Search

Salience is a core determinant of attentional processing. Although information on salience has been shown to dissipate within a few hundred milliseconds, we recently observed massive effects of salience on the delayed recall from visual working memory (VWM) more than 1300 ms after stimulus onset. Here, we manipulated presentation duration of the memory display and found that effects of salience, albeit decreasing over time, were still markedly present after 3000 ms (2000 ms presentation; Exp. 1). In an attempt to overrule this persistent influence of salience we made less salient stimuli more relevant (by rewarding their prioritized processing in Exp. 2 or by probing them more often in Exp. 3). Participants were unable to reliably prioritize low-salience stimuli. Thus, our results demonstrate that effects of salience or their repercussions have surprisingly long-lasting effects on cognitive performance that reach even relatively late processing stages and are difficult to overrule by volition.

Visual short-term memory (VSTM) ability falls throughout the life span in healthy adults. Using a continuous report task, in a large, population-based sample, we first confirmed that this decline affects the quality and quantity of reported memories as well as knowledge of which item went where. Visual and sensorimotor precision also worsened with advancing age, but this did not account for the reduced memory performance. We then considered two strategies that older individuals might be able to adopt, to offset these memory declines: the use of contextual encoding, and metacognitive monitoring of performance. Context and metacognitive awareness were both associated with significantly better performance, however these effects did not interact with age in our sample. This suggests that older adults retain their capacity to boost memory performance through attention to external context and monitoring of their performance. Strategies that focus on taking advantage of these preserved abilities may therefore help to maintain VSTM performance with advancing age. The article reports on analysis of the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) data. (PsycINFO Database Record

Interference disrupts information processing across many timescales, from immediate perception to memory over short and long durations. The widely held similarity assumption states that as similarity between interfering information and memory contents increases, so too does the degree of impairment. However, information is lost from memory in different ways. For instance, studied content might be erased in an all-or-nothing manner. Alternatively, information may be retained but the precision might be degraded or blurred. Here, we asked whether the similarity of interfering information to memory contents might differentially impact these 2 aspects of forgetting. Observers studied colored images of real-world objects, each followed by a stream of interfering objects. Across 4 experiments, we manipulated the similarity between the studied object and the interfering objects in circular color space. After interference, memory for object color was tested continuously on a color wheel, which in combination with mixture modeling, allowed for estimation of how erasing and blurring differentially contribute to forgetting. In contrast to the similarity assumption, we show that highly dissimilar interfering items caused the greatest increase in random guess responses, suggesting a greater frequency of memory erasure (Experiments 1-3). Moreover, we found that observers were generally able to resist interference from highly similar items, perhaps through surround suppression (Experiments 1 and 4). Finally, we report that interference from items of intermediate similarity tended to blur or decrease memory precision (Experiments 3 and 4). These results reveal that the nature of visual similarity can differentially alter how information is lost from memory. (PsycINFO Database Record

Short-term consolidation is the process by which stable working memory representations are created. This process is fundamental to cognition yet poorly understood. The present work examines short-term consolidation using a Bayesian hierarchical model of visual working memory recall to determine the underlying processes at work. Our results show that consolidation functions largely through changing the proportion of memory items successfully maintained until test. Although there was some evidence that consolidation affects representational precision, this change was modest and could not account for the bulk of the consolidation effect on memory performance. The time course of the consolidation function and selective influence of consolidation on specific serial positions strongly indicates that short-term consolidation induces an attentional blink. The blink leads to deficits in memory for the immediately following item when time pressure is introduced. Temporal distinctiveness accounts of the consolidation process are tested and ruled out. (PsycINFO Database Record

In this article, we demonstrate limitations of accessibility of information in visual working memory (VWM). Recently, cued-recall has been used to estimate the fidelity of information in VWM, where the feature of a cued object is reproduced from memory (Bays, Catalao, & Husain, 2009; Wilken & Ma, 2004; Zhang & Luck, 2008). Response error in these tasks has been largely studied with respect to failures of encoding and maintenance; however, the retrieval operations used in these tasks remain poorly understood. By varying the number and type of object features provided as a cue in a visual delayed-estimation paradigm, we directly assess the nature of retrieval errors in delayed estimation from VWM. Our results demonstrate that providing additional object features in a single cue reliably improves recall, largely by reducing swap, or misbinding, responses. In addition, performance simulations using the binding pool model (Swan & Wyble, 2014) were able to mimic this pattern of performance across a large span of parameter combinations, demonstrating that the binding pool provides a possible mechanism underlying this pattern of results that is not merely a symptom of one particular parametrization. We conclude that accessing visual working memory is a noisy process, and can lead to errors over and above those of encoding and maintenance limitations. (PsycINFO Database Record

A commonly expressed view is that short-term memory (STM) is nothing more than activated long-term memory. If true, this would overturn a central tenet of cognitive psychology-the idea that there are functionally and neurobiologically distinct short- and long-term stores. Here I present an updated case for a separation between short- and long-term stores, focusing on the computational demands placed on any STM system. STM must support memory for previously unencountered information, the storage of multiple tokens of the same type, and variable binding. None of these can be achieved simply by activating long-term memory. For example, even a simple sequence of digits such as "1, 3, 1" where there are 2 tokens of the digit "1" cannot be stored in the correct order simply by activating the representations of the digits "1" and "3" in LTM. I also review recent neuroimaging data that has been presented as evidence that STM is activated LTM and show that these data are exactly what one would expect to see based on a conventional 2-store view. (PsycINFO Database Record

Confidence in our memories is influenced by many factors, including beliefs about the perceptibility or memorability of certain kinds of objects and events, as well as knowledge about our skill sets, habits, and experiences. Notoriously, our knowledge and beliefs about memory can lead us astray, causing us to be overly confident in eyewitness testimony or to overestimate the frequency of recent experiences. Here, using visual working memory as a case study, we designed two experiments that strip away all these potentially misleading cues, requiring observers to make confidence judgments by directly assessing the quality of their memory representations. We show that individuals can monitor the status of information in working memory as it degrades over time. Our findings suggest that people have access to information reflecting the existence and quality of their working memories, and furthermore, that they can use this information to guide their behavior.

Findings reported in the memory literature suggest that the emotional components of an encoding episode can be dissociated from nonemotional memory. In particular, it has been found that the previous association with threatening events can be retrieved in aversive conditioning even in the absence of item identification. In the present study, we test whether emotional source memory can be independent of item recognition. Participants saw pictures of snakes paired with threatening and nonthreatening context information (poisonousness or nonpoisonousness). In the source memory test, participants were required to remember whether a snake was associated with poisonousness or nonpoisonousness. A simple extension of a well-established multinomial source monitoring model was used to measure source memory for unrecognized items. By using this model, it was possible to assess directly whether participants were able to associate a previously seen snake with poisonousness or nonpoisonousness even if the snake itself was not recognized as having been presented during the experiment. In 3 experiments, emotional source memory was only found for recognized items. While source memory for recognized items differed between emotional and nonemotional information, source memory for unrecognized items was equally absent for emotional and nonemotional information. We conclude that emotional context information is bound to item representations and cannot be retrieved in the absence of item recognition. (PsycINFO Database Record

Existing long-term memory (LTM) can boost the number of retained representations over a short delay in visual short-term memory (VSTM). However, it is unclear whether and how prior LTM affects the initial process of transforming fragile sensory inputs into durable VSTM representations (i.e., VSTM consolidation). The consolidation speed hypothesis predicts faster consolidation for familiar relative to unfamiliar stimuli. Alternatively, the perceptual boost hypothesis predicts that the advantage in perceptual processing of familiar stimuli should add a constant boost for familiar stimuli during VSTM consolidation. To test these competing hypotheses, the present study examined how the large variance in participants' prior multimedia experience with Pokémon affected VSTM for Pokémon. In Experiment 1, the amount of time allowed for VSTM consolidation was manipulated by presenting consolidation masks at different intervals after the onset of to-be-remembered Pokémon characters. First-generation Pokémon characters that participants were more familiar with were consolidated faster into VSTM as compared with recent-generation Pokémon characters that participants were less familiar with. These effects were absent in participants who were unfamiliar with both generations of Pokémon. Although familiarity also increased the number of retained Pokémon characters when consolidation was uninterrupted but still incomplete due to insufficient encoding time in Experiment 1, this capacity effect was absent in Experiment 2 when consolidation was allowed to complete with sufficient encoding time. Together, these results support the consolidation speed hypothesis over the perceptual boost hypothesis and highlight the importance of assessing experimental effects on both processing and representation aspects of VSTM. (PsycINFO Database Record

Among models of working memory, there is not yet a consensus about how to describe functions specific to storing verbal or visual-spatial memories. We presented aural-verbal and visual-spatial lists simultaneously and sometimes cued one type of information after presentation, comparing accuracy in conditions with and without informative retro-cues. This design isolates interference due specifically to maintenance, which appears most clearly in the uncued trials, from interference due to encoding, which occurs in all dual-task trials. When recall accuracy was comparable between tasks, we found that spatial memory was worse in uncued than in retro-cued trials, whereas verbal memory was not. Our findings bolster proposals that maintenance of spatial serial order, like maintenance of visual materials more broadly, relies on general rather than specialized resources, while maintenance of verbal sequences may rely on domain-specific resources. We argue that this asymmetry should be explicitly incorporated into models of working memory. (PsycINFO Database Record

We conducted a series of recognition experiments that assessed whether visual short-term memory (VSTM) is sensitive to shared category membership of to-be-remembered (tbr) images of common objects. In Experiment 1 some of the tbr items shared the same basic level category (e.g., hand axe): Such items were no better retained than others. In the remaining experiments, displays contained different images of items from the same higher-level category (e.g., food: a bagel, a sandwich, a pizza). Evidence from the later experiments did suggest that participants were sensitive to the categorical relations present in the displays. However, when separate measures of sensitivity and bias were computed, the data revealed no effects on sensitivity, but a greater tendency to respond positively to noncategory items relative to items from the depicted category. Across all experiments, there was no evidence that items from a common category were better remembered than unique items. Previous work has shown that principles of perceptual organization do affect the storage and maintenance of tbr items. The present work shows that there are no corresponding conceptual principles of organization in VSTM. It is concluded that the sort of VSTM tapped by single probe recognition methods is precategorical in nature. (PsycINFO Database Record

Recent reports have suggested that the attended features of an item may be rapidly forgotten once they are no longer relevant for an ongoing task (attribute amnesia). This finding relies on a surprise memory procedure that places high demands on declarative memory. We used intertrial priming to examine whether the representation of an item's identity is lost completely once it becomes task irrelevant. If so, then the identity of a target on one trial should not influence performance on the next trial. In 3 experiments, we replicated the finding that a target's identity is poorly recognized in a surprise memory test. However, we also observed location and identity repetition priming across consecutive trials. These data suggest that, although explicit recognition on a surprise memory test may be impaired, some information about a particular target's identity can be retained after it is no longer needed for a task. (PsycINFO Database Record

Holding recently experienced information in mind can help us achieve our current goals. However, such immediate and direct forms of guidance from working memory are less helpful over extended delays or when other related information in long-term memory is useful for reaching these goals. Here we show that information that was encoded in the past but is no longer present or relevant to the task also guides attention. We examined this by associating multiple unique features with novel shapes in visual long-term memory (VLTM), and subsequently testing how memories for these objects biased the deployment of attention. In Experiment 1, VLTM for associated features guided visual search for the shapes, even when these features had never been task-relevant. In Experiment 2, associated features captured attention when presented in isolation during a secondary task that was completely unrelated to the shapes. These findings suggest that long-term memory enables a durable and automatic type of memory-based attentional control. (PsycINFO Database Record

Visual working memory (VWM) has a limited capacity. This limitation can be mitigated by the use of focused attention: if attention is drawn to the relevant working memory content before test, performance improves (the so-called retro-cue benefit). This study tests 2 explanations of the retro-cue benefit: (a) Focused attention protects memory representations from interference by visual input at test, and (b) focusing attention enhances retrieval. Across 6 experiments using color recognition and color reproduction tasks, we varied the amount of color interference at test, and the delay between a retrieval cue (i.e., the retro-cue) and the memory test. Retro-cue benefits were larger when the memory test introduced interfering visual stimuli, showing that the retro-cue effect is in part because of protection from visual interference. However, when visual interference was held constant, retro-cue benefits were still obtained whenever the retro-cue enabled retrieval of an object from VWM but delayed response selection. Our results show that accessible information in VWM might be lost in the processes of testing memory because of visual interference and incomplete retrieval. This is not an inevitable state of affairs, though: Focused attention can be used to get the most out of VWM. (PsycINFO Database Record

Visual sensory memory refers to a transient memory lingering briefly after the stimulus offset. Although previous literature suggests that visual sensory memory is supported by a fine-grained trace for continuous representation and a coarse-grained trace of categorical information, simultaneous separation and assessment of these traces can be difficult without a quantitative model. The present study used a continuous estimation procedure to test a novel mathematical model of the dual-trace hypothesis of visual sensory memory according to which visual sensory memory could be modeled as a mixture of 2 von Mises (2VM) distributions differing in standard deviation. When visual sensory memory and working memory (WM) for colors were distinguished using different experimental manipulations in the first 3 experiments, the 2VM model outperformed Zhang and Luck (2008) standard mixture model (SM) representing a mixture of a single memory trace and random guesses, even though SM outperformed 2VM for WM. Experiment 4 generalized 2VM's advantages of fitting visual sensory memory data over SM from color to orientation. Furthermore, a single trace model and 4 other alternative models were ruled out, suggesting the necessity and sufficiency of dual traces for visual sensory memory. Together these results support the dual-trace model of visual sensory memory and provide a preliminary inquiry into the nature of information loss from visual sensory memory to WM. (PsycINFO Database Record

When people are presented with a random list of digits to remember over an interval of a few seconds, the cognitive systems that are used are mainly verbal working memory systems, and these are different from those used when remembering visuospatial information. Our previous work has demonstrated that under certain circumstances, visuospatial memory processes can assist verbal memory processes. If a sequence of random numbers is presented for immediate recall in order, memory is better if the digits are displayed on a familiar telephone keypad array compared to either an unfamiliar random keypad or a single item. We previously argued that this was evidence for the existence of processes (described in many modern theories of memory) that could integrate information held in long-term memory (knowledge about the keypad) with short-term visuospatial memory for sequences of locations and short-term verbal memory for sequences of digits. In the current article, we report a study that demonstrates that this pattern remains present in a sample of older (55–76 years) adults compared to a younger sample (19–35 years). There are important benefits of this identification of the age-resilience of linkages between different types of information in short-term memory. One specific benefit is to theories of aging, but a second, broader, benefit may be that we can capitalize upon this finding to develop strategies and techniques for boosting the efficiency of working memory in older adults, an outcome that would have many benefits to an aging population.

The capacity of visual short-term memory (VSTM) is commonly estimated by K scores obtained with a change-detection task. Contrary to common belief, K may be influenced not only by capacity but also by the rate at which stimuli are encoded into VSTM. Experiment 1 showed that, contrary to earlier conclusions, estimates of VSTM capacity obtained with a change-detection task are constrained by temporal limitations. In Experiment 2, we used change-detection and backward-masking tasks to obtain separate within-subject estimates of K and of rate of encoding, respectively. A median split based on rate of encoding revealed significantly higher K estimates for fast encoders. Moreover, a significant correlation was found between K and the estimated rate of encoding. The present findings raise the prospect that the reported relationships between K and such cognitive concepts as fluid intelligence may be mediated not only by VSTM capacity but also by rate of encoding.

By varying the probabilities that a stimulus would appear at particular times after the presentation of a cue and modeling the data by the theory of visual attention (Bundesen, 1990), Vangkilde, Coull, and Bundesen (2012) provided evidence that the speed of encoding a singly presented stimulus letter into visual short-term memory (VSTM) is modulated by the observer's temporal expectations. We extended the investigation from single-stimulus recognition to whole report (Experiment 1) and partial report (Experiment 2). Cue-stimulus foreperiods were distributed geometrically using time steps of 500 ms. In high expectancy conditions, the probability that the stimulus would appear on the next time step, given that it had not yet appeared, was high, whereas in low expectancy conditions, the probability was low. The speed of encoding the stimuli into VSTM was higher in the high expectancy conditions. In line with the Easterbrook (1959) hypothesis, under high temporal expectancy, the processing was also more focused (selective). First, the storage capacity of VSTM was lower, so that fewer stimuli were encoded into VSTM. Second, the distribution of attentional weights across stimuli was less even: The efficiency of selecting targets rather than distractors for encoding into VSTM was higher, as was the spread of the attentional weights of the target letters. (PsycINFO Database Record (c) 2014 APA, all rights reserved). Language: en

Recent empirical and theoretical work has depicted a close relationship between visual attention and visual working memory. For example, rehearsal in spatial working memory depends on spatial attention, whereas adding a secondary spatial working memory task impairs attentional deployment in visual search. These findings have led to the proposal that working memory is attention directed toward internal representations. Here we show that the close relationship between these two constructs is limited to some but not all forms of spatial attention. In five experiments, participants held color arrays, dot locations, or a sequence of dots in working memory. During the memory retention interval they performed a T-among-L visual search task. Crucially, the probable target location was cued either implicitly through location probability learning, or explicitly with a central arrow or verbal instruction. Our results showed that whereas imposing a visual working memory load diminished the effectiveness of explicit cuing, it did not interfere with probability cuing. We conclude that spatial working memory shares similar mechanisms with explicit, goal-driven attention but is dissociated from implicitly learned attention.

McDaniel and Bugg (2008) proposed that relatively uncommon stimuli and encoding tasks encourage elaborative encoding of individual items (item-specific processing), whereas relatively typical or common encoding tasks encourage encoding of associations among list items (relational processing). It is this relational processing that is thought to result in better memory for the serial order of a study list. We report 4 experiments examining memory for order demonstrating that (a) both semantic and orthographic tasks can impair memory for order when performed on individual items, (b) item-specific processing is not necessary for impairment because even an item-generic key press task harms memory for order, (c) impaired memory for order is due primarily to distraction during the processing of an item rather than between list items, and (d) even an unusual processing task will preserve memory for order as long as that task encourages the encoding of item-to-item relations. These findings suggest that an encoding task will disrupt order memory only when it is both attention grabbing (either through its atypicality or by requiring an overt response) and nonrelational.

Visual short-term memory serves as an efficient buffer for maintaining no longer directly accessible information. How robust are visual memories against interference? Memory for simple visual features has proven vulnerable to distractors containing conflicting information along the relevant stimulus dimension, leading to the idea that interacting feature-specific channels at an early stage of visual processing support memory for simple visual features. Here we showed that memory for a single randomly orientated grating was susceptible to interference from a to-be-ignored distractor grating presented midway through a 3-s delay period. Memory for the initially presented orientation became noisier when it differed from the distractor orientation, and response distributions were shifted toward the distractor orientation (by similar to 3 degrees). Interestingly, when the distractor was rendered task-relevant by making it a second memory target, memory for both retained orientations showed reduced reliability as a function of increased orientation differences between them. However, the degree to which responses to the first grating shifted toward the orientation of the task-relevant second grating was much reduced. Finally, using a dichoptic display, we demonstrated that these systematic biases caused by a consciously perceived distractor disappeared once the distractor was presented outside of participants' awareness. Together, our results show that visual short-term memory for orientation can be systematically biased by interfering information that is consciously perceived.

Pigeons' performance on a working memory task, symbolic delayed matching-to-sample, was used to examine the interaction between working memory and reference memory. Reference memory was established by training pigeons to discriminate between the comparison cues used in delayed matching as S+ and S- stimuli. Delayed matching retention tests then measured accuracy when working and reference memory were congruent and incongruent. In 4 experiments, it was shown that the interaction between working and reference memory is reciprocal: Strengthening either type of memory leads to a decrease in the influence of the other type of memory. A process dissociation procedure analysis of the data from Experiment 4 showed independence of working and reference memory, and a model of working memory and reference memory interaction was shown to predict the findings reported in the 4 experiments. (PsycINFO Database Record

There is no consensus as to why forgetting occurs in short-term memory tasks. In past work, we have shown that forgetting occurs with the passage of time, but there are two classes of theories that can explain this effect. In the present work, we investigate the reason for time-based forgetting by contrasting the predictions of temporal distinctiveness and trace decay in the procedure in which we have observed such loss, involving memory for arrays of characters or letters across several seconds. The first theory, temporal distinctiveness, predicts that increasing the amount of time between trials will lead to less proactive interference, resulting in less forgetting across a retention interval. In the second theory, trace decay, temporal distinctiveness between trials is irrelevant to the loss over a retention interval. Using visual array change detection tasks in four experiments, we find small proactive interference effects on performance under some specific conditions, but no concomitant change in the effect of a retention interval. We conclude that trace decay is the more suitable class of explanations of the time-based forgetting in short-term memory that we have observed, and we suggest the need for further clarity in what the exact basis of that decay may be.

asymmetric pattern of binding of features in working memory is a controversial topic in the literature. The binding of visual- spatial and verbal-spatial information was studied in a serial recognition task to address the contribution of spatial location, visual appearance, and verbal identity to binding in working memory. The participants (n = 32) made a recognition judgment of two sequences of four stimuli each based on a relevant dimension while ignoring changes in an irrelevant dimension. In the visual and verbal tasks, the location was irrelevant. In the spatial tasks, the visual or verbal dimension was irrelevant. Our data showed that the visual or verbal characteristics of the object were incidentally encoded with the spatial location, but the spatial location of the items was not codified together with either the verbal features or visual characteristics when a verbal strategy was limited by articulatory suppression. This asymmetry in binding memory when the participants had to retain one of the features that was presented suggests a functional interaction between specific components of modalities of information and a system that maintains the multimodal representation. Keywords: working memory, binding, visual-spatial, verbal-spatial.

Recent neuroimaging studies suggest that early sensory areas such as area V1 are recruited to actively maintain a selected feature of the item held in visual short-term memory (VSTM). These findings raise the possibility that visual attention operates in similar manners across perceptual and memory representations to a certain extent, despite memory-level and perception-level selections are functionally dissociable. If VSTM operates by retaining "reasonable copies" of scenes constructed during sensory processing (Serences et al., 2009, p. 207, the sensory recruitment hypothesis), then it is possible that selective attention can be guided by both exogenous (peripheral) and endogenous (central) cues during VSTM maintenance. Yet, the results from the previous studies that examined this issue are inconsistent. In the present study, we investigated whether attention can be directed to a specific item's location represented in VSTM with the exogenous cue in a well-controlled setting. The results from the four experiments suggest that, as observed with the endogenous cue, the exogenous cue can efficiently guide selective attention during VSTM maintenance. The finding is not only consistent with the sensory recruitment hypothesis but also validates the legitimacy of the exogenous cue use in past and future studies.

Despite claims to the contrary, experimental results by Sewell, Lilburn, and Smith (2014) appear to be consistent with limited-processing-capacity models for encoding into visual short-term memory. (PsycINFO Database Record

In his commentary, Bundesen (2018) argued that limited encoding capacity can account for the near-equivalent set size effects on performance under conditions of simultaneous and sequential presentation reported by Sewell, Lilburn, and Smith (2014). While we agree that limited encoding capacity could, in principle, account for this equivalency, we argue that such an account rests on a number of fortuitous temporal coincidences. In particular, we note that pure encoding capacity limitations appear ill equipped to explain near-equivalent simultaneous-sequential performance across a range of stimulus exposure durations, set sizes, and with stimuli with quite different attentional demands. (PsycINFO Database Record

Four experiments examined the effect of phonological similarity between items and distractors on complex span performance. Item-distractor similarity benefited serial recall when distractors followed the items they were similar to, but not when distractors preceded the items they were similar to. These findings are predicted by C-SOB (contextual serial order in a box), a computational model of complex span. The model assumes that distractors are involuntarily encoded into memory, being associated to the preceding item's list position. Distractors interfere with items by superposition of distributed representations that are associated to the same position. Superposition distorts item memory; this distortion is less severe when the distractor is similar to the item. Further support for the assumption that distractors are encoded at the position of the preceding item comes from the finding that intrusions of distractors at recall tended to come from the position of the target item. In addition, intruding distractors tend to replace items to which they are similar, showing that lack of distinctiveness also contributes to interference.

Although considerable research has examined the storage limits of visual short-term memory (VSTM), little is known about the initial formation (i.e., the consolidation) of VSTM representations. A few previous studies have estimated the capacity of consolidation to be one item at a time. Here we used a sequential-simultaneous manipulation to reexamine the limits of consolidating items into VSTM. Participants viewed briefly presented and masked color patches (targets), which were shown either sequentially or simultaneously. A probe color followed the targets and participants decided whether it matched one of the targets or was a novel color. In four experiments, we consistently found equal performance for sequential and simultaneous presentations for two targets. Worse performance in the simultaneous than the sequential condition was observed for larger set sizes (three and four). Contrary to previous results, suggesting a severe capacity limit of one item, our results indicate that consolidation into VSTM can occur in parallel and without capacity limits for at least two items.

Memory for emotional stimuli is superior to memory for neutral stimuli. This study investigated whether this memory advantage is present in implicit memory. Memory was tested with a test of explicit memory (associate cued recall) and a test of conceptual implicit memory (free association) identical in all respects apart from the retrieval instructions. After studying emotional and neutral paired associates, participants saw the first member of the pair, the cue; in the test of explicit memory participants were instructed to recall the associate; in the test of implicit memory participants were instructed to generate the first word coming to mind associated to the word. Depth of study processing dissociated performance in the tests, confirming that the free-association test was not contaminated by an intentional retrieval strategy. Emotional pairs were better recalled than neutral pairs in the test of explicit memory but not in the equivalent test of implicit memory. The absence of an emotion effect in implicit memory implies that emotional material does not have a privileged global mnemonic status; intentional retrieval is necessary for observing the emotion-related memory advantage.

Although some views of face perception posit independent processing of face identity and expression, recent studies suggest interactive processing of these 2 domains. The authors examined expression-identity interactions in visual short-term memory (VSTM) by assessing recognition performance in a VSTM task in which face identity was relevant and expression was irrelevant. Using study arrays of between 1 and 4 faces and a 1,000-ms retention interval, the authors measured recognition accuracy for just-seen faces. Results indicated that significantly more angry face identities can be stored in VSTM than happy or neutral face identities. Furthermore, the study provides evidence to exclude accounts for this angry face benefit based on physiological arousal, opportunity to encode, face discriminability, low-level feature recognition, expression intensity, or specific face sets. Perhaps processes activated by the presence of specifically angry expressions enhance VSTM because memory for the identities of angry people has particular behavioral relevance.

The information that individuals can hold in working memory is quite limited, but researchers have typically studied this capacity using simple objects or letter strings with no associations between them. However, in the real world there are strong associations and regularities in the input. In an information theoretic sense, regularities introduce redundancies that make the input more compressible. The current study shows that observers can take advantage of these redundancies, enabling them to remember more items in working memory. In 2 experiments, covariance was introduced between colors in a display so that over trials some color pairs were more likely to appear than other color pairs. Observers remembered more items from these displays than from displays where the colors were paired randomly. The improved memory performance cannot be explained by simply guessing the high-probability color pair, suggesting that observers formed more efficient representations to remember more items. Further, as observers learned the regularities, their working memory performance improved in a way that is quantitatively predicted by a Bayesian learning model and optimal encoding scheme. These results suggest that the underlying capacity of the individuals' working memory is unchanged, but the information they have to remember can be encoded in a more compressed fashion.

Visual short-term memory (VSTM) has received intensive study over the past decade, with research focused on VSTM capacity and representational format. Yet, the function of VSTM in human cognition is not well understood. Here we demonstrate that VSTM plays an important role in the control of saccadic eye movements. Intelligent human behavior depends on directing the eyes to goal-relevant objects in the world, yet saccades are very often inaccurate and require correction. We hypothesized that VSTM is used to remember the features of the current saccade target so that it can be rapidly reacquired after an errant saccade, a fundamental task faced by the visual system thousands of times each day. In four experiments, memory-based gaze correction was found to be accurate, fast, automatic, and largely unconscious. In addition, a concurrent VSTM load was found to interfere with memory-based gaze correction, but a verbal short-term memory load did not. These findings demonstrate VSTM plays a direct role in a fundamentally important aspect of visually guided behavior, and they suggest the existence of previously unknown links between VSTM representations and the occulomotor system.

Human society depends on the ability to remember the actions of other individuals, which is information that must be stored in a temporary buffer to guide behavior after actions have been observed. To date, however, the storage capacity, contents, and architecture of working memory for observed actions are unknown. In this article, the author shows that it is possible to retain information about only 2-3 actions in visual working memory at once. However, it is also possible to retain 9 properties distributed across 3 actions almost as well as 3 properties distributed across 3 actions, showing that working memory stores integrated action representations rather than individual properties. Finally, the author shows that working memory for observed actions is independent from working memory for object and spatial information. These results provide evidence for a previously undocumented system in working memory for storing information about actions. Further, this system operates by the same storage principles as visual working memory for object information. Thus, working memory consists of a series of distinct yet computationally similar mechanisms for retaining different types of visual information.

In 7 experiments, the authors explored whether visual attention (the ability to select relevant visual information) and visual working memory (the ability to retain relevant visual information) share the same content representations. The presence of singleton distractors interfered more strongly with a visual search task when it was accompanied by an additional memory task. Singleton distractors interfered even more when they were identical or related to the object held in memory, but only when it was difficult to verbalize the memory content. Furthermore, this content-specific interaction occurred for features that were relevant to the memory task but not for irrelevant features of the same object or for once-remembered objects that could be forgotten. Finally, memory-related distractors attracted more eye movements but did not result in longer fixations. The results demonstrate memory-driven attentional capture on the basis of content-specific representations. PsycINFO Database Record © 2006 APA, all rights reserved.

This placebo-controlled, double-blind, double-dummy, independent groups study directly compared effects of the benzodiazepine, lorazepam (2.0 mg/70 kg orally administered), and the anticholinergic scopolamine (0.6 mg/70 kg subcutaneously administered) on memory and attentional measures hypothesized to differentiate the drugs. At the studied doses, lorazepam and scopolamine produced similar decrements in psychomotor performance, free recall, and overall sensitivity in distinguishing between studied and nonstudied items on a recognition memory test. However, the drugs differed with respect to effects on working memory, response bias, metacognition, subjective awareness, and selective attention. In addition to providing information about the cognitive psychopharmacological profiles of drugs with distinct neurochemical and pharmacological mechanisms of action, this study also informs the understanding of memory and attentional processes.

A span task was developed to assess the amount of information infants could hold in short-term memory. In this task, infants were presented with up to 4 items in succession and then tested for recognition by successively pairing each item with a novel one. A large sample of full-terms and low-birth-weight preterms (< 1,750 g) was tested longitudinally, at 5, 7, and 12 months of age. Results were similar for both groups: (a) Longer spans were more difficult, especially at the 2 younger ages; (b) memory capacity increased over the 1 st year of life-whereas less than 25% of the sample could hold as many as 3-4 items in mind at once at the younger ages, nearly half could do so by 12 months of age; (c) there was a marked recency effect (greater memory for the final item) for spans of 3 and 4 at all ages; and (d) there were modest cross-age correlations, indicating that individual differences in memory capacity showed some stability from age to age.

The authors examined the organization of visual short-term memory (VSTM). Using a change-detection task, they reported that VSTM stores relational information between individual items. This relational processing is mediated by the organization of items into spatial configurations. The spatial configuration of visual objects is important for VSTM of spatial locations, colors, and shapes. When color VSTM is compared with location VSTM, spatial configuration plays an integral role because configuration is important for color VSTM, whereas color is not important for location VSTM. The authors also examined the role of attention and found that the formation of configuration is modulated by both top-down and bottom-up attentional factors. In summary, the authors proposed that VSTM stores the relational information of individual visual items on the basis of global spatial configuration.

The authors hypothesized that the pathophysiology of early Parkinson's disease (PD) may selectively target structures that support visual working memory for spatial relations but leave structures that support working memory for featural characteristics of objects relatively intact Fifteen PD and 15 normal control participants took a visual delayed-response test with a spatial condition and a (nonspatial) object condition, equating the perceptual difficulty of the tests for each participant. The stimuli were irregular polygons presented at different locations on a computer screen. Results revealed a selective impairment of spatial delayed response in PD, indicating a disruption of spatial working memory unconfounded by sensory processing difficulties. The selectivity of this deficit may reflect the circumscribed nature of pathophysiological change affecting the caudate nucleus in early PD. Working memory has been defined as "a brain system that

In 3 experiments, the nature of the events that interfere with spatial working memory was examined in order to clarify the roles of imagery, attention, and other processes in the short-term maintenance of location information. Looking and pointing at secondary task stimuli selectively interfered with memory for the locations of primary task stimuli. Secondary tasks that involved either mentally rotating primary task stimuli or making color or shape discriminations about primary or secondary task stimuli interfered with spatial working memory only if the required response was visually guided, but not if the response was verbal. Taken together, these findings support P.S. Goldman-Rakic's (1987) hypothesis regarding multiple representational domains and are consistent with known properties and connections of neurons believed to subserve the perception and maintenance of spatial information. A working memory task may be defined as one that requires holding onto information for a short time while it or other information is processed. Baddeley has proposed that there is a working memory system, specialized for concurrent storage and manipulation of information that is engaged by such tasks (for a recent overview, see Baddeley & Hitch, 1994). On the basis of studies of both intact and brain-damaged subjects (for a review, see Gathercole, 1994), Baddeley and his colleagues have divided the working memory system into three components: a phonological store for verbal information, a visuospatial sketchpad for visuospatial information, and a central executive that directs activities involved in manipulating and maintaining information in the two specialized stores. Perhaps the most studied example is the role of covert articulatory rehearsal in refreshing information in the phonological store. Performing a secondary task that requires articulation of verbal material decreases verbal memory span, a finding consistent with the hypothesized role of subvocalization in maintaining verbal information (e.g., Baddeley, Lewis, & Vallar, 1984). Much of the supporting evidence for the visuospatial component of Baddeley's model also comes from studies that use dual task procedures. These studies were designed to determine whether visuospatial and verbal working memory involve separate resources, and they have demonstrated that secondary verbal tasks interfere with memory for verbal information to a much greater extent than they interfere

Interfering with stimulus identification can enhance later explicit memory performance. This counterintuitive (and theoretically unexpected) phenomenon was investigated in 5 experiments. Perceptual interference enhanced category-cued recall (a conceptually driven explicit test) but had no effect on a comparable implicit memory test, category-exemplar production. This dissociation was obtained across higher levels of priming and with high-frequency as well as low-frequency exemplars. Furthermore, although perceptual interference enhanced old-new recognition memory, it did not enhance rhyme recognition (a data-driven explicit test) or source discriminability. Explanations based on enhanced semantic elaboration or enhanced encoding of spatio-temporal context do not account for the perceptual-interference effect. An account based on compensatory processing of higher level perceptual representations remains viable and is discussed in terms of the transfer-appropriate processing framework and the item-specific-relational distinction.

To account for the large demands on working memory during text comprehension and expert performance, the traditional models of working memory involving temporary storage must be extended to include working memory based on storage in long-term memory. In the proposed theoretical framework cognitive processes are viewed as a sequence of stable states representing end products of processing. In skilled activities, acquired memory skills allow these end products to be stored in long-term memory and kept directly accessible by means of retrieval cues in short-term memory, as proposed by skilled memory theory. These theoretical claims are supported by a review of evidence on memory in text comprehension and expert performance in such domains as mental calculation, medical diagnosis, and chess.

In Experiment 1, rats were given a test to determine the order of preference among 3 types of food. Two groups of rats then were trained on a 12-arm radial maze in Experiment 2, with the 3 foods placed in fixed-arm locations for 1 group and in locations that varied randomly across sessions for the other group. The results replicated those of Dallal and Meck (1990) by showing faster learning and more clustering of arm choices by food type in the fixed-locations group than in the random-locations group. Two further experiments were performed to test the chunking hypothesis. Observations of working memory in Experiment 3 and the reorganization of reference memory in Experiment 4 both supported the chunking hypothesis by showing superior spatial memory and arm chunking by food type when chunk integrity was maintained than when it was compromised.

The authors summarize developments in the concept of working memory as a multicomponent system, beginning by contrasting this approach with alternative uses of the term working memory. According to a 3-component model, working memory comprises a phonological loop for manipulating and storing speech-based information and a visuospatial sketchpad that performs a similar function for visual and spatial information. Both are supervised by a central executive, which functions as an attentional control system. A simple trace-decay model of the phonological loop provides a coherent account of the effects of word length, phonemic similarity, irrelevant speech, and articulatory suppression in verbal short-term memory tasks. This model of the loop has also proved useful in the analysis of neuropsychological, developmental and, cross-cultural data. The notion of the sketchpad is supported by selective interference with imagery in normal adults and by specific neuropsychological impairment. Analysis of the central executive is illustrated by work on deficits in the ability to coordinate subproccesses in Alzheimer's disease (AD). (PsycINFO Database Record (c) 2008 APA, all rights reserved)

Semantic and syntactic aspects of sentence comprehension were investigated for 3 patients who showed different patterns of performance on short-term memory tasks. On a sentence anomaly judgment task assessing the retention of semantic information, only patient A.B. showed a detrimental effect on comprehension with increases in the number of words to be held in an unintegrated fashion. On judgments of grammatical acceptability, only patient M.W. demonstrated a detrimental effect of increasing the number of words intervening between the words signaling that a sentence was ungrammatical. The results suggest that semantic and syntactic components must be postulated in addition to the phonological and articulatory components of A. D. Baddeley's (1986, 1990) working memory model. Although the phonological, semantic, and syntactic components may be differentiall y affected by brain damage, the components interact and support each other in normal comprehension. The working memory model initially proposed by Baddeley and Hitch (1974) has played an important role in neuropsychological studies of brain-damaged patients with language disorders. The essential insight of their model was that working memory should not be seen as a unitary store, but rather as consisting of different components with separate storage capacities. It differed in this respect from the so-called modal model of memory (Murdock, 1974), which posited a single store in which information of all types was maintained prior to transfer to long-term memory (e.g., Atkinson & Shiffrin, 1968; Waugh & Norman, 1965). Baddeley and Hitch's now well-known model separated a central executive component of working memory from peripheral storage devices dedicated to the maintenance of different types of information. The central executive was seen as an attention-controlling system with storage space of its own, which directed the processes involved in cognitive functions and which drew on the information stored in the peripheral stores. The peripheral storage devices included a phonemically based rehearsal buffer, currently termed the phonological loop, and a visual buffer, currently termed the visuospatial sketchpad (Baddeley, 1986, 1990). The phonological loop itself may be broken down into two components, a phonological storage component and an articulatory rehearsal component (Salame & Baddeley, 1982; Vallar & Baddeley, 1984a).