Claus Bundesen

• Bachelor of Science
• Professor (Full) at University of Copenhagen

Der udvikles en beregningsmæssig model for visuel genkendelse ved sammenligning af synsindtryk med hukommelsesbilleder. I modellen antages genkendelse at være baseret på template matching i form af krydskorrelation. Positions-, størrelses- og orienteringsinvarians opnås ved aksetransformationer, mens støjproblemet tackles ved gaussisk filtrering. M...

The exponential race model embodied in the theory of visual attention (TVA) and the power law generalization of the sample size model (SSPL) provide competing accounts of the mechanisms that determine how exposure duration, set size, and attention influence how many items enter visual short-term memory (VSTM). In the exponential race model, items c...

Based on the simple what first comes to mind rule, the theory of visual attention (TVA; Bundesen, 1990) provides a comprehensive account of visual attention that has been successful in explaining performance in visual categorization for a variety of attention tasks. If the stimuli to be categorized are mutually confusable, a response rule based on...

Background Gabor patterns are defined as the product of a sinusoid function and a Gaussian envelope and are commonly used in visual and attentional research due to their ability to selectively stimulate the primary visual cortex. The aim of this study was to investigate whether Gabor patterns can be used as visual stimuli in the rodent continuous p...

Serial and parallel processing in visual search have been long debated in psychology, but the processing mechanism remains an open issue. Serial processing allows only one object at a time to be processed, whereas parallel processing assumes that various objects are processed simultaneously. Here, we present novel neural models for the two types of...

Background Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder which frequently persists into adulthood. The primary goal of the current study was to (a) investigate attentional functions of stimulant medication-naïve adults with ADHD, and (b) investigate the effects of 6 weeks of methylphenidate treatment on these func...

Serial and parallel processing in visual search have been long debated in psychology but the processing mechanism remains an open issue. Serial processing allows only one object at a time to be processed, whereas parallel processing assumes that various objects are processed simultaneously. Here we present novel neural models for the two types of p...

Public Significance Statement Researchers have compared the efficiency with which we analyze sequential versus simultaneous presentations of visual stimuli. Despite claims to the contrary, the findings are compatible with the idea that our performance reflects limitations in our visual encoding capacity.

A physiologically based nonhomogeneous Poisson counter model of visual identification is presented. The model was developed in the framework of a Theory of Visual Attention (Bundesen, 1990; Kyllingsbæk, Markussen, & Bundesen, 2012) and meant for modeling visual identification of objects that are mutually confusable and hard to see. The model assume...

Phasic alertness refers to a short-lived change in the preparatory state of the cognitive system following an alerting signal. In the present study, we examined the effect of phasic auditory alerting on distinct perceptual processes, unconfounded by motor components. We combined an alerting/no-alerting design with a pure accuracy-based single-lette...

In the present study, we investigated effects of phasic alerting on visual attention in younger and older adults. We modelled parameters of visual attention based on the computational Theory of Visual Attention (TVA) and measured event-related lateralizations (ERLs) in a partial report task, in which half of the displays were preceded by an auditor...

The relationship between visual attentional selection of items in particular spatial locations and selection by nonspatial criteria was investigated in a partial report experiment with report of letters (as many as possible) from brief postmasked exposures of circular arrays of letters and digits. The data were fitted by mathematical models based o...

In the present study, we investigated effects of phasic alerting on visual attention in a partial report task, in which half of the displays were preceded by an auditory warning cue. Based on the computational Theory of Visual Attention (TVA), we estimated parameters of spatial and non-spatial aspects of visual attention and measured event-related...

Rationale: The 5-choice serial reaction time task (5-CSRTT) is widely used to measure rodent attentional functions. In humans, many attention studies in healthy and clinical populations have used testing based on Bundesen's Theory of Visual Attention (TVA) to estimate visual processing speeds and other parameters of attentional capacity. Objectiv...

A fundamental question concerning representation of the visual world in our brain is how a cortical cell responds when presented with more than a single stimulus. We find supportive evidence that most cells presented with a pair of stimuli respond predominantly to one stimulus at a time, rather than a weighted average response. Traditionally, the f...

In the partial-report task, subjects are asked to report only a portion of the items presented. Selective attention chooses which objects to represent in short-term memory (STM) on the basis of their relevance. Because STM is limited in capacity, one must sometimes choose which objects are removed from memory in light of new relevant information. W...

Accurate information about the spatial location of objects during visual search influences the allocation of processing capacity to task-relevant and task-irrelevant information. According to Load theory (Lavie, 1995), processing capacity is allocated to stimuli presented at task-relevant locations and any remaining capacity spills-over to stimuli...

A fundamental question concerning the way the visual world is represented in our brain is how a cortical cell responds when its classical receptive field contains a plurality of stimuli. Two opposing models have been proposed. In the response-averaging model, the neuron responds with a weighted average of all individual stimuli. By contrast, in the...

The effect of letter confusability on reading has received increasing attention over the last decade. Confusability scores for individual letters, derived from older psychophysical studies, have been used to calculate summed confusability scores for whole words, and effects of this variable on normal and alexic reading have been reported. On this b...

A bilateral change detection paradigm is often used to measure lateralized ERP-components, such as the Contralateral Delay Activity (CDA), believed to be associated with visual short-term memory (e.g. Vogel and Machizawa, 2004; Alvarez and Cavanagh, 2004; McCollough et al., 2007 ). Recently, Wiegand et al. (2014) developed a similar whole report pa...

The Neural Theory of Visual Attention of Bundesen et al. (2005) was proposed as a neural interpretation of Bundesen's (1990) theory of visual attention (TVA). In NTVA, visual attention operates via two mechanisms: by dynamic remapping of receptive fields of cortical cells such that more cells are devoted to behaviorally important objects than to le...

Attentional selection can be viewed as having two aspects: selection with respect to particular objects and selection with respect to particular categories. Both aspects are mathematically modeled in the theory of visual attention (TVA). In this paper, we expand the rate equation of the TVA and propose that the visual bias toward seeing an object x...

By varying the probabilities that a stimulus would appear at particular times after the presentation of a cue and modeling the data by the theory of visual attention (Bundesen, 1990), Vangkilde, Coull, and Bundesen (2012) provided evidence that the speed of encoding a singly presented stimulus letter into visual short-term memory (VSTM) is modulate...

Thalamic nuclei act as sensory, motor and cognitive relays between multiple subcortical areas and the cerebral cortex. They play a crucial role in cognitive functions such as executive functioning, memory and attention. In the acute period after thalamic stroke attentional deficits are common. The precise functional relevance of specific nuclei or...

This article reviews the foundations of the theory of visual attention (TVA) and describes recent developments in the theory. TVA is based on the principle of biased competition: All possible visual categorizations ascribing features to objects compete (race) to become encoded into visual short-term memory before it is filled up. Each of the possib...

Observers were trained to search for a particular horizontal string of three capital letters presented among similar strings consisting of exactly the same letters in different orders. The training was followed by a test in which the observers searched for a new target that was identical to one of the former distractors. The new distractor set cons...

Several studies have demonstrated a bilateral field advantage (BFA) in early visual attentional processing, that is, enhanced visual processing when stimuli are spread across both visual hemifields. The results are reminiscent of a hemispheric resource model of parallel visual attentional processing, suggesting more attentional resources on an earl...

Current behavior is largely determined by behavioral history and it’s consequences. How environmental rewards can shape the frequency and quality of behavior, has, however, only recently come under the scrutiny of attention researchers. In this domain, it is not obvious which components of attention are affected by reward, and whether the effect...

When acting in a dynamic environment we continuously trade-off the costs and benefits of attending to things. Valued-based attention thus helps us to bias the identification and selection of objects to which we assign a high value, and thus modulate both the processing speed and report accuracy of such. Here we put the hypothesis that monetary rewa...

When two targets are embedded in an RSVP stream of distractors presented to central vision, the probability of correctly identifying the second target (T2), given that the first target (T1) is correctly identified, diminishes if the targets are presented with a stimulus-onset asynchrony of less than 500 ms, a phenomenon known as the attentional bli...

In event-based prospective memory (EPM) tasks, the intention to act in response to an external event is formed, retained, and, when the event occurs, enacted. Monitoring of the environment for such an event might be necessary for triggering the memory-based response. This is thought to make attentional demands and thereby interfere with other ongoi...

Monitoring the environment for visual events while performing a concurrent task requires adjustment of visual processing priorities. By use of Bundesen’s (1990) Theory of Visual Attention, we investigated how monitoring for an object-based brief event affected distinct components of visual attention in a concurrent task. The perceptual salience of...

Background / Purpose: Here we test critical assumption of capacity allocation in Load Theory: Is the precise location information available pre-attentively to guide allocation of processing resources in an accurate way? Or alternatively, is precise location information only available at a slower rate and thus not pre-attentively? Main conclus...

According to the Theory of Visual Attention (TVA), important visual features (features with a high valence) are processed more rapidly than unimportant ones. In the present study, we tested this assumption and assessed brain correlates of reward-dependent changes in visual processing by combining the formal framework of TVA with electrophysiology (...

Conventional wisdom on psychological experiments has held that when one or more independent variables are manipulated it is essential that all other conditions are kept constant such that confounding factors can be assumed negligible (Woodworth, 1938). In practice, the latter assumption is often questionable because it is generally difficult to gua...

The human attention system helps us cope with a complex environment by supporting the selective processing of information relevant to our current goals. Understanding the perceptual, cognitive, and neural mechanisms that mediate selective attention is a core issue in cognitive neuroscience. One prominent model of selective attention, known as load...

Temporal expectation is expectation with respect to the timing of an event such as the appearance of a certain stimulus. In this paper, temporal expectancy is investigated in the context of the theory of visual attention (TVA), and we begin by summarizing the foundations of this theoretical framework. Next, we present a parametric experiment explor...

Attention shifts are facilitated if the items to be attended remain the same across trials. Some researchers argue that this priming effect is perceptual, whereas others propose that priming is postperceptual, involving facilitated response selection. The experimental findings have not been consistent regarding the roles of variables such as task d...

Background / Purpose: We aimed to identify neural correlates that mark general inter-individual and age-specific performance differences in visual attention. Our approach was a combination of parameter-based assessment of visual attention capacity, based on Bundesen’s theory of visual attention (1), and electrophysiology. Main conclusion: Our...

Studies on the temporal dynamics of attention have shown that the report of a masked target (T2) is severely impaired when the target is presented with a delay (stimulus onset asynchrony) of less than 500 ms after a spatially separate masked target (T1). This is known as the attentional dwell time. Recently, we have proposed a computational model o...

The Theory of Visual Attention (TVA; Bundesen, 1990) allows one to measure distinct visual attention parameters, such as the temporal threshold for visual perception, visual processing capacity, and visual short-term memory (VSTM) capacity. It has long been assumed that visual processing capacity and VSTM capacity parameters are nearly constant fro...

We present a new supervised component analysis method with an application to EEG. The method detects and extracts components that are predictive of behavior relative to an expected value which is derived from a formal psychological theory of visual attention. We analyze the pre-stimulus EEG activity from a single-letter recognition task and find di...

Objective: Inattentive behaviour is a defining characteristic of ADHD. Researchers have wondered about the nature of the attentional deficit underlying these symptoms. The primary purpose of the current study was to examine this attentional deficit using a novel paradigm based upon the Theory of Visual Attention (TVA). Method: The TVA paradigm enab...

Habekost, T., Vogel, A., Rostrup, E., Bundesen, C., Kyllingsbaek, S., Garde, E., Ryberg, C. & Waldemar, G. (2012). Visual processing speed in old age. Scandinavian Journal of Psychology. Mental speed is a common concept in theories of cognitive aging, but it is difficult to get measures of the speed of a particular psychological process that are no...

The attentional weight of a visual object depends on the contrast of the features of the object to its local surroundings (feature contrast) and the relevance of the features to one's goals (feature relevance). We investigated the dependency in partial report experiments with briefly presented stimuli but unspeeded responses. The task was to report...

Repetition priming of visual search traditionally refers to the reductions in reaction time when a target‚ or a target feature‚ is repeated on consecutive trials. Priming was initially thought to be a facilitated response to the target-defining feature, while repetition of irrelevant target features was thought not to benefit visual search. The sim...

An object that is relevant to the current task is more readily encoded than a similar, less relevant object (e.g., Wolfe, Cave, & Franzel, 1989). However, it is highly debated whether relevance-based selection is feasible at short exposure durations (e.g., Theeuwes, 2010). It has been argued that high local feature contrast attracts attention indep...

Perception of the second of two targets (T2) embedded in a temporal stream of distractors is often impaired as compared with perception of the first target (T1), a phenomenon known as the attentional blink (AB). Explanations of the AB commonly ascribe the impairment to a conflict in postperceptual stages of processing. Here, the standard AB paradig...

Attentional dwell time (AD) defines our inability to perceive spatially separate events when they occur in rapid succession. In the standard AD paradigm, subjects should identify two target stimuli presented briefly at different peripheral locations with a varied stimulus onset asynchrony (SOA). The AD effect is seen as a long-lasting impediment in...

Changes in sustained attention, attentional selectivity, and attentional capacity were examined in a sample of 113 participants between the ages of 12 and 75. To measure sustained attention, we employed the sustained-attention-to-response task (Robertson, Manly, Andrade, Baddeley, & Yiend, Neuropsychologia 35:747-58, 1997), a short continuous-perfo...

Background / Purpose: To test a simple Poisson counter model of identification and the effect of contrast. Main conclusion: The Poisson Counter Model provided a close fit to individual data on identification of Landolt rings with varying contrast.

We investigated how selective preparation for specific forms is affected by concurrent preknowledge of location when upcoming visual stimuli are anticipated. In three experiments, participants performed a two-choice response time (RT) task in which they discriminated between standard upright and rotated alphanumeric characters while fixating a cent...

Attentional capture by schematic emotional faces was investigated in two experiments using the flanker task devised by Eriksen and Eriksen (1974). In Experiment 1, participants were presented with a central target (a schematic face that was either positive or negative) flanked by two identical distractors, one on either side (schematic faces that w...

The Theory of Visual Attention (TVA; Bundesen, 1990) provides a quantitative account of visual attentional selectivity and capacity but does not include a parameter relating to sustained attention. We conducted two studies to examine the relationship between sustained attention and the TVA parameters relating to selectivity and capacity. In the fir...

In a crowded dynamic world, temporal expectations guide our attention in time. Prior investigations have consistently demonstrated that temporal expectations speed motor behavior. We explore effects of temporal expectation on perceptual speed in three nonspeeded, cued recognition paradigms. Different hazard rate functions for the cue-stimulus forep...

The limitations of the visual short-term memory (VSTM) system have become an increasingly popular field of study. One line of inquiry has focused on the way attention selects objects for encoding into VSTM. Using the framework of the Theory of Visual Attention (TVA; Bundesen, 1990, Psychological Review,97, 523-547) different components of attention...

The nature of attention is one of the oldest and most central problems in psychology. A huge amount of research has been produced on this subject in the last half century, especially on attention in the visual modality, but a general explanation has remained elusive. Many still view attention research as a field that is fundamentally fragmented. Th...

We identify two biases in the traditional use of Bundesen’s Theory of Visual Attention (TVA) and show that they can be substantially reduced by introducing trial-by-trial variability in the model. We analyze whole and partial report data from a comprehensive empirical study with 347 participants and elaborate on Bayesian model selection theory for...

Effects of spatial cueing on visual attention have been thoroughly investigated during the last 30 odd years. Similar to spatial cueing, temporal cueing seems to afford a performance enhancement to an observer when he or she knows the point in time at which an event will occur (Coull & Nobre, 1998). Varying the statistical distribution of cue-stimu...

The authors propose and test a simple model of the time course of visual identification of briefly presented, mutually confusable single stimuli in pure accuracy tasks. The model implies that during stimulus analysis, tentative categorizations that stimulus i belongs to category j are made at a constant Poisson rate, v(i, j). The analysis is contin...

Background / Purpose: Adults with Asperger’s syndrome were compared with a control group with respect to a wide range of basic functions of visual attention using measures of both reaction-time and accuracy. Main conclusion: Participants with Asperger’s syndrome were similar to the control group on all measures of visual attention. No strong o...

In this paper we take a step towards single-trial behavioral modeling within a Theory of Visual Attention (TVA). In selective attention tasks, such as the Partial Report paradigm, the subject is asked to ignore distractors and only report stimuli that belong to the target class. Nothing about a distractor is observed directly in the subject's overt...

Nicotine has been shown to improve both memory and attention when assessed through speeded motor responses. Since very few studies have assessed effects of nicotine on visual attention using measures that are uncontaminated by motoric effects, nicotine's attentional effects may, at least partially, be due to speeding of motor function. Using an uns...

The neural theory of visual attention and short-term memory (NTVA) proposed by Bundesen, Habekost, and Kyllingsbæk (2005) is reviewed. In NTVA, filtering (selection of objects) changes the number of cortical neurons in which an object is represented so that this number increases with the behavioural importance of the object. Another mechanism of se...

Temporal expectations play an important role in optimizing future perception and behavior, but the nature of the attentional processes affected by our expectations is still widely debated. To investigate effects of expectations on the speed of visual processing, we employed a cued single-letter recognition task with stimuli of varied durations term...

Studies of the time course of visual attention have identified a temporary functional blindness to the second of two spatially separated targets: attending to one visual stimulus may lead to impairments in identifying a second stimulus presented between 200 to 500 ms after the first. This phenomenon is known as attentional dwell time (e.g. Duncan,...

Despite a vast body of research, it remains unclear whether a singleton captures attention even if the singleton is of no relevance to the task. The present study addressed the question of how the presence of a color singleton influences the efficiency of target selection in a partial report experiment with poststimulus masks. Subjects reported the...

Common mechanisms in apparent motion perception and visual pattern matching. Scandinavian Journal of Psychology, 50, 526-534.There are close functional similarities between apparent motion perception and visual pattern matching. In particular, striking functional similarities have been demonstrated between perception of rigid objects in apparent mo...

The change detection paradigm is a popular way of measuring visual short-term memory capacity. Using the paradigm, researchers have found evidence for a capacity of about four independent visual objects, confirming classic estimates that were based on the number of items that could be reported. Here, we determine the reliability of capacity measure...

The neural theory of visual attention (NTVA) introduced by Bundesen, Habekost, and Kyllingsbæk (20056. Bundesen , C. , Habekost , T. and Kyllingsbæk , S. 2005. A neural theory of visual attention: Bridging cognition and neurophysiology. Psychological Review, 112: 291–328. [CrossRef], [PubMed], [Web of Science ®]View all references) is presented....

Direct measurements of the effects of spatial separation between stimuli in whole report from brief visual displays are reported. The stimuli were presented on the periphery of an imaginary circle centered on fixation. In Experiment 1, each display showed two capital letters (letter height approximately equal 1.3 degrees, width approximately equal...

Many researchers interpret switch costs in the explicit task-cuing procedure as reflecting endogenous task-set reconfiguration. G. D. Logan and C. Bundesen (2003) challenged this interpretation empirically and theoretically. They argued that many experiments confounded cue encoding benefits with switch costs and they showed that unconfounded switch...

Observers given brief exposures of pairs of colored bars and asked to report both the color and the orientation of each bar showed evidence of stochastic independence between reports of the 4 features (2 colors and 2 orientations). The authors also found virtually perfect stochastic independence between reports of colors and directions of motion of...

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