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Visual working memory maintains both continuous-perceptual information and discrete-categorical information about memory items. Both types of information are represented in working memory, but the representation structure remains unknown. Continuous and categorical information about a single stimulus could be represented separately, in two different representations. Alternatively, continuous and categorical information could be represented jointly as a single representation. To investigate this, we fitted two different computational models to delayed estimation data assuming either separate or joint representations of continuous and categorical information in working memory, for three different, commonly used features (orientation, color, and shape). Across a set of nine experiments, model fits clearly show that feature identity drives the representation structure, with a joint-representation structure for orientation, but a separate-representations structure for color and shape. This pattern was remarkably invariant across a variety of task contexts. Existing models miss this distinction, leading to mischaracterization of memory precision. [ABSTRACT FROM AUTHOR]

Learning advances through repetition. A classic paradigm for studying this process is the Hebb repetition effect: Immediate serial recall performance improves for lists presented repeatedly as compared to nonrepeated lists. Learning in the Hebb paradigm has been described as a slow but continuous accumulation of long-term memory traces over repetitions [e.g., Page & Norris, Phil. Trans. R. Soc. B 364, 3737–3753 (2009)]. Furthermore, it has been argued that Hebb repetition learning requires no awareness of the repetition, thereby being an instance of implicit learning [e.g., Guérard et al., Mem. Cogn. 39, 1012–1022 (2011); McKelvie, J. Gen. Psychol. 114, 75–88 (1987)]. While these assumptions match the data from a group-level perspective, another picture emerges when analyzing data on the individual level. We used a Bayesian hierarchical mixture modeling approach to describe individual learning curves. In two preregistered experiments, using a visual and a verbal Hebb repetition task, we demonstrate that 1) individual learning curves show an abrupt onset followed by rapid growth, with a variable time for the onset of learning across individuals, and that 2) learning onset was preceded by, or coincided with, participants becoming aware of the repetition. These results imply that repetition learning is not implicit and that the appearance of a slow and gradual accumulation of knowledge is an artifact of averaging over individual learning curves. [ABSTRACT FROM AUTHOR]

There is a growing interest in specifying the mechanisms underlying refreshing, i.e., the use of attention to keep working memory (WM) contents accessible. Here, we examined whether participants' visual fixations during the retention interval of a WM task indicate the current focus of internal attention, thereby serving as an online measure of refreshing. Eye movements were recorded while participants studied and maintained an array of colored dots followed by probed recall of one (Experiments 1A and 1B) or all (Experiment 2) of the memoranda via a continuous color wheel. Experiments 1A and 2 entailed an unfilled retention interval in which refreshing is assumed to occur spontaneously, and Experiment 1B entailed a retention interval embedded with cues prompting the sequential refreshment of a subset of the memoranda. During the retention interval, fixations revisited the locations occupied by the memoranda, consistent with a looking-at-nothing phenomenon in WM, but the pattern was only evident when placeholders were onscreen in Experiment 2, indicating that most of these fixations may largely reflect random gaze. Furthermore, spontaneous fixations did not predict recall precision (Experiments 1A and 2), even when ensuring that they did not reflect random gaze (Experiment 2). In Experiment 1B, refreshing cues increased fixations to the eventually tested target and predicted better recall precision, which interacted with an overall benefit of target fixations, such that the benefit of fixations decreased as the number of refreshing cues increased. Thus, fixations under spontaneous conditions had no credible effect on recall precision, whereas the beneficial effect of fixations under instructed refreshing conditions may indicate situations in which cues were disregarded. Consequently, we conclude that eye movements do not seem suitable as an online measure of refreshing. [ABSTRACT FROM AUTHOR]

People are able to prioritize more valuable information in working memory. The current study examined whether this value effect is due to the items of greater value being refreshed more than lower-value items during maintenance. To assess this possibility, we combined a probe value manipulation with a guided-refreshing procedure. Arrays of colored shapes were presented, and after a brief delay, participants reported the color of one randomly probed shape on a continuous color wheel. To manipulate probe value, one item was indicated as more valuable than the rest prior to encoding (i.e., worth more notional points), or all items were indicated as equally valuable. To guide refreshing, in some trials, two arrows were presented during maintenance, each arrow cueing the spatial location of one item. Participants were told to "think of" (i.e., refresh) the cued item. If value boosts are driven by attentional refreshing, cueing an item to be refreshed should enhance performance for items that are of low or equal value, but not items of high value, as these items would be refreshed regardless of the cue. This pattern of outcomes was observed, providing support for the hypothesis that attentional refreshing at least partially accounts for probe value effects in working memory. [ABSTRACT FROM AUTHOR]

Many theories assume that actively maintaining information in working memory (WM) predicts its retention in episodic long-term memory (LTM), as revealed by the beneficial effects of more WM time. In four experiments, we examined whether affording more time for intentional WM maintenance does indeed drive LTM. Sequences of four words were presented during trials of simple span (short time), slow span (long time), and complex span (long time with distraction; Experiments 1–2). Long time intervals entailed a pause of equivalent duration between the words that presented a blank screen (slow span) or an arithmetic problem to read aloud and solve (complex span). In Experiments 1–3, participants either serially recalled the words (intentional encoding) or completed a no-recall task (incidental encoding). In Experiment 4, all participants were instructed to intentionally encode the words, with the trials randomly ending in the serial-recall or no-recall task. To ensure similar processing of the words between encoding groups, participants silently decided whether each word was a living or nonliving thing via key press (i.e., an animacy judgment; Experiments 1 and 3–4) or read the words aloud and then pressed the space bar (Experiment 2). A surprise delayed memory test at the end of the experiment assessed LTM. Applying Bayesian cognitive models to disambiguate binding and item memory revealed consistent benefits of free time to binding memory that were specific to intentional encoding in WM. This suggests that time spent intentionally keeping information in WM is special for LTM because WM is a system that maintains bindings. [ABSTRACT FROM AUTHOR]

Highlights • Articulatory rehearsal has persistent central attentional costs. • During articulatory suppression words are retained without persistent refreshing. • The current results cast doubt on the idea that Elaboration requires central attention for an extended period of time. Abstract There is a recent surge of interest in maintenance processes in working memory, such as articulatory rehearsal, elaboration, and attentional refreshing. Yet, we know little about the central attentional demand of these processes. It has been assumed that articulatory rehearsal does not require central attention at all (Vergauwe, Camos, & Barrouillet, 2014), being in essence a cost-free strategy. In contrast, elaboration and attentional refreshing are assumed to incur large and continuous costs on central attention. We tested these assumptions in three experiments in which participants were presented with a varying number of words to rehearse. Participants were instructed to rehearse the words aloud, or to elaborate them by creating interactive images. Attentional refreshing was examined in a condition in which words were to be maintained during articulatory suppression. During retention participants carried out a series of choice reaction tasks, which were used to measure central attentional demands of the maintenance strategies. Articulatory rehearsal had costs on processing RTs that lasted for 10 s. Maintenance of words during articulatory suppression did not yield persistent costs on central attention, implying that participants did not continuously refresh the words. Finally, the current results cast doubt on the idea that elaboration requires central attention for an extended period of time. All experimental scripts and data sets reported here are available online (https://osf.io/69p8j/). [ABSTRACT FROM AUTHOR]

Highlights • We assessed the causal role of rehearsal in a serial recall task. • Instructing cumulative or fixed rehearsals increased their prevalence. • Increased rehearsal did not improve recall. • Articulatory rehearsal is an ineffective means to boost serial recall performance. Abstract Articulatory rehearsal is assumed to benefit verbal working memory. Yet, there is no experimental evidence supporting a causal link between rehearsal and serial-order memory, which is one of the hallmarks of working memory functioning. Across four experiments, we tested the hypothesis that rehearsal improves working memory by asking participants to rehearse overtly and by instructing different rehearsal schedules. In Experiments 1a, 1b, and 2, we compared an instructed cumulative-rehearsal condition against a free-rehearsal condition. The instruction increased the prevalence of cumulative rehearsal, but recall performance remained unchanged or decreased compared to the free-rehearsal baseline. Experiment 2 also tested the impact of a fixed rehearsal instruction; this condition yielded substantial performance costs compared to the baseline. Experiment 3 tested whether rehearsals (according to an experimenter-controlled protocol) are beneficial compared to a matched articulatory suppression condition that blocked rehearsals of the memoranda. Again, rehearsing the memoranda yielded no benefit compared to articulatory suppression. In sum, our results are incompatible with the notion that rehearsal is beneficial to working memory. [ABSTRACT FROM AUTHOR]

Attention helps manage the information held in visual working memory (vWM). Perceptual attention selects the stimuli to be represented in vWM, whereas internal attention prioritizes information already in vWM. In the present study we assessed the spatial precision of perceptual and internal attention in vWM. Participants encoded eight colored dots for a local-recognition test. To manipulate attention, a cue indicated the item most likely to be tested (~65% validity). The cue appeared either before the onset of the memory array (precue) or during the retention interval (retrocue). The precue guides perceptual attention to gate encoding into vWM, whereas the retrocue guides internal attention to prioritize the cued item within vWM. If attentional selection is spatially imprecise, attention should be preferentially allocated to the cued location, with a gradual drop-off of attention over space to nearby uncued locations. In this case, memory for uncued locations should vary as a function of their distance from the cued location. As compared to a no-cue condition, memory was better for validly cued items but worse for uncued items. The spatial distance between the uncued and cued locations modulated the cuing costs: Items close in space to the cued location were insulated from cuing costs. The extension of this spatial proximity effect was larger for precues than for retrocues, mostly because the benefits of attention were larger for precues. These results point to similar selection principles between perceptual and internal attention and to a critical role of spatial distance in the selection of visual representations. [ABSTRACT FROM AUTHOR]

Abstract: One of the functions that attention may serve in working memory (WM) is boosting information accessibility, a mechanism known as attentional refreshing. Refreshing is assumed to be a domain‐general process operating on visual, spatial, and verbal representations alike. So far, few studies have directly manipulated refreshing of individual WM representations to measure the WM benefits of refreshing. Recently, a guided‐refreshing method was developed, which consists of presenting cues during the retention interval of a WM task to instruct people to refresh (i.e., attend to) the cued items. Using a continuous‐color reconstruction task, previous studies demonstrated that the error in reporting a color varies linearly with the frequency with which it was refreshed. Here, we extend this approach to assess the WM benefits of refreshing different representation types, from colors to spatial locations and words. Across six experiments, we show that refreshing frequency modulates performance in all stimulus domains in accordance with the tenet that refreshing is a domain‐general process in WM. The benefits of refreshing were, however, larger for visual–spatial than verbal materials. [ABSTRACT FROM AUTHOR]

Abstract: Impairments in refreshing have been suggested as one source of working memory (WM) deficits in older age. Retro‐cues provide an important method of investigating this question: a retro‐cue guides attention to one WM item, thereby arguably refreshing it and increasing its accessibility compared with a no‐cue baseline. In contrast to the refreshing deficit hypothesis, intact retro‐cue benefits have been found in older adults. Refreshing, however, is assumed to boost not one but several WM representations when sequentially applied to them. Hence, intact refreshing requires the flexible switching of attention among WM items. So far, it remains an open question whether older adults show this flexibility. Here, we investigated whether older adults can use multiple cues to sequentially refresh WM representations. Younger and older adults completed a continuous‐color delayed‐estimation task, in which the number of retro‐cues (0, 1, or 2) presented during the retention interval was manipulated. The results showed a similar retro‐cue benefit for younger and older adults, even in the two‐cue condition in which participants had to switch attention between items to refresh representations in WM. These findings suggest that the capacity to use cues to refresh information in visual WM may be preserved with age. [ABSTRACT FROM AUTHOR]

Ageing is associated with declines in several cognitive abilities including working memory (WM). The goal of the present study was to assess whether emotional information could reduce the age gap in the quantity and quality (precision) of representations in visual WM. Young and older adults completed a serial image recognition (SIR) task and a colour-image binding (CIB) task. Results of the SIR task showed worse performance for negative than neutral and positive images within the older group, hence enlarging the age gap in WM. In the CIB task, recall precision was lower in the old than young adults, showing an ageing decline in the quality of WM representations. Positive images tended to improve precision, but this boost was similar for both age groups. In sum, emotional content did not reduce the age gap in visual WM. [ABSTRACT FROM AUTHOR]

In simple-span tasks, participants encode items sequentially for immediate serial recall. Complex-span tasks are similar, except that items are interleaved with a distraction task. Whereas immediate memory is higher in simple than complex span, in tests of episodic long-term memory, better recall for words studied in complex than simple span has been observed (McCabe, 2008). This McCabe effect has been explained by assuming that distraction displace items from working memory, forcing people to covertly retrieve items after each distraction, thereby generating better episodic retrieval-cues than during simple span. Our experiments support an alternative hypothesis: individual words are attended to and processed longer in working memory in complex-span than in simple-span trials. We reduced the presentation rate of words in simple span, creating a “slow span” condition. Across four experiments, slow span improved episodic memory compared to simple span, and this benefit was larger than the McCabe effect. [ABSTRACT FROM AUTHOR]

How do perception and language interact to form the representations that guide our thoughts and actions over the short-term? Here, we provide a first examination of this question by investigating the role of verbal labels in a continuous visual working memory (WM) task. Across four experiments, participants retained in memory the continuous color of a set of dots which were presented sequentially (Experiments 1-3) or simultaneously (Experiment 4). At test, they reproduced the colors of all dots using a color wheel. During stimulus presentation participants were required to either label the colors (color labeling) or to repeat "bababa" aloud (articulatory suppression), hence prompting or preventing verbal labeling, respectively. We tested four competing hypotheses of the labeling effect: (1) labeling generates a verbal representation that overshadows the visual representation; (2) labeling yields a verbal representation in addition to the visual one; (3) the labels function as a retrieval cue, adding distinctiveness to items in memory; and (4) labels activate visual categorical representations in long-term memory. Collectively, our experiments show that labeling does not overshadow the visual input; it augments it. Mixture modeling showed that labeling increased the quantity and quality of information in WM. Our findings are consistent with the hypothesis that labeling activates visual long-term categorical representations which help in reducing the noise in the internal representations of the visual stimuli in WM. [ABSTRACT FROM AUTHOR]

Maintenance of information in mind to the moment-to-moment cognition is accomplished by working memory (WM). WM capacity is reduced in old age, but the nature of this decline is yet not clear. The current study examined the hypothesis that the decline in visual WM performance with age is related to a reduced ability to use attention to control the contents of WM. Young (M = 26 years) and old (M = 71 years) adults performed a color reproduction task in which the precise color of a set of dots had to be maintained in mind over a brief interval and later reproduced using a continuous color wheel. Attention was manipulated by presenting a spatial cue before the onset of the memory array (a precue) or during the maintenance phase (retro-cue). The cue indicated with 100% certainty the item to be tested at the end of the trial. A precue allows the selective encoding of only the relevant item to WM, whereas a retro-cue allows WM contents to be updated by refreshing the relevant (cued) item and removing nonrelevant (noncued) items. Aging was associated with a lower capacity in the baseline (no-cue) condition. Precues and (to a smaller extent) retro-cues improved WM performance (in terms of probability of recall and memory precision). Critically, the benefits of cueing were of similar magnitude in young and older adults showing that the ability to use attention to selectively encode and update the contents of WM is preserved with aging. (PsycINFO Database Record [ABSTRACT FROM AUTHOR]

This article provides evidence that refreshing, a hypothetical attention-based process operating in working memory (WM), improves the accessibility of visual representations for recall. 'Thinking of', one of several concurrently active representations, is assumed to refresh its trace in WM, protecting the representation from being forgotten. The link between refreshing and WM performance, however, has only been tenuously supported by empirical evidence. Here, we controlled which and how often individual items were refreshed in a color reconstruction task by presenting cues prompting participants to think of specific WM items during the retention interval. We show that the frequency with which an item is refreshed improves recall of this item from visual WM. Our study establishes a role of refreshing in recall from visual WM and provides a new method for studying the impact of refreshing on the amount of information we can keep accessible for ongoing cognition. [ABSTRACT FROM AUTHOR]

During the retention interval of a working memory task, presenting a retro-cue directs attention to 1 of the items in working memory. Testing the cued item leads to faster and more accurate responses. We contrasted 5 explanations of this benefit: (a) removal of noncued items, (b) strengthening of the cued item, (c) protection from probe interference, (d) protection from degradation, and (e) prioritization during the decision process. Experiment 1 showed that retro-cues reduced the set size effect in a visual recognition task, and did so increasingly with more time available to use the retro-cue. This finding is predicted only by Hypotheses 1 and 2. Hypotheses 3 through 5 were ruled out as explanations of the retro-cue benefit in this experiment. In Experiments 2 and 3, participants encoded 2 sequentially presented memory sets. In half of the trials, 1 item from the first set was retro-cued during the interset interval. Retro-cues improved memory for the second set. This reloading benefit is predicted only by the removal hypothesis: Irrelevant contents are removed from working memory, freeing capacity to encode new contents. Experiment 3 also yielded evidence that strengthening of the cued item might contribute to the retro-cue effect. [ABSTRACT FROM AUTHOR]

Abstract: The article investigates the mechanisms of selecting and updating representations in declarative and procedural working memory (WM). Declarative WM holds the objects of thought available, whereas procedural WM holds representations of what to do with these objects. Both systems consist of three embedded components: activated long-term memory, a central capacity-limited component for building structures through temporary bindings, and a single-element focus of attention. Five experiments test the hypothesis of analogous mechanisms in declarative and procedural WM, investigating repetition effects across trials for individual representations (objects and responses) and for sets (memory sets and task sets), as well as set-congruency effects. Evidence for analogous processes was obtained from three phenomena: (1) Costs of task switching and of list switching are reduced with longer preparation interval. (2) The effects of task congruency and of list congruency are undiminished with longer preparation interval. (3) Response repetition interacts with task repetition in procedural WM; here we show an analogous interaction of list repetition with item repetition in declarative WM. All three patterns were reproduced by a connectionist model implementing the assumed selection and updating mechanisms. The model consists of two modules, an item-selection module selecting individual items from a memory set, or responses from a task set, and a set-selection module for selecting memory sets or task sets. The model codes the matrix of binding weights in the item-selection module as a pattern of activation in the set-selection module, thereby providing a mechanism for building chunks in LTM, and for unpacking them as structures into working memory. [Copyright &y& Elsevier]

• Visual working memory (VWM) has a limited capacity to store visual information. • Labels categorize the visual stimuli, increasing categorical representations in VWM. • Labeling also increases continuous information about the stimulus in VWM. • The increase in continuous information depends on the distinctiveness of the labels. • Labels that are used to categorize many stimuli, reduce memory precision. Describing our visual experiences improves their retention in visual working memory, yielding a labeling benefit. Labels vary, however, in categorical distinctiveness: they can be applied broadly or narrowly to categorize stimuli. Does categorical distinctiveness constrain the labeling benefit? Here, we varied the number of terms used to label continuously varying colors (Experiment 1) and shapes (Experiment 2). Participants memorized four items, and later recalled them using a continuous color or shape wheel. During study, participants articulated "bababa" or labeled the items with two, four, or their preferred term. Recall error decreased with increases in the number of labels. Mixture modeling showed that labeling increased the probability of recall. Memory precision, however, varied with categorical distinctiveness: broad labels reduced precision, whereas categorically distinct labels increased precision compared to no-labels. In sum, in-the-moment labeling activates categorical knowledge that facilitates the storage of visual details. Data and analysis scripts are available at: https://osf.io/mqg4k/ [ABSTRACT FROM AUTHOR]

We investigate interference between declarative and procedural representations in working memory (WM). Declarative representations are objects of thought, whereas procedural representations provide the (cognitive) actions to work upon these objects. In eight dual-task experiments we varied the number of representations to be maintained in WM (memory load). In Experiments 1–4, we varied declarative and procedural load separately in the two tasks used. In Experiments 5–8, only declarative or procedural load was manipulated in both tasks employed. We measured how much performance in the currently relevant task was impaired by increasing the load in the currently irrelevant task. These cross-task load effects were larger for Experiment 5–8 compared to Experiment 1–4. Yet, in task-switch trials we also obtained cross-task load effects in Experiment 1–4. Our findings support the distinction of declarative and procedural WM as largely independent sub-systems or distinct representational spaces. [ABSTRACT FROM AUTHOR]

Human attention is subject to fluctuations. Mind-wandering (MW) - attending to thoughts unrelated to the current task demands - is considered a ubiquitous experience. According to the Control Failure x Concerns view (McVay & Kane, 2010), MW is curbed by executive control, and task-irrelevant thoughts enter consciousness due to attentional control lapses. The generation of off-task thoughts is assumed to increase with higher number of personal concerns. Challenging this view, older adults report less MW than younger adults. Here, we addressed the hypothesis that older adults report less MW due to a lower ability to notice attention lapses and to appraise their current on-task focus. In an age-comparative study (N = 40 younger and N = 44 older adults) using a battery of three tasks spanning working memory, reading comprehension, and sustained attention, we assessed the correlation between the degree of self-reported on-task focus and task performance on a trial-by-trial basis. Younger and older adults' degree of on-task attention measured through thought probes was correlated equally strongly with performance across trials in all tasks, indicating preserved ability to monitor attentional fluctuations in healthy aging. Self-reported current concerns' number and importance did not differ across age, and they did not predict self-reported attention across tasks. Our study shows that lower rates of MW in aging do not reflect lower validity of older adults' attentional appraisal or lower levels of current concerns. [ABSTRACT FROM AUTHOR]