Spatial probability as an attentional cue in visual search

We investigated the role of spatial probabilities in target location during participants' performance of a visual search task. Experiments 1 and 2 demonstrated that spatial probabilities could serve as a powerful attentional bias that produced faster detection of targets in high-probability locations than of those in low- or random-probability locations. The effect could not be explained by repetition priming alone. Moreover, responses to targets in low-probability locations were slowed only when a distractor was present in the high-probability location. In Experiments 3-5, we compared the effects of spatial probability with an explicit endogenous cue and a salient exogenous cue. Facilitation due to spatial probability was independent of any benefit afforded by the explicit endogenous cue but interacted with the salient exogenous cue, such that the exogenous cue validity effect was compressed for targets in the high-probability location. Together, these results suggest that the spatial probabilities governing target location constitute a potent bias of visual processing and, as such, can be considered an attentional cue that differs from both typical explicit endogenous and salient exogenous cues.     

内源性注意与外源性注意的跨通道比较

该研究利用空间线索技术的实验模式,考察跨视觉和听觉通道的内源性选择注意与外源性选择性注意的相互关系。实验结果表明：(1)听觉中央线索在较长的SOA(至少500毫秒)条件下,可以引导内源性空间选择性注意;同时外周线索突现也能自动化地吸引部分注意资源。(2)听觉和视觉选择注意是分离的加工通道,但二者之间存在相互联系。     

The effects of transient attention on spatial resolution and the size of the attentional cue

It has been shown that transient attention enhances spatial resolution, but is the effect of transient attention on spatial resolution modulated by the size of the attentional cue? Would a gradual increase in the size of the cue lead to a gradual decrement in spatial resolution? To test these hypotheses, we used a texture segmentation task in which performance depends on spatial resolution, and systematically manipulated the size of the attentional cue: A bar of different lengths (Experiment 1) or a frame of different sizes (Experiments 2-3) indicated the target region in a texture segmentation display. Observers indicated whether a target patch region (oriented line elements in a background of an orthogonal orientation), appearing at a range of eccentricities, was present in the first or the second interval. We replicated the attentional enhancement of spatial resolution found with small cues; attention improved performance at peripheral locations but impaired performance at central locations. However, there was no evidence of gradual resolution decrement with large cues. Transient attention enhanced spatial resolution at the attended location when it was attracted to that location by a small cue but did not affect resolution when it was attracted by a large cue. These results indicate that transient attention cannot adapt its operation on spatial resolution on the basis of the size of the attentional cue.     

视听刺激突显性对视觉主导效应的影响

本研究使用空间任务-转换范式,控制视、听刺激的突显性,探讨自下而上注意对视觉主导效应的影响。结果表明视、听刺激突显性显著地影响视觉主导效应,实验一中当听觉刺激为高突显性时,视觉主导效应显著减弱。实验二中当听觉刺激为高突显性并且视觉刺激为低突显性时,视觉主导效应进一步减弱但依然存在。结果支持偏向竞争理论,在跨通道视听交互过程中视觉刺激更具突显性,在多感觉整合过程中更具加工优势。     

Exogenous attention can be counter-selective: onset cues disrupt sensitivity to color changes

In peripheral spatial cueing paradigms, exogenous attentional capture is commonly observed after salient onset cues or with cues contingent on target characteristics. We proposed that exogenously captured attention disrupts the selectivity to target features. We tested this by experimentally emulating the everyday observation that in a viewing situation in which the observer is monitoring a stationary display fort change to occur, the onset of a salient stimulus (onset cue) or a change in a stationary stimulus similar to the expected one (contingent cue) has a distracting effect. As predicted, we found that both types of cues reduced the target detection sensitivity but enhanced the bias to respond in a go-nogo-paradigm. With the onset cue, the sensitivity loss was more pronounced at the side of the cue, whereas the contingent cue affected both sides likewise. Moreover, the effects of the onset cue interacted with the task difficulty: the more selectivity a task required the more immune it was against disruption, but the more likely was a response. We concluded that onset capture disrupts selective attention by adding noise to the processing of the target location. The effects of contingent capture could be explained with cue-target confounding. Finally, we suggest a new model of attentional capture in which exogenous and endogenous components interact in a dynamic way.     

Matching cue size and task properties in exogenous attention

Exogenous attention is an involuntary, reflexive orienting response that results in enhanced processing at the attended location. The standard view is that this enhancement generalizes across visual properties of a stimulus. We test whether the size of an exogenous cue sets the attentional field and whether this leads to different effects on stimuli with different visual properties. In a dual task with a random-dot kinematogram (RDK) in each quadrant of the screen, participants discriminated the direction of moving dots in one RDK and localized one red dot. Precues were uninformative and consisted of either a large or a small luminance-change frame. The motion discrimination task showed attentional effects following both large and small exogenous cues. The red dot probe localization task showed attentional effects following a small cue, but not a large cue. Two additional experiments showed that the different effects on localization were not due to reduced spatial uncertainty or suppression of RDK dots in the surround. These results indicate that the effects of exogenous attention depend on the size of the cue and the properties of the task, suggesting the involvement of receptive fields with different sizes in different tasks. These attentional effects are likely to be driven by bottom-up mechanisms in early visual areas.     

Processing demand modulates the effects of spatial attention on the judged duration of a brief stimulus.

How does attention influence the judged duration of a brief stimulus? In the four experiments reported here, we show that the effect of spatial attention on duration judgment depends on the processing demand of the concurrent nontemporal task. When participants had to perform a speeded letter discrimination task in addition to duration rating, the judged duration was longer at a cued location than at an uncued location, regardless of whether the cue was exogenous or endogenous. However, when the same stimuli were presented but no concurrent nontemporal task was required, duration was judged to be shorter at the cued location, as compared with the uncued locations. Furthermore, although spatial attention influenced duration judgment, no object-based attentional effects were found. These findings suggest that, although spatial attention plays an important role in the judged duration of a briefly presented stimulus, its effect is mediated by the processing demand of the task.     

Processing demand modulates the effects of spatial attention on the judged duration of a brief stimulus

How does attention influence the judged duration of a brief stimulus? In the four experiments reported here, we show that the effect of spatial attention on duration judgment depends on the processing demand of the concurrent nontemporal task. When participants had to perform a speeded letter discrimination task in addition to duration rating, the judged duration was longer at a cued location than at an uncued location, regardless of whether the cue was exogenous or endogenous. However, when the same stimuli were presented but no concurrent nontemporal task was required, duration was judged to be shorter at the cued location, as compared with the uncued locations. Furthermore, although spatial attention influenced duration judgment, no object-based attentional effects were found. These findings suggest that, although spatial attention plays an important role in the judged duration of a briefly presented stimulus, its effect is mediated by the processing demand of the task.     

Transient attention degrades perceived apparent motion

Transient spatial attention refers to the automatic selection of a location that is driven by the stimulus rather than a voluntary decision. Apparent motion is an illusory motion created by stationary stimuli that are presented successively at different locations. In this study we explored the effects of transient attention on apparent motion. The motion target presentation was preceded by either valid attentional cues that attract attention to the target location in advance (experiments 1-4), neutral cues that do not indicate a location (experiments 1, 3, and 4), or invalid cues that direct attention to a non-target location (experiment 2). Valid attentional cues usually improve performance in various tasks. Here, however, an attentional impairment was found. Observers' ability to discriminate the direction of motion diminished at the cued location. Analogous results were obtained regardless of cue type: singleton cue (experiment 1), central non-informative cue (experiment 2), or abrupt onset cue (experiment 3). Experiment 4 further demonstrated that reversed apparent motion is less likely with attention. This seemingly counterintuitive attentional degradation of perceived apparent motion is consistent with several recent findings, and together they suggest that transient attention facilitates spatial segregation and temporal integration but impairs spatial integration and temporal segregation.     

注意控制定势和线索类型在注意捕获中的作用

采用前线索范式, 通过3个实验考察了注意控制定势和线索类型在注意捕获中的作用。实验1要求被试搜索颜色奇异项目标或突现目标, 涉及较弱的注意控制定势, 结果表明, 突现线索在作为匹配线索和不匹配线索时都能捕获注意, 而颜色奇异项线索只有在作为匹配线索时才能捕获注意。实验2要求被试搜索具体特征的红色或白色目标, 使被试建立较强的特征搜索定势, 结果表明, 颜色奇异项线索和突现线索在作为匹配线索时都能捕获注意, 但是在不匹配条件下, 颜色奇异项线索被抑制了, 而突现线索不能捕获注意; 实验3采取go/no-go范式, 要求被试对红色目标进行反应, 对白色目标进行抑制, 并通过设置不同的线索-目标时间间隔来进一步考察注意捕获的机制, 结果表明, 在600 ms间隔下, no-go突现线索被抑制, 而对于go颜色奇异项线索来说, 随着时间间隔的增加, 注意捕获效应减少。结果与相倚捕获假说和抑制独立捕获假说不符, 支持注意转移假说：自上而下的注意控制定势通过把注意从和目标不匹配的特征位置转移发挥作用; 颜色奇异项线索和突现线索的注意捕获机制相同, 但是突现线索相对于颜色奇异项线索来说, 在与目标不匹配的条件下, 更容易捕获注意, 更难被抑制。     

内外源性空间注意对多感觉整合的影响

本文采用内-外源性空间线索靶子范式, 操控内源性线索有效性(有效线索、无效线索)、外源性线索有效性(有效线索、无效线索)、目标刺激类型(视觉刺激、听觉刺激、视听觉刺激)三个自变量。通过两个不同任务难度的实验(实验1: 简单定位任务; 实验2: 复杂辨别任务)来考察内外源性空间注意对多感觉整合的影响。两个实验结果均发现外源性空间注意显著减弱了多感觉整合效应, 内源性空间注意没有显著增强多感觉整合效应; 实验2中还发现了内源性空间注意会对外源性空间注意减弱多感觉整合效应产生影响。结果表明, 与内源性空间注意不同, 外源性空间注意对多感觉整合的影响不易受任务难度的调控; 当任务较难时内源性空间注意会影响外源性空间注意减弱多感觉整合效应的过程。由此推测, 内外源性空间注意对多感觉整合的调节并非彼此独立、而是相互影响的。     

Investigating the role of exogenous cueing on selection history formation

An abundance of recent empirical data suggest that repeatedly allocating visual attention to task-relevant and/or reward-predicting features in the visual world engenders an attentional bias for these frequently attended stimuli, even when they become task irrelevant and no longer predict reward. In short, attentional selection in the past hinders voluntary control of attention in the present. But do such enduring attentional biases rely on a history of voluntary, goal-directed attentional selection, or can they be generated through involuntary, effortless attentional allocation? An abrupt visual onset triggers such a reflexive allocation of covert spatial attention to its location in the visual field, automatically modulating numerous aspects of visual perception. In this Registered Report, we asked whether a selection history that has been reflexively and involuntarily derived (i.e., through abrupt-onset cueing) also interferes with goal-directed attentional control, even in the complete absence of exogenous cues. To build spatially distinct histories of exogenous selection, we presented abrupt-onset cues twice as often at one of two task locations, and as expected, these cues reflexively modulated visual processing: task accuracy increased, and response times (RTs) decreased, when the cue appeared near the target’s location, relative to that of the distractor. Upon removal of these cues, however, we found no evidence that exogenous selection history modulated task performance: task accuracy and RTs at the previously most-cued and previously least-cued sides were statistically indistinguishable. Thus, unlike voluntarily directed attention, involuntary attentional allocation may not be sufficient to engender historically contingent selection biases.

     

A time-course analysis of attentional cueing by threatening scenes

Models of attention and emotion have assigned a special status to the processing of threatening information: Facilitated attentional capture by threat and its prioritized processing would allow for swift and adequate action to potentially dangerous stimuli. In four experiments, we examined the time-course of facilitated orienting of attention to threatening scenes in the exogenous cueing paradigm. Threat value and presentation duration of the cues were systematically varied. Facilitated attentional capture by threat was limited to highly threatening pictures presented for 100 ms. No attentional effects were observed with a 28 ms cue presentation duration. At slightly longer cue presentations, 200 ms and 500 ms, results indicated no and even reduced attentional capture by threat compared with neutral information. The present results provide support for the idea that threat facilitates fast attentional orienting to its location, followed by the inhibition of attention to threat.     

Spatial attention can be biased towards an expected dimension

A commonly held view in both exogenous and endogenous orienting is that spatial attention is associated with enhanced processing of all stimuli at the attended location. However, we often search for a specific target at a particular location, so an observer should be able to jointly specify the target identity and expected location. Whether attention can bias dimension-specific processes at a particular location is not yet clear. We used a dual task to examine the effects of endogenous spatial cues on the accuracy of perceptual judgments of different dimensions. Participants responded to a motion target and a colour target, presented at the same or different locations. We manipulated a central cue to predict the location of the motion or colour target. While overall performance in the two tasks was comparable, cueing effects were larger for the target whose location was predicted by the cue, implying that when attending a particular location, processing of the likely dimension was preferentially enhanced. Additionally, an asymmetry between the motion and colour tasks was seen; motion was modulated by attention, and colour was not. We conclude that attention has some ability to select a dimension at a particular location, indicating integration of spatial and feature-based attention.     

Stimulus discrimination following covert attentional orienting to an exogenous cue.

Five experiments explored exogenous covert visual-attentional orienting following a brief peripheral cue. On each trial an attentional cue was followed by a stimulus in an empty field at 1 of 8 locations on an imaginary circle centered on the fixation point. The cued area size and the cue-target spatial relation were manipulated. Accuracy and response time were affected by the exogenous cue validity. Attention was allocated to a specific location in a visual quadrant: A target at an uncued location in a quadrant was not facilitated as much as target at the cued location, and a target in a different quadrant was inhibited in relation to a neutral condition. Cuing 2 locations in a quadrant was not as facilitative for targets at the cued locations or as inhibitive for targets at other locations compared with cuing a single location in a quadrant. Results are discussed in the context of several extent models of covert visual-spatial attention.     

How does reward compete with goal-directed and stimulus-driven shifts of attention?

In order to behave adaptively, attention can be directed in space either voluntarily (i.e. endogenously) according to strategic goals, or involuntarily (i.e. exogenously) through reflexive capture by salient or novel events. The emotional or motivational values of stimuli can also influence attentional orienting. However, little is known about how reward-related effects compete or interact with endogenous and exogenous attention mechanisms. Here we designed a visual search paradigm in which goal-driven and stimulus-driven shifts of attention were manipulated by classic spatial cueing procedures, while an irrelevant, but previously rewarded stimulus also appeared as a distractor and hence competed with both types of spatial attention during search. Our results demonstrated that stimuli previously associated with a high monetary reward received higher attentional priority in the subsequent visual search task, even though these stimuli and reward were no longer task-relevant, mitigating the attentional orienting induced by both endogenous and exogenous cues.     

Problems inhibiting attentional capture by irrelevant stimuli in patients with frontotemporal dementia

We studied the role of the frontal lobes in orienting spatial attention and inhibiting attentional capture by goal-irrelevant stimuli, using a spatial cueing method in patients with frontotemporal dementia (FTD). Two blocks of trials were presented, one with non-predictive cues and the other with counter-predictive cues. FTD patients showed a global orienting deficit, with a greater difference between invalid and valid trials than age-matched controls. However, they were able to use the (counter-) predictiveness of the cue to reduce the invalid/valid difference when targets occurred most often in the location opposite the cue. Thus, endogenous control of attention in our FTD patients was sufficient to reorient attention on the basis of the probability of events, but not to resist the capture of attention by goal-irrelevant stimuli. These results confirm the role of frontal lobes in the inhibition of attentional capture.     

An effective attentional set for a specific colour does not prevent capture by infrequently presented motion distractors

An organism's survival depends on the ability to rapidly orient attention to unanticipated events in the world. Yet, the conditions needed to elicit such involuntary capture remain in doubt. Especially puzzling are spatial cueing experiments, which have consistently shown that involuntary shifts of attention to highly salient distractors are not determined by stimulus properties, but instead are contingent on attentional control settings induced by task demands. Do we always need to be set for an event to be captured by it, or is there a class of events that draw attention involuntarily even when unconnected to task goals? Recent results suggest that a task-irrelevant event will capture attention on first presentation, suggesting that salient stimuli that violate contextual expectations might automatically capture attention. Here, we investigated the role of contextual expectation by examining whether an irrelevant motion cue that was presented only rarely (～3–6% of trials) would capture attention when observers had an active set for a specific target colour. The motion cue had no effect when presented frequently, but when rare produced a pattern of interference consistent with attentional capture. The critical dependence on the frequency with which the irrelevant motion singleton was presented is consistent with early theories of involuntary orienting to novel stimuli. We suggest that attention will be captured by salient stimuli that violate expectations, whereas top-down goals appear to modulate capture by stimuli that broadly conform to contextual expectations.     

Irrelevant singletons capture attention: evidence from inhibition of return

Previous research has shown that a salient feature singleton may capture attention in a stimulus-driven, bottom-up fashion (e.g., Theeuwes, 1992,1994b). This conclusion has been challenged by others claiming that the observed attentional capture by irrelevant singletons may not be stimulus driven but due to top-down attentional control settings and/or nonspatial filtering costs. In the present study, we show that inhibition of return (IOR) occurs at the location of an irrelevant singleton. Participants were slower to detect a target presented at the location of the irrelevant singleton, relative to other locations. Since IOR can be observed only as a result of an exogenous, stimulus-driven shift of spatial attention, it isun-likely that top-down control settings and/or nonspatial filtering costs played a role. In line with earlier claims, the present findings provide strong evidence that salient singletons capture spatial attention in a purely bottom-up way.     

Out with the new,in with the old: Exogenous orienting to locations with physically constant stimulation

Dominant methods of investigating exogenous orienting presume that attention is captured most effectively at locations containing new events. This is evidenced by the ubiquitous use of transient stimuli as cues in the literature on exogenous orienting. In the present study, we showed that attention can be oriented exogenously toward a location containing a completely unchanging stimulus by modifying Posner’s landmark exogenous spatial-cueing paradigm. Observers searched a six-element array of placeholder stimuli for an onset target. The target was preceded by a decrement in luminance to five of the six placeholders, such that one location remained physically constant. This “nonset” stimulus (so named to distinguish it from a traditional onsetting transient) acted as an exogenous cue, eliciting patterns of facilitation and inhibition at the nonset location and demonstrating that exogenous orienting is not always evident at the location of a visual transient. This method eliminates the decades-long confounding of orienting to a location with the processing of new events at that location, permitting alternative considerations of the nature of attentional selection.