Elkan G Akyürek

Elkan G Akyürek
University of Groningen | RUG · Department of Psychology

PhD

About

69
Publications
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Introduction
Elkan G Akyürek currently works at the Department of Psychology, University of Groningen. Elkan does research in Neuroscience, Cognitive Psychology and Experimental Psychology.

Publications

Publications (69)
Article
In a series of experiments, the nature of perceptual awareness during the attentional blink was investigated. Previous work has considered the attentional blink as a discrete, all-or-none phenomenon, indicative of general access to conscious awareness. Using continuous report measures in combination with mixture modeling, the outcomes showed that p...
Article
It is unclear to what extent sensory processing areas are involved in the maintenance of sensory information in working memory (WM). Previous studies have thus far relied on finding neural activity in the corresponding sensory cortices, neglecting potential activity-silent mechanisms, such as connectivity-dependent encoding. It has recently been fo...
Article
Full-text available
Recent theoretical models propose that working memory is mediated by rapid transitions in 'activity-silent' neural states (for example, short-term synaptic plasticity). According to the dynamic coding framework, such hidden state transitions flexibly configure memory networks for memory-guided behavior and dissolve them equally fast to allow forget...
Article
Full-text available
When two targets follow each other directly in rapid serial visual presentation (RSVP), they are often identified correctly but reported in the wrong order. These order reversals are commonly explained in terms of the rate at which the two targets are processed, the idea being that the second target can sometimes overtake the first in the race towa...
Article
Full-text available
In this study, we investigated how the acute physiological effects of cocoa flavanols might result in specific cognitive changes, in particular in temporal and spatial attention. To this end, we pre-registered and implemented a randomized, double-blind, placebo- and baseline-controlled crossover design. A sample of 48 university students participat...
Preprint
Full-text available
People often fail to detect the second of two targets when there is a short time interval of ~500 msec or less between them. This phenomenon is known as the attentional blink (AB). Accumulating evidence suggests that the AB is a result of a failure to select and consolidate the second target in working memory. The current literature has assumed tha...
Preprint
Full-text available
Humans can adapt when complex patterns unfold at a faster or slower pace, for instance when remembering a grocery list that is dictated at an increasingly fast pace. Integrating information over such timescales crucially depends on working memory, but although state-of-the-art theories assume that working memory capacity can be flexibly adapted, th...
Article
Full-text available
The concealed information test (CIT) relies on bodily reactions to stimuli that are hidden in mind. However, people can use countermeasures, such as purposely focusing on irrelevant things, to confound the CIT. A new method designed to prevent countermeasures uses rapid serial visual presentation (RSVP) to present stimuli on the fringe of awareness...
Article
Full-text available
Background: Consumption of cocoa flavanols may have acute physiological effects on the brain due to their ability to activate nitric oxide synthesis. Nitric oxide mediates vasodilation, which increases cerebral blood flow, and can also act as a neurotransmitter. Objectives: This study aimed to examine whether cocoa flavanols have an acute influence...
Preprint
Full-text available
In a series of experiments, the nature of perceptual awareness during the attentional blink was investigated. Previous work has considered the attentional blink as a discrete, all-or-none phenomenon, indicative of general access to conscious awareness. Using continuous report measures in combination with mixture modeling, the outcomes showed that p...
Preprint
Full-text available
The concealed information test (CIT) relies on bodily reactions to stimuli that are hidden in mind. However, people can use countermeasures, such as purposely focusing on irrelevant things, to confound the CIT. A new method designed to prevent the use of countermeasures, based on rapid serial visual presentation (RSVP), presents each stimulus on th...
Preprint
“Activity-silent” working memory (WM) has been proposed as an energy-efficient short-term storage mechanism that does not require persistent spiking. Previously we developed a novel experimental approach to test its key predictions and showed that an external perturbation results in a subtle but reliable readout of the information in WM, even for u...
Article
Full-text available
Estimation of time depends heavily on both global and local statistical context. Durations that are short relative to the global distribution are systematically overestimated; durations that are locally preceded by long durations are also overestimated. Context effects are prominent in duration discrimination tasks, where a standard duration and a...
Preprint
Full-text available
Estimation of time depends heavily on both global and local statistical context. For instance, durations that are short relative to the global distribution are systematically overestimated; durations that are locally preceded by long durations are also overestimated. Context effects are prominent in duration discrimination tasks, where a standard d...
Article
Full-text available
In this paper, we present a functional spiking-neuron model of human working memory (WM). This model combines neural firing for encoding of information with activity-silent maintenance. While it used to be widely assumed that information in WM is maintained through persistent recurrent activity, recent studies have shown that information can be mai...
Article
Full-text available
Evidence for adaptive event integration has previously been provided using the Rapid Serial Visual Presentation (RSVP) task. However, it is not straightforward to generalize this finding to other types of tasks that measure temporal integration, because integration in such tasks is known to vary, depending on the method that is used. This variabili...
Article
Full-text available
Working memory (WM) is important to maintain information over short time periods to provide some stability in a constantly changing environment. However, brain activity is inherently dynamic, raising a challenge for maintaining stable mental states. To investigate the relationship between WM stability and neural dynamics, we used electroencephalogr...
Preprint
Full-text available
In this paper, we present a functional spiking-neuron model of human working memory (WM). This model combines neural firing for encoding of information with activity-silent maintenance. While it used to be widely assumed that information in WM is maintained through persistent recurrent activity, recent studies have shown that information can be mai...
Preprint
Full-text available
Working memory (WM) is important to maintain information over short time periods to provide some stability in a constantly changing environment. However, brain activity is inherently dynamic, raising a challenge for maintaining stable mental states. To investigate the relationship between WM stability and neural dynamics, we used electroencephalogr...
Article
Full-text available
As people age, they tend to integrate successive visual stimuli over longer intervals than younger adults. It may be expected that temporal integration is affected similarly in other modalities, possibly due to general, age-related cognitive slowing of the brain. However, the previous literature does not provide convincing evidence that this is the...
Preprint
It is unclear to what extent sensory processing areas are involved in the maintenance of sensory information in working memory (WM). Previous studies have thus far relied on finding neural activity in the corresponding sensory cortices, neglecting potential activity-silent mechanisms such as connectivity-dependent encoding. It has recently been fou...
Article
Full-text available
The effects of relative stimulus contrast on temporal integration were investigated in a missing element task. Integration frequency was strongly modulated when the contrast of either the first or the second stimulus display was reduced. When the contrast of the first display was low, integration was enhanced, while it was reduced when the contrast...
Article
Performance in a dual target rapid serial visual presentation task was investigated, dependent on whether the color or the contrast of the targets was the same or different. Both identification accuracy on the second target, as a measure of temporal attention, and the frequency of temporal integration were measured. When targets had a different col...
Article
In a randomized, double-blind, and placebo-controlled experiment, the acute effects of gamma-aminobutyric acid (GABA) supplementation on temporal and spatial attention in young healthy adults were investigated. A hybrid two-target rapid serial visual presentation task was used to measure temporal attention and integration. Additionally, a visual se...
Article
Human memory benefits from information clustering, which can be accomplished by chunking. Chunking typically relies on expertise and strategy, and it is unknown whether perceptual clustering over time, through temporal integration, can also enhance working memory. The current study examined the attentional and working memory costs of temporal integ...
Article
Full-text available
Performance in rapid serial visual presentation tasks has been shown to depend on the temporal integration of target stimuli when they are presented in direct succession. Temporal target integration produces a single, combined representation of visually compatible stimuli, which is comparatively easy to identify. It is currently unknown to what ext...
Article
We investigated the relationship between different kinds of target reports in a rapid serial visual presentation task, and their associated perceptual experience. Participants reported the identity of two targets embedded in a stream of stimuli and their associated subjective visibility. In our task, target stimuli could be combined together to for...
Article
Full-text available
Stimulus contrast and duration effects on visual temporal integration and order judgment were examined in a unified paradigm. Stimulus onset asynchrony was governed by the duration of the first stimulus in Experiment 1, and by the interstimulus interval in Experiment 2. In Experiment 1, integration and order uncertainty increased when a low contras...
Article
Full-text available
While many studies have shown that a task-irrelevant emotionally arousing stimulus can interfere with the processing of a shortly following target, it remains unclear whether an emotional stimulus can also retroactively interrupt the ongoing processing of an earlier target. In two experiments, we examined whether the presentation of a negative emot...
Data
Data of Experiment 1 and 2. (ZIP)
Data
Table of IAPS picture numbers used in Experiment 1 and 2. (DOCX)
Article
Full-text available
Background: The reduced ability to identify a second target when it is presented in close temporal succession of a first target is called the attentional blink (AB). Studies have shown large individual differences in AB task performance, where lower task performance has been associated with more reversed order reports of both targets if these were...
Article
Full-text available
In the perception of target stimuli in rapid serial visual presentations, the process of temporal integration plays an important role when two targets are presented in direct succession (at Lag 1), causing them to be perceived as a singular episodic event. This has been associated with increased reversals of target order report and elevated task pe...
Article
When two different color stimuli are presented in rapid succession, the resulting percept is sometimes that of a mixture of both colors, due to a perceptual process called color fusion. Although color fusion might seem to occur very early in the visual pathway, and only happens across the briefest of stimulus presentation intervals (< 50 ms), the p...
Article
Full-text available
In dynamic sensory environments, successive stimuli may be combined perceptually and represented as a single, comprehensive event by means of temporal integration. Such perceptual segmentation across time is intuitively plausible. However, the possible costs and benefits of temporal integration in perception remain underspecified. In the present st...
Article
Full-text available
Temporal integration is the perceptual process combining sensory stimulation over time into longer percepts that can span over 10 times the duration of a minimally detectable stimulus. Particularly in the auditory domain, such "long-term" temporal integration has been characterized as a relatively simple function that acts chiefly to bridge brief i...
Article
Full-text available
Cognitive skills, such as processing speed, memory functioning, and the ability to divide attention, are known to diminish with aging. The present study shows that, despite these changes, older adults can successfully compensate for degradations in speech perception. Critically, the older participants of this study were not pre-selected for high pe...
Article
Temporal integration was examined using a missing element task, in which task performance depends on the ability to integrate brief successive stimulus displays. Previous studies have suggested that temporal integration is under endogenous control and that integration is more likely when stimuli match the observer's temporal expectancies. Beta osci...
Article
Full-text available
The consequences of maintaining a task set in the context of the (speeded) attentional blink were investigated in a series of experiments. Observers were asked to either attend or ignore the first of two target stimuli (T1 and T2). The results showed that when T1 and T2 shared a task relevant feature that was unique to T2, but not to T1, a shallow...
Article
Full-text available
The relationship between attentional control and episodic representation was investigated in six experiments that employed a variant of the classic attentional blink paradigm. We introduced a task-irrelevant (unpredictive) color match between the first and second target stimulus in a three-stream rapid serial visual presentation task. When this mat...
Article
The deployment of attention during temporal integration was investigated with event-related potentials. Attentional selection of an integrated percept and an actual singleton were examined. Integration performance was related to modulations of the N2pc, N2, and P3 components. Singleton localization performance was reflected in N2pc and P3 only. Of...
Article
When searching for a target object presented in a context of other, irrelevant objects, the dissimilarity between target and surrounding context elements as well as the similarity between context elements themselves affect search efficiency. The present functional imaging study explored the cortical mechanisms involved in processing the same target...
Article
Full-text available
Visual STM (VSTM) is thought to be related to visual attention in several ways. Attention controls access to VSTM during memory encoding and plays a role in the maintenance of stored information by strengthening memorized content. We investigated the involvement of visual attention in recall from VSTM. In two experiments, we measured electrophysiol...
Article
In an ERP experiment, we investigated whether a 'permanent' salient distractor changes the deployment of attention to target and nontarget singletons. Observers searched for a color target in a search array that mainly consisted of black vertical lines, but also always contained a line in a task-irrelevant color. Together with this distractor, a ta...
Article
Full-text available
Three experiments were conducted to investigate the effects of working memory content on temporal attention in a rapid serial visual presentation attentional blink paradigm. It was shown that categorical similarity between working memory content and the target stimuli pertaining to the attentional task (both digits) increased attentional blink magn...
Article
Electrophysiological measurements were taken from observers performing a visual search within a single feature dimension, and between multiple dimensions. The N2pc to selected singleton target stimuli (rightward tilted lines) was increased when targets varied between feature dimensions, compared to the N2pc to the same rightward tilted line targets...
Article
To attend successfully, a specification of what is currently relevant is necessary, but not sufficient. Irrelevant stimuli that are also present in the environment must be recognized as such and filtered out at the same time. Using functional magnetic resonance imaging, we showed that posterior brain regions in parietal, occipital and temporal cort...
Article
An increase in concurrent working memory load has been shown to amplify the attentional blink. The present study investigated the temporal locus of this phenomenon, by using a dual rapid serial visual presentation paradigm that enabled the measurement of lateralized event-related potentials. The P3 component was shown to be affected by both working...
Article
Name agreement is the extent to which different people agree on a name for a particular picture. Previous studies have found that it takes longer to name low name agreement pictures than high name agreement pictures. To examine the effect of name agreement in the online process of picture naming, we compared event-related potentials (ERPs) recorded...
Article
Four experiments are reported that investigated visual event integration by using a variant of the missing element paradigm. Good performance on this task depends on whether two brief successive stimulus displays are perceived as (or integrated into) one single event. We replicated the classic finding of greater accuracy with shorter duration of th...
Article
The neural processing fate of target and nontarget singleton stimuli was investigated in a series of visual search tasks. The first experiment showed that the ERPs elicited by nontargets defined in the same feature dimension as targets were identical to those of targets until a relatively late divergence in the P3 time range. The second experiment...
Article
Full-text available
Three experiments examined the temporal dynamics of the impact of symbols with task-irrelevant spatial meanings on attentional control. In Experiments 1 and 2, participants were color-cued to report the first letter they saw in the left or right of two parallel letter streams. The cue appeared in the shape of an arrow pointing to the target stream...
Article
Full-text available
Identifying two target stimuli in a rapid stream of visual symbols is much easier if the second target appears immediately after the first target (i.e., at Lag 1) than if distractor stimuli intervene. As this phenomenon comes with a strong tendency to confuse the order of the targets, it seems to be due to the integration of both targets into the s...
Article
Full-text available
Two experiments investigated the capacity demands of stimulus and response priming in a rapid serial visual presentation (RSVP) task. Three targets were presented in a stream of visual symbols: The first two (T1 and T2) required an unspeeded manual response at the end of the trial, but the third (T3) called for an immediate,speeded manual response....
Article
Full-text available
Theories of selective attention often have a central memory component, which is commonly thought to be limited in some way and is thereby a potential bottleneck in the attentional process. There have been only a few attempts to validate this assertion, and they have produced mixed results. This study presents a specific examination of the link betw...
Article
We investigated whether it is possible to control the temporal window of attention used to rapidly integrate visual information. To study the underlying neural mechanisms, we recorded ERPs in an attentional blink task, known to elicit Lag-1 sparing. Lag-1 sparing fosters joint integration of the two targets, evidenced by increased order errors. Sho...
Article
Full-text available
When people monitor a visual stream of rapidly presented stimuli for two targets (T1 and T2), they often miss T2 if it falls into a time window of about half a second after T1 onset-the attentional blink (AB). We provide an overview of recent neuroscientific studies devoted to analyze the neural processes underlying the AB and their temporal dynami...
Article
Full-text available
Short-term memory (STM) has often been considered to be a central resource in cognition. This study addresses its role in rapid serial visual presentation (RSVP) tasks tapping into temporal attention—the attentional blink (AB). Various STM operations are tested for their impact on performance and, in particular, on the AB. Memory tasks were found t...
Article
Full-text available
In this paper, we introduce a special issue about unique and shared mechanisms underlying the performance limitations observed in dual tasks. In particular, the relationship between task-switching costs, the attentional-blink effect, and the psychological refractory period effect is reviewed. These costs are traditionally attributed to fixed and un...
Article
Full-text available
When people monitor a visual stream of rapidly presented stimuli for two targets (T1 and T2), they often miss T2 if it falls into a time window of about half a second after T1 onset--the attentional blink. However, if T2 immediately follows T1, performance is often reported being as good as that at long lags--the so-called Lag-1 sparing effect. Two...
Article
If people monitor a visual stimulus stream for targets they often miss the second (T2) if it appears soon after the first (T1)--the attentional blink. There is one exception: T2 is often not missed if it appears right after T1, i.e., at lag 1. This lag-1 sparing is commonly attributed to the possibility that T1 processing opens an attentional gate,...
Article
Full-text available
When people monitor the rapid serial visual presentation (RSVP) of stimuli for two targets (T1 and T2), they often miss T2 if it falls into a time window of about half a second after T1 onset, a phenomenon known as the attentional blink (AB). We found that overall performance in an RSVP task was impaired by a concurrent short-term memory (STM) task...

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