. Our findings indicate that implicit spatial priors shape sensory processing even at the earliest stages of cortical visual processing, evident in early visual cortex as a suppression of stimuli at locations which frequently contained distracting information. Notably, while this suppression was spatially (receptive field) specific, it did extend to nearby neutral locations, and occurred regardless of whether distractors, nontarget items or targets were presented at this location, suggesting that suppression arises before stimulus identification. Crucially, we observed similar spatially specific neural suppression even if search was only anticipated, but no search display was presented. Our results highlight proactive modulations in early visual cortex, where potential distractions are suppressed preemptively, before stimulus onset, based on learned expectations. Combined, our study underscores how the brain leverages implicitly learned prior knowledge to optimize sensory processing and attention allocation.

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bioRxiv2024

Distractor suppression operates exclusively in retinotopic coordinates

Our attention is influenced by past experiences, and recent studies have shown that individuals learn to extract statistical regularities in the environment, resulting in attentional suppression of locations that are likely to contain a distractor (high-probability location). However, little is known as to whether this learned suppression operates in retinotopic (relative to the eyes) or spatiotopic (relative to the world) coordinates. In the current study, two circular search arrays were presented side by side. Participants learned the high-probability location from a learning array presented on one side of the display (e.g., left). After several trials, participants shifted their gaze to the center of the the test array (e.g., located on the right side) in which all locations were equally likely to contain the distractor. Due to the saccade, the test array contained both a spatiotopic and a retinotopic matching location relative to the original high-probability location. The current findings show that, following saccadic eye movements, the learned suppression remained in retinotopic coordinates only, with no measurable transfer to spatiotopic coordinates. Even in a rich environment, attentional suppression still operated exclusively in retinotopic coordinates. We speculate that learned suppression may be resolved by changing synaptic weights in early visual areas. Significance statementIn our daily lives, attention is shaped by past experiences, guiding us to suppress locations that are likely to contain distractions. While this phenomenon has been studied extensively with static search displays, the real world is dynamic - we are constantly moving our eyes. This study addressed this issue by investigating what happens when we learn to suppress a likely distractor location while making eye movements. Do we suppress the same location in space (spatiotopic), or does the learned suppression persist relative to our eyes (retinotopic)? The current findings provide clear evidence of suppression in retinotopic coordinates only.

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bioRxiv2024

Neural representations of predicted events: Evidence from time-resolved EEG decoding

Through statistical learning, humans are able to extract temporal regularities, using the past to predict the future. Evidence suggests that learning relational structures makes it possible to anticipate the imminent future; yet, the neural dynamics of predicting the future and its time-course remain elusive. To examine whether future representations are denoted in a temporally discounted fashion, we used the high-temporal-resolution of electroencephalography (EEG). Observers were exposed to a fixed sequence of events at four unique spatial positions within the display. Using multivariate pattern analyses trained on independent pattern estimators, we were able to decode the spatial position of dots within full sequences, and within randomly intermixed partial sequences wherein only a single dot was presented. Crucially, within these partial sequences, subsequent spatial positions could be reliably decoded at their expected moment in time. These findings highlight the dynamic weight changes within the assumed spatial priority map and mark the first implementation of EEG to decode predicted, yet critically omitted events. Impact statementUtilizing high-temporal-resolution EEG, the dynamic weight changes of assumed spatial priority map were visualized by decoding the spatial position of expected, yet omitted, events at their expected moment in time.

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bioRxiv2023

The Electrophysiological Markers of Statistically Learned Attentional Enhancement: Evidence for a Saliency Based Mechanism

It has been well established that attention can be sharpened through the process of statistical learning - whereby visual search is optimally adapted to the spatial probabilities of a target in visual fields. Specifically, attentional processing becomes more efficient when targets appear at high relatively to low probability locations. Statistically learned attentional enhancement has been shown to differ behaviorally from the more well studied top-down and bottom-up forms of attention; and while the electrophysiological characteristics of top-down and bottom-up attention have been well explored, relatively little work has been done to characterize the electrophysiological correlates of statistically learned attentional enhancement. In the current study, EEG data was collected while participants performed the additional singleton task with an unbalanced target distribution. Encephalographic data was then analyzed for two well-known correlates of attentional processing - alpha lateralization and the N2pc component. Our results showed that statistically learned attentional enhancement is not characterized by alpha lateralization, thereby differentiating it from top-down enhancement. Yet targets at high probability locations did reliably produce larger N2pc amplitudes, a known marker of increased bottom-up capture due to higher target-distractor contrasts. These results support an interpretation of the probability cuing effects where the improved processing of targets at expected locations is mediated by a saliency-based mechanism - boosting the salience of targets appearing at high-probability locations relative to those at low-probability locations. Significance statementThings are easier to find when you have a good idea of where they should be - e.g. shoes on the floor and birds in the sky. Expectations of where things are likely to be found can be implicitly learned without much, if any, awareness. Until now, little was known about how these implicit spatial biases change the representation of items in the brain. In the current work, we present EEG recordings which suggest that the brain may represent items in common locations as more salient than in other locations in space. These findings inform how the brain represents implicit search expectations; supporting a model where items in expected areas in space capture attention more frequently because they are represented by the brain as more salient.

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bioRxiv2022

Electrophysiological indices of distractor processing in visual search are shaped by target expectations.

Although in many cases salient stimuli capture attention involuntarily, it has been proposed recently that under certain conditions the bottom-up signal generated by such stimuli can be proactively suppressed. In support of this signal suppression hypothesis, ERP studies have demonstrated that salient stimuli that do not capture attention elicit a distractor positivity (PD), a putative neural index of suppression. At the same time, it is becoming increasingly clear that regularities across preceding search episodes have a large influence on attentional selection. Yet to date, studies in support of the signal suppression hypothesis have largely ignored the role of selection history on the processing of distractors. The current study addressed this issue by examining how electrophysiological markers of attentional selection (N2pc) and suppression (PD) elicited by targets and distractors respectively were modulated when the search target randomly varied instead of being fixed across trials. Results showed that while target selection was unaffected by this manipulation, both in terms of manual response times, as well as in terms of the N2pc component, the PD component was reliably attenuated when the target features varied randomly across trials. This result demonstrates that the distractor PD, which is typically considered the marker of selective distractor processing cannot unequivocally be attributed to suppression only, as it also, at least in part, reflects the upweighting of target features.

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bioRxiv2022

Pinging the brain to reveal the hidden attentional priority map

Attention has been usefully thought of as organized in priority maps - putative maps of space where attentional priority is weighted across spatial regions in a winner-take-all competition for attentional deployment. Recent work has highlighted the influence of past experiences on the weighting of spatial priority - called selection history. Aside from being distinct from more well-studied, top-down forms of attentional enhancement, little is known about the neural substrates of history-mediated attentional priority. Using a task known to induce statistical learning of target distributions, in an EEG study we demonstrate that this otherwise invisible, latent attentional priority map can be visualized during the intertrial period using a pinging technique in conjunction with multivariate pattern analyses. Our findings not only offer a novel method of visualizing the history-mediated attentional priority map, but also shed light on the underlying mechanisms allowing our past experiences to influence future behaviour.

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bioRxiv2020

Representational Dynamics Preceding Conscious Access

Our senses are continuously bombarded with more information than our brain can process up to the level of awareness. The present study aimed to enhance understanding on how attentional selection shapes conscious access under conditions of rapidly changing input. Using an attention task, EEG, and multivariate decoding of individual target- and distractor-defining features, we specifically examined dynamic changes in the representation of targets and distractors as a function of conscious access and the task-relevance (target or distractor) of the preceding item in the RSVP stream. At the behavioral level, replicating previous work and suggestive of a flexible gating mechanism, we found a significant impairment in conscious access to targets (T2) that were preceded by a target (T1) followed by one or two distractors (i.e., the attentional blink), but striking facilitation of conscious access to targets shown directly after another target (i.e., lag-1 sparing and blink reversal). At the neural level, conscious access to T2 was associated with enhanced early- and late-stage T1 representations and enhanced late-stage D1 representations, and interestingly, could be predicted based on the pattern of EEG activation well before T1 was presented. Yet, across task conditions, we did not find convincing evidence for the notion that conscious access is affected by rapid top-down selection-related modulations of the strength of early sensory representations induced by the preceding visual event. These results cannot easily be explained by existing accounts of how attentional selection shapes conscious access under rapidly changing input conditions, and have important implications for theories of the attentional blink and consciousness more generally.

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bioRxiv2020

Neural mechanisms underlying expectation-dependent inhibition of distracting information

Predictions based on learned statistical regularities in the visual world have been shown to facilitate attention and goal-directed behavior by sharpening the sensory representation of goal-relevant stimuli in advance. Yet, how the brain learns to ignore predictable goal-irrelevant or distracting information is unclear. Here, we used EEG and a visual search task in which the predictability of a distractors location and/or spatial frequency was manipulated to determine how spatial and feature distractor expectations are neurally implemented and reduce distractor interference. We find that expected distractor features could not only be decoded pre-stimulus, but their representation differed from the representation of that same feature when part of the target. Spatial distractor expectations did not induce changes in preparatory neural activity, but a strongly reduced Pd, an ERP index of inhibition. These results demonstrate that neural effects of statistical learning critically depend on the task relevance and dimension (spatial, feature) of predictions.

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bioRxiv2020

Neural mechanisms underlying distractor inhibition on the basis of feature and/or spatial expectations.

A rapidly growing body of research indicates that inhibition of distracting information may not be under flexible, top-down control, but instead heavily relies on expectations derived from past experience about the likelihood of events. Yet, how expectations about distracting information influence distractor inhibition at the neural level remains unclear. To determine how expectations induced by distractor features and/or location regularities modulate distractor processing, we measured EEG while participants performed two variants of the additional singleton paradigm. Critically, in these different variants, target and distractor features either randomly swapped across trials, or were fixed, allowing for the development of distractor feature-based expectations. Moreover, the task was initially performed without any spatial regularities, after which a high probability distractor location was introduced. Our results show that both distractor feature- and location regularities contributed to distractor inhibition, as indicated by corresponding reductions in distractor costs during visual search and an earlier distractor-evoked Pd component. Yet, control analyses showed that while observers were sensitive to regularities across longer time scales, the observed effects to a large extent reflected intertrial repetition. Large individual differences further suggest a functional dissociation between early and late Pd components, with the former reflecting early sensory suppression related to intertrial priming and the latter reflecting suppression sensitive to expectations derived over a longer time scale. Also, counter to some previous findings, no increase in anticipatory alpha-band activity was observed over visual regions representing the expected distractor location, although this effect should be interpreted with caution as the effect of spatial statistical learning was also less pronounced than in other studies. Together, these findings suggest that intertrial priming and statistical learning may both contribute to distractor suppression and reveal the underlying neural mechanisms.

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bioRxiv2019

Learning what is irrelevant or relevant: Expectations facilitate distractor inhibition and target facilitation through distinct neural mechanisms

It is well known that attention can facilitate performance by top-down biasing processing of task-relevant information in advance. Recent findings from behavioral studies suggest that distractor inhibition is not under similar direct control, but strongly dependent on expectations derived from previous experience. Yet, how expectations about distracting information influence distractor inhibition at the neural level remains unclear. The current study addressed this outstanding question in three experiments in which search displays with repeating distractor or target locations across trials allowed observers to learn which location to selectively suppress or boost. Behavioral findings demonstrated that both distractor and target location learning resulted in more efficient search, as indexed by faster response times. Crucially, benefits of distractor learning were observed without target location foreknowledge, unaffected by the number of possible target locations, and could not be explained by priming alone. To determine how distractor location expectations facilitated performance, we applied a spatial encoding model to EEG data to reconstruct activity in neural populations tuned to the distractor or target location. Target location learning increased neural tuning to the target location in advance, indicative of preparatory biasing. This sensitivity increased after target presentation. By contrast, distractor expectations did not change preparatory spatial tuning. Instead, distractor expectations reduced distractor-specific processing, as reflected in the disappearance of the Pd ERP component, a neural marker of distractor inhibition, and decreased decoding accuracy. These findings suggest that the brain may no longer process expected distractors as distractors, once it has learned they can safely be ignored.\n\nSignificance statementWe constantly try hard to ignore conspicuous events that distract us from our current goals. Surprisingly, and in contrast to dominant attention theories, ignoring distracting, but irrelevant events does not seem to be as flexible as is focusing our attention on those same aspects. Instead, distractor suppression appears to strongly rely on learned, context-dependent expectations. Here, we investigated how learning about upcoming distractors changes distractor processing and directly contrasted the underlying neural dynamics to target learning. We show that while target learning enhanced anticipatory sensory tuning, distractor learning only modulated reactive suppressive processing. These results suggest that expected distractors may no longer be considered distractors by the brain once it has learned that they can safely be ignored.

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bioRxiv2018

Unattended but actively stored: EEG dynamics reveal a dissociation between selective attention and storage in working memory

Selective attention plays a prominent role in prioritizing information in working memory (WM), improving performance for attended representations. However, it remains unclear what the consequences of selection are for the maintenance of unattended WM representations, and whether this results in information loss. Here we tested the hypothesis that within WM, selectively attending to an item and the decision to stop storing other items involve independent mechanisms. We recorded EEG while participants performed a WM recall task in which the item most likely to be tested was cued retrospectively. By manipulating retro-cue reliability (i.e. the ratio of valid to invalid cue trials) we varied the incentive to retain uncued items. Contralateral alpha power suppression, a proxy for attention, indicated that, initially, the cued item was attended equally following high and low reliability cues, but attention was sustained throughout the delay period only after high reliability cues. Furthermore, contralateral delay activity (CDA), a proxy for storage, indicated that non-cued items were dropped sooner from WM after highly reliability cues than after cues with low reliability. These results show that attention and storage in WM are distinct processes that can behave differently depending on the relative importance of WM representations, as expressed in dissociable EEG signals.

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