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Object-based attention operates both in perception and visual working memory. While the efficient perception of auditory stimuli also requires the formation of auditory objects, little is known about their role in auditory working memory (AWM). To investigate whether attention to one object feature in AWM leads to the involuntary maintenance of another, task-irrelevant feature, we conducted four experiments. Stimuli were abstract sounds that differed on the dimensions frequency and location, only one of which was task-relevant in each experiment. The first two experiments required a match-nonmatch decision about a probe sound whose irrelevant feature value could either be identical to or differ from the memorized stimulus. Matches on the relevant dimension were detected more accurately when the irrelevant feature matched as well, whereas for nonmatches on the relevant dimension, performance was better for irrelevant feature nonmatches. Signal-detection analysis showed that changes of irrelevant frequency reduced the sensitivity for sound location. Two further experiments used continuous report tasks. When location was the target feature, changes of irrelevant sound frequency had an impact on both recall error and adjustment time. Irrelevant location changes affected adjustment time only. In summary, object-based attention led to a concurrent maintenance of task-irrelevant sound features in AWM.

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Numerous studies have indicated that both the broaden-and-build model and the motivational dimensional model emphasize the impact of emotion on spatial attention by altering the attentional scope. However, no prior research has investigated the impact of emotional valence and motivational intensity on spatial attention within the same paradigm. Furthermore, object-based attention, characterized by distinct neural mechanisms from space-based attention and also susceptible to attentional scope, represents a major pattern of selective attention. Nevertheless, it is still unclear whether and how emotional valence and motivation play a role in object-based attentional selection. Therefore, the present study aimed to explore these areas. Using a two-rectangle paradigm, Experiment 1 found that motivational intensity modulated space-based effects, whereas emotional valence modulated object-based effects. Experiment 2 used a traditional spatial cueing paradigm to further study the stability of modulating effect of motivation intensity on space-based attention, yielding results consistent with those of Experiment 1. The present study indicated that the broaden-and-build model and motivational dimensional model were not either one or the other, but both played a role in object- and space-based attention. This study provides crucial empirical evidence for theoretical complementation and integration of emotional attention.

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There is an ongoing debate between the sensory enhancement account and the attentional prioritization account concerning the mechanism underlying object-based attention. This debate remains unresolved because of the predominant use of geometric objects in previous studies, which made it difficult to experimentally dissociate the two accounts due to the prominent boundaries of these objects. The current study investigated the mechanism underlying semantic object-based attention by utilizing Chinese two-character words with different word frequencies and the event-related potentials (ERPs) technique to elucidate the ongoing debate. The behavioral results showed that the semantic object effect was observed only in the high-frequency condition. The ERP results revealed the following: (1) the N1 component was larger for the high-frequency condition compared with the low-frequency condition. However, there was no significant difference in amplitude between the N1 component elicited by invalid same object locations and invalid different object locations, irrespective of whether it occurred in high- or low-frequency conditions. (2) The P3 component elicited by invalid same object locations was larger than that elicited by invalid different object locations only in the high-frequency condition. (3) The N400 amplitude elicited by invalid same object locations was smaller than that elicited by invalid different object locations only in the high-frequency condition. These results suggest that in the absence of obvious object boundaries, the production of object-based attention is primarily driven by search strategies. Attentional prioritization, rather than sensory enhancement, is the dominant mechanism underlying object-based attention.

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The present study investigated the effect of object representation on attentional priority regarding distractor inhibition and target search processes while the statistical regularities of singleton distractor location were biased. A color singleton distractor appeared more frequently at one of six stimulus locations, called the 'high-probability location,' to induce location-based suppression. Critically, three objects were presented, each of which paired two adjacent stimuli in a target display by adding background contours (Experiment 1) or using perceptual grouping (Experiments 2 and 3). The results revealed that attention capture by singleton distractors was hardly modulated by objects. In contrast, target selection was impeded at the location in the object containing the high-probability location compared to an equidistant location in a different object. This object-based suppression in target selection was evident when object-related features were parts of task-relevant features. These findings suggest that task-irrelevant objects modulate attentional suppression. Moreover, different features are engaged in determining attentional priority for distractor inhibition and target search processes.

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Previous research has independently investigated the impact of individual personality traits and object valence on different patterns of attentional selection. However, the interactive role of individual personality traits and object valence in different patterns of attentional selection in both same and different emotional contexts remains unclear. To address the above issues, the present research used a variant of the two-rectangle paradigm, preselected individuals as introverts and extroverts, and simultaneously presented two faces with same or different emotions. Accordance to the result, in the same emotional context, personality traits and object valence did not interact to modulate both space-based effect (SBE) and object-based effect (OBE). However, in the different emotional context, personality traits and object valence interacted to modulate OBE. Specifically, for the extroverts, OBE existed no difference among negative, neutral and positive conditions. In contrast, for the introverts, the OBE was larger in the negative condition compared to those in the positive and neutral conditions. This research provides the first evidence suggesting that object-based attention can be impacted by the interaction between individual characteristics and object properties, and further proposes a preliminary framework called "context-dependent attentional selection hypothesis."

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Reward has been shown to influence selective attention, yet previous research has primarily focused on rewards associated with specific locations or features, with limited investigation into the impact of a reward object on object-based attention (OBA). Therefore, it remains unclear whether objects previously associated with rewards affect OBA. To address this issue, we conducted two experiments using a paradigm that combined a reward training phase with a modified two-rectangle paradigm. The results indicate that a reward object modulates both space-based attention (SBA) and OBA. When cues appear on a reward object, the effects of both SBA and OBA are amplified compared to when cues appear on a no-reward object. This finding supports the value-driven attentional capture (VDAC) theory, which suggests that a reward object gain enhanced saliency to capture attention, thereby providing a theoretical support for the treatment of conditions such as drug addiction.

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The current study explores the role of attention in location memory for animals and objects. Participants completed an incidental learning task where they rated animals and objects with regard to either their ease of collection to win a scavenger hunt (Experiments 1a and b) or their distance from the centre of the computer screen (Experiment 2). The images of animals and objects were pseudo-randomly positioned on the screen in both experiments. After completing the incidental learning task (and a reverse counting distractor task), participants were then given a surprise location memory recall task. In the location memory recall task, items were shown in the centre of the screen and participants used the mouse to indicate the position the item had been shown during the incidental encoding task. The results of both experiments show that location memory for objects was more accurate than for animals. While we cannot definitively identify the mechanism responsible for the difference in the location memory of objects and animals, we propose that differences in the influence of object-based attention at encoding affect location memory when tested at recall.

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Mechanisms of object-based attention (OBA) are commonly associated with the cerebral cortex. However, less is known about the involvement of subcortical visual pathways in these processes. Knowledge of the neural mechanisms subserving OBA can provide insight into the evolutionary trajectory of attentional selection. In the current study, the classic double-rectangle cueing task was implemented using a stereoscope in order to differentiate between the involvement of lower (monocular) and higher (binocular) visual pathways in OBA processes. We found that monocular visual pathways are involved in two main aspects of OBA: exogenous orienting towards a cued object (Experiment 1; N =33) and attentional deployment within a cued object (Experiment 2; N =23); this is evident by the presence of OBA only when both the cue and target were presented to the same eye. Thus, these results indicate that monocular (mostly subcortical) visual regions are not simply passing information to higher cortical areas but have a functional computational role in OBA. These findings emphasize the importance of lower regions in attentional processes and, more specifically, in OBA.

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Reallocating object-based attention across the visual field meridians is significantly faster horizontally than vertically (termed the shift direction anisotropy; SDA), implicating the meridians in reorienting object-based attention. Here, we tested the modulatory role of the meridians in the emergence of the SDA by manipulating meridian local feature contrast. Considering the notion of separate pools of attentional resources in each cortical hemisphere, we hypothesised that manipulating the horizontal meridian would selectively modulate the SDA. In four experiments, participants were presented with an "L"-shaped object and detected a target that appeared at either a cued location or at one of two equidistant non-cued locations at the far end of the horizontal or vertical object arm. Meridian local feature contrast was manipulated with perceptually strong enhancements (visible lines and colour contrast borders) and perceptually weak enhancements (illusory borders from line texture patterns and inducers). Weak enhancements of the meridians did not significantly modulate SDA magnitude; however, during perceptually strong enhancements of the horizontal meridian, the SDA was significantly reduced compared with both vertical meridian enhancement and no-enhancement conditions. Moreover, horizontal and vertical shift RTs were statistically equivalent when the horizontal meridian was enhanced with a visible line, our strongest manipulation, indicating the SDA was eliminated. These results suggest that the SDA emerges due to reallocating object-based attention across the horizontal meridian. We interpret this finding as evidence in support of the theory by which anatomical segregations of the visual system determine how pools of attentional resources resolve competition between and within cortical hemispheres.

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Our visual system consciously processes only a subset of the incoming information. Selective attention allows us to prioritize relevant inputs, and can be allocated to features, locations, and objects. Recent advances in feature-based attention suggest that several selection principles are shared across these domains and that many differences between the effects of attention on perceptual processing can be explained by differences in the underlying representational structures. Moving forward, it can thus be useful to assess how attention changes the structure of the representational spaces over which it operates, which include the spatial organization, feature maps, and object-based coding in visual cortex. This will ultimately add to our understanding of how attention changes the flow of visual information processing more broadly.

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A fundamental process of vision is to segment visual scenes into distinct objects and surfaces. Stereoscopic depth and visual motion cues are particularly important for segmentation. However, how the primate visual system uses depth and motion cues to segment multiple surfaces in 3-dimensional space is not well understood. We investigated how neurons in the middle temporal (MT) cortex represented two overlapping surfaces located at different depths and moved simultaneously in different directions. We recorded neuronal activities in MT of three male macaque monkeys while they performed discrimination tasks under different attention conditions. We found that neuronal responses to overlapping surfaces showed a robust bias toward the horizontal disparity of one of the two surfaces. For all animals, the disparity bias in response to two surfaces was positively correlated with the disparity preference of the neurons to single surfaces. For two animals, neurons that preferred the near disparities of single surfaces (near neurons) showed a near bias to overlapping stimuli, and neurons that preferred the far disparities (far neurons) showed a far bias. For the third animal, both near and far neurons showed a near bias, although the near neurons showed a stronger near bias than the far neurons. Interestingly, for all three animals, both near and far neurons showed an initial near bias relative to the average of the responses to the individual surfaces. Although attention can modulate neuronal response to better represent the attended surface, the disparity bias was still present when attention was directed away from the visual stimuli, indicating that the disparity bias cannot be explained by an attention bias. We also found that the effect of attention modulation of MT responses was consistent with object-based rather than feature-based attention. We proposed a model in which the pool size of the neuron population that weighs the responses to individual stimulus components can be variable. Our model is a novel extension of the standard normalization model and provides a unified explanation of the disparity bias across animals. Our results revealed the neural encoding rule for multiple moving stimuli located at different depths and showed new evidence of response modulation by object-based attention in MT. The disparity bias would allow subgroups of neurons to preferentially represent individual surfaces at different depths of multiple stimuli and therefore facilitate segmentation. Attention can further select a surface and enhance its neural representation.

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Numerous studies on face processing have revealed their special ability to affect attention, but relatively little research has been done on how faces guide spatial attention allocation. To enrich this field, this study resorted to the object-based attention (OBA) effect in a modified double-rectangle paradigm where the rectangles were replaced with human faces and mosaic patterns (non-face objects). Experiment 1 replicated the typical OBA effect in the non-face objects, but this effect was absent in Asian and Caucasian faces. Experiment 2 removed the eye region from Asian faces, but still found no object-based facilitation in the faces without eyes. In Experiment 3, the OBA effect was also observed for faces when the faces disappear a short period before the responses. Overall, these results revealed that when two faces are presented together, they do not exert object-based facilitation regardless of their facial features such as race and the presence of eyes. We argue that the lack of a typical OBA effect is due to the filtering cost induced by the entire face content. This cost slows down the response when attention shifts within a face and results in the absence of object-based facilitation.

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Visual stimuli compete with each other for cortical processing and attention biases this competition in favor of the attended stimulus. How does the relationship between the stimuli affect the strength of this attentional bias? Here, we used functional MRI to explore the effect of target-distractor similarity in neural representation on attentional modulation in the human visual cortex using univariate and multivariate pattern analyses. Using stimuli from four object categories (human bodies, cats, cars and houses), we investigated attentional effects in the primary visual area V1, the object-selective regions LO and pFs, the body-selective region EBA, and the scene-selective region PPA. We demonstrated that the strength of the attentional bias towards the target is not fixed but decreases with increasing distractor-target similarity. Simulations provided evidence that this result pattern is explained by tuning sharpening rather than an increase in gain. Our findings provide a mechanistic explanation for behavioral effects of target-distractor similarity on attentional biases and suggest tuning sharpening as the underlying mechanism in object-based attention.

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Divisive normalization of the neural responses by the activity of the neighboring neurons has been proposed as a fundamental operation in the nervous system based on its success in predicting neural responses recorded in primate electrophysiology studies. Nevertheless, experimental evidence for the existence of this operation in the human brain is still scant. Here, using functional MRI, we examined the role of normalization across the visual hierarchy in the human visual cortex. Using stimuli form the two categories of human bodies and houses, we presented objects in isolation or in clutter and asked participants to attend or ignore the stimuli. Focusing on the primary visual area V1, the object-selective regions LO and pFs, the body-selective region EBA, and the scene-selective region PPA, we first modeled single-voxel responses using a weighted sum, a weighted average, and a normalization model and demonstrated that although the weighted sum and weighted average models also made acceptable predictions in some conditions, the response to multiple stimuli could generally be better described by a model that takes normalization into account. We then determined the observed effects of attention on cortical responses and demonstrated that these effects were predicted by the normalization model, but not by the weighted sum or the weighted average models. Our results thus provide evidence that the normalization model can predict responses to objects across shifts of visual attention, suggesting the role of normalization as a fundamental operation in the human brain.

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This study investigated whether modes of attentional selection (location-based or object-based) are modulated by the cue type, specifically social cues such as eye gaze and pointing fingers, or by a non-social cue, such as an arrow. Earlier studies have demonstrated that the object-based attention effect was found only with arrow cues when presenting a spatial cue at either end of a rectangle: gaze cues did not yield object-based facilitation. We examined whether this deficiency of object-based attention is generalized to social cues such as pointing fingers. We measured the reaction times to the target at each cued location, an opposite side of a cued location in the same object, or the location in a different object equidistant from the cued location for each cue. Results indicated that only the gaze cue weakened the object-based attention effect, even under the condition of participants' voluntary extension of their attentional focus. The pointing cue induced sufficient object-based facilitation, as did the arrow cue. These results suggest that the deficiency of object-based attention was observed only for the gaze cue, and that it would be caused by a factor that is unique to the gaze cue, which narrows the attentional focus.

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The allocation of attention to objects raises several intriguing questions: What are objects, how does attention access them, what anatomical regions are involved? Here, we review recent progress in the field to determine the mechanisms underlying object-based attention. First, findings from unconscious priming and cueing suggest that the preattentive targets of object-based attention can be fully developed object representations that have reached the level of identity. Next, the control of object-based attention appears to come from ventral visual areas specialized in object analysis that project downward to early visual areas. How feedback from object areas can accurately target the object's specific locations and features is unknown but recent work in autoencoding has made this plausible. Finally, we suggest that the three classic modes of attention may not be as independent as is commonly considered, and instead could all rely on object-based attention. Specifically, studies show that attention can be allocated to the separated members of a group-without affecting the space between them-matching the defining property of feature-based attention. At the same time, object-based attention directed to a single small item has the properties of space-based attention. We outline the architecture of object-based attention, the novel predictions it brings, and discuss how it works in parallel with other attention pathways.

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When we look at an image, its features are represented in our visual system in a highly distributed manner, calling for a mechanism that binds them into coherent object representations. There have been different proposals for the neuronal mechanisms that can mediate binding. One hypothesis is that binding is achieved by oscillations that synchronize neurons representing features of the same perceptual object. This view allows separate communication channels between different brain areas. Another hypothesis is that binding of features that are represented in different brain regions occurs when the neurons in these areas that respond to the same object simultaneously enhance their firing rate, which would correspond to directing object-based attention to these features. This review summarizes evidence in favor of and against these two hypotheses, examining the neuronal correlates of binding and assessing the time course of perceptual grouping. I conclude that enhanced neuronal firing rates bind features into coherent object representations, whereas oscillations and synchrony are unrelated to binding.

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Animacy plays an essential role in survival and adaptive behaviour. Previous studies have found that dangerous or threatening animals can capture and hold attention. However, it is unclear whether and how neutral animate objects guide attentional allocation. It is also uncertain whether the modulation of animate objects on attentional allocation is based on the object itself (object-based attention) or its location (space-based attention). Therefore, the present study adopted the well-established two-rectangle paradigm and used animate and inanimate objects as stimuli to test the abovementioned problems. The results revealed that object-based effects were obtained for both animate and inanimate objects. However, the object-based effects were larger when the cue appeared on the animate objects than on the inanimate objects, due to faster response to invalid same-object trials and slower response to invalid different-object trials. Beyond that, we also further confirmed that animacy itself, not the low-level visual complexity, led to the differential object-based effects. These results suggest that neutral animals also mattered to our attentional allocation and animacy can modulate object-based attentional selection by capturing and holding visual attention on the animate objects. Ultimately, the present study not only enriches our understanding of how neutral animate objects guide attentional allocation and support the attentional prioritisation theory, but also further extends and amends the animate-monitoring hypothesis.

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Contextual information involves invariant properties that are critical in selective attention. There is no direct evidence showing the effect of contextual information on object-based selective attention. The current study aimed to investigate the role of contextual uncertainty on object-based effect using a flanker task and to clarify the contradictory results obtained in previous studies. Herein, contextual uncertainty specifically referred to the configurations of the stimuli presented randomly as vertical or horizontal displays (high contextual uncertainty) that was reduced by showing consistent configurations within a block, via implicit learning of configuration (low contextual uncertainty). In Experiment 1, the object-based effect was observed under the high uncertainty condition and disappeared under the low uncertainty condition, demonstrating that contextual uncertainty modulated object-based attention. Experiment 2 provided explicit knowledge of the configural orientations, which can be utilised to sufficiently guide subsequent perception with increase in cueing interval, and therefore, affected contextual uncertainty. Relative to a short cueing interval, the long cueing interval enabled the participants to utilise the contextual knowledge for guiding visual attention and reducing uncertainty. Consistent with the finding in Experiment 1, the explicit manipulation of contextual uncertainty affected the object-based effect. The results proved that the contextual uncertainty played an important role in prioritisation in the object-based attentional selection. The mechanism of the interplay between contextual uncertainty and object-based attention was discussed.

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We typically think of intuitive physics in terms of high-level cognition, but might aspects of physics also be extracted during lower-level visual processing? Might we not only think about physics, but also see it? We explored this using multiple tasks in online adult samples with objects covered by soft materials-as when you see a chair with a blanket draped over it-where you must account for the physical interactions between cloth, gravity, and object. In multiple change-detection experiments (n = 200), observers from an online testing marketplace were better at detecting image changes involving underlying object structure versus those involving only the superficial folds of cloths-even when the latter were more extreme along several dimensions. And in probe-comparison experiments (n = 100), performance was worse when both probes (vs. only one) appeared on image regions reflective of underlying object structure (equating visual properties). This work collectively shows how vision uses intuitive physics to recover the deeper underlying structure of scenes.

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