Negative emotional state modulates visual working memory in the late consolidation phase

All identical objects reduce memory load at the late maintenance stage in working memory

Visual working memory (VWM) is critical for temporarily storing and manipulating visual information but is limited in capacity. Previous research suggests that perceptual organization, such as grouping identical objects, may alleviate VWM resource constraints, yet the underlying mechanisms remain unclear. This study investigated whether identical orientation stimuli reduce VWM resource consumption and whether this reduction occurs during encoding or maintenance phase. Using the contralateral delay activity (CDA), an event-related potential (ERP) component that indexes the number of items stored in VWM, we examined three memory conditions: all-same (i.e., four identical orientations), partial-same (i.e., two pairs of identical orientations), and all-different (i.e., four different orientations) conditions. Behavioral results showed improved VWM performance as the number of identical orientations increased, with the highest performance in the all-same condition. ERP results revealed no significant differences in early CDA amplitudes across conditions, suggesting that identical stimuli do not reduce VWM resource consumption during early maintenance phase. However, late CDA amplitudes were significantly reduced in the all-same condition compared to the partial-same and all-different conditions, indicating that the benefits of identical objects emerge during the late maintenance phase. Notably, partially identical stimuli did not reduce VWM load, highlighting the complexity of integrating partially redundant information. These findings highlight the distinct contributions of early consolidation and maintenance phases in optimizing VWM through perceptual grouping and provide evidence that the facilitative effect of identical objects relies on their complete repetition and late-stage cognitive processes.

Do emotionally negative events impair working memory as a result of intrusive thoughts?

Individuals exposed to highly stressful negative events show alterations in working memory (WM) function. The correlational nature of these studies makes it impossible to determine whether exposure to negative events itself decreases WM. Such events elicit intrusive thoughts which may cause interference in WM. The main objective of this study was to verify the causal impact of a recent negative event on WM, and to examine the role of intrusive thoughts. One hundred and twenty participants completed a WM task (n-Back). Then, 90 of these participants watched an emotionally negative video and 30 watched a neutral video. The emotional impact of the video was assessed, and the frequency of intrusive thoughts were measured. WM was measured a second time (n-Back) while recording EEG (P300). Contrary to our hypothesis, the negative video did not impair behavioural WM performance compared to the neutral video. However, it disrupted WM neurocognitive processes (lower P300 amplitude) under low WM load. In the high load condition, greater emotional reaction was linked to poorer accuracy and more intrusive thoughts, which in turn slowed response times. Our results suggest that the impact of negative emotions on WM depends on both individual sensitivity and cognitive load.

Is a picture worth the same emotions everywhere? Validation of images from the Nencki affective picture system in Malaysia

Several validated image sets, such as NAPS, IAPS, GAPED, and OASIS, have been developed to elicit affective states. However, these image sets were primarily validated on Western populations within European and American contexts, and none have been fully validated in a Southeast Asian sample, where emotional restraint may also be valued similarly to the East Asian contexts. This study aimed to validate and provide norms for the Nencki Affective Picture System (NAPS; Marchewka et al., 2014) within a Malaysian sample. Subsets from the 1356 NAPS images consisting of five image categories (faces, people, objects, landscapes, animals) were presented sequentially to 409 Malaysian adults aged 18 and above, who rated images for valence, arousal and approach/avoidance on a 9-point Likert scale. Valence, arousal and approach/avoidance norms were compared against the original European sample. Malaysian men and women rated images with lower valence and motivation than Europeans, but Malaysian men showed higher arousal ratings compared to European men, while Malaysian women exhibited the opposite pattern, with lower arousal ratings than European women. A linear regression was found instead of a classic 'boomerang' shaped quadratic regression previously observed in Western samples, suggesting that emotional suppression may be at play, in line with social norms. The Malaysian normative ratings will be freely available to all researchers.

Comparing retro-cue benefit mechanisms in visual working memory: completely valid vs. highly valid retro-cues

Visual working memory (VWM) plays a crucial role in temporarily maintaining and manipulating visual information. Retro-cue benefit (RCB) refers to the enhancement of memory performance when attention is directed toward a subset of items in VWM after their initial encoding. Our recent electroencephalogram (EEG) studies indicate that cue validity affects the mechanisms underlying RCB formation. However, previous research has not thoroughly examined whether these mechanisms differ between completely valid and highly valid cue conditions. This study investigates the consistency of RCB mechanisms under conditions of complete (100%) and high (80%) retro-cue validity. We manipulated retro-cue validity and examined cognitive processing mechanisms under different validity conditions using EEG. Specifically, we focused on the N2pc component, which reflects attentional resource allocation, and the contralateral delay activity (CDA) component, which reflects the quantity of information retained in VWM. The results, encompassing both behavioral and event-related potential (ERP) findings, show that participants in both the 100% and 80% cue validity conditions exhibit robust RCB. Notably, the degree of RCB remains consistent across these conditions, indicating that participants utilize retro-cues to enhance VWM performance to the same extent. In the 80% cue validity condition, a significant retro-cue cost (RCC) was observed, indicating that participants selectively discarded uncued items from VWM. In invalid trials, response accuracy drops to chance levels, supporting the removal hypothesis. ERP results reveal that attentional resource allocation (N2pc) and the quantity of retained information (CDA) remain uniform across cue validity conditions. The mechanism responsible for RCB formation appears to involve an all-or-nothing process of discarding uncued information rather than a flexible resource allocation strategy. This study provides insights into attention allocation and information-processing mechanisms in VWM, suggesting that conclusions drawn from tasks with completely valid retro-cues can be integrated with findings from highly valid cue tasks. These findings also illuminate the flexibility of internal attentional resource allocation during RCB formation and contribute to our understanding of attention processes in VWM.

Dimension-based retro-cue benefit in working memory does not require unfocused dimension removal

Introduction

Within the maintenance phase of visual working memory (VWM), previous researchers presented retro-cues orienting to a probed dimension across all multidimension stimuli and found a robust dimension-based retro-cue benefit (RCB): VWM performance for cued dimension was better than no/neutral-cue baseline. This improvement is often attributed to the prioritization of information related to the focused dimension and the removal of information related to the unfocused dimension from VWM. However, it remains unclear whether the removal of the uncued dimension is necessary to observe this dimension-based RCB.

Methods

In the current study, we first manipulated the number of retro-cues to investigate this question. We used colored, oriented bars as stimuli and two sequential retro-cues oriented to different dimensions in the double-cue condition. The last presented cue in each trial was always valid. Therefore, the unfocused dimension in the first cue display was probed in double-cue trials. Experiment 1 adopted change detection tasks and three cue type conditions (no-cue, single-cue, double-cue). Experiment 2 divided the single-cue condition into early- and late- cue conditions, using recall tasks to elevated probe precision. Experiment 3 further added double-neutral and double-same cue types and eliminated the different influences of post-memory masks on each dimension respectively.

Results

Results across these experiments showed a robust pattern of no worse performances for the double-cue condition than for the single-cue condition.

Discussion

Because the dimension-based single cue benefit was observed especially in early-cue trials, we supposed that the dimension-based RCB does not require removing the unfocused dimension from VWM.

Influence of presentation duration on filtering of irrelevant stimuli in visual working memory

In environments teeming with distractions, the ability to selectively focus on relevant information is crucial for advanced cognitive processing. Existing research using event-related potential (ERP) technology has shown active suppression of irrelevant stimuli during the consolidation phase of visual working memory (VWM). In previous studies, participants have always been given sufficient time to consolidate VWM, while suppressing distracting information. However, it remains unclear whether the suppression of irrelevant distractors requires continuous effort throughout their presence or whether this suppression is only necessary after the consolidation of task-relevant information. To address this question, our study examines whether distractor suppression is necessary in scenarios where consolidation time is limited. This research investigates the effect of varying presentation durations on the filtering of distractors in VWM. We tasked participants with memorizing two color stimuli and ignoring four distractors, presented for either 50 ms or 200 ms. Using ERP technology, we discovered that the distractor-induced distractor positivity (PD) amplitude is larger during longer presentation durations compared to shorter ones. These findings underscore the significant impact of presentation duration on the efficacy of distractor suppression in VWM, as prolonged exposure results in a stronger suppression effect on distractors. This study sheds light on the temporal dynamics of attention and memory, emphasizing the critical role of stimulus timing in cognitive tasks. These findings provide valuable insights into the mechanisms underlying VWM and have significant implications for models of attention and memory.

The differential impact of face distractors on visual working memory across encoding and delay stages

External distractions often occur when information must be retained in visual working memory (VWM)-a crucial element in cognitive processing and everyday activities. However, the distraction effects can differ if they occur during the encoding rather than the delay stages. Previous research on these effects used simple stimuli (e.g., color and orientation) rather than considering distractions caused by real-world stimuli on VWM. In the present study, participants performed a facial VWM task under different distraction conditions across the encoding and delay stages to elucidate the mechanisms of distraction resistance in the context of complex real-world stimuli. VWM performance was significantly impaired by delay-stage but not encoding-stage distractors (Experiment 1). In addition, the delay distraction effect arose primarily due to the absence of distractor process at the encoding stage rather than the presence of a distractor during the delay stage (Experiment 2). Finally, the impairment in the delay-distraction condition was not due to the abrupt appearance of distractors (Experiment 3). Taken together, these findings indicate that the processing mechanisms previously established for resisting distractions in VWM using simple stimuli can be extended to more complex real-world stimuli, such as faces.

Perceptual encoding benefit of visual memorability on visual memory formation

Human observers often exhibit remarkable consistency in remembering specific visual details, such as certain face images. This phenomenon is commonly attributed to visual memorability, a collection of stimulus attributes that enhance the long-term retention of visual information. However, the exact contributions of visual memorability to visual memory formation remain elusive as these effects could emerge anywhere from early perceptual encoding to post-perceptual memory consolidation processes. To clarify this, we tested three key predictions from the hypothesis that visual memorability facilitates early perceptual encoding that supports the formation of visual short-term memory (VSTM) and the retention of visual long-term memory (VLTM). First, we examined whether memorability benefits in VSTM encoding manifest early, even within the constraints of a brief stimulus presentation (100-200 ms; Experiment 1). We achieved this by manipulating stimulus presentation duration in a VSTM change detection task using face images with high- or low-memorability while ensuring they were equally familiar to the participants. Second, we assessed whether this early memorability benefit increases the likelihood of VSTM retention, even with post-stimulus masking designed to interrupt post-perceptual VSTM consolidation processes (Experiment 2). Last, we investigated the durability of memorability benefits by manipulating memory retention intervals from seconds to 24 h (Experiment 3). Across experiments, our data suggest that visual memorability has an early impact on VSTM formation, persisting across variable retention intervals and predicting subsequent VLTM overnight. Combined, these findings highlight that visual memorability enhances visual memory within 100-200 ms following stimulus onset, resulting in robust memory traces resistant to post-perceptual interruption and long-term forgetting.

A negative emotional state impairs individuals' ability to filter distractors from working memory: an ERP study

Capacity-limited visual working memory (VWM) requires that individuals have sufficient memory space and the ability to filter distractors. Negative emotional states are known to impact VWM storage, yet their influence on distractor filtering within VWM remains underexplored. We conducted direct neural measurement of participants (n = 56) who conducted a lateralized change detection task with distractors, while manipulating the emotional state by presenting neutral or negative images before each trial. We found a detrimental effect of distractors on memory accuracy under both neutral and negative emotional states. Using the event-related potential (ERP) component, contralateral delay activity (CDA; sensitive to VWM load), to observe the VWM load in each condition, we found that in the neutral state, the participants showed significantly higher late CDA amplitudes when remembering 4 targets compared with 2 targets and 2 targets with 2 distractors but no significant difference when remembering 2 targets compared with 2 targets with 2 distractors. In the negative state, no significant CDA amplitude differences were evident when remembering 4 targets and 2 targets, but CDA was significantly higher when remembering 2 targets with 2 distractors compared with 2 targets. These results suggest that the maximum number of items participants could store in VWM was lower under negative emotional states than under neutral emotional states. Importantly, the participants could filter out distractors when in a neutral emotional state but not in a negative emotional state, indicating that negative emotional states impair their ability to filter out distractors in VWM.

Exploring the Interplay of Working Memory, Apathy, and Mood/Emotional Factors

BACKGROUND

Previous investigations on healthy humans showed conflicting evidence regarding the impact of mood on working memory performance. A systematic investigation of how mood affects apathy levels in healthy participants is currently missing.

METHODS

We administered a visuospatial (VS) and a numerical (N) n-back task to a sample of 120 healthy individuals. In these participants, using a series of questionnaires, we also evaluated apathy, mood, working memory, perceived stress, PTSD symptoms caused by the COVID-19 pandemic outbreak, and general psychiatric symptoms. Successively, we investigated their performance in the n-back task as a function of scores to these questionnaires.

RESULTS

Participants performed better in the N block than in the VS one. Their accuracy decreased as a function of the n-back difficulty. We reported no differences in working memory performance or apathy as a function of mood, stress, or PTSD symptoms. We found that phobic anxiety negatively predicted accuracy to the numerical n-back task and that subjects with greater anxiety and difficulty in regulating emotions also showed higher levels of withdrawal from the task.

CONCLUSION

The study's results suggest that while mood did not significantly affect working memory performance, strong associations were found between WMQ scores and working memory capabilities.

Dynamic and static angry faces influence time perception differently-Evidence from ERPs

The dynamic characteristics of facial expressions might affect time perception. Compared with static emotional faces, dynamic emotional faces are more intense, have higher ecological validity, and contain time series information, which may lead to time overestimation. In the present study, we aimed at investigating how dynamic characteristics of angry facial expressions affect time perception, as measured using event-related potentials (ERPs). Dynamic and static angry and neutral faces with different durations (400, 600, 800, 1000, 1200, 1400, and 1600 ms) were presented in the classical temporal bisection paradigm. Participants were asked to judge whether the duration of the presented face was closer to 400 or 1600 ms. The behavioral results showed a significant overestimation effect for dynamic angry faces compared with static faces, both in terms of proportion of long and Bisection Point. The ERP results indicated that the processing mechanisms are significantly different between judging the duration of dynamic and static angry faces. Dynamic angry faces evoked a larger N2 and Late Positive Potential than did static faces, while the static angry faces evoked a larger P2 and Early Posterior Negativity. The Contingent Negative Variation showed a complex change pattern over time. Our results indicate that dynamic angry facial expressions influence time perception differently than do static faces. Static angry faces were processed earlier and were considered to cause an overestimation of time through early emotional arousal and attentional bias, while dynamic angry faces may have caused the overestimation of time through response inhibition and late sustained attention.

Alterations in working memory maintenance of fearful face distractors in depressed participants: An ERP study

Task-irrelevant threatening faces (e.g., fearful) are difficult to filter from visual working memory (VWM), but the difficulty in filtering non-threatening negative faces (e.g., sad) is not known. Depressive symptoms could also potentially affect the ability to filter different emotional faces. We tested the filtering of task-irrelevant sad and fearful faces by depressed and control participants performing a color-change detection task. The VWM storage of distractors was indicated by contralateral delay activity, a specific event-related potential index for the number of objects stored in VWM during the maintenance phase. The control group did not store sad face distractors, but they automatically stored fearful face distractors, suggesting that threatening faces are specifically difficult to filter from VWM in non-depressed individuals. By contrast, depressed participants showed no additional consumption of VWM resources for either the distractor condition or the non-distractor condition, possibly suggesting that neither fearful nor sad face distractors were maintained in VWM. Our control group results confirm previous findings of a threat-related filtering difficulty in the normal population while also suggesting that task-irrelevant non-threatening negative faces do not automatically load into VWM. The novel finding of the lack of negative distractors within VWM storage in participants with depressive symptoms may reflect a decreased overall responsiveness to negative facial stimuli. Future studies should investigate the mechanisms underlying distractor filtering in depressed populations.

The facilitating effect of identical objects in visual working memory

According to the associative network of memory representations proposed by embedded processes models, the links between related memory representations were automatically established, which rendered these representations more easily activated. The present study adopted color recall tasks to explore whether the memory performance of identical objects was enhanced via the strengthening links between them, producing facilitating effect of identical objects. In Experiment 1, the number of identical items was manipulated. The results evidenced the facilitating effect, which was positively related to the number of identical objects. Experiment 2 modulated the spatial location of identical objects, which suggested that the facilitating effect was absent when two pairs of identical objects were located diagonally. Furthermore, Experiment 3 suggested that the facilitating effect was observed for the identical items which were presented in the second and fourth quadrants, rather than the first and third quadrants. Together, these results evidenced the facilitating effect of identical objects, which, however, was affected by spatial bias.

Encoding specificity instead of online integration of real-world spatial regularities for objects in working memory

Most objects show high degrees of spatial regularity (e.g. beach umbrellas appear above, not under, beach chairs). The spatial regularities of real-world objects benefit visual working memory (VWM), but the mechanisms behind this spatial regularity effect remain unclear. The "encoding specificity" hypothesis suggests that spatial regularity will enhance the visual encoding process but will not facilitate the integration of information online during VWM maintenance. The "perception-alike" hypothesis suggests that spatial regularity will function in both visual encoding and online integration during VWM maintenance. We investigated whether VWM integrates sequentially presented real-world objects by focusing on the existence of the spatial regularity effect. Throughout five experiments, we manipulated the presentation (simultaneous vs. sequential) and regularity (with vs. without regularity) of memory arrays among pairs of real-world objects. The spatial regularity of memory objects presented simultaneously, but not sequentially, improved VWM performance. We also examined whether memory load, verbal suppression and masking, and memory array duration hindered the spatial regularity effect in sequential presentation. We found a stable absence of the spatial regularity effect, suggesting that the participants were unable to integrate real-world objects based on spatial regularities online. Our results support the encoding specificity hypothesis, wherein the spatial regularity of real-world objects can enhance the efficiency of VWM encoding, but VWM cannot exploit spatial regularity to help organize sampled sequential information into meaningful integrations.

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

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

Negative and Positive Bias for Emotional Faces: Evidence from the Attention and Working Memory Paradigms

Visual attention and visual working memory (VWM) are two major cognitive functions in humans, and they have much in common. A growing body of research has investigated the effect of emotional information on visual attention and VWM. Interestingly, contradictory findings have supported both a negative bias and a positive bias toward emotional faces (e.g., angry faces or happy faces) in the attention and VWM fields. We found that the classical paradigms-that is, the visual search paradigm in attention and the change detection paradigm in VWM-are considerably similar. The settings of these paradigms could therefore be responsible for the contradictory results. In this paper, we compare previous controversial results from behavioral and neuroscience studies using these two paradigms. We suggest three possible contributing factors that have significant impacts on the contradictory conclusions regarding different emotional bias effects; these factors are stimulus choice, experimental setting, and cognitive process. We also propose new research directions and guidelines for future studies.

The two-stage process in visual working memory consolidation

Two hypotheses have been proposed to explain the formation manner for visual working memory (VWM) representations during the consolidation process: an all-or-none process hypothesis and a coarse-to-fine process hypothesis. However, neither the all-or-none process hypothesis nor the coarse-to-fine process hypothesis can stipulate clearly how VWM representations are formed during the consolidation process. In the current study, we propose a two-stage process hypothesis to reconcile these hypotheses. The two-stage process hypothesis suggests that the consolidation of coarse information is an all-or-none process in the early consolidation stage, while the consolidation of detailed information is a coarse-to-fine process in the late consolidation stage. By systematically manipulating the encoding time of memory stimuli, we asked participants to memorize one (Experiment 1) or two (Experiment 2) orientations in different encoding time intervals. We found that the memory rate increased linearly as the encoding time increased. More importantly, VWM precision remained constant when the encoding time was short, while the precision increased linearly as the encoding time increased when the encoding time was sufficient. These results supported the two-stage process hypothesis, which reconciles previous conflicting findings in the literature.