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There has been a longstanding debate about whether lexical and semantic processing of words is serial or parallel. We addressed this debate using partially valid cueing, where one of two words is cued. The cue was valid on 80% and invalid on the other 20% of the trials. The task was semantic categorization, and performance was measured by accuracy. The new feature was to limit attentional switching using a postmask of consonants that closely followed the presentation of words. We found a large effect of cueing and, most importantly, performance for the uncued word was at chance. This chance performance was consistent with serial processing, but not with typical parallel processing. This result adds to the evidence from other recent studies that the lexical and semantic processing of words is serial.

Divided attention effects have been observed across a variety of stimuli and perceptual tasks, which have given rise to both object-based and space-based theories of divided attention. Object-based theories assert that processing information from multiple objects is limited, whereas space-based theories assert that processing information from multiple locations is limited. Extant results in the literature are collectively inconsistent with both simple object-based theories and simple space-based theories of divided attention. Using a visual search task with the extended simultaneous-sequential method to reveal capacity limitations, we found evidence of limited-capacity processing of object properties and unlimited-capacity processing of feature contrast. We found no evidence of a separate spatial limitation. A multiple pathway processing theory can account for these and a large body of previous results. According to this theory, tasks that require object processing must follow a limited-capacity pathway and therefore incur divided attention effects. Tasks that depend on only feature contrast can follow a separate unlimited-capacity processing pathway and therefore do not incur divided attention effects.

Representing objects as continuous across time requires the establishment of correspondence, whereby current stimuli are represented as deriving from the same object as earlier stimuli. Spatiotemporal continuity and surface-feature similarity play important roles in these correspondence processes. Because objects are often represented across extended periods of time, visual working memory (VWM) content should also play a role in object correspondence. We tested this prediction using Ternus motion. Displays consisted of three-disk arrays that shifted horizontally by one position between frames. Depending on how correspondence is resolved, Ternus displays are perceived as group motion, where all three disks appear to move together, or element motion, where one disk appears to jump across the others. Reports of which motion is perceived provide an index of how correspondence was resolved. Ternus displays were adapted such that the color of some disks biased element motion while the color of others biased group motion. Maintaining one or the other of the colors in VWM for later report systematically biased which type of motion was perceived (Experiments 1 and 2). When color was incidental to the VWM task, however, it did not (Experiment 3). These results confirm that VWM content contributes to object correspondence. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

When responding to the identity of a visual target, nearby stimuli (flankers) that are associated with the same response as the target cause faster and more accurate responding than flankers that are associated with different responses. Because this flanker-congruence effect (FCE) decreases with increasing target-flanker separation, it was thought to reflect limited precision of spatial selection mechanisms. Later studies, however, showed that FCEs are larger when the target and flankers are the same color compared to when they are different colors. This led to the group selection hypothesis, which states that flankers are perceptually grouped with the target and are obligatorily selected along with it, regardless of spatial separation. An alternative hypothesis, the image segmentation hypothesis, states that feature differences facilitate the segmentation of visual information into relevant and irrelevant parts, thereby mitigating the limitations of spatial precision of selection mechanisms. We test between these hypotheses using a design in which targets and flankers are grouped or not grouped, while holding feature differences in the stimulus constant. Contrary to earlier results (Driver & Baylis, 1989; Baylis & Driver, 1992), we found that same-colored flankers do not yield larger FCEs than different-colored flankers when feature differences are held constant. We conclude that similarity effects on the FCE reflect differential support for image segmentation, prior to selection, rather than the obligatory selection of perceptually grouped flankers and targets.

Spatial cues help participants detect a visual target when it appears at the cued location. One hypothesis for this cueing effect, called selective perception, is that cueing a location enhances perceptual encoding at that location. Another hypothesis, called selective decision, is that the cue has no effect on perception, but instead provides prior information that facilitates decision-making. We distinguished these hypotheses by comparing a simultaneous display with two spatial locations to sequential displays with two temporal intervals. The simultaneous condition had a partially valid spatial cue, and the sequential condition had a partially valid temporal cue. Selective perception predicts no cueing effect for sequential displays given there is enough time to switch attention. In contrast, selective decision predicts cueing effects for sequential displays regardless of time. We used endogenous cueing of a detection-like coarse orientation discrimination task with clear displays (no external noise or postmasks). Results showed cueing effects for the sequential condition, supporting a decision account of selective attention for endogenous cueing of detection-like tasks.

Anne Treisman and colleagues developed an influential theoretical framework surrounding the construct of "object files" as a means of understanding the functional need for an episodic representation of objects as they move, change, disappear, and reappear from view (Kahneman, Treisman, & Gibbs, Cognitive Psychology, 24, 175-219, 1992; Treisman, The Quarterly Journal of Experimental Psychology, 40, 201-237, 1988). Within that framework, object files are defined through the process of object correspondence, whereby stimuli are associated with and represented as later instantiations of existing object representations and are used to selectively update those representations. A central assertion of the object file framework is that object correspondence is established on the basis of spatiotemporal continuity, without regard to feature information. We tested this assertion by investigating whether feature information, separate from spatiotemporal information, can determine how object correspondence is resolved. We used the perception of causality in simple dynamic displays, which provides a means of inferring how object correspondence is resolved. We found that, contrary to the spatiotemporal dominance assertion, feature information is used to resolve object correspondence. We suggest that the object-file framework be extended to reflect the importance of both feature and spatiotemporal information in establishing and maintaining episodic object representations.

Divided attention has little effect for simple tasks, such as luminance detection, but it has large effects for complex tasks, such as semantic categorization of masked words. Here, we asked whether the semantic categorization of visual objects shows divided attention effects as large as those observed for words, or as small as those observed for simple feature judgments. Using a dual-task paradigm with nameable object stimuli, performance was compared with the predictions of serial and parallel models. At the extreme, parallel processes with unlimited capacity predict no effect of divided attention; alternatively, an all-or-none serial process makes two predictions: a large divided attention effect (lower accuracy for dual-task trials, compared to single-task trials) and a negative response correlation in dual-task trials (a given response is more likely to be incorrect when the response about the other stimulus is correct). These predictions were tested in two experiments examining object judgments. In both experiments, there was a large divided attention effect and a small negative correlation in responses. The magnitude of these effects was larger than for simple features, but smaller than for words. These effects were consistent with serial models, and rule out some but not all parallel models. More broadly, the results help establish one of the first examples of likely serial processing in perception.

We used a form of ambiguous apparent motion known as Ternus motion to isolate the effects of object-based and space-based attention, and to explore functional differences between them. Two frames of horizontally aligned disks that were shifted by one position between frames were temporally separated by either a short or a long inter-stimulus interval (ISI). Short ISI displays were perceived as element motion where one disk appeared to jump across the other two. Long ISI displays were perceived as group motion where all three disks appeared to move together. Because element and group motion imply mutually exclusive object structures, adding stimuli (e.g., a small gap) to one disk in each frame created conditions of orthogonal object and location status (same or different), depending on ISI. We used two tasks with different functional demands, an identification task (Experiments 1 and 3a) in which observers responded to a single attribute of the final stimulus, and a comparison task (Experiments 2 and 3b) in which observers compared two attributes across two stimuli. Reliable object-specific effects occurred only with the comparison task, whereas location-specific effects occurred with both tasks. These results confirm that attention can be directed to objects separately from spatial locations and vice versa, and, moreover, that object-based and space-based attention are engaged differently depending on the processing demands of the task.

The visual system constructs perceptions based on ambiguous information. For motion perception, the correspondence problem arises, i.e., the question of which object went where. We asked at which level of processing correspondence is solved – lower levels based on information that is directly available in the retinal input or higher levels based on information that has been abstracted beyond the input directly available at the retina? We used a Ponzo-like illusion to manipulate the perceived size and separations of elements in an ambiguous apparent motion display. Specifically, we presented Ternus displays – for which the type of motion that is perceived depends on how correspondence is resolved – at apparently different distances from the viewer using pictorial depth cues. We found that the perception of motion depended on the apparent depth of the displays, indicating that correspondence processes utilize information that is produced at higher-level processes. Electronic supplementary material The online version of this article (10.3758/s13423-020-01786-9) contains supplementary material, which is available to authorized users.

How well can one perceive simultaneous stimuli at two widely spaced visual locations? Are the stimuli processed independently? If not, does the dependency affect perception, disrupt signals in later stages, or both? To address these questions, we measured effects of divided attention using a dual-task paradigm with stimuli presented in noise on either side of fixation. This paradigm was applied to detecting Gabor patches and to the semantic categorization of words. We measured dual-task deficits which are a decline in mean performance for a dual task compared to a single task. There was such a deficit for categorizing two words but relatively little deficit for detecting two Gabors. We also measured congruency effects which are when performance at one location depends on whether the stimulus at the other location requires the same response. There was such a congruency effect for detecting two Gabors but relatively little congruency effect for categorizing two words. Further experiments were consistent with the dual-task deficit in word categorization being perceptual, but the congruency effect in Gabor detection being due to later processes. Results of additional experiments showed that the congruency effect was consistent with either graded selection errors or with all-or-none selection followed by graded interactive processing. To answer our opening question: for Gabor detection, perceptual processes were largely independent but later processes caused congruency effects; for word categorization, perceptual processes had capacity limits but even in combination with later processes caused relatively little congruency effects. In summary, there was evidence for two different kinds of dependency. Such complementary dependencies are inconsistent with theories of divided attention that depend on a single dependency such as a single resource or single source of interactive processing.

Our visual system establishes correspondence between objects and thus enables us to perceive an object, like a car on the road, as moving continuously. A central question regarding correspondence is whether our visual system uses relatively unprocessed image-based information or further processed object-based information to establish correspondence. While it has been shown that some object-based attributes, such as perceived lightness, can influence correspondence, manipulating object-based information typically involves at least minimal changes of image-based information as well, making it difficult to clearly distinguish between the two levels. To avoid this confound, we manipulated object-based information prior to the task in which we measured correspondence. We used 3-element Ternus displays to assess correspondence. These are ambiguous apparent-motion displays that, depending on how correspondence is solved, are perceived as either one element jumping across the others or as all three elements moving together as a group. We manipulated object-based information by presenting one of two object histories prior to the Ternus display. In one, they moved or changed luminance independently, and thus appeared independent from each other. In the other, the elements moved or changed their luminance all together and thus appeared grouped with each other. We found that the object history did influence how the Ternus displays were perceived, thereby confirming that object-based information alone can be used as a basis for establishing correspondence in line with object-based theories of correspondence.

The visual system can calculate summary statistics over time. For example, the multiple frames of a movie showing a dynamically changing disk can be collapsed to form a single representation of that disk's mean size. Summary representations of dynamic information may engage online updating processes that establish a running average of the mean by continuously adjusting the persisting representation of the average in tandem with the arrival of incoming information. Alternatively, summary representations may involve subsampling strategies that reflect limitations in the degree to which the visual system can integrate information over time. Observers watched movies of a disk that changed size smoothly at different rates and then reported the disk's average size by adjusting the diameter of a response disk. Critically, the movie varied in duration. Size estimates depended on the duration of the movie. They were constant and fairly accurate for movie durations up to approximately 600 ms, at which point accuracy decreased with increasing duration to imprecise levels by about 1,000 ms. Summary statistics established over time are unlikely to be updated continuously and may instead be restricted by subsampling processes, such as limited temporal windows of integration. (PsycINFO Database Record

The present study combines the object-reviewing paradigm (Kahneman, Treisman, & Gibbs, 1990) with the checkershadow illusion (Adelson, 1995) in order to contrast the effects of objects’ luminance versus lightness on the object-specific preview benefit. To this end, we manipulated objects’ luminance and the amount of illumination given by an informative background scene in four experiments. In line with previous studies (Moore, Stephens, & Hein, 2010), there was no object-specific preview benefit when objects were presented on a uniformly colored background and luminance switched between objects. In contrast, when objects were presented on the checkershadow illusion background which provided an explanation for the luminance switch, a reliable object-specific preview benefit was observed. This suggests that object correspondence as measured by the object-reviewing paradigm can be influenced by scene-induced, perceived lightness of objects’ surfaces. We replicated this finding and moreover showed that the scene context only influences the object-specific preview benefit if the objects are perceived as part of the background scene.

Summary The presence of lifeguards on beaches and at pools has the potential to prevent many drowning incidents. This article examines the visual components of the lifeguard's job, discussing some of the major challenges they face during surveillance. These include optical challenges (turbidity and turbulence of the water, light refraction, and glare), scene challenges (elevated set size affecting clutter and perceptual ‘blindnesses’), stimulus challenges (searching for multiple targets that are complex, dynamic, ill-defined, and rare), and attentional challenges, including but not limited to vigilance issues. The differences between basic laboratory research and the lifeguarding task are explored, with recommendations for future study. Copyright © 2015 John Wiley & Sons, Ltd.

The visual system may condense the vast amount of information in the natural world by summarizing properties across collections of similar items (Ariely, 2001). Under this view, once these summary ...

The SIPHER technique uses mathematically-uncomplicated processing to impart interesting effects upon a static image. Importantly, it renders certain areas of an image more perceptible than others, and draws a human observer’s attention to particular objects or portions of an image scene. By varying coefficients of the processing in a time-ordered sequence, we can create a multi-frame video wherein the frame-to-frame temporal dynamics further enhance human perception of image objects. In this article we first explain the mathematical formulations and present results from applying SIPHER to simple three-dimensional shapes. Then we explore SIPHER’s utility in enhancing visual perception of targets or objects of military interest, in imagery with some typical backgrounds. We also explore how and why these effects enhance human visual perception of the image objects.

In perception, divided attention refers to conditions in which multiple stimuli are relevant to an observer. To measure the effect of divided attention in terms of perceptual capacity, we introduce an extension of the simultaneous-sequential paradigm. The extension makes predictions for fixed-capacity models as well as for unlimited-capacity models. We apply this paradigm to two example tasks, contrast discrimination and word categorization, and find dramatically different effects of divided attention. Contrast discrimination has unlimited capacity, consistent with independent, parallel processing. Word categorization has a nearly fixed capacity, consistent with either serial processing or fixed-capacity, parallel processing. We argue that these measures of perceptual capacity rely on relatively few assumptions compared to most alternative measures.

What role do surface features (e.g., color) play in the establishment and maintenance of episodic representations of objects (object files)? Mitroff and Alvarez (2007) showed that stimuli that were linked by a continuous spatiotemporal history yielded object-specific preview benefits--a standard index of object files-whereas stimuli linked only by shared surface features did not. Here, it is shown that abruptly changing the features of an object that has been established on the basis of spatiotemporal history can disrupt object-specific preview benefits (Experiments 1 and 2). Moreover, under some conditions, feature match alone can give rise to the preview benefits (Experiment 3). These results indicate that surface features, as well as spatiotemporal factors, play an important role in establishing and maintaining episodic object representations.

A central bar presented in counterphase with two flanking bars creates the perception of only two bars, instead of three, flickering (standing wave of invisibility illusion). Current explanations of this illusion highlight the importance of local interactions between the central bar and the flankers as a reason for the invisibility of the central bar. In three experiments, we show that the reduction in visibility of the central bar occurs even when the flankers are spatially separated from the central bar. Thus local mechanisms-low-level lateral inhibition or border-ownership competition-do not suffice to account for the decreased visibility. Furthermore, the reduced visibility of the central bar is accompanied by the perception of the flankers in apparent motion at all separations. We suggest an account of the standing wave phenomenon in terms of object updating: The representation of the central bar is updated with the representation of the flankers leaving the perception of just the flankers moving across space. The stimuli for the key conditions from this study, in QuickTime format, may be down loaded from http://app.psychonomic-journals.org/content/supplemental.

The spatial extent of attention was investigated by measuring sensitivity to stimuli at to-be-ignored locations. Observers detected a stimulus at a cued location (target), while ignoring otherwise identical stimuli at nearby locations (foils). Only an attentional cue distinguished target from foil. Several experiments varied the contrast and separation of targets and foils. Two theories of selection were compared: contrast gain and a version of attention switching called an all-or-none mixture model. Results included large effects of separation, rejection of the contrast gain model, and the measurement of the size and profile of the spatial extent of attention.

When the stimulus onset asynchrony (SOA) between the cue and the target is short, exogenous spatial cues usually produce a response time benefit. However, consistent with several recent studies, we have found that a short stimulus onset asynchrony is not sufficient. At least one more factor—the number of cue and target locations—also plays a role. Even more interesting, when 8 cue and target locations are used, the effect of an exogenous cue produces a cost on valid cue trials, and the spatial metric of this negative cuing effect depends on whether the cue remains visible at target onset. It has long been known that certain salient events can evoke an involuntary shift of covert visual attention. Based on early work by Posner and Cohen (e.g., Posner & Cohen, 1984), a standard paradigm for studying these shifts has been developed. The task requires a simple detection response to a visual target presented away from fixation. Shortly before the target presentation, an uninformative cue (i.e., a stimulus whose location is uncorrelated with the location of the target) appears in one of the possible target locations. Typically, responses to targets in the same location as the cue are faster than responses to targets presented elsewhere, at least when the cueto-target stimulus onset asynchrony (SOA) is short (e.g., less than 200 ms). The standard explanation for this spatial cuing effect is that covert visual attention is summoned to the location of the salient cue. This summoning or capture of attention facilitates the processing of any item that appears in the same location and, conversely, interferes with the processing of distant items (for a recent review, see Prinzmetal, McCool, & Park, 2005). The nature of exogenous orienting has been studied intensively with the Posner cuing paradigm, a simple detection task with an uninformative peripheral cue. (For a demonstration of the effects using more complicated tasks, see Lupianez, Milliken, Solano, Weaver, & Tipper, 2001). A large part of this research has been aimed at disentangling the mechanisms that underlie the biphasic facilitation and inhibition that are observed at various SOAs between the cue and the target (McAuliffe & Pratt, 2005; Tassinari, Aglioti, Chelazzi, Peru, & Berlucchi, 1994). The emergent hypothesis

Memory for multiple features might be limited by the number of features, the number of objects, or both. To focus on the role of features, we tested memory for a variable number of features within a single object. Subjects studied a single ellipse that varied in four features: size, orientation, contrast, and position. We conducted two experiments that differed in how memory was tested. If performance is limited only by the number of objects to be remembered, there should be no effect of the number of relevant features within a single object. Instead, for both experiments, the proportion correct was lower when four features had to be remembered rather than one. The magnitude of these effects varied with the details of the two experiments. Although similar results have been reported for experiments using multiple objects, the present experiments are some of the first to have demonstrated such an effect for a single object. This result is inconsistent with theories in which visual memory has a discrete limit on the number of stored objects, and no limit on the stored features within an object. Instead, it seems likely that objects and features both play roles in limiting performance in memory tasks.

The simultaneous–sequential method was used to test the processing capacity of establishing mean orientation summaries. Four clusters of oriented Gabor patches were presented in the peripheral visual field. One of the clusters had a mean orientation that was tilted either left or right while the mean orientations of the other three clusters were roughly vertical. All four clusters were presented at the same time in the simultaneous condition whereas the clusters appeared in temporal subsets of two in the sequential condition. Performance was lower when the means of all four clusters had to be processed concurrently than when only two had to be processed in the same amount of time. The advantage for establishing fewer summaries at a given time indicates that the processing of mean orientation engages limited-capacity processes (Experiment 1). This limitation cannot be attributed to crowding, low target-distractor discriminability, or a limited-capacity comparison process (Experiments 2 and 3). In contrast to the limitations of establishing multiple summary representations, establishing a single summary representation unfolds without interference (Experiment 4). When interpreted in the context of recent work on the capacity of summary statistics, these findings encourage reevaluation of the view that early visual perception consists of summary statistic representations that unfold independently across multiple areas of the visual field.

Inattentional blindness (IB), which is the lack of awareness of stimuli that appear in unattended regions of the visual field, can be used as an operational definition of unattended. Using separate online measures in combination with IB can be used to probe specific aspects of processing that are engaged by unattended stimuli. Previous applications of this method have provided evidence that unattended stimuli can engage processes that lead to grouping‐by‐similarity (Moore & Egeth, 1997), as well as processes involved in the perceptual completion of partially visible surfaces (Moore, Grosjean, & Lleras, 2003). Here we applied this method to address the question of whether unattended stimuli can engage response–end processes. Specifically, we used a stimulus–response compatibility effect, the Simon effect (e.g., Simon & Rudell, 1967), as an online measure of response selection. As assessed through this measure, unattended stimuli failed to engage response‐selection processes.

A common means of investigating object-specific selection is thetwo-rectangles method, in which a target appears at one end of two rectangles (Egly, Driver, & Rafal, 1994). Prior to target presentation, one end of two parallel rectangles is cued by brightening the three line segments along one of its ends. When the target appears in the opposite end of the cued rectangle, responses tend to be faster and more accurate than when it appears in the end of the other rectangle, which is equally distant from the cue. This effect has been taken as evidence of object-specific selection of information. The present study rules out the concern that the object-specific effect that is found with this method is caused by the directional nature of the cue. That is, the three-sided cue, which essentially points to the “sameobject” location, does not itself give rise to the object-specific advantage. These results are discussed in terms of the combined roles of explicit object structure in the scene, past experience, and task set as contributing to the way in which information is organized and selected from a scene.

Onset of a movement-related brain potential (lateralized readiness potential, LRP) was used to divide reaction time (RT) into two intervals: (1) stimulus onset to LRP onset, and (2) LRP onset to onset of the overt response. Effects on these intervals of advance information about the to-be-signaled response and of the mapping between fingers and response buttons were examined. These effects were used to reach conclusions about the organization of response preparation and about the identity of the processes influenced by advance information. In the absence of advance information, response preparation involved two steps. First, two of the four possible response alternatives were prepared, then one of these two was prepared further. Which pair of responses was prepared during the first step depended on the spatial arrangement of the fingers on the buttons, rather than on any common anatomical feature. Advance information about the upcoming response allowed the first step to be performed prior to the response signal, thus removing its contribution to RT. The second step, however, remained unaffected.

Studying inattentional processing is made difficult by the fact that measuring it often results in observers attending to the stimuli in question. Here it is suggested that inattentional blindness—the lack of awareness of stimuli that appear in unattended regions of the visual field—be used as an operational definition of unattended. Separate online measures, taken while the stimuli are still present, can then be used to probe specific aspects of processing. Applying this method to the perceptual completion of partial surfaces, an online measure of modal and amodal completion was developed, and then used within an experiment in which inattentional blindness to the surfaces was assessed. The results indicated that surface completion can be engaged by unattended stimuli. More generally, the study illustrates the usefulness of this approach for probing what processing does and does not occur for stimuli that appear in unattended regions of the visual field.

J. T. Enns and V. Di Lollo (1997) discovered a new form of visual masking that they labeled object substitution masking (OSM). OSM occurs when 4 dots, presented around a target, trail in the display after target offset. The present study showed that the physical presence of the masking dots after target offset is not necessary for OSM. Instead, the continued presence of a changing high-level representation associated with the target suffices to yield OSM. Apparent motion was used to define such representation. In these experiments, the initial display offset and was followed by a 2nd display where masks appeared at new locations. Only when the spatiotemporal properties of the stimuli on the 2nd display supported the perception of the target moving and turning into the mask was OSM observed.

Does visual processing differ for action and recognition? To address this question, the authors capitalized on research showing that color is preferred over binocular disparity in the ventral (recognition) stream, whereas disparity is preferred over color in the dorsal (action) stream. Participants searched for oblique targets among vertical distractors in displays defined only by color or disparity. Action-task participants stamped the target with a handheld block, whereas recognition-task participants lifted the block through a target-compatible gap. Analyses of reaction time and time-varying hand orientation showed that disparity and color displays were processed equally efficiently during action, but disparity was processed less efficiently than color during recognition. The results suggest that visual processing differs for action and recognition.

This project examined whether previous visual history can bias perceptual dominance during onset rivalry. A predictive sequence of non-rivalrous stimuli preceded dichoptically presented rivalrous displays. One of the dichoptic images was the implied next step of the preceding sequence while the other was not. Observers reported their initial dominant percept. Across five experiments, we found that motion sequences biased perceptual selection such that a rivalrous stimulus that continued a motion sequence tended to dominate one that did not. However, signals generated by complex pattern of motion information or verbal-semantic information had no influence on selection. These results are consistent with the view that onset rivalry is an early phase of rivalry that is likely insensitive to modulation by factors originating beyond the visual system.

During everyday scene viewing, the human visual system faces many challenges. The most frequent disruption of the visual input occurs during saccadic eye movements. Every time we execute a saccade, the perceptual input is disrupted by both saccadic suppression and shifts of objects’ retinal locations. Despite these frequent changes, the visual system is quite efficient at representing a stable visual world (i.e. establishing visual stability). We have previously proposed that transsaccadic integration depends on an object-mediated updating (OMU) process (Tas, Moore, & Hollingworth, 2012). According to this view, the representation of the saccade target object depends on visual stability. Specifically, if stability is established, the post-saccadic object is perceived as the continuation of the pre-saccadic object. In this case, the properties of the pre-saccadic object are overwritten by the post-saccadic properties. In contrast, when visual stability is disrupted, the pre- and post-saccadic objects are represented as separate objects. Therefore, the properties of the pre-saccadic object are protected from overwriting. In the present study, we tested this assumption directly. Specifically, we asked whether visual stability modulates the availability of the pre-saccadic object's features for report.

We assessed the processing capacity of establishing statistical summary representations (SSRs) of mean size in visual displays using the simultaneous-sequential method. Four clusters of stimuli, each composed of several circles with various diameters, were presented around fixation. Observers searched for the cluster with the largest or smallest mean size. In the simultaneous condition, all four clusters were presented concurrently; in the sequential condition, the clusters appeared two at a time. We found that the processing capacity of SSRs for multiple ensembles was as extreme as a fixed-rate bottleneck process (Experiment 1). A control experiment confirmed that this was not caused by having to compare the results of multiple averaging processes (Experiment 2). In contrast to computing SSRs across ensembles, computing SSRs for a single ensemble using the same stimuli was consistent with unlimited-capacity processing (Experiment 3). Contrary to existing claims, summary representations appear to be extracted independently for items within single ensembles but not multiple ensembles. A developing understanding of capacity limitations in perceptual processing is discussed.

It is often the case that stimuli (or aspects of a stimulus) are referred to as being “task-irrelevant.” Here, we recount where this label originated and argue that the use of this label is at odds with the concept of “relevance” that has arisen in the contingent-capture literature. This is not merely a matter of labels, but a matter of inference: When people describe a flanker stimulus as being “task-irrelevant,” they may be (and sometimes are) tempted to infer that the conditions that were studied in the flanker task generalize to other tasks and other types of stimuli. Here, we show that this generalization is not warranted. The flanker effect exists not because attention has failed at selecting only the target from the display, but rather, the effect arises precisely because attention succeeded at selecting target-like (i.e., attentionally relevant) stimuli from the display. As a result, the flanker effect should not be used to infer how stimuli that are entirely unrelated to a participant’s main task would be processed. We propose the use of a new terminology to replace this potentially misleading label.

To maintain stable object representations as our eyes or the objects themselves move, the visual system must determine how newly sampled information relates to existing object representations. To solve this correspondence problem, the visual system uses not only spatiotemporal information (e.g., the spatial and temporal proximity between elements), but also feature information (e.g., the similarity in size or luminance between elements). Here we asked whether motion correspondence relies solely on image-based feature information, or whether it is influenced by scene-based information (e.g., the perceived sizes of surfaces or the perceived illumination conditions). We manipulated scene-based information separately from image-based information in the Ternus display, an ambiguous apparent-motion display, and found that scene-based information influences how motion correspondence is resolved, indicating that theories of motion correspondence that are based on “scene-blind” mechanisms are insufficient.

Seven experiments were conducted in order to explore the conditions under which visual attention can be allocated in depth. In each experiment, observers were cued to the most likely target location in stereoscopic depth displays, and targets could appear in either the cued location or in another location. In Experiments 1 and 2, we show that previous failures to observe effects of cuing in depth may have depended on the specific timing characteristics of the displays. In Experiments 3, 4, and 5, we eliminated the hypothesis, suggested by Experiments 1 and 2, that in order to allocate attention in depth, attention must be allocated to a specific object token. Experiment 6 provides evidence that, in the absence of other organizing information (e.g., color), attention can be allocated in depth on the basis of the surface information available in the display. Finally, in Experiment 7, we demonstrate that, although sufficient, surface information is not necessary for the allocation of attention; color supported the allocation of attention across multiple items that failed to fall on a single coherent surface in depth. Together, these findings suggest that attention in depth, like attention in two-dimensional displays, is determined by the perceptual organization of the display.

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

Recent evidence has suggested that relatively precise information about the location and visual form of a saccade target object is retained across a saccade. However, this information appears to be available for report only when the target is removed briefly, so that the display is blank when the eyes land. We hypothesized that the availability of precise target information is dependent on whether a post-saccade object is mapped to the same object representation established for the presaccade target. If so, then the post-saccade features of the target overwrite the presaccade features, a process of object mediated updating in which visual masking is governed by object continuity. In two experiments, participants' sensitivity to the spatial displacement of a saccade target was improved when that object changed surface feature properties across the saccade, consistent with the prediction of the object-mediating updating account. Transsaccadic perception appears to depend on a mechanism of object-based masking that is observed across multiple domains of vision. In addition, the results demonstrate that surface-feature continuity contributes to visual stability across saccades.

Sensory information must be processed selectively in order to represent the world and guide behavior. How does such selection occur? Here we consider two alternative classes of selection mechanisms: In blocking, unattended stimuli are blocked entirely from access to downstream processes, and in attenuation, unattended stimuli are reduced in strength but if strong enough can still access downstream processes. Existing evidence as to whether blocking or attenuation is a more accurate model of human performance is mixed. Capitalizing on a general distinction between blocking and attenuation—blocking cannot be overcome by strong stimuli, whereas attenuation can—we measured how attention interacted with the strength of stimuli in two spatial selection paradigms, spatial filtering and spatial monitoring. The evidence was consistent with blocking for the filtering paradigm and with attenuation for the monitoring paradigm. This approach provides a general measure of the fate of unattended stimuli.