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There is consistent debate over whether capacity in working memory (WM) is subject to an item limit, or whether an unlimited number of items can be held in this online memory system. The item limit hypothesis clearly predicts guessing responses when capacity is exceeded, and proponents of this view have highlighted evidence for guessing in visual working memory tasks. Nevertheless, various models that deny item limits can explain the same empirical patterns by asserting extremely low fidelity representations that cannot be distinguished from guesses. To address this ambiguity, we employed a task for which guess responses elicited a qualitatively distinct pattern from low fidelity memories. Inspired by work from Rouder et al. (2014), we employed an orientation WM task that required subjects to recall the precise orientation of each of six memoranda presented 1 s earlier. The orientation stimuli were created by rotating the position of a "clock hand" inside a circular region that was demarcated by four colored quadrants. Critically, when observers guess with these stimuli, the distribution of responses is biased towards the center of these quadrants, creating a "banded" pattern that cannot be explained by a low precision memory. We confirmed the presence of this guessing pattern using formal model comparisons, and we show that the prevalence of this pattern matches observers' own reports of when they thought they were guessing. Thus, these findings provide further evidence for guessing behaviors predicted by item limit models of WM capacity. [ABSTRACT FROM AUTHOR]

The change detection paradigm has been a widely used approach for measuring capacity in visual working memory (WM). In this task, subjects see an array of visual items, followed by a short blank delay and a single test item. Their task is to indicate whether that test item changed relative to the item in the sample array. This task provides reliable measurements of WM capacity that exhibit robust correlations with many outcome variables of interest. Here, we offer a new variant of this task that we call "change localization." This task is closely modeled after the change detection task described above, except that the test array contains the same number of items as the sample array, and one item has always changed in each trial. The subject's task is to select the changed item in the test array. Using both color and shape stimuli, scores in the change localization task were highly correlated with those in the change detection task, suggesting that change localization taps into the same variance in WM ability. Moreover, the change localization task was far more reliable than change detection, such that only half the number of trials were required to achieve robust reliability. To further validate the approach, we replicated known effects from the literature, demonstrating that they could be detected with far fewer trials than with change detection. Thus, change localization provides a highly reliable and sensitive approach for measuring visual working memory capacity. [ABSTRACT FROM AUTHOR]

There exists an intricate relationship between attention and working memory. Recent work has further established that attention and working memory fluctuate synchronously, by tightly interleaving sustained attention and working memory tasks. This work has raised many open questions about physiological signatures underlying these behavioral fluctuations. Across two experiments, we explore pupil dynamics using real-time triggering in conjunction with an interleaved sustained attention and working memory task. In Experiment 1, we use behavioral real-time triggering and replicate recent findings from our lab (deBettencourt et al., 2019) that sustained attention fluctuates concurrently with the number of items maintained in working memory. Furthermore, highly attentive moments, detected via behavior, also exhibited larger pupil sizes. In Experiment 2, we develop a novel real-time pupil-triggering technique to track pupil size fluctuations in real time and trigger working memory probes. We show that this pupil triggering procedure reveals differences in sustained attention, as indexed by response time. These experiments reflect methodological advances in real-time triggering and further disentangle the relationship among general arousal, sustained attention, and working memory. [ABSTRACT FROM AUTHOR]

Working memory maintains information in a readily accessible state and has been shown to degrade as the length of the retention interval increases. Previous research has suggested that this decline is attributable to changes in precision as well as sudden loss of item representations. Here, by measuring trial-to-trial variations in performance, we examined an orthogonal distinction between the maximum number of items that an individual can store, and the probability of achieving that maximum. Across two experiments, we replicated the finding that performance declines after long (10 s) retention intervals, as well as past observations that forgetting was due to probabilistic dropping of individual items rather than all-or-none losses of the stored memories. Critically, longer retention intervals did not reduce the maximum amount of information that could be stored in working memory. Instead, lower attentional control accounted for a decreased probability of maintaining the maximum number of items in working memory. Thus, longer retention intervals impact working memory storage via fluctuations in attentional control that lower the probability of achieving a stable maximum storage capacity. [ABSTRACT FROM AUTHOR]

Biased-competition models assert that spatial attention facilitates visual perception by biasing competitive interactions in favor of relevant input. In line with this view, past work has shown that the benefits of covert spatial attention are greatest when targets must compete with interfering stimuli. Here we propose a boundary condition for the resolution of interference via exogenous attention: Attention resolves visual interference between targets and distractors, but only when they can be individuated into distinct representations. Thus, we propose that biased competition may be object-based. We replicated previous observations of larger attention effects when targets were flanked by irrelevant distractors (interference-present displays) than when targets were presented alone (interference-absent displays). Critically, we then showed that this amplification of cueing effects in the presence of interference is eliminated when strong crowding hampers individuation of the targets and distractors. Likewise, when targets were embedded within a noise mask that did not evoke the percept of an individuated distractor, the attention effects were equivalent across noise and lone-target displays. Thus, we conclude that exogenous spatial attention resolves interference in an object-based fashion that depends on the perception of individuated targets and distractors. [ABSTRACT FROM AUTHOR]

Numerous studies have demonstrated that retrieval from long-term memory (LTM) can enhance subsequent memory performance, a phenomenon labeled the retrieval practice effect. However, the almost exclusive reliance on categorical stimuli in this literature leaves open a basic question about the nature of this improvement in memory performance. It has not yet been determined whether retrieval practice improves the probability of successful memory retrieval or the quality of the retrieved representation. To answer this question, we conducted three experiments using a mixture modeling approach (Zhang & Luck, ) that provides a measure of both the probability of recall and the quality of the recalled memories. Subjects attempted to memorize the color of 400 unique shapes. After every 10 images were presented, subjects either recalled the last 10 colors (the retrieval practice condition) by clicking on a color wheel with each shape as a retrieval cue or they participated in a control condition that involved no further presentations (Experiment 1) or restudy of the 10 shape/color associations (Experiments 2 and 3). Performance in a subsequent delayed recall test revealed a robust retrieval practice effect. Subjects recalled a significantly higher proportion of items that they had previously retrieved relative to items that were untested or that they had restudied. Interestingly, retrieval practice did not elicit any improvement in the precision of the retrieved memories. The same empirical pattern also was observed following delays of greater than 24 hours. Thus, retrieval practice increases the probability of successful memory retrieval but does not improve memory quality. [ABSTRACT FROM AUTHOR]

A classic question concerns whether humans can attend multiple locations or objects at once. Although it is generally agreed that the answer to this question is 'yes,' the limits on this ability are subject to extensive debate. According to one view, attentional resources can be flexibly allocated to a variable number of locations, with an inverse relationship between the number of selected locations and the quality of information processing at each location. Alternatively, these resources might be quantized in a 'discrete' fashion that enables concurrent access to a small number of locations. Here, we report a series of experiments comparing these alternatives. In each experiment, we cued participants to attend a variable number of spatial locations and asked them to report the orientation of a single, briefly presented target. In all experiments, participants' orientation report errors were well-described by a model that assumes a fixed upper limit in the number of locations that can be attended. Conversely, report errors were poorly described by a flexible-resource model that assumes no fixed limit on the number of locations that can be attended. Critically, we showed that these discrete limits were predicted by cue-evoked neural activity elicited before the onset of the target array, suggesting that performance was limited by selection processes that began prior to subsequent encoding and memory storage. Together, these findings constitute novel evidence supporting the hypothesis that human observers can attend only a small number of discrete locations at an instant. [ABSTRACT FROM AUTHOR]

The precision of visual working memory (WM) representations declines monotonically with increasing storage load. Two distinct models of WM capacity predict different shapes for this precision-by-set-size function. Flexible-resource models, which assert a continuous allocation of resources across an unlimited number of items, predict a monotonic decline in precision across a large range of set sizes. Conversely, discrete-resource models, which assert a relatively small item limit for WM storage, predict that precision will plateau once this item limit is exceeded. Recent work has demonstrated such a plateau in mnemonic precision. Moreover, the set size at which mnemonic precision reached asymptote has been strongly predicted by estimated item limits in WM. In the present work, we extend this evidence in three ways. First, we show that this empirical pattern generalizes beyond orientation memory to color memory. Second, we rule out encoding limits as the source of discrete limits by demonstrating equivalent performance across simultaneous and sequential presentations of the memoranda. Finally, we demonstrate that the analytic approach commonly used to estimate precision yields flawed parameter estimates when the range of stimulus space is narrowed (e.g., a 180º rather than a 360º orientation space) and typical numbers of observations are collected. Such errors in parameter estimation reconcile an apparent conflict between our findings and others based on different stimuli. These findings provide further support for discrete-resource models of WM capacity. [ABSTRACT FROM AUTHOR]

A core tenet of the original conflict-monitoring model is that regulation is triggered automatically when conflict is present and that the same regulation mechanism explains both trial-to-trial adaptation effects as well as effects of block-wise conflict manipulations. We present here results from two experiments using the Stroop task that show (a) that adaptation effects in the absence of response repetitions may occur only at the beginning of testing and that (b) robust block-wise effects can be found even in the absence of trial-by-trial effects. Furthermore, we show that the failure to eliminate target-to-distractor repetitions can produce artificial trial-to-trial adaptation effects. Based on the evidence of a weak link between conflict and conflict adaptation, we argue that a wider range of possible reasons for conflict adaptation effects needs to be taken into consideration. [ABSTRACT FROM AUTHOR]

According to the 'conflict-monitoring' model, a leading theory of cognitive control, information-processing conflict registered in the anterior cingulate cortex (ACC) triggers the prefrontal cortex to reduce conflict susceptibility. Here we show that the existing empirical support for an online modulation of susceptibility to conflict through immediately preceding conflict, the 'conflict-adaptation effect', needs to be reevaluated. In a human cognitive control task, we found that it was not the stimulus-independent level of conflict that was responsible for the conflict-adaptation effect but rather an episodic memory phenomenon: stimulus-specific priming. [ABSTRACT FROM AUTHOR]

The article discusses a study about the development of an approach that uses functional magnetic resonance imaging (fMRI) in real time to detect when the subject's brain is no longer in an attentive state and provides them with continuous feedback to get them back on track. The study required subjects to attend to either the face or scene aspect of a composite stimulus. It suggested that the neurofeedback improves behavioral performance.

The article focuses on the functional imaging study suggesting that basal ganglia act as filter in the brain which is inversely correlated with unnecessary storage before stimulus presentation. It is emphasized that efficiency variations in filtering of relevant from irrelevant information could contribute to individual differences in working memory. The study suggests that important cognitive differences between individuals may stem from interaction of basal ganglia and prefrontal cortex (PFC).

A retraction of the article "The plateau in mnemonic resolution across large set sizes indicates discrete resource limits in visual working memory" published in the journal "Atten Percept Psychophys" in 2015 is presented.

The anterior cingulate cortex is involved in decisions between conflicting response tendencies. This executive function seems to involve separate pathways for manual and verbal responses. [ABSTRACT FROM AUTHOR]