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Although some studies showed that training can improve the ability of cross-dimension conjunction search, less is known about the underlying mechanism. Specifically, it remains unclear whether training of visual conjunction search can successfully bind different features of separated dimensions into a new function unit at early stages of visual processing. In the present study, we utilized stimulus specificity and generalization to provide a new approach to investigate the mechanisms underlying perceptual learning (PL) in visual conjunction search. Five experiments consistently showed that after 40 to 50 min of training of color-shape/orientation conjunction search, the ability to search for a certain conjunction target improved significantly and the learning effects did not transfer to a new target that differed from the trained target in both color and shape/orientation features. However, the learning effects were not strictly specific. In color-shape conjunction search, although the learning effect could not transfer to a same-shape different-color target, it almost completely transferred to a same-color different-shape target. In color-orientation conjunction search, the learning effect partly transferred to a new target that shared same color or same orientation with the trained target. Moreover, the sum of transfer effects for the same color target and the same orientation target in color-orientation conjunction search was algebraically equivalent to the learning effect for trained target, showing an additive transfer effect. The different transfer patterns in color-shape and color-orientation conjunction search learning might reflect the different complexity and discriminability between feature dimensions. These results suggested a feature-based attention enhancement mechanism rather than a unitization mechanism underlying the short-term PL of color-shape/orientation conjunction search.

It is well known that attentional capture by an irrelevant salient item is contingent on top-down feature selection, but whether attentional capture may be modulated by top-down spatial attention remains unclear. Here, we combined behavioral and ERP measurements to investigate the contribution of top-down spatial attention to attentional capture under modified spatial cueing paradigms. Each target stimulus was preceded by a peripheral circular cue array containing a spatially uninformative color singleton cue. We varied target sets but kept the cue array unchanged among different experimental conditions. When participants' task was to search for a colored letter in the target array that shared the same peripheral locations with the cue array, attentional capture by the peripheral color cue was reflected by both a behavioral spatial cueing effect and a cue-elicited N2pc component. When target arrays were presented more centrally, both the behavioral and N2pc effects were attenuated but still significant. The attenuated cue-elicited N2pc was found even when participants focused their attention on the fixed central location to identify a colored letter among an RSVP letter stream. By contrast, when participants were asked to identify an outlined or larger target, neither the behavioral spatial cueing effect nor the cue-elicited N2pc was observed, regardless of whether the target and cue arrays shared same locations or not. These results add to the evidence that attentional capture by salient stimuli is contingent upon feature-based task sets, and further indicate that top-down spatial attention is important but may not be necessary for contingent attentional capture.

Gender differences in feedback processing have been observed among adolescents and adults through event-related potentials. However, information on whether and how this feedback processing is affected by feedback valence, feedback type, and individual sensitivity in reward/punishment among children remains minimal. In this study, we used a guessing game task coupled with electroencephalography to investigate gender differences in feedback processing, in which feedback to reward and punishment was presented in the context of monetary and social conditions. Results showed that boys were less likely to switch their response after punishment, had generally less feedback-related negativity (FRN) amplitude, and longer FRN latency in monetary and punishment conditions than girls. Moreover, FRN for monetary punishment, which is related to individual difference in reward sensitivity, was observed only in girls. The study provides gender-specific evidence for the neural processing of feedback, which may offer educational guidance for appropriate feedback for girls and boys.

Top‐down spatial attention can modulate contingent attentional capture, but the underlying mechanism is still not clear. Using variants of spatial cueing paradigms, our previous event‐related potential study showed that peripheral color singleton cues with task‐relevant features captured attention (indexed by cue‐elicited N2pc) even when the targets appeared at central locations, but the magnitude of attentional capture was smaller than when the targets appeared at same peripheral locations. One reasonable explanation is that the modulation effect is due to spatial relevance of cues. However, several other confounding factors might also explain the modulation effect, such as task difficulty, spread of attentional window, and inside/outside relation between cue and attentional window. In the present study, we rearranged the relative locations between cues and targets to control these factors and to further examine whether inequivalence of attentional capture across attended and unattended locations was a common phenomenon. In two experiments, color singleton cues elicited apparent N2pc components when participants were searching for targets possessing the same color, which replicated typical findings of contingent attentional capture. More importantly, the modulation effect of top‐down spatial attention on the cue‐elicited N2pc still existed even when the factors of task difficulty (Experiment 1), spread of attentional window (Experiment 1), or inside/outside relation between cue and attentional window (Experiment 2) were controlled. These results consistently demonstrate that attentional capture by a color singleton is stronger at spatially relevant locations than at spatially irrelevant locations, suggesting an important role of spatial relevance on contingent attentional capture.

Summary We presented one eye with a monocular-boundary-contour (MBC) square, created by phase-shifting a central region of grating relative to a larger uniform grating surround, and the fellow eye with the larger uniform grating. In addition, the grating within the MBC region was rendered with lower contrast relative to the remaining stimulus. Despite this, we found the lower contrast MBC region dominated the perceived cyclopean contrast, with the corresponding region in the fellow eye being suppressed. Secondly, we found for dichoptic stimuli with half-images having square grating regions of different BC strengths, the interocular BC strength ratio determined the perceived contrast of the cyclopean square. Thirdly, we found perceived spatial phase of the cyclopean square was dominated by the spatial phase of the MBC half-image. Altogether, these psychophysical findings provided evidence for a border-to-interior representation strategy, that constructing surface begins at the boundary contour (BC), in binocular contrast and phase integration.

To our knowledge, the present studies are the first to discover a relatively strong correlation between IOR-OT and cognitive functions in older adults. These findings provide new evidence supporting the inhibition deficit theory of aging and lay the foundation of using IOR-OT as an objective measure of cognitive functions in the aging population.

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