Retro-cue Benefit Research Articles

An age-related deficit in preserving the benefits of attention in working memory.

Deficits in the use of attention to refresh representations are argued to underlie age-related decline in working memory (WM). Retro-cues guide attention to WM contents, enabling the direct assessment of refreshing in WM. This preregistered study investigated aging deficits in refreshing via retro-cues and the preservation of refreshing boosts after distraction incurred by a secondary task. The distractor task is assumed to impede refreshing by engaging attention away from the memoranda. Any free time available before or after distractor processing, however, can be used to resume refreshing thereby ameliorating distractor-related interference. Accordingly, by varying the time available to complete the distractor task, one can vary refreshing opportunities, an effect known as cognitive load. Using an individually calibrated task that controlled for WM capacity and speed of processing, we demonstrate that focusing attention on WM representations is similarly efficient in younger and older adults. However, younger adults were able to retain this retro-cue benefit despite increasing cognitive load, whereas increasing cognitive load reduced the retro-cue benefit in older adults, suggesting that they are less able to protect focused representations from distractor-interference. This shows that aging impacts specific subcomponents of refreshing, such that the benefit of focusing attention is relatively intact in older age, but older adults struggle to preserve the refreshing benefit against distraction. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Two distinct mechanisms of selection in working memory: Additive last-item and retro-cue benefits

In working memory research, individual items are sometimes said to be in the “focus of attention”. According to one view, this occurs for the last item in a sequentially presented list (last-item benefit). According to a second view, this occurs when items are externally cued during the retention interval (retro-cue benefit). We investigated both phenomena at the same time to determine whether both result from the same cognitive mechanisms. If that were the case, retro-cue benefits should be reduced when the retro-cue is directed to the item that already benefits from being presented last. We measured speed-accuracy-tradeoff functions with the response-deadline paradigm to measure retrieval dynamics in a short-term recognition task. Across three experiments, we found that retro-cues benefited the last item and other items to the same extent. The additivity of the last-item benefit and the retro-cue benefit points towards the co-existence of at least two distinct forms of attentional prioritization in working memory.

Retroactive Attentional Shifts Predict Performance in a Working Memory Task: Evidence by Lateralized EEG Patterns.

Shifts of attention within working memory based on retroactive (retro-) cues were shown to facilitate performance in working memory tasks. Although posterior asymmetries in the EEG, such as the contralateral delay activity (CDA), have been used to study the active storage of lateralized working memory representations, results on the relation of such asymmetric effects to retro-cue benefits remain inconclusive. We recorded EEG in a retro-cue working memory task with lateralized items and a continuous performance response. Following either a selective or neutral retro-cue, participants adjusted the orientation of a central memory probe to the cued item. Selective retro-cues elicited an early posterior contralateral negativity (PCN), anterior directing attention negativity (ADAN) and a later modulation of CDA indicating that active storage was concentrated on the cued information. By dividing all trials into three within-condition performance quantiles, we could further show that high working memory accuracy was associated with a sustained increase of the CDA effect following the retro-cue. These results suggest that focusing resources on the active storage of relevant representations is an important factor regarding retro-cue benefits in working memory tasks.

The functional role of alpha-band oscillations for the retro-cueing benefit in visual working memory.

The functional role of alpha-band oscillations for the retro-cueing benefit in visual working memory.

The Retro-Cue Benefit for Verbal Material and Its Influence on the Probability of Intrusions Under Dual-Task Conditions.

It is well established in the working memory literature, that performance can be improved by cueing attention toward the position of a to-be-tested item, even after that item's presentation. This retro-cue benefit is often characterized as the joint outcome of two different effects: facilitation of recall and memory strengthening at the cued position. While the latter has been mainly explained by increased context-content binding, competing hypotheses exist to explain the facilitation of recall. The present study focuses on two of these hypotheses: the removal of non-cued information and the protection of cued information against interference. I replicate the retro-cue effect for verbal material and provide strong evidence for its protective effect. However, I did not find support for the removal hypothesis. This lack of support follows from two empirical findings: Retro-cueing does not decrease, rather increases the conditional probability of intrusions, and the retro-cue benefit does not interact with memory load.

Is refreshing in working memory impaired in older age? Evidence from the retro-cue paradigm.

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.

Sequential whole report accesses different states in visual working memory.

Working memory (WM) enables a rapid access to a limited number of items that are no longer physically present. WM studies usually involve the encoding and retention of multiple items, while probing a single item only. Hence, little is known about how well multiple items can be reported from WM. Here we asked participants to successively report each of up to 8 encoded Gabor patches from WM. Recall order was externally cued, and stimulus orientations had to be reproduced on a continuous dimension. Participants were able to sequentially report items from WM with an above-chance precision even at high set sizes. It is important that we observed that precision varied systematically with report order: It dropped steeply from the first to the second report but decreased only slightly thereafter. The observed trajectory of precision decrease across reports was better captured as a discontinuous rather than an exponential function, suggesting that items were reported from different states in visual WM. The following 3 experiments replicated these findings. In particular, they showed that the observed drop could not be explained by a retro-cueing benefit of the first report, a longer delay duration for later reports or a visual interference effect of the first report. Instead, executive interference of the first report reduced precision of subsequent reports. Together, the results show that a sequential whole-report procedure allows the assessment of qualitatively different states in visual WM. (PsycINFO Database Record

Exploring the switching of the focus of attention within working memory: A combined event-related potential and behavioral study

Working memory enables humans to maintain selected information for cognitive processes and ensures instant access to the memorized contents. Theories suggest that switching the focus of attention between items within working memory realizes the access. This is reflected in object-switching costs in response times when the item for the task processing is to be changed. Another correlate of attentional allocation in working memory is the P3a-component of the human event-related potential. The aim of this study was to demonstrate that switching of attention within working memory is a separable processing step. Participants completed a cued memory-updating task in which they were instructed to update one memory item at a time out of a memory list of four digits by applying a mathematical operation indicated by a target sign. The hypotheses predicted (1) prolonged updating times in switch (different item compared to previous trial) versus repetition trials (same item), (2) an influence of cues (valid/neutral) presented before the mathematical target on switching costs, and (3) that the P3a-component is more pronounced in the cue-target interval in the valid cue condition and more pronounced in the post-target interval in the neutral cue condition. A student's t-test verified the first hypothesis, repeated-measurement analyses of variance demonstrated that hypotheses 2 and 3 should be rejected. Results suggest that switching of attention within working memory could not be separated from further processing steps and retro-cue benefits are not due to a head start of retrieval as well as that switch costs represent internal processes.

A neural model of retrospective attention in visual working memory

An informative cue that directs attention to one of several items in working memory improves subsequent recall of that item. Here we examine the mechanism of this retro-cue effect using a model of short-term memory based on neural population coding. Our model describes recalled feature values as the output of an optimal decoding of spikes generated by a tuned population of neurons. This neural model provides a better account of human recall data than an influential model that assumes errors can be described as a mixture of normally distributed noise and random guesses. The retro-cue benefit is revealed to be consistent with a higher firing rate of the population encoding the cued versus uncued items, with no difference in tuning specificity. Additionally, a retro-cued item is less likely to be swapped with another item in memory, an effect that can also be explained by greater activity of the underlying population. These results provide a parsimonious account of the effects of retrospective attention on recall and demonstrate a principled method for investigating neural representations with behavioral tasks.

Remapping high-capacity, pre-attentive, fragile sensory memory

Humans typically make several saccades per second. This provides a challenge for the visual system as locations are largely coded in retinotopic (eye-centered) coordinates. Spatial remapping, the updating of retinotopic location coordinates of items in visuospatial memory, is typically assumed to be limited to robust, capacity-limited and attention-demanding working memory (WM). Are pre-attentive, maskable, sensory memory representations (e.g. fragile memory, FM) also remapped? We directly compared trans-saccadic WM (tWM) and trans-saccadic FM (tFM) in a retro-cue change-detection paradigm. Participants memorized oriented rectangles, made a saccade and reported whether they saw a change in a subsequent display. On some trials a retro-cue indicated the to-be-tested item prior to probe onset. This allowed sensory memory items to be included in the memory capacity estimate. The observed retro-cue benefit demonstrates a tFM capacity considerably above tWM. This provides evidence that some, if not all sensory memory was remapped to spatiotopic (world-centered, task-relevant) coordinates. In a second experiment, we show backward masks to be effective in retinotopic as well as spatiotopic coordinates, demonstrating that FM was indeed remapped to world-centered coordinates. Together this provides conclusive evidence that trans-saccadic spatial remapping is not limited to higher-level WM processes but also occurs for sensory memory representations.

Beyond the magic number four: Remapping high-capacity, pre-attentive, fragile working memory.

Visual short term memory allows us to access visual information after termination of its retinal input. Generally, a distinction is made between a robust, capacity-limited form (working memory, WM) and high-capacity, pre-attentive, maskable forms (sensory memory, e.g. fragile memory, FM). Eye movements pose a challenge for spatial memory because retinotopically coded coordinates need to be updated with every saccade (spatial remapping). This computationally intense process has been considered strictly limited to WM. To answer the question whether fragile, pre-attentive memory items are also remapped we directly compared trans-saccadic WM (tWM) and FM (tWM) capacity. Participants memorized oriented bars and reported on a change in probe displays after making a saccade. A predictive retro-cue indicated future targets and protected FM from being masked by the memory probe, which is known to increase capacity estimates due to the inclusion of FM items (retro-cue benefit). If only stable, attended memory items can be remapped, then capacity after a saccade should be that of tWM, even if capacity was high before the saccade (FM). We found that tFM capacity was considerably higher than tWM capacity. This demonstrates that in addition to attended items in WM, non-attended items in FM were also remapped. In a second experiment, we retroactively masked items to disrupt the retro-cue benefit. The results show that masks at the retinotopic location as well as at the spatiotopic location reduced the retro-cue benefit. This confirms that FM items have been remapped to task-relevant, world-centered coordinates. We provide conclusive evidence for the existence of high-capacity, trans-saccadic, fragile visual memory and challenge the strongly held belief that trans-saccadic memory is identical to robust WM. This has important implications for our understanding of spatial remapping, which is thought to be intimately linked to spatial attention. Our results demonstrate that un-attended items can also be remapped. Meeting abstract presented at VSS 2017

On the contribution of motor planning to the retroactive cuing benefit in working memory: Evidence by mu and beta oscillatory activity in the EEG

Attention can be allocated toward mental representations in working memory also after the initial encoding of information has been completed. It was shown that focusing on only one item within working memory transfers this representation into a protected state, reducing its susceptibility to interference by incoming signals. The present study investigated the nature of this retroactive cue (retro-cue) benefit by means of oscillatory activity in the EEG. In a working memory task with a retro-cue indicating one, two or three memory representations as relevant and a block-wise distractor display presented after the retro-cue, participants had to remember the orientation of a colored bar. On behavioral level, we found that the interfering effect of the distractor display on memory performance could be prevented when a retro-cue reduced the number of attended representations in working memory. However, only the one-item retro-cue led to an overall increase in task performance compared to a condition without a retro-cue. The neural basis of this special representational status was investigated by means of oscillatory parameters in the EEG and a clustering approach on level of the independent components (ICs) in the signal. The retroactive reduction of attended working memory representations was reflected in a suppression of alpha power over right parietal and parieto-occipital sites. In addition, we found that an IC cluster representing oscillatory activity in the mu/beta range (10–12 Hz and 20–24 Hz) with a source in sensorimotor cortex revealed a power suppression already prior to the memory probe following the one-item retro-cue. This suggests that the retro-cue benefit results in large parts from the possibility to focus attention on one particular item in working memory and initiate motor planning processes already ahead of the probe stimulus indicating the respective response.

Working memory capacity differentially influences responses to tDCS and HD-tDCS in a retro-cue task

There is growing interest in non-invasive brain stimulation techniques. A drawback is that the relationship between stimulation and cognitive outcomes for various tasks are unknown. Transcranial direct current stimulation (tDCS) provides diffuse current spread, whereas high-definition tDCS (HD-tDCS) provides more targeted current. The direction of behavioral effects after tDCS can be difficult to predict in cognitive realms such as attention and working memory (WM). Previously, we showed that in low and high WM capacity groups tDCS modulates performance in nearly equal and opposite directions on a change detection task, with improvement for the high capacity participants alone. Here, we used the retro-cue paradigm to test attentional shifting among items in WM to investigate whether WM capacity (WMC) predicted different behavioral consequences during anodal tDCS or HD-tDCS to posterior parietal cortex (PPC). In two experiments, with 24 participants each, we used different stimulus categories (colored circles, letters) and stimulation sites (right, left PPC). The results showed a significant (Experiment 1) or trending (Experiment 2) WMC x stimulation interaction. Compared to tDCS, after HD-tDCS the retro-cueing benefit was significantly greater for the low WMC group but numerically worse for the high WMC group. These data highlight the importance of considering group differences when using non-invasive neurostimulation techniques.

The (Un)Clear Effects of Invalid Retro-Cues.

Studies with the retro-cue paradigm have shown that validly cueing objects in visual working memory long after encoding can still benefit performance on subsequent change detection tasks. With regard to the effects of invalid cues, the literature is less clear. Some studies reported costs, others did not. We here revisit two recent studies that made interesting suggestions concerning invalid retro-cues: One study suggested that costs only occur for larger set sizes, and another study suggested that inclusion of invalid retro-cues diminishes the retro-cue benefit. New data from one experiment and a reanalysis of published data are provided to address these conclusions. The new data clearly show costs (and benefits) that were independent of set size, and the reanalysis suggests no influence of the inclusion of invalid retro-cues on the retro-cue benefit. Thus, previous interpretations may be taken with some caution at present.

Getting more from visual working memory: Retro-cues enhance retrieval and protect from visual interference.

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

A retroactive spatial cue improved VSTM capacity in mild cognitive impairment and medial temporal lobe amnesia but not in healthy older adults

Visual short-term memory (VSTM) is a vital cognitive ability, connecting visual input with conscious awareness. VSTM performance declines with mild cognitive impairment (MCI) and medial temporal lobe (MTL) amnesia. Many studies have shown that providing a spatial retrospective cue (“retrocue”) improves VSTM capacity estimates for healthy young adults. However, one study has demonstrated that older adults are unable to use a retrocue to inhibit irrelevant items from memory. It is unknown whether patients with MCI and MTL amnesia will be able to use a retrocue to benefit their memory. We administered a retrocue and a baseline (simultaneous cue, “simucue”) task to young adults, older adults, MCI patients, and MTL cases. Consistent with previous findings, young adults showed a retrocue benefit, whereas healthy older adults did not. In contrast, both MCI patients and MTL cases showed a retrocue benefit – the use of a retrocue brought patient performance up to the level of age-matched controls. We speculate that the patients were able to use the spatial information from the retrocue to reduce interference and facilitate binding items to their locations.

Forgotten but not gone: Retro-cue costs and benefits in a double-cueing paradigm suggest multiple states in visual short-term memory.

Visual short-term memory (VSTM) performance is enhanced when the to-be-tested item is cued after encoding. This so-called retro-cue benefit is typically accompanied by a cost for the noncued items, suggesting that information is lost from VSTM upon presentation of a retrospective cue. Here we assessed whether noncued items can be restored to VSTM when made relevant again by a subsequent second cue. We presented either 1 or 2 consecutive retro-cues (80% valid) during the retention interval of a change-detection task. Relative to no cue, a valid cue increased VSTM capacity by 2 items, while an invalid cue decreased capacity by 2. Importantly, when a second, valid cue followed an invalid cue, capacity regained 2 items, so that performance was back on par. In addition, when the second cue was also invalid, there was no extra loss of information from VSTM, suggesting that those items that survived a first invalid cue, automatically also survived a second. We conclude that these results are in support of a very versatile VSTM system, in which memoranda adopt different representational states depending on whether they are deemed relevant now, in the future, or not at all. We discuss a neural model that is consistent with this conclusion.

Invalid retro-cues can eliminate the retro-cue benefit: Evidence for a hybridized account.

The contents of visual working memory (VWM) are capacity limited and require frequent updating. The retrospective cueing (retro-cueing) paradigm clarifies how directing internal attention among VWM items boosts VWM performance. In this paradigm a cue appears prior to retrieval, but after encoding and maintenance. The retro-cue effect (RCE) refers to superior VWM after valid versus neutral retro-cues. Here we investigated the effect of the invalid retro-cues' inclusion on VWM performance. We conducted 2 pairs of experiments, changing both probe type (recognition and recall) as well as presence and absence of invalid retro-cue trials. Furthermore, to fully characterize these effects over time, we used extended post-retro-cue delay durations. In the first set of experiments, probing VWM using recognition indicated that the RCE remained consistent in magnitude with or without invalid retro-cue trials. In the second set of experiments, VWM was probed with recall. Here, the RCE was eliminated when invalid retro-cues were included. This finer-grained measure of VWM fidelity showed that all items were subject to decay over time. We conclude that the invalid retro-cues impaired the protection of validly cues items, but they remain accessible, suggesting greater concordance with a prioritization account.

Recall and Recognition Effects on Retro-Cue Benefit

Recall and Recognition Effects on Retro-Cue Benefit

Retro-cue benefits in working memory without sustained focal attention

In working memory (WM) tasks, performance can be boosted by directing attention to one memory object: When a retro-cue in the retention interval indicates which object will be tested, responding is faster and more accurate (the retro-cue benefit). We tested whether the retro-cue benefit in WM depends on sustained attention to the cued object by inserting an attention-demanding interruption task between the retro-cue and the memory test. In the first experiment, the interruption task required participants to shift their visual attention away from the cued representation and to a visual classification task on colors. In the second and third experiments, the interruption task required participants to shift their focal attention within WM: Attention was directed away from the cued representation by probing another representation from the memory array prior to probing the cued object. The retro-cue benefit was not attenuated by shifts of perceptual attention or by shifts of attention within WM. We concluded that sustained attention is not needed to maintain the cued representation in a state of heightened accessibility.