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Memory-based attentional capture by colour and shape contents in visual working memory
Abstract
Current theories assume that there is substantial overlap between visual working memory (VWM) and visual attention functioning, such that active representations in VWM automatically act as an attentional set, resulting in attentional biases towards objects that match the mnemonic content. Most evidence for this comes from visual search tasks in which a distractor similar to the memory interferes with the detection of a simultaneous target. Here we provide additional evidence using one of the most popular paradigms in the literature for demonstrating an active attentional set: The contingent spatial orienting paradigm of Folk and colleagues. This paradigm allows memory-based attentional biases to be more directly attributed to spatial orienting. Experiment 1 demonstrated a memory-contingent spatial attention effect for colour but not for shape contents of VWM. Experiment 2 tested the hypothesis that the placeholders used for spatial cueing interfered with the shape processing, and showed that memory-based attentional capture for shape returned when placeholders were removed. The results of the present study are consistent with earlier findings from distractor interference paradigms, and provide additional evidence that biases in spatial orienting contribute to memory-based influences on attention.
... Some studies reported memory-based interference (e.g., Olivers, Meijer, & Theeuwes, 2006) while others did not (e.g., Woodman & Luck, 2007). Studies using shape instead of color distractors were equally inconclusive, with some (e.g., Kim & Cho, 2016;Soto, Heinke, Humphreys, & Blanco, 2005), but not all (Downing & Dodds, 2004;Houtkamp & Roelfsema, 2006) reporting memory-based interference. A possible explanation for the discrepancy was offered by Olivers (2009), who observed that most studies reporting memory-based interference used fixed targets for the search task, while the others used search targets that changed from trial to trial. ...
... A solution to the conundrum is made difficult by the methodological differences between the two lines of research. Some research on memory-based interference avoided dimensional overlap between the memorized stimulus and the target stimulus (Kim & Cho, 2016;Olivers et al., 2006;Soto et al., 2005;Woodman & Luck, 2007) to prevent voluntary shifts of attention to the memorized stimulus. Notably, participants may attend to the memorized stimulus when it appears as a distractor in the search display to refresh VWM (Woodman & Luck, 2007). ...
In a visual search task, sensory input is matched to a representation of the search target in visual working memory (VWM). This representation is referred to as attentional template. We investigated the conditions that allow for more than a single attentional template. The attentional template of color targets was measured by means of the contingent attentional capture paradigm. We found that attentional templates did not differ between search with 1 and 2 memorized target colors, suggesting that dual target search allowed for multiple attentional templates. In the same paradigm, we asked participants to memorize target and distractor color with equal precision. Both were presented before the search task. An attentional template was set up for the target, but not for the distractor color, suggesting that keeping a color in VWM does not automatically result in the creation of multiple attentional templates. Importantly, the precision of recall of the distractor color was worse than the precision of recall of the target color, regardless of instructions, suggesting that participants always allocated fewer VWM resources to the distractor color. Thus, 2 attentional templates may be set up, but only when the 2 colors receive an equal amount of resources in VWM (i.e., in dual target search). In contrast, when 1 item is deprioritized because of task demands, it receives fewer resources in VWM and multiple attentional templates cannot be established. Thus, unequal roles in the search task prevented the simultaneous operation of multiple attentional templates in VWM. (PsycINFO Database Record (c) 2019 APA, all rights reserved).
... Furthermore, the selection processes interact functionally. Attending to an item leads to an increase in the likelihood of choosing the item (Krajbich, Armel, & Rangel, 2010;Stewart, Hermens, & Matthews, 2016), and the decision to search for an item facilitates attention toward the item (Desimone & Duncan, 1995;Kim & Beck, 2020a;Kim & Cho, 2016;Wolfe, 1994). In addition to the conceptual similarity and functional link, decision-making and selective attention share a critical factor affecting selection, value. ...
Kim and Beck (2020b) demonstrated that value-driven attention is based on relative value rather than absolute value, suggesting that prospect theory is relevant to our understanding of value-driven attention. To further this understanding, the present study investigated the impacts of diminishing sensitivity on value-driven attention. According to diminishing sensitivity, changes in outcomes have greater impacts nearer the reference point of 0 than farther from the point. Thus, the difference between 100 looms larger than that between 1000, due to their different ratios (100/1 > 1000/901). However, according to the absolute difference hypothesis, the differences should have similar impacts due to the absolute differences being the same (100 - 1 = 1000 - 901). Experiment 1 investigated whether diminishing sensitivity operates in the modified value-driven attention paradigm while controlling the impact of absolute differences. In the training phase, 100-point and 1000-point color targets had references of 1-point and 901-point color targets, respectively. In the test phase, 100-point color distractors attracted attention more than 1000-point color distractors, supporting the diminishing sensitivity hypothesis. Experiment 2 examined the absolute difference hypothesis while controlling the impact of diminishing sensitivity. Contrary to the absolute difference hypothesis, the test phase showed that 1000-point color distractors (compared with 10-point colors for a 990 absolute difference in the training phase) failed to attract attention more than 100-point color distractors (compared with 1-point colors, for a 99 absolute difference). These results suggest that diminishing sensitivity rather than absolute difference influences value-driven attention, further supporting the relevance of prospect theory to value-driven attention.
... Critically, visual search is disrupted more strongly on trials where the color of the salient non-target matches the "accessory" representation (e.g., a red circle). This memory-based interference was observed when search targets remained fixed through blocks of trials (Gunseli et al., 2016;Kim & Cho, 2016;Kumar et al., 2009;Olivers et al., 2006;Soto et al., 2005;Soto et al., 2008;van Moorselaar et al., 2014). In this situation, the corresponding attentional template may be transferred to LTM Gunseli et al., 2014;Reinhart et al., 2016;Woodman et al., 2013;, allowing the "accessory" representation to become "active" in WM and to interfere with the ongoing search task. ...
Recently, working memory (WM) has been conceptualized as a limited resource, distributed flexibly and strategically between an unlimited number of representations. In addition to improving the precision of representations in WM, the allocation of resources may also shape how these representations act as attentional templates to guide visual search. Here, we reviewed recent evidence in favor of this assumption and proposed three main principles that govern the relationship between WM resources and template-guided visual search. First, the allocation of resources to an attentional template has an effect on visual search, as it may improve the guidance of visual attention, facilitate target recognition, and/or protect the attentional template against interference. Second, the allocation of the largest amount of resources to a representation in WM is not sufficient to give this representation the status of attentional template and thus, the ability to guide visual search. Third, the representation obtaining the status of attentional template, whether at encoding or during maintenance, receives an amount of WM resources proportional to its relevance for visual search. Thus defined, the resource hypothesis of visual search constitutes a parsimonious and powerful framework, which provides new perspectives on previous debates and complements existing models of template-guided visual search.
... Therefore, memory-matching colour rather than shape actively guides attention when features are held in VWM. Previous studies have also reported that colour features are more effective in guiding attention than other features, such as shape (Kim & Cho, 2016;Soto et al., 2005;Williams, 1966). However, in these studies, researchers only asked participants to hold one object in VWM, with colour and other features. ...
completing a visual search task. Guidance effects were found when either color or both color and shape in VWM matched one of the search distractors but not when shape matched. This demonstrated that the more salient feature in VWM can actively guide attention, while the less salient feature cannot. However, when shape in VWM was cued to be more relevant (prioritized) in Experiment 2, we found guidance effects in both color-match and shape-match conditions. That is, both more salient but non-cued color and less salient but cued shape could be active in VWM such that attentional selection was affected by the matching color or shape in the visual search task. This suggests that bottom-up perceptual saliency and top-down retro-cues can jointly determine active state in VWM.
... When participants kept a color in VWM during the search task, capture increased when the distractor color matched the color stored in VWM (Olivers, Meijer, & Theeuwes, 2006), suggesting that attention was automatically guided by the contents of working memory. Memory-based capture has been replicated in many studies (e.g., Bahle, Beck, & Hollingworth, 2018;Hollingworth & Beck, 2016;Jung, Han, & Min, 2019;Kerzel & Witzel, 2019;Kim & Cho, 2016; van Moorselaar, Theeuwes, & Olivers, 2014;Whitehead, Ooi, Egner, & Woldorff, 2019) (reviewed in Olivers et al., 2011;Soto, Hodsoll, Rotshtein, & Humphreys, 2008). Most of the studies on memory-based attentional capture focused on capture by individual features stored in VWM and there is some controversy as to whether all features of an object encoded in VWM guide attention. ...
... However, a prolongation by VWM-matching distractors was not always observed [14][15][16][17]. It has been argued that attentional capture by VWM-matching objects is only elicited, when the VWM representation is currently in an active rather than an accessory state in VWM [2,[17][18][19][20]. Whether the VWM representation will be active or accessory is determined by several task constraints [1,2,15], such as whether participants relate the two tasks and try, for instance, to find the memory-matching item, or use it to refresh their memory for the later recognition task. ...
Selecting a target based on a representation in visual working memory (VWM) affords biasing covert attention towards objects with memory-matching features. Recently, we showed that even task-irrelevant features of a VWM template bias attention. Specifically, when participants had to saccade to a cued shape, distractors sharing the cue’s search-irrelevant color captured the eyes. While a saccade always aims at one target location, multiple locations can be attended covertly. Here, we investigated whether covert attention is captured similarly as the eyes. In our partial report task, each trial started with a shape-defined search cue, followed by a fixation cross. Next, two colored shapes, each including a letter, appeared left and right from fixation, followed by masks. The letter inside that shape matching the preceding cue had to be reported. In Experiment 1, either target, distractor, both, or no object matched the cue’s irrelevant color. Target-letter reports were most frequent in target-match trials and least frequent in distractor-match trials. Irrelevant cue and target color never matched in Experiment 2. Still, participants reported the distractor more often to the target’s disadvantage, when cue and distractor color matched. Thus, irrelevant features of a VWM template can influence covert attention in an involuntarily object-based manner when searching for trial-wise varying targets.
... The attentional template is thought to be stored in visual working memory (Bundesen, Habekost, & Kyllingsbaek, 2005;Chelazzi, Miller, Duncan, & Desimone, 1993), but it may be offloaded into long-term memory when the target does not change over successive trials (see Carlisle, Arita, Pardo, & Woodman, 2011). The previous literature has been concerned with the question whether the content of visual working memory automatically guides attentional selection (e.g., Downing & Dodds, 2004;Foerster & Schneider, 2018;Hollingworth & Beck, 2016;Houtkamp & Roelfsema, 2006;Kim & Cho, 2016;Olivers, Meijer, & Theeuwes, 2006;Soto, Heinke, Humphreys, & Blanco, 2005;Woodman & Luck, 2007) or with the question how simultaneous control of attention is achieved when there are multiple attentional templates (Hollingworth, Matsukura, & Luck, 2013;Ort, Fahrenfort, & Olivers, 2017). ...
Voluntary attentional selection requires the match of sensory input to a stored representation of the target features. We compared the precision of attentional selection to the precision of the underlying memory representation of the target. To measure the precision of attentional selection, we used a cue-target paradigm where participants searched for a colored target. Typically, RTs are shorter at the cued compared to uncued locations when the cue has the same color as the target. In contrast, cueing effects are absent or even inverted when cue and target colors are dissimilar. By systematically varying the difference between cue and target color, we calculated a function relating cue color to cueing effects. The width of this function reflects the precision of attentional selection and was compared to the precision of judgments of the target color on a color wheel. The precision of the memory representation was far better than the precision of attentional selection. When the task was made more difficult by increasing the similarity between the target and the nontarget stimuli in the target display, the precision of attentional selection increased, but was still worse than the precision of memory. When the search task was made more difficult, we also observed that for dissimilar cue colors, RTs were slower at cued than at uncued locations (i.e., same location costs), suggesting that improvements in attentional selectivity were achieved by suppressing non-target colors.
... The behavioral results suggest that the memorized color may bias the recruitment of visual attention toward the target location, regardless of stimulation site, as indicated by greater search accuracies and faster search RTs during the valid condition relative to the neutral and invalid conditions. This is consistent with several findings in the literature regarding memory-based attentional capture (Soto et al., 2006b;Kim and Cho, 2016). In the current study, the activation of the search target template and the memorized template accumulated during the visual search and together contributed to the subjects' response. ...
The contents of working memory (WM) can affect the subsequent visual search performance, resulting in either beneficial or cost effects, when the visual search target is included in or spatially dissociated from the memorized contents, respectively. The right dorsolateral prefrontal cortex (rDLPFC) and the right posterior parietal cortex (rPPC) have been suggested to be associated with the congruence/incongruence effects of the WM content and the visual search target. Thus, in the present study, we investigated the role of the dorsolateral prefrontal cortex and the PPC in controlling the interaction between WM and attention during a visual search, using repetitive transcranial magnetic stimulation (rTMS). Subjects maintained a color in WM while performing a search task. The color cue contained the target (valid), the distractor (invalid) or did not reappear in the search display (neutral). Concurrent stimulation with the search onset showed that relative to rTMS over the vertex, rTMS over rPPC and rDLPFC further decreased the search reaction time, when the memory cue contained the search target. The results suggest that the rDLPFC and the rPPC are critical for controlling WM biases in human visual attention.
To investigate whether attentional suppression is merely a byproduct of target facilitation or a result of independent mechanisms for distractor suppression, the present study examined whether attentional suppression takes place when target facilitation hardly occurs using a spatial cueing paradigm. Participants searched for target letters that were not red, i.e., a negative color. On each trial, a target color was randomly chosen among 12 colors to prevent establishing attentional control for target colors and to reduce intertrial priming for target colors. Immediately before a target display, a noninformative spatial cue was presented at one of the possible target locations. The cue was rendered in a negative color, which was to be ignored, to detect targets or the reference color, which was never presented for target and non-target letters. Experiment 1 showed that negative color cues captured attention less than reference color cues, suggesting feature-based attentional suppression. The suppression effect was replicated when the temporal interval between the onsets of the cue and target displays was reduced in Experiments 2 and 3, suggesting proactive suppression. Experiment 3 directly confirmed no attentional control settings for target colors and intertrial priming. These findings suggest that distractor features can guide attention at the pre-attentive stage when target features are not used to attend to targets.
The contents of working memory (WM) guide visual attention, but the neural mechanisms underlying WM biases remains unclear. Here, we used simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) approaches to characterize the timing and location of the neural response underlying WM guidance during a visual search task. Behaviorally, we observed faster search performance when the WM contents matching targets (valid) compared to when WM contents did not reappear (neutral). The EEG data showed similar benefit effects of posterior N1 component, in which targets induced larger N1 amplitudes in the valid condition than in the neutral condition. Interestingly, the fMRI activation in left supramarginal gyrus (SMG)/inferior parietal lobule (IPL) and bilateral occipital cortex was lower in the valid compared to neutral conditions. Importantly, the magnitude of the increased N1 activity and the decreased fMRI activity in the left SMG/IPL predicted the extent of search improvement at an individual subject level. These results suggest that information held in WM enhances early object discrimination during attentional selection, and the left SMG/IPL may be a critical region in mediating goal-directed processing under WM biases in human visual attention.
Observers adopt attentional control setting (ACS) based on their goals; stimuli that match the current goal will capture attention, whereas stimuli that do not match the current goal will not. In the present study, we revisited the role of VWM in maintaining ACSs capable of guiding attentional capture. Participants completed a Posner cueing task while either remembering a colour (Experiments 1a/1b) or searching for a colour (Experiments 2/3). To encourage the use of VWM, the colour changed on each trial. Results indicate that merely remembering a colour using VWM did not prevent memory non-matching colours from capturing attention (Experiments 1a/1b). Conversely, when participants searched for one colour, VWM supported an ACS that eliminated capture by non-matching colours (Experiments 2/3), though not if participants searched for two colours (Experiment 3). We conclude that VWM can maintain an ACS of one searched-for item that is capable of guiding attentional capture.
Along with the improvement of eye-tracking technology, more and more distinct field of researches have introduced movements of the eye in relation to the head to understand user behavior. Most of current researches focus on the perception process of single 2-dimensional images by fixed eye-tracking devices or the head-mount devices. A method of applying eye-tracking on the analysis of the interaction between users and objects in 3D navigational space is proposed in this article. It aims to understand the visual stimulation of 3D objects and the user’s spatial navigational reactions while receiving the stimulation, and proposes the concept of 3D object attention heat map. It also proposes to construct a computational visual attention model for different geometric featured 3D objects by applying the method of feature curves. The VR results of this study also provide future assistance in the incoming immersive world. This study sets to promote eye-tracking from the mainstream of 2D field to 3D spaces and points to a deeper understanding between human and artificial product or natural objects. It would also serve an important role in the field of human-computer interaction, product usability, aids devices for cognition degenerative individuals, and even the field of visual recognition of daily human behavior.
Various theoretical proposals have been put forward to explain how memory representations control attention during visual search. In this study, we use the first saccade on each trial as a way to quantify the attentional impact of multiple types of representations held in working memory. Across two experiments, we found that a search target maintained in working memory was attended over 20 times more frequently than a non-memory-matching distractor. In addition, an item matching an additional object represented in working memory was attended 2 times more frequently than a non-memory matching distractor. These findings show that there is a measurable attentional impact of items maintained in working memory for a future task, however, such representations have a much weaker attentional impact than working memory representations of search targets.
Five spatial cuing experiments tested 2 hypotheses regarding attentional capture: (a) Attentional capture is contingent on endogenous attentional control settings, and (b) attentional control settings are limited to the distinction between dynamic and static discontinuities (C. L. Folk, R. W. Remington, & J. C. Johnston, 1992). In Experiments 1 and 2, apparent-motion precues produced significant costs in performance for targets signaled by motion but not for targets signaled by color or abrupt onset. Experiment 3 established that this pattern is not due to differences in the difficulty of target discrimination. Experiments 4 and 5 revealed asymmetric capture effects between abrupt onset and apparent motion related to stimulus salience. The results support the hypotheses of Folk et al. (1992) and suggest that stimulus salience may also play a role in attentional capture.
In three experiments, we examined the influence of visual working memory (VWM) on the metrics of saccade landing position in a global effect paradigm. Participants executed a saccade to the more eccentric object in an object pair appearing on the horizontal midline, to the left or right of central fixation. While completing the saccade task, participants maintained a color in VWM for an unrelated memory task. Either the color of the saccade target matched the memory color (target match), the color of the distractor matched the memory color (distractor match), or the colors of neither object matched the memory color (no match). In the no-match condition, saccades tended to land at the midpoint between the two objects: the global, or averaging, effect. However, when one of the two objects matched VWM, the distribution of landing position shifted toward the matching object, both for target match and for distractor match. VWM modulation of landing position was observed even for the fastest quartile of saccades, with a mean latency as low as 112 ms. Effects of VWM on such rapidly generated saccades, with latencies in the express-saccade range, indicate that VWM interacts with the initial sweep of visual sensory processing, modulating perceptual input to oculomotor systems and thereby biasing oculomotor selection. As a result, differences in memory match produce effects on landing position similar to the effects generated by differences in physical salience.
Investigating eye movements has been a promising approach to uncover the role of visual working memory in early attentional processes. Prior research has already demonstrated that eye movements in search tasks are more easily drawn toward stimuli that show similarities to working memory content, as compared with neutral stimuli. Previous saccade tasks, however, have always required a selection process, thereby automatically recruiting working memory. The present study was an attempt to confirm the role of working memory in oculomotor selection in an unbiased saccade task that rendered memory mechanisms irrelevant. Participants executed a saccade in a display with two elements, without any instruction to aim for one particular element. The results show that when two objects appear simultaneously, a working memory match attracts the first saccade more profoundly than do mismatch objects, an effect that was present throughout the saccade latency distribution. These findings demonstrate that memory plays a fundamental biasing role in the earliest competitive processes in the selection of visual objects, even when working memory is not recruited during selection.
Recent perspectives on selective attention posit a central role for visual working memory (VWM) in the top‐down control of attention. According to the biased‐competition model (Desimone & Duncan, 1995), active maintenance of an object in VWM gives matching (Downing, 2000) or related (Moores, Laiti, & Chelazzi, 2003) objects in the environment a competitive advantage over other objects in gaining access to limited processing resources. Participants in this study performed a visual search task while simultaneously maintaining a second item in VWM. On half of the trials, this item appeared as a distractor item in the search array. We found no evidence that this item interferes with successful selection of the search target, as measured with response time in a target detection task and accuracy in a target discrimination task. These results are consistent with two general models: One in which a representation of the current task biases the competition between items in a unitary VWM, or one in which VWM is fractionated to allow for maintenance of critical items that are not immediately relevant to the task.
Representations in visual working memory (VWM) influence attention and gaze control in complex tasks, such as visual search, that require top-down selection to resolve stimulus competition. VWM and visual attention clearly interact, but the mechanism of that interaction is not well understood. In the research reported here, we demonstrated that in the absence of stimulus competition or goal-level biases, VWM representations of object features influence the spatiotemporal dynamics of extremely simple eye movements. The influence of VWM therefore extends into the most basic operations of the oculomotor system.
Working memory (WM) and attention have been studied as separate cognitive constructs, although it has long been acknowledged that attention plays an important role in controlling the activation, maintenance, and manipulation of representations in WM. WM has, conversely, been thought of as a means of maintaining representations to voluntarily guide perceptual selective attention. It has more recently been observed, however, that the contents of WM can capture visual attention, even when such internally maintained representations are irrelevant, and often disruptive, to the immediate external task. Thus, the precise relationship between WM and attention remains unclear, but it appears that they may bidirectionally impact one another, whether or not internal representations are consistent with the external perceptual goals. This reciprocal relationship seems, further, to be constrained by limited cognitive resources to handle demands in either maintenance or selection. We propose here that the close relationship between WM and attention may be best described as a give-and-take interdependence between attention directed toward either actively maintained internal representations (traditionally considered WM) or external perceptual stimuli (traditionally considered selective attention), underpinned by their shared reliance on a common cognitive resource. Put simply, we argue that WM and attention should no longer be considered as separate systems or concepts, but as competing and influencing one another because they rely on the same limited resource. This framework can offer an explanation for the capture of visual attention by irrelevant WM contents, as well as a straightforward account of the underspecified relationship between WM and attention.
Attentional capture is an unintentional shift of visuospatial attention to the location of a distractor that is either highly salient, or relevant to the current task set. The latter situation is referred to as contingent capture, in that the effect is contingent on a match between characteristics of the stimuli and the task-defined attentional-control settings of the viewer. Contingent capture has been demonstrated for low-level features, such as color, motion, and orientation. In the present paper we show that contingent capture can also occur for conceptual information at the superordinate level (e.g., sports equipment, marine animal, dessert food). This effect occurs rapidly (i.e., within 200 ms), is a spatial form of attention, and is contingent on attentional-control settings that change on each trial, suggesting that natural images can be decoded into their conceptual meaning to drive shifts of attention within the time course of a single fixation. (PsycINFO Database Record (c) 2012 APA, all rights reserved).
Three experiments examined contingent attentional capture, which is the finding that cuing effects are larger when cues are perceptually similar to a target than when they are dissimilar to the target. This study also analyzed response times (RTs) in terms of the underlying distributions for valid cues and invalid cues. Specifically, an ex-Gaussian analysis and a vincentile analysis examined the influence of top-down attentional control settings on the shift and skew of RT distributions and how the shift and the skew contributed to the cuing effects in the mean RTs. The results showed that cue/target similarity influenced the size of cuing effects. The RT distribution analyses showed that the cuing effects reflected only a shifting effect, not a skewing effect, in the RT distribution between valid cues and invalid cues. That is, top-down attentional control moderated the cuing effects in the mean RTs through distribution shifting, not distribution skewing. The results support the contingent orienting hypothesis (Folk, Remington, & Johnston, Journal of Experimental Psychology: Human Perception and Performance, 18, 1030-1044, 1992) over the attentional disengagement account (Theeuwes, Atchley, & Kramer, 2000) as an explanation for when top-down attentional settings influence the selection of salient stimuli.
Event-related potentials (ERPs) were recorded from 24 subjects in a visual selective-attention task in which two words were each presented both in a prime display and in a probe display with the target word defined by color. Subjects' task for the prime display was a physical one (target word presented in upper or lower case letters), while the probe display task was a lexical decision. In addition to a neutral condition, four conditions were realized by varying the target probe: The target probe word was (1) a repetition of the target prime (attended repetition), (2) a semantically associated word to the target prime (attended semantic), (3) a repetition of the distractor prime (unattended repetition), or (4) a word semantically associated to the distractor prime (unattended semantic). An attended semantic and an attended repetition priming effect was observed by means of both RT and N400. The N400 differentiated between these two attended priming conditions while RT did not. No unattended priming effects were found with behavioral data. The N400 amplitude modulation, however, was also present for unattended priming but was attenuated compared to the attended condition. The data suggest (1) that automatic processes are sufficient to evoke an N400 effect, and (2) that the N400 effect is a more sensitive indicator for priming effects than response times.
Models of attentional deployment in visual search commonly specify that the short-term, or working memory, system plays a central role in biasing attention mechanisms to select task relevant information. In contrast, the role of long-term memory in guiding search is rarely articulated. Our review of recent studies calls for the need to revisit how existing models explain the role of working memory and long-term memory in search. First, the role of working memory in guiding attentional selection and search is much more complex than many current theories propose. Second, both explicit and implicit long-term memory representations have such clear influences on visual search performance that they deserve more prominent treatment in theoretical models. These new findings in the literature should stir the conception of new models of visual search. Visual search tasks have long been used by cognitive scientists to study the deployment of attention to targets within complex arrays of distractor stimuli (Green & Anderson, 1956; Green, McGill, & Jenkins, 1953; Neisser, 1964). An attractive feature of the visual search task is that it taxes perceptual processing while presumably placing minimal demands on memory in contrast to other paradigms popularized during the same period (e.g., Sternberg, 1966). Technically speaking, a subject only needs to remember what to search for and how to respond to its presence or absence. Such considerations may have helped make visual search such a popular tool for Please address all correspondence to for valuable discussions regarding the issues addressed in this paper. GFW is supported by an individual NRSA from the National Institute of Health (F32 EY015043) and MMC is supported by a grant from the National Eye Institute (R01 EY014193).
The study of attentional capture has provided a rich context for assessing the relative influence of top-down and bottom-up factors in visual perception. Some have argued that attentional capture by a salient, irrelevant stimulus is contingent on top-down attentional set (e.g., Folk, Remington, & Johnston, Journal of Experimental Psychology: Human Perception and Performance 18:1030-1044, 1992). Others, however, have argued that capture is driven entirely by bottom-up salience and that top-down factors influence the postallocation speed of disengagement from the irrelevant stimulus (e.g., Theeuwes, Acta Psychologica 135:77-99, 2010a). In support of this speed-of-disengagement hypothesis, recent findings from the modified spatial-cuing paradigm show that cues carrying a no-go target property produce reverse, or negative, cuing effects, consistent with inhibition of the cue location from which attention has been very quickly disengaged (Belopolsky, Schreij, & Theeuwes, Perception, & Psychophysics, 72, 326-341, 2010). Across six experiments, we show that this inhibitory process can be dissociated from shifts of spatial attention and is, thus, not a reliable marker of capture. We conclude that the data are inconsistent with the predictions of the disengagement hypothesis.
Across many studies, researchers have found that representations in working memory (WM) can guide visual attention toward items that match the features of the WM contents. While some researchers have contended that this occurs involuntarily, others have suggested that the impact of WM contents on attention can be strategically controlled. Here, we varied the probability that WM items would coincide with either targets or distractors in a visual search task to examine (1) whether participants could intentionally enhance or inhibit the influence of WM items on attention and (2) whether cognitive control over WM biases would also affect access to the memory contents in a surprise recognition test. We found visual search to be faster when the WM item coincided with the search target, and this effect was enhanced when the memory item reliably predicted the location of the target. Conversely, visual search was slowed when the memory item coincided with a search distractor, and this effect was diminished, but not abolished, when the memory item was reliably associated with distractors. This strategic dampening of the influence of WM items on attention came at a price to memory, however, as participants were slowest to perform WM recognition tests on blocks in which the WM contents were consistently invalid. These results document that attentional capture by WM contents is partly, but not fully, malleable by top-down control, which appears to adjust the state of the WM contents to optimize search behavior. These data illustrate the role of cognitive control in modulating the strength of WM biases of selection, and they support a tight coupling between WM and attention.
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.
The biased competition theory proposes that items matching the contents of visual working memory will automatically have an advantage in the competition for attention. However, evidence for an automatic effect has been mixed, perhaps because the memory-driven attentional bias can be overcome by top-down suppression. To test this hypothesis, the Pd component of the event-related potential waveform was used as a marker of attentional suppression. While observers maintained a color in working memory, task-irrelevant probe arrays were presented that contained an item matching the color being held in memory. We found that the memory-matching probe elicited a Pd component, indicating that it was being actively suppressed. This result suggests that sensory inputs matching the information being held in visual working memory are automatically detected and generate an "attend-to-me" signal, but this signal can be overridden by an active suppression mechanism to prevent the actual capture of attention.
Recent studies have revealed a strong relationship between visual working memory and selective attention, such that attention is biased by what is currently on our mind. However, other data show that not all memorized items influence the deployment of attention, thus calling for a distinction within working memory: whereas active memory items function as an attentional template and directly affect perception, other, accessory items do not. We review recent evidence that items compete for the status of 'attentional template' that contains only one object at a time. Neurophysiological results provide insight into these different memory states by revealing a more intricate organization of working memory than was previously thought.
To assess whether working memory contents can effectively bias visual selection even when they do not represent the current target in the attention task, we recorded the ERP activity from participants performing both a memory task and, in the retention period, a visual search task. In this task, a distracter matching the memory content could be presented on the same side (congruent trials) or on the opposite side (incongruent trials) relative to the target location (Experiment 1 and Experiment 2). On some trials, only the matching distracter (but no target) was presented (catch trials, Experiment 2). Results showed that the N2pc component was modulated by the presence and location of a matching distracter. We interpret these results as evidence that the involuntary control exerted by the irrelevant memory contents coexists with the strategic mechanism related to the search target, influencing attention selection with roughly equal power. In Experiment 3, we found that the modulation of the N2pc is not strictly related to the active maintenance of the memory-target features but can also be elicited by repetition priming. Overall, these findings suggest that, together with the physical properties of the stimuli presented in the visual field, irrelevant memory contents represent a powerful class of factors that lead to involuntary attentional control.
Biased competition theory proposes that representations in working memory drive visual attention to select similar inputs. However, behavioral tests of this hypothesis have led to mixed results. These inconsistent findings could be due to the inability of behavioral measures to reliably detect the early, automatic effects on attentional deployment that the memory representations exert. Alternatively, executive mechanisms may govern how working memory representations influence attention based on higher-level goals. In the present study, we tested these hypotheses using the N2pc component of participants' event-related potentials to directly measure the early deployments of covert attention. Participants searched for a target in an array that sometimes contained a memory-matching distractor. In Experiments 1 to 3, we manipulated the difficulty of the target discrimination and the proximity of distractors, but consistently observed that covert attention was deployed to the search targets and not the memory-matching distractors. In Experiment 4, we showed that when participants' goal involved attending to memory-matching items, these items elicited a large and early N2pc. Our findings demonstrate that working memory representations alone are not sufficient to guide early deployments of visual attention to matching inputs and that goal-dependent executive control mediates the interactions between working memory representations and visual attention.
On the contingent capture account, top-down attentional control settings restrict involuntary attentional capture to items that match the features of the search target. Attention capture is involuntary, but contingent on goals and intentions. The observation that only target-similar items can capture attention has usually been taken to show that the content of the attentional control settings consists of specific feature values. In contrast, the present study demonstrates that the top-down target template can include information about the relationship between the target and nontarget features (e.g., redder, darker, larger). Several spatial cuing experiments show that a singleton cue that is less similar to the target but that shares the same relational property that distinguishes targets from nontargets can capture attention to the same extent as cues that are similar to the target. Moreover, less similar cues can even capture attention more than cues that are identical to the target when they are relationally better than identical cues. The implications for current theories of attentional capture and attentional guidance are discussed.
A recent study has proposed that attentional window determines when the color singletons capture visual attention (Belopolsky, Zwaan, Theeuwes, & Kramer, 2007). The present study used the additional singleton paradigm of Theeuwes (1992) and showed that capture was abolished when the size of the attentional window was reduced by focusing on RSVP stream in the center of the screen. Narrowing of attentional window also resulted in increase in search slope even in such a simple task as the pop-out detection. These findings suggest that attentional window plays a crucial role in visual selection and in the occurrence of attentional capture.
Theories of visual attention suggest that working memory representations automatically guide attention toward memory-matching objects. Some empirical tests of this prediction have produced results consistent with working memory automatically guiding attention. However, others have shown that individuals can strategically control whether working memory representations guide visual attention. Previous studies have not independently measured automatic and strategic contributions to the interactions between working memory and attention. In this study, we used a classic manipulation of the probability of valid, neutral, and invalid cues to tease apart the nature of such interactions. This framework utilizes measures of reaction time (RT) to quantify the costs and benefits of attending to memory-matching items and infer the relative magnitudes of automatic and strategic effects. We found both costs and benefits even when the memory-matching item was no more likely to be the target than other items, indicating an automatic component of attentional guidance. However, the costs and benefits essentially doubled as the probability of a trial with a valid cue increased from 20% to 80%, demonstrating a potent strategic effect. We also show that the instructions given to participants led to a significant change in guidance distinct from the actual probability of events during the experiment. Together, these findings demonstrate that the influence of working memory representations on attention is driven by both automatic and strategic interactions.
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.
In the present study, we explored the mechanisms involved in the contingent capture phenomenon, using a variant of the classic precuing paradigm of Folk, Remington, and Johnston (1992). Rather than keeping the target fixed over a whole block of trials (as has traditionally been done with contingent capture experiments), we encouraged participants to adopt a top-down set before each trial. If top-down attentional set determines which property captures attention, as is claimed by the contingent capture hypothesis, one would expect that only properties that match the top-down set would capture attention. We showed that even though participants knew what the target would be on the upcoming trial, both relevant and irrelevant properties captured attention (Experiment 1). An intertrial analysis (Experiments 1 and 2) showed that previous contingent capture findings may, to a large extent, be explained by intertrial priming. In addition, when participants were further forced into adopting the required top-down set (Experiments 3 and 4), irrelevant cues were suppressed, suggesting that top-down control might operate through disengagement of attention from the location of a property that does not match top-down goals. The present findings suggest that top-down control and intertrial priming make their own distinct contributions to the contingent capture phenomenon.
The classic theory of spatial attention hypothesized 2 modes, voluntary and involuntary. Folk, Remington, and Johnston (1992) reported that even involuntary attention capture by stimuli requires a match between stimulus properties and what the observer is looking for. This surprising conclusion has been confirmed by many subsequent studies. In these studies, however, the observer typically looks for the same property throughout an entire session. Real-world behavior, in contrast, often requires frequent shifts in attentional set. The present study examined whether such shifts weaken attentional settings, allowing task-irrelevant objects to capture attention. Surprisingly, fluctuating control settings did not increase vulnerability to capture by salient stimuli (color singletons and abrupt onsets). We conclude that the attention control system is remarkably flexible, able to rapidly and fully adopt new settings and abandon old settings.
An important question is whether visual attention (the ability to select relevant visual information) and visual working memory (the ability to retain relevant visual information) share the same content representations. Some past research has indicated that they do: Singleton distractors interfered more strongly with a visual search task when they were identical or related to the object held in memory. However, other research has failed to find such effects despite using very similar procedures. The present study, using the same combined working memory and attentional capture paradigm, demonstrates which factors do (varied mapping, low stimulus energy) and which factors do not (exact type of visual memory method used, difficult nature of search, heterogeneity of displays, and instruction) contribute to this discrepancy.
The deployment of visual attention can be strongly modulated by stimuli matching the contents of working memory (WM), even when WM contents are detrimental to performance and salient bottom-up cues define the critical target [D. Soto et al. (2006)Vision Research, 46, 1010-1018]. Here we investigated the electrophysiological correlates of this early guidance of attention by WM in humans. Observers were presented with a prime to either identify or hold in memory. Subsequently, they had to search for a target line amongst different distractor lines. Each line was embedded within one of four objects and one of the distractor objects could match the stimulus held in WM. Behavioural data showed that performance was more strongly affected by the prime when it was held in memory than when it was merely identified. An electrophysiological measure of the efficiency of target selection (the N2pc) was also affected by the match between the item in WM and the location of the target in the search task. The N2pc was enhanced when the target fell in the same visual field as the re-presented (invalid) prime, compared with when the prime did not reappear in the search display (on neutral trials) and when the prime was contralateral to the target. Merely identifying the prime produced no effect on the N2pc component. The evidence suggests that WM modulates competitive interactions between the items in the visual field to determine the efficiency of target selection.
We combined event-related brain potentials (ERPs) and behavioral measures to test whether subliminal visual stimuli can capture attention in a goal-dependent manner. Participants searched for visual targets defined by a specific color. Search displays served as metacontrast masks for preceding cue displays that contained one cue in the target color. Although this target-color cue was spatially uninformative, it produced behavioral spatial cuing effects and triggered an ERP correlate of attentional selection (i.e., the N2pc component). These results demonstrate that target-color cues captured attention, in spite of the fact that cue localization performance assessed in separate blocks was at chance level. We conclude that task-set contingent attentional capture is not restricted to supraliminal stimuli, but is also elicited by visual events that are not consciously perceived.
In a recent article, Schreij, Owens, and Theeuwes (2008) reported that abruptly onsetting distractors produce costs in performance even when spatial-cuing effects confirm the presence of a top-down set for color. The authors argued that these results show that abruptly onsetting new objects capture attention independent of a top-down set and, thus, provide conclusive evidence against the theory that attentional capture is contingent on top-down attentional control settings (Folk, Remington, & Johnston, 1992). In the following article, we argue that, contrary to the conclusion drawn by Schreij et al., their own data (1) disconfirm the claim that their abrupt onsets captured spatial attention and (2) are consistent with nonspatial interference accounts of singleton-distractor effects. In support of the nonspatial account, we show that in a paradigm similar to Schreij et al.'s, distractors that do not capture attention can nonetheless influence responses to a target. We conclude that the results of Schreij et al. do not represent a challenge to contingent capture theory.
Four experiments tested a new hypothesis that involuntary attention shifts are contingent on the relationship between the properties of the eliciting event and the properties required for task performance. In a variant of the spatial cuing paradigm, the relation between cue property and the property useful in locating the target was systematically manipulated. In Experiment 1, invalid abrupt-onset precues produced costs for targets characterized by an abrupt onset but not for targets characterized by a discontinuity in color. In Experiment 2, invalid color precues produced greater costs for color targets than for abrupt-onset targets. Experiment 3 provided converging evidence for this pattern. Experiment 4 investigated the boundary conditions and time course for attention shifts elicited by color discontinuities. The results of these experiments suggest that attention capture is contingent on attentional control settings induced by task demands.
Four experiments addressed the degree of top-down control over attentional capture in visual search for featural singletons. In a modified spatial cuing paradigm, the spatial relationship and featural similarity of target and distractor singletons were systematically varied. Contrary to previous studies, all 4 experiments showed that when searching for a singleton target, an irrelevant featural singleton captures spatial attention only when defined by the same feature value as the target. Experiments 2, 3 and 4 provided a potential explanation for the discrepancy with previous studies by showing that irrelevant singletons can produce distraction effects that are dissociable from shifts of spatial attention. The results suggest the existence of 2 distinct forms of attentional capture.
Miller (1956) summarized evidence that people can remember about seven chunks in short-term memory (STM) tasks. However, that number was meant more as a rough estimate and a rhetorical device than as a real capacity limit. Others have since suggested that there is a more precise capacity limit, but that it is only three to five chunks. The present target article brings together a wide variety of data on capacity limits suggesting that the smaller capacity limit is real. Capacity limits will be useful in analyses of information processing only if the boundary conditions for observing them can be carefully described. Four basic conditions in which chunks can be identified and capacity limits can accordingly be observed are: (1) when information overload limits chunks to individual stimulus items, (2) when other steps are taken specifically to block the recording of stimulus items into larger chunks, (3) in performance discontinuities caused by the capacity limit, and (4) in various indirect effects of the capacity limit. Under these conditions, rehearsal and long-term memory cannot be used to combine stimulus items into chunks of an unknown size; nor can storage mechanisms that are not capacity-limited, such as sensory memory, allow the capacity-limited storage mechanism to be refilled during recall. A single, central capacity limit averaging about four chunks is implicated along with other, noncapacity-limited sources. The pure STM capacity limit expressed in chunks is distinguished from compound STM limits obtained when the number of separately held chunks is unclear. Reasons why pure capacity estimates fall within a narrow range are discussed and a capacity limit for the focus of attention is proposed.
Four experiments explored the interrelations between working memory, attention, and eye movements. Observers had to identify a tilted line amongst vertical distractors. Each line was surrounded by a colored shape that could be precued by a matching item held in memory. Relative to a neutral baseline, in which no shapes matched the memory item, search was more efficient when the memory cue matched the shape containing the target, and it was less efficient when the cued stimulus contained a distractor. Cuing affected the shortest reaction times and the first saccade in search. The effect occurred even when the memory cue was always invalid but not when the cue did not have to be held in memory. There was also no evidence for priming effects between consecutive trials. The results suggest that there can be early, involuntary top-down directing of attention to a stimulus matching the contents of working memory.
Paying attention to an object facilitates its storage in working memory. The authors investigate whether the opposite is also true: whether items in working memory influence the deployment of attention. Participants performed a search for a prespecified target while they held another item in working memory. In some trials this memory item was present in the search display as a distractor. Such a distractor has no effect on search time if the search target is in the display. In that case, the item in working memory is unlikely to be selected as a target for an eye movement, and if the eyes do land on it, fixation duration is short. In the absence of the target, however, there is a small but significant effect of the memory item on search time. The authors conclude that the target for visual search has a special status in working memory that allows it to guide attention. Guidance of attention by other items in working memory is much weaker and can be observed only if the search target is not present in the display.
In 7 experiments, the authors explored whether visual attention (the ability to select relevant visual information) and visual working memory (the ability to retain relevant visual information) share the same content representations. The presence of singleton distractors interfered more strongly with a visual search task when it was accompanied by an additional memory task. Singleton distractors interfered even more when they were identical or related to the object held in memory, but only when it was difficult to verbalize the memory content. Furthermore, this content-specific interaction occurred for features that were relevant to the memory task but not for irrelevant features of the same object or for once-remembered objects that could be forgotten. Finally, memory-related distractors attracted more eye movements but did not result in longer fixations. The results demonstrate memory-driven attentional capture on the basis of content-specific representations.
In many theories of cognition, researchers propose that working memory and perception operate interactively. For example, in previous studies researchers have suggested that sensory inputs matching the contents of working memory will have an automatic advantage in the competition for processing resources. The authors tested this hypothesis by requiring observers to perform a visual search task while concurrently maintaining object representations in visual working memory. The hypothesis that working memory activation produces a simple but uncontrollable bias signal leads to the prediction that items matching the contents of working memory will automatically capture attention. However, no evidence for automatic attentional capture was obtained; instead, the participants avoided attending to these items. Thus, the contents of working memory can be used in a flexible manner for facilitation or inhibition of processing.
Previous studies have shown that visual attention can be captured by stimuli matching the contents of working memory (WM). Here, the authors assessed the nature of the representation that mediates the guidance of visual attention from WM. Observers were presented with either verbal or visual primes (to hold in memory, Experiment 1; to verbalize, Experiment 2; or merely to attend, Experiment 3) and subsequently were required to search for a target among different distractors, each embedded within a colored shape. In half of the trials, an object in the search array matched the prime, but this object never contained the target. Despite this, search was impaired relative to a neutral baseline in which the prime and search displays did not match. An interesting finding is that verbal primes were effective in generating the effects, and verbalization of visual primes elicited similar effects to those elicited when primes were held in WM. However, the effects were absent when primes were only attended. The data suggest that there is automatic encoding into WM when items are verbalized and that verbal as well as visual WM can guide visual attention.
Prime pictures of emotional scenes appeared in parafoveal vision, followed by probe pictures either congruent or incongruent in affective valence. Participants responded whether the probe was pleasant or unpleasant (or whether it portrayed people or animals). Shorter latencies for congruent than for incongruent prime-probe pairs revealed affective priming. This occurred even when visual attention was focused on a concurrent verbal task and when foveal gaze-contingent masking prevented overt attention to the primes but only if these had been preexposed and appeared in the left visual field. The preexposure and laterality patterns were different for affective priming and semantic category priming. Affective priming was independent of the nature of the task (i.e., affective or category judgment), whereas semantic priming was not. The authors conclude that affective processing occurs without overt attention--although it is dependent on resources available for covert attention--and that prior experience of the stimulus is required and right-hemisphere dominance is involved.
Visual attention is the collection of mechanisms by which relevant visual information is selected, and irrelevant visual information is ignored. Visual working memory is the mechanism by which relevant visual information is retained, and irrelevant information is suppressed. In addition to this overlap in definition, a strong overlap in brain areas active during attention and working memory tasks is found. The present paper reviews the behavioral evidence for and against the hypothesis that visual working memory and attention are best regarded as one and the same cognitive function, with the same capacity, the same control processes, and the same representational content. The data are best explained by a unified model in which multiple representations can be maintained, but only one receives the current focus of attention. Task circumstances then determine how successful this central representation can be prioritized over its mnemonic competitors.
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.
Whether or not certain physical events can capture attention has been one of the most debated issues in the study of attention. This discussion is concerned with how goal-directed and stimulus-driven processes interact in perception and cognition. On one extreme of the spectrum is the idea that attention capture is primarily stimulus driven and automatic. On the other end is the notion that attention capture is always contingent on the goals of the observer, and thus under top-down control. This review discusses the empirical evidence for each of these viewpoints and the theoretical consequences. In addition, there is a discussion of the issues that remain controversial within the debate between the two viewpoints. It is concluded that visual selection depends on the interaction between bottom-up and top-down processes with a special role for spatial attention as the top-down gatekeeper for attention capture. WIREs Cogn Sci 2010 1 872-881 For further resources related to this article, please visit the WIREs website.
Copyright © 2010 John Wiley & Sons, Ltd.
We argue that to best comprehend many data sets, plotting judiciously selected sample statistics with associated confidence intervals can usefully supplement, or even replace, standard hypothesis-testing procedures. We note that most social science statistics textbooks limit discussion of confidence intervals to their use in between-subject designs. Our central purpose in this article is to describe how to compute an analogous confidence interval that can be used in within-subject designs. This confidence interval rests on the reasoning that because between-subject variance typically plays no role in statistical analyses of within-subject designs, it can legitimately be ignored; hence, an appropriate confidence interval can be based on the standard within-subject error term--that is, on the variability due to the subject condition interaction. Computation of such a confidence interval is simple and is embodied in Equation 2 on p. 482 of this article. This confidence interval has two useful properties. First, it is based on the same error term as is the corresponding analysis of variance, and hence leads to comparable conclusions. Second, it is related by a known factor 2 to a confidence interval of the difference between sample means; accordingly, it can be used to infer the faith one can put in some pattern of sample means as a reflection of the underlying pattern of population means. These two properties correspond to analogous properties of the more widely used between-subject confidence interval.
Visual working memory and visual attention are intimately related, such that working memory encoding and maintenance reflects actively sustained attention to a limited number of visual objects and events important for ongoing cognition and action. Although attention is typically considered to operate over perceptual input, a recent taxonomy proposes to additionally consider how attention can be directed to internal perceptual representations in the absence of sensory input, as well as other internal memories, choices, and thoughts (Chun, Golomb, & Turk-Browne, 2011). Such internal attention enables prolonged binding of features into integrated objects, along with enhancement of relevant sensory mechanisms. These processes are all limited in capacity, although different types of working memory and attention, such as spatial vs. object processing, operate independently with separate capacity. Overall, the success of maintenance depends on the ability to inhibit both external (perceptual) and internal (cognitive) distraction. Working memory is the interface by which attentional mechanisms select and actively maintain relevant perceptual information from the external world as internal representations within the mind.
To investigate how attentional capture in visual search is affected by generalized top-down search strategies, ERPs and behavioral performance were measured in two experiments where spatially nonpredictive color singleton cues preceded visual search arrays that contained one of two equally likely color singletons. When both singletons served as targets, irrelevant-color singleton cues produced behavioral attentional capture effects and elicited an N2pc component, indicative of a singleton search mode. When responses were required to only one of the two color singletons, the same cues no longer elicited behavioral spatial cuing effects, and the N2pc to these cues was attenuated and delayed, in line with the hypothesis that search was now guided by a feature-specific search strategy. Results demonstrate that the ability of visual singleton stimuli to capture attention is not simply determined by their bottom-up salience, but strongly modulated by top-down task sets.
In the past two decades, attention has been one of the most investigated areas of research in perception and cognition. The Psychology of Attention presents a systematic review of the main lines of research on attention; the topics range from perception of threshold stimuli to memory storage and decisionmaking. The book develops empirical generalizations about the major issues and suggests possible underlying theoretical principles.
Harold E. Pashler argues that widely assumed notions of processing resources and automaticity are of limited value in understanding human information processing. He proposes a central bottleneck for decisionmaking and memory retrieval, and describes evidence that distinguishes this limitation from perceptual limitations and limited-capacity short-term memory.
The purpose of this review is to formulate a revised model of information processing that takes into account recent research on memory storage, selective attention, effortful versus automatic processing, and the mutual constraints that these areas place on one another. One distinctive aspect of the proposed model is the inclusion of two phases of sensory storage in each modality. The first phase extends sensation of several hundred milliseconds, whereas the second phase is a vivid recollection of sensation. The mechanism of at least the longer phase is the activation of features in long-term memory, comparable to the mechanism of non-sensory, short-term storage. Another distinctive aspect of the model is that habituation/dishabituation and central executive processes together are assumed to determine the focus of attention, without the need for either an early or a late attentional filter. Research issues that contribute to a comparison of models is discussed. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
A new hypothesis about the role of focused attention is proposed. The feature-integration theory of attention suggests that attention must be directed serially to each stimulus in a display whenever conjunctions of more than one separable feature are needed to characterize or distinguish the possible objects presented. A number of predictions were tested in a variety of paradigms including visual search, texture segregation, identification and localization, and using both separable dimensions (shape and color) and local elements or parts of figures (lines, curves, etc. in letters) as the features to be integrated into complex wholes. The results were in general consistent with the hypothesis. They offer a new set of criteria for distinguishing separable from integral features and a new rationale for predicting which tasks will show attention limits and which will not.
The relationship between working memory and selective attention has traditionally been discussed as operating in one direction: Attention filters incoming information, allowing only relevant information into short-term processing stores. This study tested the prediction that the contents of visual working memory also influence the guidance of selective attention. Participants held a sample object in working memory on each trial. Two objects, one matching the sample and the other novel, were then presented simultaneously. As measured by a probe task, attention shifted to the object matching the sample. This effect generalized across object type, attentional-probe task, and working memory task. In contrast, a matched task with no memory requirement showed the opposite pattern, demonstrating that this effect is not simply due to exposure to the sample. These results confirm a specific prediction about the influence of working memory contents on the guidance of attention.
Spatial selective attention and spatial working memory have largely been studied in isolation. Studies of spatial attention have provided clear evidence that observers can bias visual processing towards specific locations, enabling faster and better processing of information at those locations than at unattended locations. We present evidence supporting the view that this process of visual selection is a key component of rehearsal in spatial working memory. Thus, although working memory has sometimes been depicted as a storage system that emerges 'downstream' of early sensory processing, current evidence suggests that spatial rehearsal recruits top-down processes that modulate the earliest stages of visual analysis.
Pillsbury (1908) suggested that deciding to search for something in a scene consists of nothing more than forming a visual image of the target. If so, imaging should trigger search even when it would be more advantageous not to search. Subjects were cued to form an image of a specified object (e.g., tiger) and to press a key when they had done so. This initiated the presentation of a sequence of pictures, with a single target digit interspersed; the subject's task was to report this digit. The sequence contained a picture of the same type of object that the subject had just imaged (e.g., a tiger), either before or after the target digit. If this picture was detected involuntarily, an attentional blink should have impaired digit detection when the picture preceded the digit. This was confirmed in two experiments, even when instructions specifically encouraged subjects to discard the image and to avoid searching for it. The results support Pillsbury's hypothesis.