Backward-walking biological motion orients attention to moving away instead of moving toward.

Walking direction is an important attribute of biological motion because it carries key information, such as the specific intention of the walker. Although it is known that spatial attention is guided by walking direction, it remains unclear whether this attentional shift is reflexive (i.e., constantly shifts to the walking direction) or not. A richer interpretation of this effect is that attention is guided to seek the information that is necessary to understand the motion. To investigate this issue, we examined how backward-walking biological motion orients attention because the intention of walking backward is usually to avoid something that walking forward would encounter. The results showed that attention was oriented to the walking-away direction of biological motion instead of the walking-toward direction (Experiment 1), and this effect was not due to the gaze direction of biological motion (Experiment 2). Our findings suggest that the attentional shift triggered by walking direction is not reflexive, thus providing support for the rich interpretation of these attentional effects.

Deployment of Attention on Handshakes.

Understanding the social structures between objects, organizing, and selecting them accordingly, is fundamental to social cognition. We report an example that demonstrates the object association learned from social interactions could impact visual attention. Particularly, when two hands approach each other to perform a handshake, they tend to be attended to as a unit because of the cooperative relationship exhibited in the action: even a cue presented on a non-target hand may facilitate a response to the targets that appear on the non-cued hand (Experiment 1), indicating that attentional shift between two hands was facilitated; furthermore, the response to a target on one hand is significantly impaired by a distractor on the other hand (Experiment 2), implying that it is difficult to selectively confine attention to a single hand. These effects were dependent on the existence of the hands when cue and target appeared (Experiment 3); neither perceptual familiarity, or physical fit can explain all the attention effects (Experiment 4). These results have bearings on the perceptual root of social cognition.

Object formation in visual working memory: Evidence from object-based attention.

We report on how visual working memory (VWM) forms intact perceptual representations of visual objects using sub-object elements. Specifically, when objects were divided into fragments and sequentially encoded into VWM, the fragments were involuntarily integrated into objects in VWM, as evidenced by the occurrence of both positive and negative object-based attention effects: In Experiment 1, when subjects' attention was cued to a location occupied by the VWM object, the target presented at the location of that object was perceived as occurring earlier than that presented at the location of a different object. In Experiment 2, responses to a target were significantly slower when a distractor was presented at the same location as the cued object (Experiment 2). These results suggest that object fragments can be integrated into objects within VWM in a manner similar to that of visual perception.

Object-based Encoding in Visual Working Memory: Evidence from Memory-driven Attentional Capture.

Visual working memory (VWM) adopts a specific manner of object-based encoding (OBE) to extract perceptual information: Whenever one feature-dimension is selected for entry into VWM, the others are also extracted. Currently most studies revealing OBE probed an 'irrelevant-change distracting effect', where changes of irrelevant-features dramatically affected the performance of the target feature. However, the existence of irrelevant-feature change may affect participants' processing manner, leading to a false-positive result. The current study conducted a strict examination of OBE in VWM, by probing whether irrelevant-features guided the deployment of attention in visual search. The participants memorized an object's colour yet ignored shape and concurrently performed a visual-search task. They searched for a target line among distractor lines, each embedded within a different object. One object in the search display could match the shape, colour, or both dimensions of the memory item, but this object never contained the target line. Relative to a neutral baseline, where there was no match between the memory and search displays, search time was significantly prolonged in all match conditions, regardless of whether the memory item was displayed for 100 or 1000 ms. These results suggest that task-irrelevant shape was extracted into VWM, supporting OBE in VWM.

Social constraints from an observer's perspective: Coordinated actions make an agent's position more predictable.

Action prediction, a crucial ability to support social activities, is sensitive to the individual goals of expected actions. This article reports a novel finding that the predictions of observed actions for a temporarily invisible agent are influenced, and even enhanced, when this agent has a joint/collective goal to implement coordinated actions with others (i.e., with coordination information). Specifically, we manipulated the coordination information by presenting two chasers and one common target to perform coordinated or individual chases, and subjects were required to predict the expected action (i.e., position) for one chaser after it became momentarily invisible. To control for possible low-level physical properties, we also established some intense paired controls for each type of chase, such as backward replay (Experiment 1), making the chasing target invisible (Experiment 2) and a direct manipulation of the goal-directedness of one chaser's movements to disrupt coordination information (Experiment 3). The results show that the prediction error for invisible chasers depends on whether the second chaser is coordinated with the first, and this effect vanishes when the chasers behaves with exactly the same motions, but without coordination information between them; furthermore, this influence results in enhancing the performance of action prediction. These findings extend the influential factors of action prediction to the level of observed coordination information, implying that the functional characteristic of mutual constraints of coordinated actions can be utilized by vision.

Organization principles in visual working memory: Evidence from sequential stimulus display.

Although the mechanisms of visual working memory (VWM) have been studied extensively in recent years, the active property of VWM has received less attention. In the current study, we examined how VWM integrates sequentially presented stimuli by focusing on the role of Gestalt principles, which are important organizing principles in perceptual integration. We manipulated the level of Gestalt cues among three or four sequentially presented objects that were memorized. The Gestalt principle could not emerge unless all the objects appeared together. We distinguished two hypotheses: a perception-alike hypothesis and an encoding-specificity hypothesis. The former predicts that the Gestalt cue will play a role in information integration within VWM; the latter predicts that the Gestalt cue will not operate within VWM. In four experiments, we demonstrated that collinearity (Experiment 1) and closure (Experiment 2) cues significantly improved VWM performance, and this facilitation was not affected by the testing manner (Experiment 3) or by adding extra colors to the memorized objects (Experiment 4). Finally, we re-established the Gestalt cue benefit with similarity cues (Experiment 5). These findings together suggest that VWM realizes and uses potential Gestalt principles within the stored representations, supporting a perception-alike hypothesis.

How to break the configuration of moving objects? Geometric invariance in visual working memory.

Visual working memory is highly sensitive to global configurations in addition to the features of each object. When objects move, their configuration varies correspondingly. In this study, we explored the geometric rules governing the maintenance of a dynamic configuration in visual working memory. Our investigation is guided by Klein's Erlangen program, a hierarchy of geometric stability that includes affine, projective, and topological invariants. In a change-detection task, memory displays were categorized by which geometric invariance was violated by the objects' motions. The results showed that (a) there was no decrement in memory performance until the projective invariance was violated, (b) more dramatic changes (such as a topological change) did not further enlarge the decrement, and (c) objects causing the violation of projective invariance were better encoded into memory. These results collectively demonstrate that projective invariance is the only geometric property determining the maintenance of a dynamic configuration in visual working memory.

The working memory Ponzo illusion: Involuntary integration of visuospatial information stored in visual working memory.

Visual working memory (VWM) has been traditionally viewed as a mental structure subsequent to visual perception that stores the final output of perceptual processing. However, VWM has recently been emphasized as a critical component of online perception, providing storage for the intermediate perceptual representations produced during visual processing. This interactive view holds the core assumption that VWM is not the terminus of perceptual processing; the stored visual information rather continues to undergo perceptual processing if necessary. The current study tests this assumption, demonstrating an example of involuntary integration of the VWM content, by creating the Ponzo illusion in VWM: when the Ponzo illusion figure was divided into its individual components and sequentially encoded into VWM, the temporally separated components were involuntarily integrated, leading to the distorted length perception of the two horizontal lines. This VWM Ponzo illusion was replicated when the figure components were presented in different combinations and presentation order. The magnitude of the illusion was significantly correlated between VWM and perceptual versions of the Ponzo illusion. These results suggest that the information integration underling the VWM Ponzo illusion is constrained by the laws of visual perception and similarly affected by the common individual factors that govern its perception. Thus, our findings provide compelling evidence that VWM functions as a buffer serving perceptual processes at early stages.

The role of spatial configuration in multiple identity tracking.

BACKGROUND: The simultaneous tracking and identification of multiple moving objects encountered in everyday life requires one to correctly bind identities to objects. In the present study, we investigated the role of spatial configuration made by multiple targets when observers are asked to track multiple moving objects with distinct identities. METHODOLOGY/PRINCIPAL FINDINGS: The overall spatial configuration made by the targets was manipulated: In the constant condition, the configuration remained as a virtual convex polygon throughout the tracking, and in the collapsed condition, one of the moving targets (critical target) crossed over an edge of the virtual polygon during tracking, destroying it. Identification performance was higher when the configuration remained intact than when it collapsed (Experiments 1a, 1b, and 2). Moreover, destroying the configuration affected the allocation of dynamic attention: the critical target captured more attention than did the other targets. However, observers were worse at identifying the critical target and were more likely to confuse it with the targets that formed the virtual crossed edge (Experiments 3-5). Experiment 6 further showed that the visual system constructs an overall configuration only by using the targets (and not the distractors); identification performance was not affected by whether the distractor violated the spatial configuration. CONCLUSIONS/SIGNIFICANCE: In sum, these results suggest that the visual system may integrate targets (but not distractors) into a spatial configuration during multiple identity tracking, which affects the distribution of dynamic attention and the updating of identity-location binding.

Social grouping: perceptual grouping of objects by cooperative but not competitive relationships in dynamic chase.

Historically, perceptual grouping is associated with physical principles. This article reports a novel finding that social information-cooperative but not competitive relationships-can drive perceptual grouping of objects in dynamic chase. Particularly, each relationship was constructed with human-generated chasing motions (i.e., two predators and one prey), and its role on perceptual grouping was examined by grouping-induced effect-attentional consequences. The results showed that: (1) Predators can be perceived as a group due to their cooperative relationship, causing attention to automatically spread within grouped predators, thus the response to target appearing on uncued predator is also facilitated; and (2) The attentional effect on competitive predators has no difference from any condition which controls low-level motion patterns, even including the random-motion condition wherein no grouping factor was contained. These findings extend perceptual grouping into the social field, implying that social information gets involved in visual cognition at an early perceptual stage.

Anger and selective attention to reward and punishment in children.

Anger is a negative emotion associated with approach motivation and may influence children's attention preference. Three experiments examined the effect of anger on the attentional biases accompanying reward versus punishment cues in Chinese 5- and 6-year-olds. Experiment 1 tested children who were prone to report angry feelings in an unfair game. Experiment 2 measured children who were rated by parents and teachers for temperamental anger. Experiment 3 explored children who reported angry feelings in a frustrating attention task with rigged and noncontingent feedback after controlling for temperament anger. Results suggested that both the angry and anger-prone children were faster to engage attention toward the reward cues than toward the punishment cues in the three experiments. Furthermore, the angry children in the frustrating attention task (and those with poor attention focusing by parental report) were slower in disengaging attention away from the reward versus punishment cues (especially after negative feedback). Results support the approach motivation of anger, which can facilitate children's attention toward the appetitive approach-related information. The findings are discussed in terms of the adaptive and maladaptive function of anger.

Does visual working memory work as a few fixed slots?

The present study investigated whether visual working memory (VWM) functions as a few (about 3 ∼ 4) fixed slots by examining how the distribution of VWM is adjusted. Adopting a change-detection paradigm, we required subjects to memorize four items, one of which was prioritized. If VWM functions as 3 ∼ 4 slots, allocating multiple slots to the prioritized item would leave no slot for some other items; consequently no information would be stored for them, leading to a substantial decrease in change-detection performance no matter whether small or large changes occurred. The result showed that small changes on the unfavoured items were detected less accurately, indicating that more VWM was allocated to the favoured item. Yet meanwhile large changes that occurred on those unfavoured items could still be detected as well as those on the favoured one, indicating that each of them was still stored to some extent rather than completely discarded. The results suggested that VWM may not work as 3 ∼ 4 fixed slots. Possible mechanisms were discussed based on the present results, including a modified slot model with more available slots, a continuous resource model, and a hierarchical model that assumes storage of ensemble information in addition to the information of individual items.

Coarse-to-fine construction for high-resolution representation in visual working memory.

BACKGROUND: This study explored whether the high-resolution representations created by visual working memory (VWM) are constructed in a coarse-to-fine or all-or-none manner. The coarse-to-fine hypothesis suggests that coarse information precedes detailed information in entering VWM and that its resolution increases along with the processing time of the memory array, whereas the all-or-none hypothesis claims that either both enter into VWM simultaneously, or neither does. METHODOLOGY/PRINCIPAL FINDINGS: We tested the two hypotheses by asking participants to remember two or four complex objects. An ERP component, contralateral delay activity (CDA), was used as the neural marker. CDA is higher for four objects than for two objects when coarse information is primarily extracted; yet, this CDA difference vanishes when detailed information is encoded. Experiment 1 manipulated the comparison difficulty of the task under a 500-ms exposure time to determine a condition in which the detailed information was maintained. No CDA difference was found between two and four objects, even in an easy-comparison condition. Thus, Experiment 2 manipulated the memory array's exposure time under the easy-comparison condition and found a significant CDA difference at 100 ms while replicating Experiment 1's results at 500 ms. In Experiment 3, the 500-ms memory array was blurred to block the detailed information; this manipulation reestablished a significant CDA difference. CONCLUSIONS/SIGNIFICANCE: These findings suggest that the creation of high-resolution representations in VWM is a coarse-to-fine process.

Robust object-based encoding in visual working memory.

Recently, researchers have begun to investigate how nonspatial perceptual information is extracted into visual working memory (VWM), focusing particularly on object-based encoding (OBE). That is, whenever even one feature-dimension is selected for entry into VWM, the others are also extracted automatically. While there is evidence supporting robust OBE in VWM, some researchers have argued that it is restricted to certain conditions, suggesting that OBE might be weak. The current study analyzed the experimental differences between prior studies revealing OBE and the ones that failed, and suggested that there were three critical differences in the experimental settings. Studies supporting robust OBE predominantly were conducted by probing an "irrelevant-change distracting effect," in which a change of stored irrelevant-feature dramatically affects performance. To examine whether OBE in VWM is robust or weak, we manipulated these three aspects under the irrelevant-change distracting effect to check whether OBE could be erased. In three experiments, we found similar degrees of the distracting effect between the experimental condition (controlling these factors) and the control condition; this suggests that these factors do not affect OBE. We conclude that robust OBE exists in VWM.

Perceived causalities of physical events are influenced by social cues.

In simple mechanical events, we can directly perceive causal interactions of the physical objects. Physical cues (especially spatiotemporal features of the display) are found to associate with causal perception. Here, we demonstrate that cues of a completely different domain--social cues--also impact the causal perception of physical events: The causally ambiguous events are more likely to be perceived as causal if the faces superimposed on the objects change from neutral to fearful. This effect has the following major properties: (a) The effect is caused by social information because it disappears when the faces are inverted or when the expression changes are unreasonable; (b) the social cues are integrated in a temporal window different from physical cues; and (c) the social cues impact the perception process rather than the decision process as the impact also appears in the causality-induced illusion. These findings suggest that the visual system relies on social information to infer the causal structure of the physical world.

Biased number perception of schematic expressions in abstinent heroin abusers compared to normal controls.

BACKGROUND AND OBJECTIVES: Drug-dependent people exhibit biases when evaluating discrete emotional facial expressions. Little is known about how drug abusers process multiple expressions presented simultaneously. The present study investigated the number perception of schematic emotional expressions by abstinent heroin abusers. METHODS: Eighty-four heroin abstainers with varied lengths of abstinence (short-term, mid-term, and long-term) and twenty healthy controls were examined. A method of limits was deployed to obtain estimates (points of subjective equality) of perceived numbers of schematic faces (expressing positive, neutral, or negative emotion). RESULTS: Major results include the following: 1) heroin-abstinent participants showed significantly lower points of subjective equality for negative and neutral faces, but not for positive faces, compared to control participants; 2) heroin-abstinent participants showed lower points of subjective equality for negative faces and higher ones for positive faces when compared to neutral faces, while no such differences were found in control participants. CONCLUSION: Heroin abusers demonstrate an exaggerated perception of number when exposed to negative expressions, even after a period of abstinence as long as 10 months. In addition, the current results could also reflect an underestimated perception of number during exposure to positive expressions and a heightened baseline for neutral expressions, or the attribution of negative valence to neutral expressions by heroin abusers.

Contralateral delay activity tracks object identity information in visual short term memory.

Previous studies suggested that ERP component contralateral delay activity (CDA) tracks the number of objects containing identity information stored in visual short term memory (VSTM). Later MEG and fMRI studies implied that its neural source lays in superior IPS. However, since the memorized stimuli in previous studies were displayed in distinct spatial locations, hence possibly CDA tracks the object-location information instead. Moreover, a recent study implied the activation in superior IPS reflected the location load. The current research thus explored whether CDA tracks the object-location load or the object-identity load, and its neural sources. Participants were asked to remember one color, four identical colors or four distinct colors. The four-identical-color condition was the critical one because it contains the same amount of identity information as that of one color while the same amount of location information as that of four distinct colors. To ensure the participants indeed selected four colors in the four-identical-color condition, we also split the participants into two groups (low- vs. high-capacity), analyzed late positive component (LPC) in the prefrontal area, and collected participant's subjective-report. Our results revealed that most of the participants selected four identical colors. Moreover, regardless of capacity-group, there was no difference on CDA between one color and four identical colors yet both were lower than 4 distinct colors. Besides, the source of CDA was located in the superior parietal lobule, which is very close to the superior IPS. These results support the statement that CDA tracks the object identity information in VSTM.

Tracking object number or information load in visual working memory: revisiting the cognitive implication of contralateral delay activity.

Two accounts prevail for the ERP component contralateral delay activity (CDA). One is that CDA tracks the number of objects stored in visual working memory (VWM), the more objects the higher amplitude (object number account). The other is that CDA reflects the maintained information load (information load account), the higher load the higher amplitude. The two accounts were tested by manipulating the information load and the object number of stored objects. Two or four arrows with low- or high-resolution information were remembered in separate blocks. In two experiments we found that the CDA-amplitude was higher for 4 arrows than for 2 arrows in low-resolution condition, yet no difference in high-resolution condition. Critically, there was no difference on CDA-amplitude among 2 low- and high-resolution objects, as well as 4 high-resolution objects, yet all were significantly lower than 4 low-resolution arrows. These results supported the object number account of CDA.

Losing control in front of a fearful face: the effect of emotional information on cognitive control.

How is our cognitive control system modulated by emotional information, especially fearful stimuli? An intuitive hypothesis is that fearful stimuli would enhance cognitive control so that people could switch from the ongoing task to emergent events more quickly to secure themselves. To test this hypothesis, we investigated the influence of emotional information on the shift function of cognitive control by using the task-cueing procedure, in which face images were presented as cues. With the gender of faces indicating which task to do, we manipulated the emotional valence of faces (neutral vs. fearful), finding that the switch costs were larger in the trials containing fearful cues than in the trials containing neutral cues (Experiment 1). This effect was not caused by enlarging task-set interference (Experiment 2), nor by slowing down cue encoding (Experiment 3). Contrary to the intuitive hypothesis, our results suggested that the endogenous task-set reconfiguration process was impaired when fearful faces were presented. We speculated that the benefit of decreasing cognitive flexibility in face of fearful stimuli is to speed up response in a dangerous environment, and this accelerating response is achieved by suppressing the goal-directed system to permit the fast, automatic stimulus-driven system to govern behaviours.