The temporal advantage for reloading vs. uploading conscious representations decays over time.

In motion-induced blindness (MIB), a static target superimposed on a global moving pattern frequently disappears and reappears into consciousness. We previously reported an intriguing illusory temporal reversal whereby a new stimulus onset (e.g. a dot flash) presented during MIB triggers an early reappearance of the target, yet is systematically perceived as occurring after the target reappearance. This illusion implies that the unconscious target representation can be quickly reactivated, with a temporal advantage for its conscious reloading as compared to the conscious uploading of a newly presented visual stimulus. However, it remains unclear whether the temporal advantage for conscious representation reloading strengthens, decays, or remains constant over time after we lose the initial conscious access to the stimulus. To address this question, we examined the relation between the duration of MIB and the percentage of illusory temporal reversals, and we found a negative correlation between the two measures, both between and within observers. The results suggest that although the unconscious target representation retains a certain level of activation during MIB, the temporal advantage for reloading its preexisting representation into consciousness decays over time.

Face features and face configurations both contribute to visual crowding.

Crowding refers to the inability to recognize an object in peripheral vision when other objects are presented nearby (Whitney & Levi Trends in Cognitive Sciences, 15, 160-168, 2011). A popular explanation of crowding is that features of the target and flankers are combined inappropriately when they are located within an integration field, thus impairing target recognition (Pelli, Palomares, & Majaj Journal of Vision, 4(12), 12:1136-1169, 2004). However, it remains unclear which features of the target and flankers are combined inappropriately to cause crowding (Levi Vision Research, 48, 635-654, 2008). For example, in a complex stimulus (e.g., a face), to what extent does crowding result from the integration of features at a part-based level or at the level of global processing of the configural appearance? In this study, we used a face categorization task and different types of flankers to examine how much the magnitude of visual crowding depends on the similarity of face parts or of global configurations. We created flankers with face-like features (e.g., the eyes, nose, and mouth) in typical and scrambled configurations to examine the impacts of part appearance and global configuration on the visual crowding of faces. Additionally, we used "electrical socket" flankers that mimicked first-order face configuration but had only schematic features, to examine the extent to which global face geometry impacted crowding. Our results indicated that both face parts and configurations contribute to visual crowding, suggesting that face similarity as realized under crowded conditions includes both aspects of facial appearance.

Biased attention near another's hand following joint action.

Previous research has shown that attention is prioritized for the space near the hand, leading to faster detection of visual targets appearing close to one's own hand. In the present study, we examined whether observers are also facilitated in detecting targets presented near another's hand by having participants perform a Posner cueing task while sitting next to a friend. Across blocks, either the participant or the friend placed a hand next to one of the target locations. Our results robustly showed that participants detected targets appearing near their own hands more quickly than targets appearing away from their hands, replicating previous work demonstrating that spatial attention is prioritized near one's own hand (Experiments 1-4). No such attentional bias effects were found for targets appearing near the friend's hand, suggesting that spatial attention is not automatically prioritized near another's hand (Experiments 1 and 2). However, participants were faster to detect targets near the friend's hand following a joint action task, suggesting a shared body representation plays an influential role in biasing attention to the space near another's hand (Experiment 4).

The influence of flankers on race categorization of faces.

Context affects multiple cognitive and perceptual processes. In the present study, we asked how the context of a set of faces would affect the perception of a target face's race in two distinct tasks. In Experiments 1 and 2, participants categorized target faces according to perceived racial category (Black or White). In Experiment 1, the target face was presented alone or with Black or White flanker faces. The orientation of flanker faces was also manipulated to investigate how face inversion effect would interact with the influences of flanker faces on the target face. The results showed that participants were more likely to categorize the target face as White when it was surrounded by inverted White faces (an assimilation effect). Experiment 2 further examined how different aspects of the visual context would affect the perception of the target face by manipulating flanker faces' shape and pigmentation, as well as their orientation. The results showed that flanker faces' shape and pigmentation affected the perception of the target face differently. While shape elicited a contrast effect, pigmentation appeared to be assimilative. These novel findings suggest that the perceived race of a face is modulated by the appearance of other faces and their distinct shape and pigmentation properties. However, the contrast and assimilation effects elicited by flanker faces' shape and pigmentation may be specific to race categorization, since the same stimuli used in a delayed matching task (Experiment 3) revealed that flanker pigmentation induced a contrast effect on the perception of target pigmentation.

Contextual influences on rapid object categorization in natural scenes.

The current study aimed to investigate the effects of scene context on rapid object recognition using both behavioral and electrophysiological measures. Participants performed an animal/non-animal go/no-go categorization task in which they had to decide whether or not a flashed scene contained an animal. Moreover, the influence of scene context was manipulated either by retaining, deleting, or phase-randomizing the original scene background. The results of Experiments 1 and 2 showed that participants responded more accurately and quickly to objects appearing with their original scene backgrounds. Moreover, the event-related potential (ERP) data obtained from Experiment 2 showed that the onset latency of the frontal go/no-go ERP difference was delayed for objects appearing with phase-randomized scene backgrounds compared to objects appearing with their original scene backgrounds, providing direct evidence that scene context facilitates object recognition. Additionally, an increased frontal negativity along with a decreased late positive potential for processing objects presented in meaningless scene backgrounds suggest that the categorization task becomes more demanding when scene context is eliminated. Together, the results of the current study are consistent with previous research showing that scene context modulates object processing.

The influence of location and visual features on visual object memory.

In five experiments, we examined the influence of contextual objects' location and visual features on visual memory. Participants' visual memory was tested with a change detection task in which they had to judge whether the orientation (Experiments 1A, 1B, and 2) or color (Experiments 3A and 3B) of a target object was the same. Furthermore, contextual objects' locations and visual features were manipulated in the test image. The results showed that change detection performance was better when contextual objects' locations remained the same from study to test, demonstrating that the original spatial configuration is important for subsequent visual memory retrieval. The results further showed that changes to contextual objects' orientation, but not color, reduced orientation change detection performance; and changes to contextual objects' color, but not orientation, impaired color change detection performance. Therefore, contextual objects' visual features are capable of affecting visual memory. However, selective attention plays an influential role in modulating such effects.

The Effect of Spatial and Nonspatial Contextual Information on Visual Object Memory.

Recent research has found visual object memory can be stored as part of a larger scene representation rather than independently of scene context. The present study examined how spatial and nonspatial contextual information modulate visual object memory. Two experiments tested participants' visual memory by using a change detection task in which a target object's orientation was either the same as it appeared during initial viewing or changed. In addition, we examined the effect of spatial and nonspatial contextual manipulations on change detection performance. The results revealed that visual object representations can be maintained reliably after viewing arrays of objects. Moreover, change detection performance was significantly higher when either spatial or nonspatial contextual information remained the same in the test image. We concluded that while processing complex visual stimuli such as object arrays, visual object memory can be stored as part of a comprehensive scene representation, and both spatial and nonspatial contextual changes modulate visual memory retrieval and comparison.