Attentional episodes in visual perception

Attention and feature binding in the temporal domain

Previous studies have shown that illusory conjunction can emerge for both spatially and temporally proximal objects. However, the mechanisms involved in binding in the temporal domain are not yet fully understood. In the current study, we investigated the role of attentional processes in correct and incorrect temporal binding, and specifically how feature binding is affected by the speed of attentional engagement. In two experiments, participants searched for a target in a rapid serial visual presentation stream and reported its colour and alphanumeric identity. Temporal binding errors were frequent. Critically, when participants reported the identity of a distractor instead of a target, they were also more likely to report the colour of this distractor. This association was observed both within and between individuals. These findings suggest that attentional engagement facilitates the binding of temporally co-occurring features. We discuss these results within a 'diachronic' framework of selective attention, and also consider other factors that contribute to temporal binding errors.

The role of distractors in rapid serial visual presentation reveals the mechanism of attentional blink by EEG-based univariate and multivariate analyses

Attentional blink pertains to the performance of participants with a severe decline in identifying the second target presented after the first target reported correctly within 200-500 ms in a rapid serial visual presentation. The current study was conducted to investigate the neural mechanism of the effect of the distractor (D1) that immediately follows first target to attentional blink by altering whether D1 was substituted with a blank with electroencephalography recording. The results showed that D1 interfered with the attentional enhancement and working memory encoding in both single-target rapid serial visual presentation task and dual-target rapid serial visual presentation task, which were mainly manifested in delayed and attenuated P3a and diminished P3b of first target. Single-trial analysis indicated that first target and second target will compete with each other for working memory encoding resources in short lag, but not in the long lag. In addition, D1 interfered with the working memory encoding of second target under short lag rather than long lag in the dual-target rapid serial visual presentation task. These results suggested that attentional blink can be attributed to the limited working memory encoding resource, whereas the amount of available resources is subject to modulation by attention. The D1 hinders the attention enhancement of first target, thereby exacerbating attentional blink.

The brain network underlying attentional blink predicts symptoms of attention deficit hyperactivity disorder in children

Attention deficit hyperactivity disorder (ADHD) is a chronic neuropsychiatric disease that can markedly impair educational, social, and occupational function throughout life. Behavioral deficits may provide clues to the underlying neurological impairments. Children with ADHD exhibit a larger attentional blink (AB) deficit in rapid serial visual presentation (RSVP) tasks than typically developing children, so we examined whether brain connectivity in the neural network associated with AB can predict ADHD symptoms and thus serve as potential biomarkers of the underlying neuropathology. We first employed a connectome-based predictive model analysis of adult resting-state functional magnetic resonance imaging data to identify a distributed brain network for AB. The summed functional connectivity (FC) strength within the AB network reliably predicted individual differences in AB magnitude measured by a classical dual-target RSVP task. Furthermore, the summed FC strength within the AB network predicted individual differences in ADHD Rating Scale scores from an independent dataset of pediatric patients. Our findings suggest that the individual AB network could serve as an applicable neuroimaging-based biomarker of AB deficit and ADHD symptoms.

The temporal cost of deploying attention limits accurate target identification in rapid serial visual presentation

Lag-1 sparing is a common exception to the attentional blink, where a target presented directly after T1 can be identified and reported accurately. Prior work has proposed potential mechanisms for lag 1 sparing, including the boost and bounce model and the attentional gating model. Here, we apply a rapid serial visual presentation task to investigate the temporal limitations of lag 1 sparing by testing three distinct hypotheses. We found that endogenous engagement of attention to T2 requires between 50 and 100 ms. Critically, faster presentation rates yielded lower T2 performance, whereas decreased image duration did not impair T2 detection and report. These observations were reinforced by subsequent experiments controlling for short-term learning and capacity-dependent visual processing effects. Thus, lag-1 sparing was limited by the intrinsic dynamics of attentional boost engagement rather than by earlier perceptual bottlenecks such as insufficient exposure to images in the stimulus stream or visual processing capacity limitations. Taken together, these findings support the boost and bounce theory over earlier models that focus only on attentional gating or visual short-term memory storage, informing our understanding of how the human visual system deploys attention under challenging temporal constraints.

Lexico-semantic Activation of Translation Equivalents During the Attentional Blink

The attentional blink (AB) refers to the impaired identification of the second target (T2) when presented within approximately 500ms after the first target (T1). Although the AB is eliminated when two targets can be integrated into a single compound word, it remains unclear whether the lexico-semantic organization of translation equivalents modulates the magnitude of the AB. In the present study, we examined consecutive targets' processing in a rapid serial visual presentation (RSVP) paradigm using Chinese-English translation equivalents and non-translation equivalents. The results demonstrated that an overall presence of the AB effect was observed when T1 and T2 were non-translation equivalents. However, the AB effect disappeared completely when the two target words were translation equivalents. Taken together, these findings suggest that Chinese-English bilinguals are translating intentionally between Mandarin and English, which facilitates lexical access to word meaning from the two languages at the initial stages of visual word processing. Furthermore, such lexico-semantic activation of translation equivalents attributes to the elimination of the AB.

Role of time in binding features in visual working memory

Previous research on feature binding in visual working memory has supported a privileged role for location in binding an object's nonspatial features. However, humans are able to correctly recall feature conjunctions of objects that occupy the same location at different times. In a series of behavioral experiments, we investigated binding errors under these conditions, and specifically tested whether ordinal position can take the role of location in mediating feature binding. We performed two dual report experiments in which participants had to memorize three colored shapes presented sequentially at the screen center. When participants were cued with the ordinal position of one item and had to report its shape and color, report errors for the two features were largely uncorrelated. In contrast, when participants were cued, for example, with an item's shape and reported an incorrect ordinal position, they had a high chance of making a corresponding error in the color report. This pattern of error correlations closely matched the predictions of a model in which color and shape are bound to each other only indirectly via an item's ordinal position. In a third experiment, we directly compared the roles of location and sequential position in feature binding. Participants viewed a sequence of colored disks displayed at different locations and were cued either by a disk's location or its ordinal position to report its remaining properties. The pattern of errors supported a mixed strategy with individual variation, suggesting that binding via either time or space could be used for this task. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

On target selection as reflected by posterior ERP components in feature-guided visual search

The N2pc event-related potential is a widely studied ERP component that reflects the covert deployment of visuo-spatial attention to target stimuli displayed laterally relative to fixation. Recently, an analogous ERP component, named N2pcb, has been proposed as a marker of the deployment of visuo-spatial attention to targets displayed on the vertical midline. Two studies that investigated the N2pcb component found analogous results, using however two different algorithms to compute the amplitude of N2pcb. One study subtracted the ipsilateral activity elicited by a lateral target from the bilateral activity elicited by a target displayed on the vertical midline, whereas the other study subtracted the bilateral activity elicited by target-absent displays from the bilateral activity elicited by a target displayed on the vertical midline. Here we show both algorithms estimate properly the N2pc as well as the N2pcb components. In addition, we explored whether the singleton detection positivity (SDP) component, a posterior bilateral positivity temporally concomitant to N2pc recently reported in studies using singleton search, could be observed in the present study in which a target was defined by a combination of features. Given that such component was indeed found using feature search, we named this component posterior processing positivity (PPP), and showed that bilateral activity elicited by target-absent displays is an adequate baseline for its correct isolation.

Examining the relationship between working memory consolidation and long-term consolidation

An emerging area of research is focused on the relationship between working memory and long-term memory and the likely overlap between these processes. Of particular interest is how some information first maintained in working memory is retained for longer periods and eventually preserved in long-term memory. The process of stabilizing transient memory representations for lasting retention is referred to as consolidation in both the working memory and long-term memory literature, although these have historically been viewed as independent constructs. The present review aims to investigate the relationship between working memory consolidation and long-term memory consolidation, which both have rich, but distinct, histories. This review provides an overview of the proposed models and neural mechanisms of both types of consolidation, as well as clinical findings related to consolidation and potential approaches for the manipulation of consolidation. Finally, two hypotheses are proposed to explain the relationship between working memory consolidation and long-term memory consolidation.

Modelling the simultaneous encoding/serial experience theory of the perceptual moment: a blink of meta-experience

One way to understand a system is to explore how its behaviour degrades when it is overloaded. This approach can be applied to understanding conscious perception by presenting stimuli in rapid succession in the 'same' perceptual event/moment. In previous work, we have identified a striking dissociation during the perceptual moment, between what is encoded into working memory [Lag-1 sparing in the attentional blink (AB)] and what is consciously perceived (Lag-1 impairing in the experiential blink). This paper links this dissociation to what, taking inspiration from the metacognition literature, could be called meta-experience; i.e. how the ability to track and comment on one's visual experience with subjectivity ratings reflects objective performance. Specifically, we provide evidence that the information (in bits) associated with an encoding into working memory decouples from the experiential reflection upon that perceptual/encoding event and that this decoupling is largest when there is the greatest perceptual overload. This is the meta-experiential blink. Meta-experiential self-observation is common to many computational models, including connectionist interpretations of consciousness, Bayesian observers and the readout-enhanced simultaneous type/serial token (reSTST) model. We assess how our meta-experiential blink data could be modelled using the concept of self-observation, providing model fits to behavioural and electroencephalogram responses in the reSTST model. We discuss the implications of our computational modelling of parallel encoding but serial experience for theories of conscious perception. Specifically, we (i) inform theories of Lag-1 sparing during the AB and (ii) consider the implications for the global workspace theory of conscious perception and higher-order theories of consciousness.

The diachronic account of attentional selectivity

Many models of attention assume that attentional selection takes place at a specific moment in time that demarcates the critical transition from pre-attentive to attentive processing of sensory input. We argue that this intuitively appealing standard account of attentional selectivity is not only inaccurate, but has led to substantial conceptual confusion. As an alternative, we offer a 'diachronic' framework that describes attentional selectivity as a process that unfolds over time. Key to this view is the concept of attentional episodes, brief periods of intense attentional amplification of sensory representations that regulate access to working memory and response-related processes. We describe how attentional episodes are linked to earlier attentional mechanisms and to recurrent processing at the neural level. We review studies that establish the existence of attentional episodes, delineate the factors that determine if and when they are triggered, and discuss the costs associated with processing multiple events within a single episode. Finally, we argue that this framework offers new solutions to old problems in attention research that have never been resolved. It can provide a unified and conceptually coherent account of the network of cognitive and neural processes that produce the goal-directed selectivity in perceptual processing that is commonly referred to as 'attention'.

A dynamic normalization model of temporal attention

Vision is dynamic, handling a continuously changing stream of input, yet most models of visual attention are static. Here, we develop a dynamic normalization model of visual temporal attention and constrain it with new psychophysical human data. We manipulated temporal attention-the prioritization of visual information at specific points in time-to a sequence of two stimuli separated by a variable time interval. Voluntary temporal attention improved perceptual sensitivity only over a specific interval range. To explain these data, we modelled voluntary and involuntary attentional gain dynamics. Voluntary gain enhancement took the form of a limited resource over short time intervals, which recovered over time. Taken together, our theoretical and experimental results formalize and generalize the idea of limited attentional resources across space at a single moment to limited resources across time at a single location.

Visual Memory Scan Slopes: Their Changes over the First Two Seconds of Processing

Using the prime–probe comparison paradigm, Jacob, Breitmeyer, and Treviño (2013) demonstrated that information processing in visual short-term memory (VSTM) proceeds through three stages: sensory visible persistence (SVP), nonvisible informational persistence (NIP), and visual working memory (VWM). To investigate the effect of increasing the memory load on these stages by using 1, 3, and 5 display items, measures of VSTM performance, including storage, storage-slopes, and scan-slopes, were obtained. Results again revealed three stages of VSTM processing, but with the NIP stage increasing in duration as memory load increased, suggesting a need, during the NIP stage, for transfer and encoding delays of information into VWM. Consistent with this, VSTM scan-slopes, in ms/item, were lowest during the first NIP stage, highest during the second NIP stage, and intermediate during the third, non-sensory VWM stage. The results also demonstrated a color-superiority effect, as all VSTM scan-slopes for color were lower than those for shape and as all VSTM storages for color are greater than those for shape, and the existence of systematic pair-wise correlations between all three measures of VSTM performance. These findings and their implications are related to other paradigms and methods used to investigate post-stimulus processing in VSTM.

Attention to a Moment in Time Impairs Episodic Distinctiveness during Rapid Serial Visual Presentation

Human attention is limited in the ability to select and segregate relevant distinct events from the continuous flow of external information while concurrently encoding their temporal succession. While it is well-known that orienting attention to one external target stimulus impairs the encoding of ensuing relevant external events, it is still unknown whether orienting attention to internally generated events can interfere with concurrent processing of external input. We addressed this issue by asking participants to identify a single target embedded among distractors in a non-spatial rapid serial visual presentation (RSVP) stream and to indicate whether that target appeared before or after an internally estimated midpoint of the stream. The results indicate that (a) such an internally generated temporal benchmark does not interfere with the identification of a subsequent physical target stimulus but (b) the two events cannot be accurately segregated when the physical target immediately follows the internally generated temporal event. These findings indicate that the asymmetrical distribution around the midpoint of order reversals reflects an impaired temporal discrimination ability. Orienting attention to a moment in time reduces episodic distinctiveness as much as orienting attention to external events.

What processes are disrupted during the attentional blink? An integrative review of event-related potential research

Reporting the second of two targets is impaired when these appear in close succession, a phenomenon known as the attentional blink (AB). Despite decades of research, what factors limit our ability to process multiple sequentially presented events remains unclear. Specifically, two central issues remain open: does failure to report the second target (T2) reflect a structural limitation in working memory (WM) encoding or a disruption to attentional processes? And is perceptual processing of the stimulus that we fail to report impaired, or only processes that occur after this stimulus is identified? We address these questions by reviewing event-related potential (ERP) studies of the AB, after providing a brief overview of the theoretical landscape relevant to these debates and clarifying key concepts essential for interpreting ERP studies. We show that failure to report the second target is most often associated with disrupted attentional engagement (associated with a smaller and delayed N2pc component). This disruption occurs after early processing of T2 (associated with an intact P1 component), weakens its semantic processing (typically associated with a smaller N400 component), and prevents its encoding into WM (associated with absent P3b). However, failure to encode T2 in WM can occur despite intact attentional engagement and semantic processing. We conclude that the AB phenomenon, which reflects our limited ability to process sequential events, emerges from the disruption of both attentional engagement and WM encoding.

Trace conditioning as a test for animal consciousness: a new approach

Trace conditioning involves the pairing of a neutral conditioned stimulus (CS), followed by a short interval with a motivationally significant unconditioned stimulus (UCS). Recently, trace conditioning has been proposed as a test for animal consciousness due to its correlation in humans with subjective report of the CS-UCS connection. We argue that the distractor task in the Clark and Squire (1998) study on trace conditioning has been overlooked. Attentional inhibition played a crucial role in disrupting trace conditioning and awareness of the CS-UCS contingency in the human participants of that study. These results may be understood within the framework of the Temporal Representation Theory that asserts consciousness serves the function of selecting information into a representation of the present moment. While neither sufficient nor necessary, attentional processes are the primary means to select stimuli for consciousness. Consciousness and attention are both needed by an animal capable of flexible behavioral response. Consciousness keeps track of the current situation; attention amplifies task-relevant stimuli and inhibits irrelevant stimuli. In light of these joint functions, we hypothesize that the failure to trace condition under distraction in an organism known to successfully trace condition otherwise can be one of several tests that indicates animal consciousness. Successful trace conditioning is widespread and by itself does not indicate consciousness.

The Sync-Fire/deSync model: Modelling the reactivation of dynamic memories from cortical alpha oscillations

We propose a neural network model to explore how humans can learn and accurately retrieve temporal sequences, such as melodies, movies, or other dynamic content. We identify target memories by their neural oscillatory signatures, as shown in recent human episodic memory paradigms. Our model comprises three plausible components for the binding of temporal content, where each component imposes unique limitations on the encoding and representation of that content. A cortical component actively represents sequences through the disruption of an intrinsically generated alpha rhythm, where a desynchronisation marks information-rich operations as the literature predicts. A binding component converts each event into a discrete index, enabling repetitions through a sparse encoding of events. A timing component - consisting of an oscillatory "ticking clock" made up of hierarchical synfire chains - discretely indexes a moment in time. By encoding the absolute timing between discretised events, we show how one can use cortical desynchronisations to dynamically detect unique temporal signatures as they are reactivated in the brain. We validate this model by simulating a series of events where sequences are uniquely identifiable by analysing phasic information, as several recent EEG/MEG studies have shown. As such, we show how one can encode and retrieve complete episodic memories where the quality of such memories is modulated by the following: alpha gate keepers to content representation; binding limitations that induce a blink in temporal perception; and nested oscillations that provide preferential learning phases in order to temporally sequence events.

Location-independent feature binding in visual working memory for sequentially presented objects

Spatial location is believed to have a privileged role in binding features held in visual working memory. Supporting this view, Pertzov and Husain (Attention, Perception, & Psychophysics, 76(7), 1914–1924, 2014) reported that recall of bindings between visual features was selectively impaired when items were presented sequentially at the same location compared to sequentially at different locations. We replicated their experiment, but additionally tested whether the observed impairment could be explained by perceptual interference during encoding. Participants viewed four oriented bars in highly discriminable colors presented sequentially either at the same or different locations, and after a brief delay were cued with one color to reproduce the associated orientation. When we used the same timing as the original study, we reproduced its key finding of impaired binding memory in the same-location condition. Critically, however, this effect was significantly modulated by the duration of the inter-stimulus interval, and disappeared if memoranda were presented with longer delays between them. In a second experiment, we tested whether the effect generalized to other visual features, namely reporting of colors cued by stimulus shape. While we found performance deficits in the same-location condition, these did not selectively affect binding memory. We argue that the observed effects are best explained by encoding interference, and that memory for feature binding is not necessarily impaired when memoranda share the same location.

Brain Structure and Functional Connectivity Associated with Individual Differences in the Attentional Blink

The attentional blink (AB) has been central in characterizing the limit of temporal attention and consciousness. The neural mechanism of the AB is still in hot debate. With a large sample size, we combined multiple behavioral tests, multimodal MRI measures, and transcranial magnetic stimulation to investigate the neural basis underlying the individual differences in the AB. We found that AB magnitude correlated with the executive control functioning of working memory (WM) in behavior, which was fully mediated by T1 performance. Structural variations in the right temporoparietal junction (rTPJ) and its intrinsic functional connectivity with the left inferior frontal junction (lIFJ) accounted for the individual differences in the AB, which was moderated by the executive control of working memory. Disrupting the function of the lIFJ attenuated the AB deficit. Our findings clarified the neural correlates of the individual differences in the AB and elucidated its relationship with the consolidation-driven inhibitory control process.

Perceived Duration Depends Upon Target Detection in Rapid Serial Visual Presentation Sequence

It is well known that the perceived duration for a given time period decreases with the reduction of the number of perceived events. We examined whether target detection failures in viewing Rapid Serial Visual Presentation (RSVP) sequence, caused by attentional blink, affect this reduction of perceived duration. In two experiments, trials consisted of displays of two series of RSVP sequences; in the first sequence (the comparison), two, one, or no numerals were presented as targets embedded within the string of letters, while in the second sequence (the standard), only alphabetic letters were presented. In each trial, participants judged whether the duration of the comparison is perceived as longer than that of the standard (Experiment 1), or whether the number of frames in the comparison is perceived as more than that in the standard (Experiment 2). Results showed that perceived duration was inflated with target detection, but not with the increment of presented frames although number of perceived frames was inflated with both target detection and increment of presented frames. These results suggest that perceived duration in viewing RSVP sequences is determined by the cognitive load necessary to accomplish target detection rather than by the number of perceived frames.

Coordinating the interaction between past and present: Visual working memory for feature bindings overwritten by subsequent action to matching features

The object-file framework forwarded by Kaheman, Treisman, and Gibbs (1992) has been enormously influential in our understanding of how the visual system links together prior visual content with a current input. Although this framework was initially developed to account for the perceptual benefits associated with feature conjunction repetitions, the present series of experiments examines how the core processes of this framework may also help explain behavior in tasks that require explicit remembering of visual information over the short term. Building off our previous work (Fiacconi & Milliken, 2012, 2013), here we introduce a procedure that affords the opportunity to examine the contributions of object-file review processes to both speeded performance and visual short-term memory (VWM) within the same task. Across two experiments we demonstrate a novel coupling between memory accuracy and speeded performance, such that the conditions that promote faster performance also tend to produce better memory, and vice versa. These findings are discussed in relation to the object-file framework and suggest that the object-file review processes known to guide behavior in speeded performance tasks may also have important mnemonic consequences. Together, these findings unite two lines of research to which Anne Treisman made indelible contributions.

Fearful expressions of rapidly presented hybrid-faces modulate the lag 1 sparing in the attentional blink

There is evidence that emotional stimuli impair attention for subsequent stimuli when presented in rapid visual succession. We investigated whether non-visible emotions of hybrid faces showing either happy or afraid expressions only in their Low Spatial Frequencies (LSF) and neutral expressions in their High Spatial Frequencies (HSF) modulate temporal selective attention. In a Rapid Serial Visual Presentation (RSVP) paradigm, two target-faces (T1 and T2) were presented briefly at different temporal distances (lags) in a stream of inverted distractor-faces: T1s were either neutral, happy-hybrid or afraid-hybrid faces; T2s were always neutral faces. When participants reported T1 and T2 gender, performance was impaired across all early lags, especially after afraid-hybrid faces. When participants reported T1 orientation and T2 gender, results showed that the LSF emotion of T1s affected temporal selective attention engendering a longer AB (over lag 2 and lag 3) than neutral T1s. Interestingly, only afraid-hybrid T1s improved processing of T2 at lag 1 (i.e., sparing). Our findings show that some core emotional content is implicitly processed from the LSF of hybrid T1s since the effects on temporal selective attention are emotion specific.

Attentional flexibility and prioritization improves long-term memory

Recent evidence suggests the focus of attention (FoA) is a flexible resource within working memory (WM) used to temporarily maintain some information in a highly accessible state. This flexibility comes at the expense of other representations, demonstrating a resource trade-off in WM maintenance. The present experiments evaluate how flexibility within the FoA impacts long-term memory (LTM) for semantically meaningful information. A WM probe-recognition task was used in which two items were presented in black and a single item was presented in red. To encourage the prioritization and uninterrupted preferential maintenance of specific items, a process we call online refreshing, the red item was associated with a greater point-reward value than were the black items. This WM task was followed by a surprise delayed LTM test. In Experiment 1, the FoA flexibly adjusted to maintain non-recent semantic information with evidence for a resource trade-off across list positions. Flexibility also directly improved LTM. In Experiment 2, reward value was equated across red and black items to evaluate whether an alternative explanation, distinctiveness of encoding, could account for the LTM findings. When reward value was equated, the cued item did not encourage flexible orienting of the FoA toward non-recent items and there was no benefit of the distinct red item on LTM performance. While supportive of past research, these data further demonstrate that semantic information can be flexibly prioritized at the expense of other list positions and that this is directly tied to improvements in LTM.

Action Real-Time Strategy Gaming Experience Related to Increased Attentional Resources: An Attentional Blink Study

Action real-time strategy gaming (ARSG) is a cognitively demanding task which requires attention, sensorimotor skills, team cooperation, and strategy-making abilities. A recent study found that ARSG experts had superior visual selective attention (VSA) for detecting the location of a moving object that could appear in one of 24 different peripheral locations (Qiu et al., 2018), suggesting that ARSG experience is related to improvements in the spatial component of VSA. However, the influence of ARSG experience on the temporal component of VSA-the detection of an item among a sequence of items presented consecutively and quickly at a single location-still remains understudied. Using behavioral and electrophysiological measures, this study examined whether ARSG experts had superior temporal VSA performance compared to non-experts in an attentional blink (AB) task, which is typically used to examine temporal VSA. The results showed that the experts outperformed the non-experts in their detection rates of targets. Furthermore, compared to the non-experts, the experts had faster information processing as indicated by earlier P3 peak latencies in an AB period, more attentional resources distributed to targets as indicated by stronger P3 amplitudes, and a more flexible deployment of attentional resources. These findings suggest that experts were less prone to the AB effect. Thus, long-term ARSG experience is related to improvements in temporal VSA. The current findings support the benefit of video gaming experience on the development of VSA.

Cognitive architecture and capacity of the cognitive system responsible for Same - Different judgments

Participants tend to match identical pairs of stimuli faster than different pairs. Despite many endeavours to explain this fast-same effect, there is still no theoretical consensus. A potential reason for the lack of consensus is that the cognitive architecture and capacity underlying such phenomenon is assumed and not formally tested. For example, the dual-process approach suggests that Same responses arise from a parallel treatment, whereas Different responses arise from a serial treatment. It also suggests that in both conditions, the capacity of the process is unaffected by workload (unlimited capacity). Alternative approaches argue that the fast-same effect can be explained by parallel or coactive architectures with channels working in either limited or super capacity. In this study, we formally assess the architecture (three possibilities: serial, parallel and coactive) and the capacity (three possibilities: unlimited, limited and super-capacity) of the cognitive system in a Same-Different task using Systems Factorial Technology (SFT). We recruited twenty participants to perform a double-factorial task lasting four sessions. Because of the lack of effectiveness of the blurring manipulation, we cannot draw a strong conclusion about the cognitive architecture. As for the capacity, the results show that it is mostly limited for the majority of participants. However, between 300 and 500 ms, participants tend to have a much stronger processing capacity in the Same condition compared to the Different condition. This short but strong burst of activity for identical stimuli might explain the fast-same effect.

Attentional Access to Multiple Target Objects in Visual Search

Most investigations of visual search have focused on the discrimination between a search target and other task-irrelevant distractor objects (selection). The attentional limitations that arise when multiple target objects in the same display have to be processed simultaneously (access) remain poorly understood. Here, we employed behavioral and electrophysiological measures to investigate the factors that determine whether multiple target objects can be accessed in parallel. Performance and N2pc components were measured for search displays that contained either a single target or two target objects. When two target objects were present, they either had the same or different target-defining features. Participants reported whether search displays contained a single target, two targets with shared features, or two targets with different features. There were performance costs as well as reduced N2pc amplitudes for two-target/different relative to two-target/same displays, suggesting that access to multiple target objects defined by different features was impaired. These behavioral and electrophysiological costs were also observed in a task where all search display objects were physically different, but not during color or shape singleton search, confirming that they do not reflect a low-level perceptual grouping of physically identical targets. These results demonstrate strong feature-specific limitations of visual access, as proposed by the Boolean map theory of visual attention. They suggest that multiple target objects can be accessed in parallel only when they share task-relevant features and demonstrate that mechanisms of visual access can be studied with electrophysiological markers.

Do familiar memory items decay?

There is a long-standing debate over whether the passage of time causes forgetting from working memory, a process called trace decay. Researchers providing evidence against the existence of trace decay generally study memory by presenting familiar verbal memory items for 1 s or more per memory item, during the study period. In contrast, researchers providing evidence for trace decay tend to use unfamiliar nonverbal memory items presented for 1 s or less per memory item, during the study period. Taken together, these investigations suggest that familiar items may not decay while unfamiliar items do decay. The availability of verbal rehearsal and the time to consolidate a memory item into working memory during presentation may also play a role in whether or not trace decay will occur. Here we explore these alternatives in a series of experiments closely modeled after studies demonstrating time-based forgetting from working memory, but using familiar verbal memory items in place of the unfamiliar memory items used to observe decay in the past. Our findings suggest that time-based forgetting is persistent across all of these factors while simultaneously challenging prominent views of trace decay. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

What do people typically do between list items? The nature of attention-based mnemonic activities depends on task context

It is commonly assumed that attention-demanding postencoding processes take place during the free time immediately following encoding of each memory item in a list. These processes are thought to prevent loss of information from working memory (WM). We tested whether interitem pauses during presentation of a list are used to focus attention (a) on the last-presented memory item or (b) on all items currently in WM, and (c) whether this changes over time. Here, we presented black probe letters between to-be-remembered red letters. Participants judged whether each probe letter corresponded to the last-presented memory item (last-item match group) or to any of the memory items presented up to that point in the list (any-item match group). To examine mnemonic processing as a function of time, the delay between the to-be-remembered letter and the following probe was manipulated in three experiments. When preprobe delays and interitem intervals were relatively short (Experiment 1), recall performance was observed to be better in the last-item match group and this did not change as a function of the duration of the delay before the probe. When preprobe delays and interitem intervals were longer however (Experiment 2), this disruptive effect of Any-item match instructions was no longer observed. This pattern was found again in Experiment 3 and suggests that the nature of the attention-demanding postencoding processes taking place in between memory items depends on task context in a systematic manner. The results are discussed in terms of previously proposed attention-demanding processes; specifically, consolidation and refreshing. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

An attentional blink in the absence of spatial attention: a cost of awareness?

The attentional blink refers to the finding that when two visual targets appear within 200-500 ms, observers often miss the second target. In three experiments, we disentangle the roles of spatial attention to and conscious report of the first event in eliciting this cost. We show that allocating spatial attention to the first event is not necessary for a blink to occur: the full temporal pattern of the blink arises when the first event is consciously detected, despite the fact that it is not spatially attended, whereas no cost is observed when the first event is missed. We then show that spatial attention is also not sufficient for eliciting a blink, though it can deepen the blink when accompanied by conscious detection. These results demonstrate that there is no cost associated with the initiation of an attentional episode, whereas explicit conscious detection comes at a price. These findings demonstrate the temporal flexibility of attention and underscore the potential role of subjective awareness in understanding processing limitations, although this role may be contingent on the encoding in working memory necessary for conscious report.

Attention flexibly trades off across points in time

Sensory signals continuously enter the brain, raising the question of how perceptual systems handle this constant flow of input. Attention to an anticipated point in time can prioritize visual information at that time. However, how we voluntarily attend across time when there are successive task-relevant stimuli has been barely investigated. We developed a novel experimental protocol that allowed us to assess, for the first time, both the benefits and costs of voluntary temporal attention when perceiving a short sequence of two or three visual targets with predictable timing. We found that when humans directed attention to a cued point in time, their ability to perceive orientation was better at that time but also worse earlier and later. These perceptual tradeoffs across time are analogous to those found across space for spatial attention. We concluded that voluntary attention is limited, and selective, across time.

The attentional blink: why does Lag-1 sparing occur when the dependent measure is accuracy, but Lag-1 deficit when it is RT?

Perception of the second of two targets (T1, T2) displayed in rapid sequence is impaired if it comes shortly after the first (attentional blink, AB). In an exception, known as Lag-1 sparing, T2 is virtually unimpaired if it is presented directly after T1. Three experiments examined the seemingly inconsistent findings that Lag-1 sparing occurs in accuracy but Lag-1 deficit occurs in RT. Experiment 1 pointed to masking of T2 as the critical factor. When T2 was not masked, the results replicated the conventional findings. The novel finding was that Lag-1 sparing occurred in RT, provided that T2 was masked. An account was provided by a psychological refractory period-based model in which processing was said to occur in two broadly sequential stages: stimulus selection and response planning. Experiments 2 and 3 tested predictions from the PRP-based model regarding Lag-1 sparing/Lag-1 deficit. In Experiment 2, we increased T2 salience, notionally reducing the duration of the T2 selection stage, with corresponding reduction in Lag-1 sparing. In Experiment 3, we manipulated the compatibility between the T1 stimulus and the response to notionally decrease/increase the duration of the T1 response-planning stage with corresponding increment/decrement in Lag-1 sparing. The results of both experiments confirmed predictions from the PRP-based model.

Sparing and impairing: Emotion modulation of the attentional blink and the spread of sparing in a 3-target RSVP task

The performance impairment (attentional blink, AB) on a second target (T2) when it is presented within 200-500 ms after a first target (T1) during rapid serial visual presentation (RSVP) is typically attributed to resource depletion. The AB does not occur when targets appear in immediate sequence (sparing). Recently, this account has been challenged by findings that the lag 1 sparing can spread to later lags when using a 3-target RSVP. Two experiments using the 3-targets RSVP investigated the relative contribution of resource depletion and attentional enhancement and/or inhibition on the AB and the sparing when T1 (Exp. 1) or T3 (Exp. 2) are emotionally salient. Findings showed a greater sparing for neutral T3s when preceded by negative compared with neutral T1s (Exp. 1) and for negative T3s (Exp. 2). In contrast, the AB on neutral T3s was greater after negative than after neutral T1s (Exp. 1), but it was reduced when T3 was negative (Exp. 2). The AB and the sparing also depended on how many targets before T3 were correctly reported. These findings indicate that although there is a cost for processing multiple targets, the emotional modulations of the AB and the sparing are better explained by an interplay between emotion-enhancement and capacity limitations on temporal selective attention.

What You See Is What You Remember: Visual Chunking by Temporal Integration Enhances Working Memory

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 integration of successive target stimulus pairs embedded in rapid serial visual presentation. ERPs were measured as a function of behavioral reports: One target, two separate targets, or two targets reported as a single integrated target. N2pc amplitude, reflecting attentional processing, depended on the actual number of successive targets. The memory-related CDA and P3 components instead depended on the perceived number of targets irrespective of their actual succession. The report of two separate targets was associated with elevated amplitude, whereas integrated as well as actual single targets exhibited lower amplitude. Temporal integration thus provided an efficient means of processing sensory input, offloading working memory so that the features of two targets were consolidated and maintained at a cost similar to that of a single target.

Summary statistics in the attentional blink

We used the attentional blink (AB) paradigm to investigate the processing stage at which extraction of summary statistics from visual stimuli ("ensemble coding") occurs. Experiment 1 examined whether ensemble coding requires attentional engagement with the items in the ensemble. Participants performed two sequential tasks on each trial: gender discrimination of a single face (T1) and estimating the average emotional expression of an ensemble of four faces (or of a single face, as a control condition) as T2. Ensemble coding was affected by the AB when the tasks were separated by a short temporal lag. In Experiment 2, the order of the tasks was reversed to test whether ensemble coding requires more working-memory resources, and therefore induces a larger AB, than estimating the expression of a single face. Each condition produced a similar magnitude AB in the subsequent gender-discrimination T2 task. Experiment 3 additionally investigated whether the previous results were due to participants adopting a subsampling strategy during the ensemble-coding task. Contrary to this explanation, we found different patterns of performance in the ensemble-coding condition and a condition in which participants were instructed to focus on only a single face within an ensemble. Taken together, these findings suggest that ensemble coding emerges automatically as a result of the deployment of attentional resources across the ensemble of stimuli, prior to information being consolidated in working memory.

Perceptual episodes, temporal attention, and the role of cognitive control: Lessons from the attentional blink

The ability to identify a target is usually hindered if it appears shortly after another target. This simple and somewhat intuitive observation is qualified by a multitude of unexpected findings and conflicting theories that originate from the attentional blink paradigm. In this review, the major results, implications, and outstanding questions that stem from the paradigm are presented and discussed. The extant literature suggests that when the temporal domain is densely stacked with numerous stimuli, the entities that underlie attentional selection and cognitive control are brief perceptual episodes. Specifically, attention is deployed over an interval that frequently encompasses several stimuli. Most theories agree that the length and boundaries of this interval are influenced by cognitive control mechanisms. However, there is little agreement as to the extent and nature of this influence. Some theories suggest that control is needed in order to initiate a temporally limited attentional response. Other theories argue that cognitive control is actively suppressing attentional mechanisms in order to terminate the perceptual episode. Another formulation suggests that both ends of the interval are partially controlled and that the exertion of control corresponds to the focusing of attention on a narrow interval. The contents of perceptual episodes, as well as their deficiencies, can shed light on the features that guide attentional deployment, the goals that guide cognitive control, and the interactions between these mechanisms. Electrophysiological recordings are extremely useful when one tries to pinpoint the timing of attentional selection. Other neural indicators can elucidate the factors that define perceptual episodes.

Right visual-field advantage in the attentional blink: Asymmetry in attentional gating across time and space

When two targets are presented in a rapid serial visual presentation (RSVP), recognition of the second target (T2) is usually reduced when presented 150-500 ms after the first target, demonstrating an attentional blink (AB). Previous studies have shown a left visual-field (LVF) advantage in T2 recognition, when T2 was embedded in one of two streams, demanding top-down attention for its recognition. Here, we explored the impact of bottom-up saliency on spatial asymmetry in the AB. When T2 was spatially shifted outside from the RSVP, creating an abrupt onset of T2, right T2s showed a right visual-field (RVF) advantage. In lag-1 trials, right T2s were not only better recognized, but also showed a low T1-T2 order error rate. In contrast, recognized left T2s exhibited high order error rate. Without abrupt onset, symmetrical AB was found and order error rate was similarly low in both sides. Follow-up experiments showed that, while RVF advantage was related to bottom-up saliency, order errors were affected by T1 mask. The discrepancy between LVF and RVF advantage in the AB could be resolved in terms of two mechanisms of attentional gating: top-down attentional gating, which is biased towards LVF, and bottom-up attentional gating, which is biased towards RVF.

Adults blink more deeply: a comparative study of the attentional blink across different age groups

The attentional blink (AB) is thought to help the visual system parse and categorize rapidly changing information by segmenting it into temporal chunks, and is elicited using Rapid Serial Visual Presentation. It is reflected in a decrease in accuracy at detecting the second of two targets presented within 200-500 ms of the first, and its development appears to be protracted on tasks that require set-shifting. Here, younger (M = 8.5 years) and older (M = 12.8 years) children and adults (M = 19.13 years) completed a simple AB task with no set-shift requirement in which participants detected two letters in a stream of numbers presented at a rate of 135 ms/item. In addition to assessing the developmental course of the AB on this simple task, we also assessed temporal order errors, or swaps. The AB and its associated characteristics are present in both groups but developmental differences were noted in the depth of the AB, and the presence or absence of lag-1 sparing. These developmental changes were explained by changes in a single parameter, inhibition, using the eTST model, which suggests that the AB is an adaptive function of the visual system.

Reconsidering Temporal Selection in the Attentional Blink

Two episodes of attentional selection cannot occur very close in time. This is the traditional account of the attentional blink, whereby observers fail to report the second of two temporally proximal targets. Recent analyses have challenged this simple account, suggesting that attentional selection during the attentional blink is not only (a) suppressed, but also (b) temporally advanced then delayed, and (c) temporally diffused. Here, we reanalyzed six data sets using mixture modeling of report errors, and revealed much simpler dynamics. Exposing a problem inherent in previous analyses, we found evidence of a second attentional episode only when the second target (T2) follows the first (T1) by more than 100 to 250 ms. When a second episode occurs, suppression and delay reduce steadily as lag increases and temporal precision is stable. At shorter lags, both targets are reported from a single episode, which explains why T2 can escape the attentional blink when it immediately follows T1 (Lag-1 sparing).

Extended temporal integration in rapid serial visual presentation: Attentional control at Lag 1 and beyond

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 performance in classic paradigms. Yet, most current models of temporal attention do not incorporate a mechanism of temporal integration and it is currently an open question whether temporal integration is a factor in attentional processing: It might be an independent process, perhaps little more than a sensory sampling rate parameter, isolated to Lag 1, where it leaves the attentional dynamics otherwise unaffected. In the present study, these boundary conditions were tested. Temporal target integration was observed across sequences of three targets spanning an interval of 240ms. Integration rates furthermore depended strongly on bottom-up attentional filtering, and to a lesser degree on top-down control. The results support the idea that temporal integration is an adaptive process that is part of, or at least interacts with, the attentional system. Implications for current models of temporal attention are discussed.

Pre-target oscillatory brain activity and the attentional blink

Reporting the second of two targets within a stream of distracting words during rapid serial visual presentation (RSVP) is impaired when the targets are separated by a single distractor word, a deficit in temporal attention that has been referred to as the attentional blink (AB). Recent conceptual and empirical work has pointed to pre-target brain states as potential mediators of the AB effect. The current study examined differences in pre-target electrophysiology between correctly and incorrectly reported trials, considering amplitude and phase measures of alpha oscillations as well as the steady-state visual evoked potential (ssVEP) evoked by the RSVP stream. For incorrectly reported trials, relatively lower alpha-band power and greater ssVEP inter-trial phase locking were observed during extended time periods preceding presentation of the first target. These results suggest that facilitated processing of the pre-target distracter stream indexed by reduced alpha and heightened phase locking characterizes a dynamic brain state that predicts lower accuracy in terms of reporting the second target under strict temporal constraints. Findings align with hypotheses in which the AB effect is attributed to neurocognitive factors such as fluctuations in pre-target attention or to cognitive strategies applied at the trial level.

The whole is faster than its parts: evidence for temporally independent attention to distinct spatial locations

Behavioral and electrophysiological evidence suggests that visual attention operates in parallel at distinct spatial locations and samples the environment in periodic episodes. This combination of spatial and temporal characteristics raises the question of whether attention samples locations in a phase-locked or temporally independent manner. If attentional sampling rates were phase locked, attention would be limited by a global sampling rate. However, if attentional sampling rates were temporally independent, they could operate additively to sample higher rates of information. We tested these predictions by requiring participants to identify targets in 2 or 4 rapid serial visual presentation (RSVP) streams, synchronized or asynchronized to manipulate the rate of new information globally (across streams). Identification accuracy exhibited little or no change when the global rate of new information doubled from 7.5 to 15 Hz (Experiment 1) or quadrupled to 30 Hz (Experiment 2). This relatively stable identification accuracy occurred even though participants reliably discriminated 7.5 Hz synchronous displays from displays globally asynchronized at 15 and 30 Hz (Metamer Control Experiment). Identification accuracy in the left visual field also significantly exceeded that in the right visual field. Overall, our results are consistent with temporally independent attention across distinct spatial locations and support previous reports of a right parietal "when" pathway specialized for temporal attention.