All set! Evidence of simultaneous attentional control settings for multiple target colors

Although models of visual search have often assumed that attention can only be set for a single feature or property at a time, recent studies have suggested that it may be possible to maintain more than one attentional control setting. The aim of the present study was to investigate whether spatial attention could be guided by multiple attentional control settings for color. In a standard spatial cueing task, participants searched for either of two colored targets accompanied by an irrelevantly colored distractor. Across five experiments, results consistently showed that nonpredictive cues matching either target color produced a significant spatial cueing effect, while irrelevantly colored cues did not. This was the case even when the target colors could not be linearly separated from irrelevantly cue colors in color space, suggesting that participants were not simply adopting one general color set that included both target colors. The results could not be explained by intertrial priming by previous targets, nor could they be explained by a single inhibitory set for the distractor color. Overall, the results are most consistent with the maintenance of multiple attentional control settings.     

Target-uncertainty effects in attentional capture: Color-singleton set or multiple attentional control settings?

Previous spatial cuing studies have shown that the capture of spatial attention is contingent on top-down attentional control settings whose specificity varies as a function of the certainty of the defining features of the target. For example, when the target is a singleton defined by one specific color, observers adopt a control setting for that color. When the target can be one of two possible colors, however, observers appear to adopt a control setting for color singletons in general (see, e.g., Folk & Remington, 2008). The present study tested whether such results instead reflect the simultaneous maintenance of control settings for multiple colors (Adamo, Pun, Pratt, & Ferber, 2008). Observers searched for targets that were unpredictably red or green, preceded by spatial cues that were red, green, or blue. All three cue types produced evidence of capture, consistent with a general set for color singletons rather than the maintenance of multiple control settings.     

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.     

Independent, synchronous access to color and motion features

We investigated the role of attention in pairing superimposed visual features. When moving dots alternate in color and in motion direction, reports of the perceived color and motion reveal an asynchrony: the most accurate reports occur when the motion change precedes the associated color change by approximately 100ms [Moutoussis, K., & Zeki, S. (1997). A direct demonstration of perceptual asynchrony in vision. Proceedings of the Royal Society of London B, 264, 393-399]. This feature binding asynchrony was probed by manipulating endogenous and exogenous attention. First, endogenous attention was manipulated by changing which feature dimension observers were instructed to attend to first. This yielded little effect on the asynchrony. Second, exogenous attention was manipulated by briefly presenting a ring around the target, cueing the report of the color and motion seen within the ring. This reduced or eliminated the apparent latency difference between color and motion. Accuracy was best predicted by timing of each feature relative to the cue rather than the timing of the two features relative to each other, suggesting independent attentional access to the two features with an exogenous attention cue. The timing of attentional cueing affected feature pairing reports as much as the timing of the features themselves.     

Does attention affect visual feature integration?

Two questions are investigated in this work: first, whether the integration of color and shape information is affected by attending to the stimulus location, and second, whether attending to a stimulus location enhances the perceptual representation of the stimulus or merely affects decision processes. In three experiments, subjects were briefly presented with colored letters. On most trials, subjects were precued to the stimulus location (valid cue); on some trials, a nonstimulus location was cued (invalid cue). Subjects were less likely to incorrectly combine colors and letter shapes following a valid cue. The attentional facilitation afforded by the cue was not limited to feature integration but also affected the registration of features. However, when the amount of feature information was strictly controlled, attention still affected feature integration. The results indicate that orienting attention to the location of the cue affects the quality of the perceptual representation for features and their integration.     

Response effects of equated values of event frequency, repetition, and alternation in one-and two-cue probability learning

An experiment using 50 college students equated cue values of frequency, repetition, and alternation in one- and two-cue partially random sequences in order to determine whether the cues were responded to independently or in combination and to test earlier results concerning cue saliency. Using improved methods of data analysis, previous findings that repetition is more salient than frequency and frequency more salient than alternation were replicated. In spite of the saliency differences, the design employed demonstrated that both cues in two-cue sequences were responded to and that responses to one-cue appeared to be independent of responses to the other.     

Simultaneous control of attention by multiple working memory representations

Working memory representations play a key role in controlling attention by making it possible to shift attention to task-relevant objects. Visual working memory has a capacity of three to four objects, but recent studies suggest that only one representation can guide attention at a given moment. We directly tested this proposal by monitoring eye movements while observers performed a visual search task in which they attempted to limit attention to objects drawn in two colors. When the observers were motivated to attend to one color at a time, they searched many consecutive items of one color (long run lengths) and exhibited a delay prior to switching gaze from one color to the other (switch cost). In contrast, when they were motivated to attend to both colors simultaneously, observers' gaze switched back and forth between the two colors frequently (short run lengths), with no switch cost. Thus, multiple working memory representations can concurrently guide attention.     

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.     

A static color discontinuity can capture spatial attention when the target is an abrupt-onset singleton

C. L. Folk, R. W. Remington, and J. C. Johnston's (1992) contingent involuntary orienting hypothesis states that a salient visual feature will involuntarily capture attention only when the observer's attentional set includes similar features. In four experiments, when the target's relevant feature was its being an abruptly onset singleton, attentional capture occurred for a static discontinuity cue that was the boundary between a group of red Xs contiguously joined to a group of green Os within a single row. Such an attentional capture effect is novel and contrary to Folk et al.'s (1992) hypothesis, because the attentional set for the target should have included abrupt onset but not color discontinuity, which was the feature that captured attention. These capture effects were involuntary because they occurred even when the target never appeared in the same location as the cue, and color could not have been used as a cue to signal the appearance of the target array (cf. B. S. Gibson & E. M. Kelsey, 1998).     

The costs of switching attentional sets

People prioritize those aspects of the visual environment that match their attentional set. In the present study, we investigated whether switching from one attentional set to another is associated with a cost. We asked observers to sequentially saccade toward two color-defined targets, one on the left side of the display, the other on the right, each among a set of heterogeneously colored distractors. The targets were of the same color (no attentional set switch required) or of different colors (switch of attentional sets necessary), with each color consistently tied to a side, to allow observers to maximally prepare for the switch. We found that saccades were less accurate and slower in the switch condition than in the no-switch condition. Furthermore, whenever one of the distractors had the color associated with the other attentional set, a substantial proportion of saccades did not end on the target, but on this distractor. A time course analysis revealed that this distractor preference turned into a target preference after about 250-300 ms, suggesting that this is the time required to switch attentional sets.     

Can one pay attention to a particular color?

In an array of elements whose colors vary can we selectively choose to process all the items of a particular color preferentially in relation to those of another color? We addressed this question by presenting subjects with arrays containing many elements, and recording reaction times to a luminance change of one of the elements. Half the elements had one color and the other half another color--the spatial distribution being random. In two tasks--a simple detection of this change or a choice reaction time to the polarity of the change--we found that reaction times were independent of the number of items in the array. Cuing the subjects as to the color of the target item had no significant influence on the detection task, but subjects were faster if cued for the discrimination task. A further experiment replicated these findings and examined possible costs and benefits. Our final experiment separated the roles of attentional guidance and postattentional processes by having subjects judge the orientation of the target element and varying the magnitude of the target flash that defined which element was the target. We found that this judgment was also affected by color cuing, and that the size of the effect interacted with the flash strength, suggesting that color cuing has its influence at the stage of attentional guidance. We conclude that subjects can selectively attend to items on the basis of color given the appropriate task and stimulus dynamics.     

颜色特征加工任务间的注意瞬脱研究

本研究以两个实验对颜色特征加工任务间的注意瞬脱效应进行探讨。实验一要求被试对首先呈现的两个色块(记忆项)与随后呈现的两个色块(检测项)是否相同进行比较。结果发现,在记忆项与检测项的SOA为220ms的条件下,记忆项加工对认知资源的持续占用使检测项的加工绩效下降。实验二含两个需相继执行的任务(T1和T2),二者均为比较同时呈现在屏幕左右两侧的两色块颜色是否相同。结果发现,对颜色特征的觉察即可产生注意瞬脱效应,其大小及时程与经典的采用字母识别任务的研究获得的注意瞬脱效应相当。上述结果表明,特征搜索的完成需有限认知资源的参与。然而,注意瞬脱过程中,特征加工与需对知觉对象细节信息进行提取的辨别任务(如字母辨别任务)在消耗认知资源的量上并无差别。     

Abrupt onsets capture attention independent of top-down control settings

Previous research using a spatial cuing paradigm in which a distractor cue preceded the target has shown that new objects presented with abrupt onsets only capture attention when observers are set to look for them (e.g., Folk, Remington, & Johnston, 1992). In the present study, we used the same spatial cuing paradigm as Folk et al. (1992) to demonstrate that even when observers have an attentional set for a color singleton or a specific color feature, an irrelevant new object presented with an abrupt onset interfered with search. We also show that the identity of the abrupt-onset distractor affects responses to the target, indicating that at some point spatial attention was allocated to the abrupt onset. We conclude that abrupt onsets ornew objects override a top-down set for color. Abrupt onsets or new objects appear to capture attention independently of top-down control settings.     

Age-related changes in the control of attention in depth

In 2 experiments, the authors examined the control of spatial attention in depth in advanced age. Observers viewed 2 sets of lines that overlapped in two-dimensional (2-D) space but that were presented at different depth locations. An exogenous cue indicated the depth at which a colored target line would appear. On some trials, a distracting colored element was also presented. The luminance of this distracter varied from high to low. For both older and younger adults, distractors slowed reaction time less if they were at a different depth from the target. This effect was more robust for older adults with low-luminance distractors, indicating an important role for target features as well as attentional control. Adding another feature (i.e., color) that distinguished between target and distracter reduced the effects of slowing shown by the older observers and eliminated the cost of low-luminance distractors for all observers. The results suggest that attentional control in depth is maintained in aging.     

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).     

Peripheral cuing by abrupt-onset cues: the influence of color in S-R corresponding conditions

Research on visuospatial attention indicates that a peripheral abrupt-onset cue at target position (valid condition) facilitates processing of the target, whereas a cue at another position interferes. This validity effect seems to be contingent on a similarity of the cue's color to the set of target colors (cf. J. Exp. Psychol.: Human Percep. Perform. 18 (1992) 1030). In Experiments 1-3, we confirm this contingency with cues that have the potential to activate responses. Thus, attentional capture and response capture are apparently governed by the same principle. In Experiment 2, it is demonstrated that color priming is not responsible for the contingency. In Experiment 3, it is shown that a more efficient reallocation of attention after color-dissimilar cues than after color-similar cues might contribute to the contingency.     

Multiple attentional control settings at distinct locations without the confounding of repetition priming

An attentional control setting (ACS), which is based on the task goal, induces involuntary attentional capture by a stimulus possessing a target-defining feature. It is unclear whether ACSs are maintained for multiple targets defined as conjunctions of a color and location. In the present study we examined the possibility of local ACSs for dual targets defined as combinations of color and location, using different paradigms: visual search in Experiment 1, and spatial cueing in Experiment 2. In Experiment 1, a distractor captured attention only when its features matched the ACSs. Likewise, in Experiment 2, a significant attentional capture effect was found only with a matching cue, whose color and location were in line with the conjunction of the target definition. Importantly, the identical pattern of attentional capture was also obtained for a neutral-color target, which was unlikely to be primed by any color of the cue. Thus, these findings imply that the attentional bias depending on the match between the cue and target did not result from cue–target repetition priming. The present study highlights that top-down attentional control can be set flexibly to accomplish a complex task goal efficiently.     

Facilitation versus inhibition in non-spatial attribute discrimination tasks

Inhibition of Return is a delay in initiating attentional shifts to previously inspected locations. It has been explained as a mechanism to facilitate visual search of a scene by inhibiting the allocation of attention to locations that have already been examined. We (Hu, Samuel, &; Chan, Journal of Experimental Psychology: General, 2010) recently demonstrated that similar processing costs can appear when a non-spatial attribute (color or shape) repeats—detection of a target stimulus was slower if the target shared color or shape with a recently presented cue. In the current study, we test whether such inhibitory effects occur for non-spatial attribute repetition when observers must make a discrimination judgment about targets. We found two independent effects: First, there was a standard location-based IOR effect—target discrimination was slower when the target appeared in the same location as a preceding cue. Second, reaction times were faster if the target's color or shape matched the cue's color or shape; this facilitation effect contrasts with both the location-based inhibition that was present in the current experiments, and with the inhibitory effect of feature repetition in our previous detection task study. The data are best accounted for by a three-factor model recently suggested by Lupiáñez (Attention and time, 2010).     

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。     

Determining whether attentional control settings are inclusive or exclusive

The aim of the present study was to determine whether attentional control settings operate with an inclusive rule (orient attention to stimuli that share a task-relevant feature with the target) or an exclusive rule (do not orient attention to stimuli that do not share a task-relevant feature with the target). All three experiments used a variation of the Folk and Remington (e.g., Folk, Remington, & Johnston, 1992) paradigm. In Experiment 1, cuing effects were found for combination cues (cues containing an onset feature and a color feature) with both onset and color targets. Experiment 2, using a delay between cue and target, revealed inhibition of return (IOR) for combination cues with onset and color targets. Unexpectedly, IOR was also found for onset cues with color targets, and this finding was confirmed in Experiment 3. These findings indicate that attentional control settings use an inclusive rule. Moreover, the presence of IOR with onset cues and color targets suggests that onset cues may automatically capture attention, but attention control settings allow for rapid disengagement when the onset cue does not contain a task-relevant feature.