Microsaccades reflect attention shifts: a mini review of 20 years of microsaccade research.

Microsaccades are small, involuntary eye movements that occur during fixation. Since the 1950s, researchers have conducted extensive research on the role of microsaccades in visual information processing, and found that they also play an important role in human advanced visual cognitive activities. Research over the past 20 years further suggested that there is a close relationship between microsaccades and visual attention, yet lacking a timely review. The current article aims to provide a state-of-the-art review and bring microsaccades studies into the sight of attention research. We firstly introduce basic characteristics about microsaccades, then summarized the empirical evidence supporting the view that microsaccades can reflect both external (perception) and internal (working memory) attention shifts. We finally conclude and highlight three promising avenues for future research.

Dual routes of chunking social interaction: Insights from grouping two agent actions in working memory.

Humans have evolved the sophisticated ability to extract social relations embedded in interactive entities. One typical demonstration is a social chunking phenomenon wherein the cognitive system chunks individual actions into a unified episode basing on perceived interactive actions. However, the mechanisms underlying social chunking remain to be elucidated. Most studies have adopted static images and manipulated interactions through agents' facingness (face-to-face vs. back-to-back). Connecting agents via directed contingent actions is crucial in forming real-life social interaction. Hence, we employed dynamic actions as stimuli, separated physical- and communicative-contingency interactive actions, and predicted that domain-general physical regularities and domain-specific social relationships are crucial in social interactions, respectively. We tested this prediction by using an involuntary chunking effect in working memory, wherein two individual actions are involuntarily chunked when containing task-irrelevant interactive information. We found that involuntary chunking occurred for both types of upright interactive actions (Experiments 1, 3, 5, and 6). Inverting actions erased the chunking of communicative- but not physical-contingency actions (Experiments 2, 4, and 5). The facingness of dyads did not participate in chunking physical-contingency actions but was a prerequisite for chunking communicative-contingency actions (Experiments 3 and 6). These results reveal the dual routes of chunking interactive actions. Moreover, they suggest that the chunking mechanisms of dynamic social interaction are distinct from those of static images, highlighting the importance of using dynamic stimuli to explore the mechanisms of social interaction in emerging people-watching interdisciplinarity. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Mood congruency affects physiological synchrony but not empathic accuracy in a naturalistic empathy task.

Empathy is a crucial aspect of our daily lives, as it enhances our wellbeing and is a proxy for prosocial behavior. It encompasses two related but partially distinct components: cognitive and affective empathy. Both are susceptible to context, biases and an individual's physiological state. Few studies have explored the effects of a person's mood on these empathy components, and results are mixed. The current study takes advantage of an ecological, naturalistic empathy task - the empathic accuracy (EA) task - in combination with physiological measurements to examine and differentiate between the effects of one's mood on both empathy components. Participants were induced with positive or negative mood and presented videos of targets narrating autobiographical negative stories, selected from a Chinese empathy dataset that we developed (now publicly available). The stories were conveyed in audio-only, visual-only and full-video formats. Participants rated the target's emotional state while watching or listening to their stories, and physiological measures were taken throughout the process. Importantly, similar measures were taken from the targets when they narrated the stories, allowing a comparison between participants' and targets' measures. We found that in audio-only and visual-only conditions, participants whose moods were congruent with the target showed higher physiological synchrony than those with incongruent mood, implying a mood-congruency effect on affective empathy. However, there was no mood effect on empathic accuracy (reflecting cognitive empathy), suggesting a different influence of mood on the two empathy components.

A domain-general frontoparietal network interacts with domain-preferential intermediate pathways to support working memory task.

Working memory (WM) is essential for cognition, but the underlying neural mechanisms remain elusive. From a hierarchical processing perspective, this paper proposed and tested a hypothesis that a domain-general network at the top of the WM hierarchy can interact with distinct domain-preferential intermediate circuits to support WM. Employing a novel N-back task, we first identified the posterior superior temporal gyrus (pSTG), middle temporal area (MT), and postcentral gyrus (PoCG) as intermediate regions for biological motion and shape motion processing, respectively. Using further psychophysiological interaction analyses, we delineated a frontal-parietal network (FPN) as the domain-general network. These results were further verified and extended by a delayed match to sample (DMS) task. Although the WM load-dependent and stimulus-free activations during the DMS delay phase confirm the role of FPN as a domain-general network to maintain information, the stimulus-dependent activations within this network during the DMS encoding phase suggest its involvement in the final stage of the hierarchical processing chains. In contrast, the load-dependent activations of intermediate regions in the N-back task highlight their further roles beyond perception in WM tasks. These results provide empirical evidence for a hierarchical processing model of WM and may have significant implications for WM training.

Atypical development of social and nonsocial working memory capacity among preschoolers with autism spectrum disorders.

Individuals with autism spectrum disorders (ASD) have shown impaired performance in canonical and nonsocial working memory (WM). However, no study has investigated social WM and its early development. Using biological motion stimuli, our study assessed the development of social and nonsocial WM capacity among children with or without ASD across the age span between 4 and 6 (N = 150). While typically developing (TD) children show a rapid development from age 5 to 6, children with ASD showed a delayed development for both social and nonsocial WM capacity, reaching a significant group difference at age 6. Furthermore, we found a negative correlation between social (but not nonsocial) WM capacity and the severity of autistic symptoms among children with ASD. In contrast, there is a positive correlation between both types of WM capacity and intelligence among TD children but not among children with ASD. Our findings thus indicate that individuals with ASD miss the rapid development of WM capacity in early childhood and, particularly, their delayed social WM development might contribute to core symptoms that critically depend on social information processing.

Emotion recognition dysfunction after anesthesia and cardiac surgery.

Cognitive dysfunction after anesthesia and surgery has long been recognized. Recently, researchers provided empirical evidence for social cognition dysfunction (SCD) after anesthesia and surgery. In the present study, we concentrated on the deficits in emotion recognition, one of the most important clinical perspectives in SCD, in patients who underwent cardiac surgery. Biological motion (BM) was considered as the stimulus of interest, and patients' abilities of BM emotion perception and action perception before and after anesthesia and surgery were examined. In total, 60 adult patients (40-72 years old) completed the BM recognition task, which required them to label the types of actions and emotions of perceived BM. The results showed that while action perception remained intact after cardiac surgery, 18.3% of patients exhibited deficits in emotion perception, further confirming the existence of SCD after anesthesia and surgery.

Is the social chunking of agent actions in working memory resource-demanding?

Retaining social interactions in working memory (WM) for further social activities is vital for a successful social life. Researchers have noted a social chunking phenomenon in WM: WM involuntarily uses the social interaction cues embedded in the individual actions and chunks them as one unit. Our study is the first to examine whether the social chunking in WM is an automatic process, by asking whether social chunking of agent actions in WM is resource-demanding, a key hallmark of automaticity. We achieved this by probing whether retaining agent interactions in WM as a chunk required more attention than retaining actions without interaction. We employed a WM change-detection task with actions containing social interaction cues as memory stimuli, and required participants only memorizing individual actions. As domain-general attention and object-based attention are suggested playing a key role in retaining chunks in WM, a secondary task was inserted in the WM maintenance phase to consume these two types of attention. We reestablished the fact that the social chunking in WM required no voluntary control (Experiments 1 and 2). Critically, we demonstrated substantial evidence that social chunking in WM did not require extra domain-general attention (Experiment 1) or object-based attention (Experiment 2). These findings imply that the social chunking of agent actions in WM is not resource-demanding, supporting an automatic view of social chunking in WM.

Development of information integration in the visual working memory of preschoolers.

Visual working memory (WM) plays a pivotal role in integrating fragments into meaningful units, but no study has addressed how visual WM integration takes place in children. The current study examined whether WM integration emerges once preschoolers master Gestalt cue and can retain two representations in WM (automatic integration hypothesis), or still needs time to mature (maturation-of-integration hypothesis). Four experiments (N = 168, 81 females, 4- to 6-year-olds, Chinese, in Hangzhou, China, from 2016.10 to 2021.11) were conducted. Although 4-year-olds can retain two objects in WM and benefit from Gestalt cues in simultaneous display (Cohen's ds >1.00), they failed when memory arrays were presented sequentially. Meanwhile, 5- and 6-year-olds consistently demonstrated WM integration ability (all Cohen's ds >0.69), supporting the maturation-of-integration hypothesis.

Diverting the focus of attention in working memory through a perceptual task.

Working memory (WM) has a limited capacity; however, this limitation can be mitigated by selecting individual items from the set currently held in WM for prioritization. The selection mechanism underlying this prioritization ability is referred to as the focus of attention (FOA) in WM. Although impressive progress has been achieved in recent years, a fundamental question remains unclear: Do perception and WM share one FOA? In the current study, we investigated the hypothesis that only a perceptual task tapping object-based attention can divert the FOA in WM. We adopted a retro-cue WM paradigm and inserted a perceptual task after the offset of the cue. Critically, we manipulated the type of attention (object-based attention in Experiments 1-3, feature-based attention in Experiment 4, and spatial attention in Experiment 5) consumed by the perceptual task. We found that participants were able to prioritize a retro-cued representation in WM, and the retro-cue benefit on memory accuracy was intact regardless of the perceptual task. Critically, the retro-cue benefit on the response time of WM task was significantly reduced only after an object-based attention perceptual task (Experiments 1, 2, 3a, and 3b), while remaining constant after a feature-based attention (Experiment 4) or spatial attention (Experiment 5) perceptual task. These results suggest that WM and perception share an object-based FOA, and an object-based attention perceptual task can divert the FOA in WM. Meanwhile, the current study further confirms that sustained attention is not necessary for selective maintenance in WM. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Object-based encoding in visual working memory: A critical revisit.

Visual working memory (VWM) is responsible for the temporal retention and manipulation of visual information. It has been suggested that VWM employs an object-based encoding (OBE) manner to extract highly discriminable information from visual perception: Whenever one feature dimension of the objects is selected for entry into VWM, the other task-irrelevant highly discriminable dimension is also extracted into VWM involuntarily. However, the task-irrelevant feature in OBE studies might reflect a high capacity fragile VWM (FVWM) trace that stores maskable sensory representations. To directly compare the VWM storage hypothesis and the FVWM storage hypothesis, we used a unique characteristic of FVWM that the representations in FVWM could be erased by backward masks presented at the original locations of the memory array. We required participants to memorise the orientations of three coloured bars while ignoring their colours, and presented backward masks during the VWM maintenance interval. In four experiments, we consistently observed that the OBE occurs regardless of the presentation of the backward masks, except when even the task-relevant features in VWM were significantly interrupted by immediate backward masks, suggesting that the task-irrelevant features of objects are stored in VWM rather than in FVWM.

Visual working memory impairs visual detection: A function of working memory load or sensory load?

Researchers have explored the influence of visual working memory (VWM) load on visual perception in the past decade. One of their key findings is that a high VWM load leads to reduced visual detection sensitivity to incoming visual stimuli. However, recent studies imply that persistent sensory processing continues after the memory array is offset. It is possible that the impaired visual detection is due to the sensory load of the residual sensory processing of the memory array (sensory load account) rather than the working memory load of the VWM task (VWM load account). We performed four experiments to examine the impacts on visual detection. Experiment 1 manipulated the retention time of the memory array while keeping the VWM load constant, revealing reduced visual detection along with retention time. Experiments 2 and 3 manipulated the VWM load while maintaining a constant sensory load, and visual detection was not affected. Experiment 4 affirmed that the findings in Experiments 1-3 were reliable. Together, the results of the current study suggest that the residual sensory load, rather than the VWM load of the VWM task, impairs visual detection. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Does the presence of more features in a bound representation in working memory require extra object-based attention?

Recent studies have examined the role of attention in retaining bound representations in working memory (WM) and found that object-based attention plays a pivotal role. However, no study has investigated whether maintaining bound representations with more features in WM requires extra object-based attention. We investigated this by examining whether a secondary task consuming object-based attention was more disruptive to the maintenance of bindings in WM when more features were stored per object. We instructed participants to memorize three bound representations in a WM task while manipulating the number of features (two vs. three features) contained in each representation. Moreover, we manipulated whether a secondary task consuming object-based attention was interpolated into the maintenance phase of WM. If extra object-based attention was required after the addition of an extra feature in the bound representation, the secondary task would result in a greater disruption of the three- rather than two-featured binding. In two experiments, we found that the added secondary task significantly impaired the binding performance, but the performance of the two- and three-featured bindings was disrupted to the same extent. These results suggest that the presence of more features in a bound representation in WM does not require extra object-based attention.

Social Cognitive Dysfunction in Elderly Patients After Anesthesia and Surgery.

Extensive studies have revealed that cognitive processing was impaired after anesthesia and surgery, particularly for the elderly patients. However, most of the existing studies focused on the general cognitive deficits (e.g., delayed neuro-cognitive recovery and POCD). Although diagnosis of social abilities has been used in various clinical fields, few studies have investigated the potential deficit on social cognition after anesthesia and surgery. The current study examined whether there was any social cognitive dysfunction after anesthesia and surgery. We achieved this by taking biological motion (BM) as the stimuli of interest, the perception of which has been taken as the hallmark of social cognition. The elderly patients (aged ≥ 60 years) were required to judge whether an upright BM stimulus appeared among the dynamic noises to test their social cognition, as well as do a Mini-Mental State Examination to test their general cognition. The two tests were performed at both 1-day before and 7-day after the surgery. Results showed that 31.25% of patients exhibited BM perception deficit after anesthesia and surgery relative to before anesthesia and surgery, implying that social cognitive dysfunction existed. Meanwhile, social cognitive dysfunction was independent from delayed neurocognitive recovery.

The role of attention in retaining the binding of integral features in working memory.

Previous studies have suggested that retaining bindings in working memory (WM) requires more object-based attention than retaining constituent features. However, we still need to address the object-based attention hypothesis to determine both the generality (Does the object-based attention hypothesis of binding apply to feature bindings other than those tested?) and the reality (Was the observed effect in previous studies an artifact of the testing process?). We addressed these two issues by focusing on the binding of integral features, which was ignored in previous studies. Integral features can be manipulated independently but cannot be attended to or processed independently of each other, and they are primarily perceived in a more unitary fashion. Consequently, integral-feature bindings should be processed as integrated units without the help of extra object-based attention. We examined whether or not the object-based attention hypothesis applied to integral-feature bindings (generality), and these results enabled us to check the reality of the hypothesis. In line with our prediction, we found that a secondary task consuming object-based attention did not selectively impair the binding performance (Experiments 1, 2, 3, 5, and 7). The absence of selective binding impairment was not attributable to the use of an invalid secondary task (Experiment 4), failure to memorize the binding between length and width (Experiment 6), tapping the incorrect type of attention (Experiment 6), the feasibility of feature categorization (Experiment 7), or poor task performance (Experiment 7). Overall, these results suggest that the object-based attention hypothesis does not fit for the integral-feature bindings, and that the pivotal role of object-based attention reported by previous studies was reliable.

Visual working-memory capacity load does not modulate distractor processing.

Over the last decade, researchers have explored the influence of visual working-memory (WM) load on selective attention in general, by focusing on the modulation of visual WM load on distractor processing in perception. However, there were three distinct hypotheses (perceptual-load hypothesis, resolution hypothesis, and domain-specific hypothesis) with different predictions. While the perceptual-load hypothesis suggests that visual WM capacity load serves as a type of perceptual load, the latter two hypotheses consider visual WM capacity load acting as a type of central executive load, with a constraint that the domain-specific hypothesis claimed that only a content overlap existed between WM load and the perceptual task. By adding a flanker task into the maintenance phase of visual WM, here we attempted to understand the influence of visual WM load on distractor processing. We systematically manipulated the parameters of the task setting between WM and flanker tasks (Experiments 1-4), the perceptual load of flanker task (Experiment 5), the settings of the flanker stimuli and the WM load (Experiment 6), and the content overlap between WM task and flanker task and the exposure time of flanker task (Experiments 7, 8, and 9). However, in 11 out of 12 sub-experiments we consistently found that the visual WM load did not modulate the distractor processing. The implications of these findings are discussed.

Object-based attention in retaining binding in working memory: Influence of activation states of working memory.

It has been suggested that retaining bindings in working memory (WM) requires more object-based attention than retaining constituent features. Recent studies have found that when memorized stimuli are presented sequentially, the most recent stimulus is in a highly accessible privileged state such that it is retained in a relatively automatic and resource-free manner, whereas the other stimuli are in a non-privileged state. The current study investigated whether the activation states of WM modulate the role of object-based attention in retaining bindings in WM. To address this question, we presented three colored shapes sequentially and added a transparent-motion task (Experiment 1) or a mental rotation task (Experiment 2) into the WM maintenance phase to consume object-based attention. We consistently found that consuming object-based attention led to a larger impairment to bindings relative to constituent features, which is independent of the WM activation states, suggesting that object-based attention is critical in retaining bindings in WM across activation states of WM.

Event-based encoding of biological motion and location in visual working memory.

We make use of discrete yet meaningful events to orient ourselves to the dynamic environment. Among these events, biological motion, referring to the movements of animate entities, is one of the most biologically salient. We usually encounter biological motions of multiple human beings taking place simultaneously at distinct locations. How we encode biological motions into visual working memory (VWM) to form a coherent experience of the external world and guide our social behaviour remains unclear. This study for the first time addressed the VWM encoding mechanism of biological motions and their corresponding locations. We tested an event-based encoding hypothesis for biological motion and location: When one element of an event is required to be memorised, the irrelevant element of an event will also be extracted into VWM. We presented participants with three biological motions at different locations and required them to memorise only the biological motions or their locations while ignoring the other dimension. We examined the event-based encoding by probing a distracting effect: If the event-based encoding took place, the change of irrelevant dimension in the probe would lead to a significant distraction and impair the performance of detecting target dimension. We found significant distracting effects, which lasted for 3 s but vanished at 6 s, regardless of the target dimension (biological motions vs. locations, Experiment 1) and the exposure time of memory array (1 s vs. 3 s, Experiment 2). These results together support an event-based encoding mechanism during VWM encoding of biological motions and their corresponding locations.

Emotional states affect the retention of biological motion in working memory.

Retaining biological motion (BM), or the movements of animate entities, in working memory (WM) is critical to human social life. Moreover, as functioning members of society, we always process BM in a specific emotional state. However, no WM study to date has explored the influence of emotional state on processing BM in WM. As a first step, the current study examined the influence of emotional state on WM capacity for BM. We first induced a specific (positive, negative, or neutral) emotional state and then asked the participants to complete a WM task measuring WM capacity for BM. In Experiment 1, we found that a negative emotional state impaired WM capacity for BM relative to neutral and positive emotional states, with no difference between the latter 2. Experiment 2, adopting µ and α suppression as electroencephalogram (EEG) indices, further confirmed that a negative emotional state reduced the number of BM stimuli retained in WM. Overall, the current study suggests that a negative emotional state has a considerably negative effect on WM capacity for BM. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Agent identity drives adaptive encoding of biological motion into working memory.

To engage in normal social interactions, we have to encode human biological motions (BMs, e.g., walking and jumping), which is one of the most salient and biologically significant types of kinetic information encountered in everyday life, into working memory (WM). Critically, each BM in real life is produced by a distinct person, carrying a dynamic motion signature (i.e., identity). Whether agent identity influences the WM processing of BMs remains unknown. Here, we addressed this question by examining whether memorizing BMs with different identities promoted the WM processing of task-irrelevant clothing colors. Two opposing hypotheses were tested: (a) WM only stores the target action (element-based hypothesis) and (b) WM stores both action and irrelevant clothing color (event-based hypothesis), interpreting each BM as an event. We required participants to memorize actions that either performed by one agent or distinct agents, while ignoring clothing colors. Then we examined whether the irrelevant color was also stored in WM by probing a distracting effect: If the color was extracted into WM, the change of irrelevant color in the probe would lead to a significant distracting effect on action performance. We found that WM encoding of BMs was adaptive: Once the memorized actions had different identities, WM adopted an event-based encoding mode regardless of memory load and probe identity (Experiment 1, different-identity group of Experiment 2, and Experiment 3). However, WM used an element-based encoding mode when memorized-actions shared the same identity (same-identity group of Experiment 2) or were inverted (Experiment 4). Overall, these findings imply that agent identity information has a significant effect on the WM processing of BMs.