When something old becomes something new: spatiotemporal object continuity and attentional capture

This article examines the possibility that the visal system treats dynamic cues a instances of new perceptual objects undersome circumstances. Using the contingent capture paradigm (C. L. Folk, R. W. Remington, & J. C. Johnston, 1992), the author compared luminance change cues of different magnitude for their ability to capture attention when participants were set for new objects. Wheras small luminance changes failed to produce attentional capture, large luminance changs indeed captured attention, suggesting that they were treated as compatible with the participants' attentional set for new objects. It is argued that sufficiently large luminance transients led to a disurption of spatiotemporal object continuity and precipitated the emergence of a new perceptual object.     

Can new objects override attentional control settings?

Previous research suggests that attentional capture by abrupt onsets is contingent on top-down attentional control settings. Four experiments addressed whether similar contingencies hold for capture elicited by the appearance of new perceptual objects. In a modified spatial cuing task, targets defined by abrupt onset or color were paired with distractors consisting of an abrupt brightening of an existing object or the abrupt appearance of a new object. In Experiments 1 and 2, when subjects searched for an onset target, both distractor types produced evidence of capture. When subjects searched for a color target, however, distractors produced no evidence of attentional capture, regardless of whether they consisted of a new perceptual object or not. Experiments 3-5 showed that the lack of distractor effects in the color-target condition cannot be accounted for by rapid recovery from capture. It was concluded that attentional capture by new objects is subject to top-down modulation by attentional control settings.     

Attentional capture by motion onsets is modulated by perceptual load

The onset of motion captures attention during visual search even if the motion is not task relevant, which suggests that motion onsets capture attention in a stimulus-driven manner. However, we have recently shown that stimulus-driven attentional capture by abruptly appearing objects is attenuated under conditions of high perceptual load. In the present study, we examined the influence of perceptual load on attentional capture by another type of dynamic stimulus: the onset of motion. Participants searched for a target letter through briefly presented low- and high-load displays. On each trial, two irrelevant flankers also appeared, one with a motion onset and one that was static. Flankers defined by a motion onset captured attention in the low-load but not in the high-load displays. This modulation of capture in high-load displays was not the result of overall lengthening of reaction times (RTs) in this condition, since search for a single low-contrast target lengthened RTs but did not influence capture. These results, together with those of previous studies, suggest that perceptual load can modulate attentional capture by dynamic stimuli.     

Attentional capture by items that match episodic long-term memory representations

A remarkable ability of the human visual system is the implementation of attentional control settings (ACSs) that govern what stimuli capture or hold attention. We provide evidence that ACSs can be specified by episodic long-term memory representations. In all experiments, participants memorized 30 images of objects that they then monitored for in an attention task, inducing an episodic-based ACS. In Experiments 1a and 1b, only studied cues in a cueing task captured attention. We confirmed these cueing effects reflect capture by testing for inhibition of return in Experiment 2a, and controlled for perceptual masking by cues in Experiment 2b. In Experiment 3 we determined that ACSs are specifically supported by episodic retrieval, by dividing studied images into two sets and designating one as the targets in a rapid serial visual presentation task: Only target-set matching distractors produced a spatial blink (captured attention). These results extend our understanding of the representations specifying ACSs.     

Perceptual load modulates attentional capture by abrupt onsets

The abrupt appearance of a new object captures attention, even when the object is task irrelevant. These findings suggest that abrupt onsets capture attention in a stimulus-driven manner and are not susceptible to top-down influences on attentional control. However, previous studies examining the ability of abrupt onsets to capture attention have used search displays that lacked significant complexity. Because attention is a limited capacity mechanism, it is possible that increasing the complexity, or perceptual load, of the search arrays may modulate capture by abrupt onsets. We used a flanker task to examine the effect of perceptual load on attentional capture by abruptly appearing objects. Subjects searched for a target letter through low-load (set size=1) and high-load (set size=6) displays. On each trial, irrelevant flankers also appeared, one as an onset and the other as an offset. Onset flankers affected search in low-load but not high-load displays. This modulation of attentional capture was not caused by generalized slowing when subjects searched through high-load displays; search for a single perceptually degraded target slowed response times but did not affect attentional capture. These findings demonstrate that attentional capture by an abrupt onset is attenuated when people search through high-load scenes.     

Visual motion and attentional capture

Previous work has shown that abrupt visual onsets capture attention. This occurs even with stimuli that are equiluminant with the background, which suggests that the appearance of a new perceptual object, not merely a change in luminance, captures attention. Three experiments are reported in which this work was extended by investigating the possible role of visual motion in attentional capture. Experiment 1 revealed that motion can efficiently guide attention when it is perfectly informative about the location of a visual search target, but that it does not draw attention when it does not predict the target’s position. This result was obtained with several forms of motion, including oscillation, looming, and nearby moving contours. To account for these and other results, we tested anew-object account of attentional capture in Experiment 2 by using a global/local paradigm. When motion segregated a local letter from its perceptual group, the local letter captured attention as indexed by an effect on latency of response to the task-relevant global configuration. Experiment 3 ruled out the possibility that the motion in Experiment 2 captured attention merely by increasing the salience of the moving object. We argue instead that when motion segregates a perceptual element from a perceptual group, a new perceptual object is created, and this event captures attention. Together, the results suggest that motion as such does not capture attention but that the appearance of a new perceptual object does.     

Irrelevant onsets cause inhibition of return regardless of attentional set

It is disputed whether onsets capture spatial attention either in a purely stimulus-driven fashion or only when they are contingent on one's attentional set. According to the latter assumption, interference from irrelevant onsets may result from nonspatial filtering costs. In the present study, we used inhibition of return (IOR) as a marker for spatial attention. IOR occurs mainly for locations that attention has visited before. Participants searched for a red object among white objects. An attentional set for redness was demonstrated by a spatial validity effect of red cues on response times. However, a stronger validity effect was found for irrelevant white onsets, which slowed responses when the onset contained a distractor, but speeded them when the onset contained a target. Most importantly, this onset benefit for targets turned into a deficit at longer SOAs, indicating IOR. We conclude that onset distractors capture spatial attention regardless of the observer's attentional set.     

What variety of attention is automatically captured by peripheral cues?

Previous studies have shown that the voluntary allocation of attention to a location in space can influence accuracy in two ways. First, additional processing resources can be allocated to the attended location, leading to an improvement in perceptual quality for objects presented at that location. Second, decision processes can be restricted to information arising from the attended location, which improves accuracy without influencing the perceptual representation. The present study examined the operation of these two attentional mechanisms when nonpredictive peripheral cues were used to capture attention automatically. Experiment 1 showed that, like predictive cues, nonpredictive cues influence accuracy by summoning perceptual resources and also by influencing decision processes. However, both the cues and the targets in this experiment were defined by luminance increments, making it possible that the cuing effects were mediated by a task-controlled attentional set rather than being fully automatic. Experiments 2 and 3 examined this possibility by using luminance-defined cues and color-defined targets; evidence was again obtained for both perceptual-level and decision-level attention effects. The capture of attention by a nonpredictive peripheral cue thus appears to influence both perceptual resource allocation and postperceptual decision processes.     

Reflexive attention attenuates change blindness (but only briefly)

Humans are remarkably insensitive to large changes in a visual display if the change occurs simultaneously with a secondary perceptual event. A widely held view is that this change blindness occurs because the secondary perceptual event prevents the change from capturing attention. However, whereas some studies have shown that top-down attentional priming can attenuate change blindness, the evidence regarding the effect of bottom-up attentional capture on change blindness is less clear-cut. Here, we compare the effects of attentional capture on change detection with participants' performance on a well-established attentional paradigm (a Posner-style cuing task). Experiment 1 established the time course of attentional capture in our paradigm. Experiment 2 demonstrated that this attentional capture was associated with facilitated change detection at short (150-msec), but not long (480-msec), latencies. These data show that reflexive attentional shifts facilitate change detection and are consistent with the view that shifts of attention are a necessary precondition for visual awareness.     

Inhibition of return to occluded objects

Since many visual objects are vulnerable to occlusion, an active process that tracks objects behind occluders confers considerable ecological validity to the visual system. We studied this possibility by testing whether inhibition of return can be observed with occluded objects. In our experiments, two moving objects disappeared or reappeared behind occluders while a cue and a probe were presented. Contrary to the results of a previous study (Tipper, Weaver, Jerreat, & Burak, 1994), responses were consistently delayed for the cued object that was occluded when it was cued (Experiment 1), when it was probed (Experiment 2), or both (Experiment 3). These results suggest that attention can select occluded objects that are out of view. Our findings are in line with prior studies that have demonstrated similar perceptual/attentional effects for occluded objects, as well as for visible objects.     

Coordination of voluntary and stimulus-driven attentional control in human cortex

Visual attention may be voluntarily directed to particular locations or features (voluntary control), or it may be captured by salient stimuli, such as the abrupt appearance of a new perceptual object (stimulus-driven control). Most often, however, the deployment of attention is the result of a dynamic interplay between voluntary attentional control settings (e.g., based on prior knowledge about a target's location or color) and the degree to which stimuli in the visual scene match these voluntary control settings. Consequently, nontarget items in the scene that share a defining feature with the target of visual search can capture attention, a phenomenon termed contingent attentional capture. We used functional magnetic resonance imaging to show that attentional capture by target-colored distractors is accompanied by increased cortical activity in corresponding regions of retinotopically organized visual cortex. Concurrent activation in the temporoparietal junction and ventral frontal cortex suggests that these regions coordinate voluntary and stimulus-driven attentional control settings to determine which stimuli effectively compete for attention.     

You can't stop new motion: Attentional capture despite a control set for colour

When a stationary object begins to move, visual spatial attention is reflexively deployed to the location of that object. We tested whether this capture of attention by new motion is entirely stimulus driven, or whether it is contingent on an observer's goals. Participants monitored a visual display for a colour change, inducing an attentional control set (ACS) for colour. Across the three performed experiments, irrelevant new-motion cues always captured visual spatial attention, despite the ACS for colour. This persistence of the attentional cueing effect demonstrates that ACSs, in particular an ACS for colour, cannot prevent new motion from capturing attention. Unlike other stimulus types, such as luminance changes, colour singletons, and new objects, new motion may always capture attention regardless of an observer's goals. This conclusion entails that new motion is an important determinant of when, and to where, visual spatial attention is deployed.     

Do new objects capture attention?

The visual system relies on several heuristics to direct attention to important locations and objects. One of these mechanisms directs attention to sudden changes in the environment. Although a substantial body of research suggests that this capture of attention occurs only for the abrupt appearance of a new perceptual object, more recent evidence shows that some luminance-based transients (e.g., motion and looming) and some types of brightness change also capture attention. These findings show that new objects are not necessary for attention capture. The present study tested whether they are even sufficient. That is, does a new object attract attention because the visual system is sensitive to new objects or because it is sensitive to the transients that new objects create? In two experiments using a visual search task, new objects did not capture attention unless they created a strong local luminance transient.     

Unique temporal change is the key to attentional capture

Abstract— Attentional capture refers to the observation that some events break through and attract one's attention even when one is engaged in a task for which these events are irrelevant. Previous research, focusing primarily on spatial factors, has shown that a new object is more salient in this regard than an abrupt change in an object's features. Here we show that feature changes can be as effective as new objects in capturing attention, provided that they occur during a period of temporal calm. Conversely, both feature changes and new objects are far less effective in capturing attention when they occur simultaneously with other display changes, such as coincident with the initial onset of the display or with small visual transients that occur during a display transition. These results highlight the importance of considering both space and time in studies of attentional capture; the most effective stimulus is unique in both dimensions.     

无关工作记忆表征的负性情绪信息能否捕获视觉注意?一项眼动研究

研究通过分析视觉搜索任务的首次注视点和行为反应时, 探讨无关工作记忆表征的负性情绪信息对视觉注意选择的影响。实验1发现在反映早期注意选择的首次注视点百分率指标上, 不管工作记忆表征的情绪效价如何, 均出现了显著的注意捕获效应; 实验2发现当采用中性情绪靶子刺激时, 首次注视点百分率指标上仍表现出了稳健的注意捕获效应; 在首次注视点持续时间指标上, 实验1和实验2均发现记忆匹配条件的干扰刺激显著小于控制条件的干扰刺激, 表现出注意的快速脱离; 而在行为反应时指标上, 早期的注意捕获效应消失(实验1), 甚至被反转为注意抑制效应(实验2)。这些结果表明在早期注意选择阶段, 记忆驱动的注意捕获效应不受工作记忆表征情绪效价的影响, 但认知控制会在早期注意捕获之后促使注意快速脱离记忆匹配的干扰刺激, 其作用效果受靶子刺激情绪效价的调节。     

Object-Based Visual Selection: Evidence From Perceptual Completion

A large body of evidence suggests that visual attention selects objects as well as spatial locations. If attention is to be regarded as truly object based, then it should operate not only on object representations that are explicit in the image, but also on representations that are the result of earlier perceptual completion processes. Reporting the results of two experiments, we show that when attention is directed to part of a perceptual object, other parts of that object enjoy an attentional advantage as well. In particular, we show that this object-specific attentional advantage accrues to partly-occluded objects and to objects defined by subjective contours. The results corroborate the claim that perceptual completion precedes object-based attentional selection.     

Does low perceptual load enable capture by colour singletons?

There is considerable debate as to whether colour singletons can capture attention in a stimulus-driven manner. In this study, we explore one potential capture enabling condition—low perceptual load. To test this hypothesis, we manipulated perceptual load in a flanker task in which flanking letters sometimes were colour singletons. If low load enhances capture by colour singletons, then colour singletons should produce an especially large increase in overall reaction times and in flanker–target compatibility effects. Neither of these predictions was confirmed in any of the four experiments reported here, although we did replicate the classic load effects from previous studies. These experiments indicate that although perceptual load does strongly modulate overall performance, it does not facilitate capture by colour singletons. This finding contrasts sharply with findings from other types of salient stimuli (abrupt onsets and moving objects). Implications for theories of attentional capture will be discussed.     

Inhibition of return and attentional control settings

In the present study, we used a spatial cuing paradigm in conjunction with a choice identification task to investigate whether exogenous attentional orienting and inhibition of return are affected by attentional control settings. As in previous studies (e.g., Folk, Remington, & Johnston, 1992), onset- and color-defined targets were crossed with uninformative onset- and color-defined cues. As expected, when the cue-target stimulus onset asynchrony (SOA) was short (i.e., 100 msec), the results showed that exogenous attentional orienting was contingent on attentional set; attentional capture occurred in response to a particular cue only when the feature that defined the cue also defined the target (Folk et al., 1992). More importantly, when the cue-target SOA was long (i.e., 1,000 msec), the results showed that the occurrence of inhibition of return was also contingent on attentional set, at least partially so; inhibition of return occurred in response to onset cues only when they preceded onset targets. In contrast, inhibition of return never occurred in response to color cues (at a variety of long SOAs). The associations and dissociations that were observed between exogenous attentional orienting and inhibition of return are discussed in terms of posterior and anterior attention networks in the brain (Posner & Petersen, 1990).     

Attentional capture under high perceptual load

Attentional capture by abrupt onsets can be modulated by several factors, including the complexity, or perceptual load, of a scene. We have recently demonstrated that observers are less likely to be captured by abruptly appearing, task-irrelevant stimuli when they perform a search that is high, as opposed to low, in perceptual load (Cosman & Vecera, 2009), consistent with perceptual load theory. However, recent results indicate that onset frequency can influence stimulus-driven capture, with infrequent onsets capturing attention more often than did frequent onsets. Importantly, in our previous task, an abrupt onset was present on every trial, and consequently, attentional capture might have been affected by both onset frequency and perceptual load. In the present experiment, we examined whether onset frequency influences attentional capture under conditions of high perceptual load. When onsets were presented frequently, we replicated our earlier results; attentional capture by onsets was modulated under conditions of high perceptual load. Importantly, however, when onsets were presented infrequently, we observed robust capture effects. These results conflict with a strong form of load theory and, instead, suggest that exposure to the elements of a task (e.g., abrupt onsets) combines with high perceptual load to modulate attentional capture by task-irrelevant information.     

Context and competition in the capture of visual attention

Competition-based models of visual attention propose that perceptual ambiguity is resolved through inhibition, which is stronger when objects share a greater number of neural receptive fields (RFs). According to this theory, the misallocation of attention to a salient distractor--that is, the capture of attention--can be indexed in RF-scaled interference costs. We used this pattern to investigate distractor-related costs in visual search across several manipulations of temporal context. Distractor costs are generally larger under circumstances in which the distractor can be defined by features that have recently characterised the target, suggesting that capture occurs in these trials. However, our results show that search for a target in the presence of a salient distractor also produces RF-scaled costs when the features defining the target and distractor do not vary from trial to trial. Contextual differences in distractor costs appear to reflect something other than capture, perhaps a qualitative difference in the type of attentional mechanism deployed to the distractor.