Distinct,but top-down modulable color and positional priming mechanisms in visual pop-out search

Three experiments examined reaction time (RT) performance in visual pop-out search. Search displays comprised of one color target and two distractors which were presented at 24 possible locations on a circular ellipse. Experiment 1 showed that re-presentation of the target at a previous target location led to expedited RTs, whereas presentation of the target at a distractor location led to slowed RTs (relative to target presentation at a previous empty location). RTs were also faster when the color of the target was the same across consecutive trials, relative to a change of the target’s color. This color priming was independent of the positional priming. Experiment 2 revealed larger positional facilitation, relative to Experiment 1, when position repetitions occurred more likely than chance level; analogously, Experiment 3 revealed stronger color priming effects when target color repetitions were more likely. These position and color manipulations did not change the pattern of color (Experiment 2) and positional priming effects (Experiment 3). While these results support the independency of color and positional priming effects (e.g., Maljkovic and Nakayama in Percept Psychophys 58:977–991, 1996), they also show that these (largely ‘automatic’) effects are top-down modulable when target position and color are predictable (e.g., Müller et al. in Vis Cogn 11:577–602, 2004).     

自我相关信息对视觉搜索主动抑制的易化作用

工作记忆表征会以自上而下的方式调控注意选择过程, 其中一种表现就是能够对储存的干扰物表征产生注意的主动抑制, 进而提高对目标的搜索效率。另一方面, 凸显性刺激也会以自下而上的方式优先捕获注意。那么, 当保持在工作记忆中的干扰物为更具社会凸显性特征的刺激(如与自己有关的信息)时, 会对视觉搜索过程中的注意抑制产生怎样的影响, 目前尚不清楚。本研究采用短暂联结任务和工作记忆引导的视觉搜索任务范式, 探讨了自我凸显性对注意主动抑制的影响。结果发现, 相比他人和中性条件, 当工作记忆表征为自我联结刺激时, 目标搜索反应更快。本研究从行为层面为自我相关信息能够易化主动抑制过程提供了证据。     

Contingent capture in cueing: the role of color search templates and cue-target color relations

Visual search studies have shown that attention can be top-down biased to a specific target color, so that only items with this color or a similar color can capture attention. According to some theories of attention, colors from different categories (i.e., red, green, blue, yellow) are represented independently. However, other accounts have proposed that these are related—either because color is filtered through broad overlapping channels (4-channel view), or because colors are represented in one continuous feature space (e.g., CIE space) and search is governed by specific principles (e.g., linear separability between colors, or top-down tuning to relative colors). The present study tested these different views using a cueing experiment in which observers had to select one target color (e.g., red) and ignore two or four differently colored distractors that were presented prior to the target (cues). The results showed clear evidence for top-down contingent capture by colors, as a target-colored cue captured attention more strongly than differently colored cues. However, the results failed to support any of the proposed views that different color categories are related to one another by overlapping channels, linear separability, or relational guidance (N = 96).     

Visual search for singleton feature targets across dimensions: Stimulus- and expectancy-driven effects in dimensional weighting

Four pop-out search experiments investigated whether dimension-based visual attention is top-down modulable. Observers searched for singleton feature targets defined, variably across trials, by a color or an orientation difference to nontargets. Observers were precued to the most probable target-defining dimension (e.g., by the word color) or feature (red) on a given trial. Results revealed expedited reaction times (RTs) for valid-dimension targets relative to neutral-cue conditions, and slowed RTs for invalid-dimension targets. Cue information as to precise target feature yielded some extra effect only for color targets. The dimensional cuing significantly reduced, but did not abolish, the dimension-specific influence of the previous target on detection of the current target (same-dimension RT < different-dimension RT). These findings confirm that top-down dimensional set modulates stimulus-driven dimension processes in the detection of pop-out signals. ((c) 2003 APA, all rights reserved)     

颜色和形状工作记忆对非空间返回抑制效应的影响

为进一步考察非空间返回抑制效应是否受工作记忆内容的影响,分别采用颜色和形状工作记忆内容,通过两个实验考察了工作记忆对非空间返回抑制效应的影响。实验结果表明,在颜色和形状工作记忆条件下,均产生了颜色或形状返回抑制效应,并且颜色或形状返回抑制效应量之间均无显著差异,颜色和形状工作记忆内容只增加了判断靶刺激的反应时。研究结论对进一步认识工作记忆内容与非空间返回抑制效应之间的关系有重要参考价值。     

Effects of relevant and irrelevant color singletons on inhibition of return and attentional capture

We tested whether color singletons lead to saccadic and manual inhibition of return (IOR; i.e., slower responses at cued locations) and whether IOR depended on the relevance of the color singletons. The target display was preceded by a nonpredictive cue display. In three experiments, half of the cues were response-relevant, because participants had to perform a discrimination task at the cued location. With the exception of Experiment 2, none of the cue colors matched the target color. We observed saccadic IOR after color singletons, which was greater for slow than for fast responses. Furthermore, when the relevant cue color matched the target color, we observed attentional capture (i.e., faster responses at cued locations) with rapid responses, but IOR with slower responses, which provides evidence for attentional deallocation. When the cue display was completely response-irrelevant in two additional experiments, we did not find evidence for IOR. Instead, we found attentional capture when the cue color matched the target color. Also, attentional capture was greater for rapid responses and with short cue–target intervals. Thus, IOR emerges when cues are relevant and do not match the target color, whereas attentional capture emerges with relevant and irrelevant cues that match the target color.     

Auditory, tactile, and multisensory cues facilitate search for dynamic visual stimuli

Presenting an auditory or tactile cue in temporal synchrony with a change in the color of a visual target can facilitate participants’ visual search performance. In the present study, we compared the magnitude of unimodal auditory, vibrotactile, and bimodal (i.e., multisensory) cuing benefits when the nonvisual cues were presented in temporal synchrony with the changing of the target’s color (Experiments 1 and 2). The target (a horizontal or vertical line segment) was presented among a number of distractors (tilted line segments) that also changed color at various times. In Experiments 3 and 4, the cues were also made spatially informative with regard to the location of the visual target. The unimodal and bimodal cues gave rise to an equivalent (significant) facilitation of participants’ visual search performance relative to a no-cue baseline condition. Making the unimodal auditory and vibrotactile cues spatially informative produced further performance improvements (on validly cued trials), as compared with cues that were spatially uninformative or otherwise spatially invalid. A final experiment was conducted in order to determine whether cue location (close to versus far from the visual display) would influence participants’ visual search performance. Auditory cues presented close to the visual search display were found to produce significantly better performance than cues presented over headphones. Taken together, these results have implications for the design of nonvisual and multisensory warning signals used in complex visual displays.     

Parallel coding of conjunctions in visual search

Two experiments investigated whether the conjunctive nature of nontarget items influenced search for a conjunction target. Each experiment consisted of two conditions. In both conditions, the target item was a red bar tilted to the right, among white tilted bars and vertical red bars. As well as color and orientation, display items also differed in terms of size. Size was irrelevant to search in that the size of the target varied randomly from trial to trial. In one condition, the size of items correlated with the other attributes of display items (e.g., all red items were big and all white items were small). In the other condition, the size of items varied randomly (i.e., some red items were small and some were big, and some white items were big and some were small). Search was more efficient in the size-correlated condition, consistent with the parallel coding of conjunctions in visual search     

On the limits of top-down control of visual selection

In the present study, observers viewed displays in which two equally salient color singletons were simultaneously present. Before each trial, observers received a word cue (e.g., the word red, or green) or a symbolic cue (a circle colored red or green) telling them which color singleton to select on the upcoming trial. Even though many theories of visual search predict that observers should be able to selectively attend the target color singleton, the results of the present study show that observers could not select the target singleton without interference from the irrelevant color singleton. The results indicate that the irrelevant color singleton captured attention. Only when the color of the target singleton remained the same from one trial to the next was selection perfect--an effect that is thought to be the result of passive automatic intertrial priming. The results of the present study demonstrate the limits of top-down attentional control.     

Selective attention modulates implicit learning

The effect of selective attention on implicit learning was tested in four experiments using the "contextual cueing" paradigm (Chun & Jiang, 1998, 1999). Observers performed visual search through items presented in an attended colour (e.g., red) and an ignored colour (e.g., green). When the spatial configuration of items in the attended colour was invariant and was consistently paired with a target location, visual search was facilitated, showing contextual cueing (Experiments 1, 3, and 4). In contrast, repeating and pairing the configuration of the ignored items with the target location resulted in no contextual cueing (Experiments 2 and 4). We conclude that implicit learning is robust only when relevant, predictive information is selectively attended.     

Top-down search for color prevents voluntary directing of attention to informative singleton cues

Visuo-spatial attention can be directed in a top-down controlled way to search for color targets and it can be captured by color contrasts, regardless of color identity. Here we tested whether participants can both search for a particular color target (e.g., red) and make use of a color-contrast cue that predicted the target's most likely position to direct their attention voluntarily. Our results show that this was impossible for the participants. Results support that top-down search for particular colors is incommensurate with directing attention to just any color contrast. The results are discussed in light of the current debates concerning the roles of color and color contrast for visuo-spatial attention.     

Detection costs and contingent attentional capture

Peripheral cues reduce reaction times (RTs) to targets at the cued location with short cue-target SOAs (cueing benefits) but increase RTs at long SOAs (cueing costs or inhibition of return). In detection tasks, cueing costs occur at shorter SOAs and are larger compared with identification tasks. To account for effects of task, detection cost theory claims that the integration of cue and target into an object file makes it more difficult to detect the target as a new event, which is the principal task-requirement in detection tasks. The integration of cue and target is expected to increase when cue and target are similar. We provided evidence for detection cost theory in the modified spatial cueing paradigm. Two types of cues (onset, color) were paired with two types of targets (onset, color) in separate blocks of trials. In the identification task, we found cueing benefits with matching (i.e., similar) cue-target pairs (onset-onset, color-color) and no cueing effects with nonmatching cue-target pairs (onset-color, color-onset), which replicates previous work. In the detection task, cueing effects with matching cues were reduced and even turned into cueing costs for onset cues with onset targets, suggesting that cue-target integration made it more difficult to detect targets at the cued location as new events. In contrast, the results for nonmatching cue-target pairs were not affected by task. Furthermore, the pattern of false alarms in the detection task provides a measure of similarity that may explain the size of cueing benefits and costs.     

Interaction between scene-based and array-based contextual cueing

Contextual cueing refers to the cueing of spatial attention by repeated spatial context. Previous studies have demonstrated distinctive properties of contextual cueing by background scenes and by an array of search items. Whereas scene-based contextual cueing reflects explicit learning of the scene–target association, array-based contextual cueing is supported primarily by implicit learning. In this study, we investigated the interaction between scene-based and array-based contextual cueing. Participants searched for a target that was predicted by both the background scene and the locations of distractor items. We tested three possible patterns of interaction: (1) The scene and the array could be learned independently, in which case cueing should be expressed even when only one cue was preserved; (2) the scene and array could be learned jointly, in which case cueing should occur only when both cues were preserved; (3) overshadowing might occur, in which case learning of the stronger cue should preclude learning of the weaker cue. In several experiments, we manipulated the nature of the contextual cues present during training and testing. We also tested explicit awareness of scenes, scene–target associations, and arrays. The results supported the overshadowing account: Specifically, scene-based contextual cueing precluded array-based contextual cueing when both were predictive of the location of a search target. We suggest that explicit, endogenous cues dominate over implicit cues in guiding spatial attention.     

Why does the effect of short-SOA exogenous cuing on simple RT depend on the number of display locations?

When the stimulus onset asynchrony (SOA) between the cue and target is short (i.e., less than 200 msec) and the number of display locations is small (e.g., only two), exogenous spatial cues produce a benefit in simple response time (RT). However, several recent experiments have found significant costs in these tasks when a large number of display locations is employed (e.g., eight), even at the very short SOAs that usually produce a benefit. The present study explored the dependence of exogenous cuing on the number of display locations and found evidence that both the overall validity of the cues and the specific validity of the cue on the previous trial have strong, additive effects. When a large number of display locations is used, both of these factorswork against a benefit of exogenous cuing on simple RT, reversing the typical finding into a cost. These two effects are suggested to occur within motor and perceptual processes, respectively.     

Automatic priming of attentional control by relevant colors

We tested whether color word cues automatically primed attentional control settings during visual search, or whether color words were used in a strategic manner for the control of attention. In Experiment 1, we used color words as cues that were informative or uninformative with respect to the target color. Regardless of the cue's informativeness, distractors similar to the color cue captured more attention. In Experiment 2, the participants either indicated their expectation about the target color or recalled the last target color, which was uncorrelated with the present target color. We observed more attentional capture by distractors that were similar to the participants' predictions and recollections, but no difference between effects of the recollected and predicted colors. In Experiment 3, we used 100%-informative word cues that were congruent with the predicted target color (e.g., the word "red" informed that the target would be red) or incongruent with the predicted target color (e.g., the word "green" informed that the target would be red) and found that informative incongruent word cues primed attention capture by a word-similar distractor. Together, the results suggest that word cues (Exps. 1 and 3) and color representations (Exp. 2) primed attention capture in an automatic manner. This indicates that color cues automatically primed temporary adjustments in attention control settings.     

How much processing do nonattended stimuli receive? Apparently very little, but...

The early versus late selection issue in attention models was examined by means of a new methodology. Through cues or precues, attention was directed to one location of a multistimulus visual display and, while attention was so engaged, the identity of a stimulus located at a different position in the display was changed. By varying the time after display onset before the stimulus was changed, we controlled the preview time that the original stimulus was represented on the retina. Then, using a marker cue, we directed the subject's attention to the location of the changed stimulus. The subject's response was a timed discrimination between two possible target letters. The data of main interest was the effect of preview time upon the subject's latency in identifying the new target that appeared in the changed location. We found that the preview time of the original stimulus, before RT was affected to the new target, depended upon whether the original stimulus was a neutral (noise) letter or whether it was the alternative target. When the original stimulus was a noise letter, RTs to the new target were just as fast as those obtained in the control condition in which the target was present throughout the preview interval and did not change its identity. Significant effects upon RT were obtained at preview times of 83 msec when the original stimulus was one of the targets that changed to the alternative target. Preview times also varied as a function of precuing. Preview times were correspondingly shortened when the first cue occurred 50 msec before display onset, thus providing an extra 50 msec for attention to be directed to the first display location. The results were interpreted in terms of two separate information-processing systems in the human: an automatic system and an attentional system. Even though a stimulus may have been automatically processed, when the attention system is directed to that stimulus, processing starts at the beginning again.     

The interaction of objective and subjective organizations in a localization search task

We investigated how both objective and subjective organizations affect perceptual organization and how this perceptual organization, in turn, influences observers’ performance in a localization search task. Two groups of observers viewing exactly the same stimuli (objective organization) performed in significantly different ways, depending on how they were induced to parse the display (subjective organization). In Experiments 1 and 2, the observers were asked to describe the location of a tilted target among a varying number of vertical or horizontal distractors. Subjective organization was induced by instructing observers to parse the display into either three horizontal regions (rows) or three vertical regions (columns). The position of the target was critical: location performance, as assessed by reaction time and errors, was consistently impaired at the locations adjacent to the boundaries defining the regions, producing what we refer to as thesubjective boundary effect. Furthermore, the extent of this effect depended on whether the stimulus-driven and conceptually driven information concurred or conflicted. This made location information more or less accessible. In Experiment 1, the strength of objective grouping was a function of the proximity of the items (near or far conditions) and their orientation in a 6×6 matrix. In Experiment 2, the strength of objective grouping was a function of similarity of color (items were color coded by rows or by columns) and the orientation of the items in a 9×9 matrix. The subjective boundary effect was more pronounced when the display promoted grouping in the direction orthogonal to that of the task (e.g., when observers parsed by rows but vertical distractors were closer together [Experiment 1] or color coded [Experiment 2] to induce global columns). In contrast, this effect decreased when the direction of both objective and subjective organizations was parallel (e.g., when observers parsed by rows and horizontal distractors were closer together [Experiment 1] or were color coded [Experiment 2] to induce global rows). A localization search task proved to be an ideal forum in which objective and subjective organizations interacted. We discuss how these results indicated that observers’ performance in a localization task was determined by the interaction of objective and subjective organizations, and that the resulting perceptual organization constrained coarse location information.     

Is location cueing inherently superior to color cueing? Not if color is presented early enough

A possible source for the advantage of location cueing over non-spatial cueing is that orienting attention by a location cue is feasible prior to stimulus onset, whereas that is normally not the case with orienting by a non-spatial cue. To examine how critical that source is for observing an advantage, we eliminated it: In a color-preview condition, subjects were to detect a target presented on the background of one of two differently colored circles (where color-location assignment was random). In a no-preview condition, the circles were both gray, but the target was either red or green (where color assignment was random). Cue type (location vs color) was also manipulated. The color preview in Experiment 1 (in which color onset preceded cue onset) was found helpful: Whereas a substantial disparity in validity effects of the two cue types was obtained with no preview, no significant difference was found when a color preview was introduced. The validity effects of both cue types were found to be about the same also in Experiment 2, in which color onset was exactly synchronized with cue onset, and SOA was manipulated. Furthermore, the absence of an SOA x cue type interaction indicated that the time course of the color cue validity did not lag after the time course of the location cue validity, which seems incompatible with the hypothesis that a color cue cannot affect orienting without first computing a location from it prior to cue onset. Overall, the results suggest that the time course of color cueing is not inherently different from that of location cueing once its main disadvantages are removed.     

视空工作记忆负载对真实场景搜索绩效的影响

采用视空工作记忆任务和真实场景搜索任务相结合的双任务范式, 结合眼动技术将搜索过程划分为起始阶段、扫描阶段和确认阶段, 探究视空工作记忆负载对真实场景搜索绩效的影响机制, 同时考查试次间搜索目标是否变化、目标模板的具体化程度以及搜索场景画面的视觉混乱度所起的调节作用。结果表明, 视空工作记忆负载会降低真实场景搜索的成绩, 在搜索过程中表现为视空负载条件下扫描阶段持续时间的延长、注视点数目的增加和空间负载条件下确认阶段持续时间的延长, 视空负载对搜索过程的影响与目标模板的具体化程度有关; 空间负载会降低真实场景搜索的效率, 且与搜索画面的视觉混乱度有关, 而客体负载则不会。由此可见, 视空工作记忆负载对真实场景搜索绩效的影响不同, 空间负载对搜索过程的影响比客体负载更长久, 二者均受到目标模板具体化程度的调节; 仅空间负载会降低真实场景的搜索效率, 且受到搜索场景画面视觉混乱度的调节。     

Implicit learning of a speed-contingent target feature

Previous human implicit learning studies have mostly investigated implicit associations between two consecutive stimuli or between a stimulus and the subsequent response (e.g., Cleeremans, Destrebecqz, & Boyer, Trends in Cognitive Sciences, 2(10), 406–416, 1998). In the present study, participants’ response speed was used as a cue to predict an upcoming target feature. We called this new type of cueing, “cueing-by-response” (CBR). We investigated whether CBR could be learned implicitly. Participants performed two tasks: participants quickly responded to a target in the simple detection task and determined the orientation of a new target in the consecutive visual search task. We applied a contingency that the target location in the visual search task was determined by the participant’s response speed in the preceding simple detection task. The results demonstrated that participants learned the contingency without conscious awareness; they searched for the target more efficiently in the visual search task as the experiment progressed. But when the target appeared in a random location, this efficiency disappeared. Moreover, the experimental group exhibited faster response speeds to the target in the visual search task compared with the control groups, which had no contingency. These results suggest that individuals may use the relative speed of their own response as a predictive cue to guide spatial attention toward upcoming target locations, and CBR can be implicitly learned.