Display Set Size Research Articles

Increased display complexity reveals effects of salience in action control.

In action-control research, typically, stimulus sparse displays are used. This might be one reason why previous theorizing focuses on the (top-down) demands of response selection (e.g., what key to press), while often ignoring (bottom-up) demands of stimulus selection (e.g., what stimulus to attend). However, complex perceptual situations may pose selection demands that make additional, response-unrelated feature dimensions relevant for response selection. The major stimulus characteristic affecting perceptual selection is salience. In research on visual attention, there is a debate about the conditions under which salience becomes effective. We related both debates in two experiments, in which we modulated display set size as well as salience in a stimulus-response binding task. In sum, the data of these experiments (pooled N = 138) demonstrated that salience furthered the integration of stimulus features in displays with many stimuli more than in sparse displays. Our results demonstrate the neglected impact of salience on action-control when going beyond the very simplistic displays common in action-control research. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Proactive suppression can be applied to multiple salient distractors in visual search.

There is a growing body of research demonstrating that the capture of attention by a single salient distractor can be prevented via proactive suppression. In real-world contexts, there are often several distracting events that compete for attention, but it is entirely unknown whether multiple objects can be suppressed concurrently. We used behavioral and electrophysiological measures to investigate the existence and time course of multiple-item suppression. We employed search displays that contained either one or two uniquely colored distractors that differed in their salience (S+ and S-), or no such distractors. Search performance improved with the number of salient distractors, indicating that the suppression of multiple items reduced the effective display set size. This was also the case when the target color was no longer fully predictable, ruling out an alternative explanation in terms of attentional guidance by target templates. In an experiment where S+ and S- always appeared together in the same display, the PD component (a marker of proactive suppression) was triggered exclusively by the more salient distractor (S+), indicative of single-item suppression. However, when displays with one or both salient distractors were intermixed, a reliable PD component was also triggered by S-, even when it was accompanied by S+ in the same display. These results show that multiple concurrent salient signals can be proactively inhibited. They demonstrate that signal suppression processes can be adaptively employed to counteract visual distraction at different locations, in order to facilitate the attentional selection of relevant objects in crowded visual environments. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The cognitive loci of the display and task-relevant set size effects on distractor interference: Evidence from a dual-task paradigm.

The congruency effect of a task-irrelevant distractor has been found to be modulated by task-relevant set size and display set size. The present study used a psychological refractory period (PRP) paradigm to examine the cognitive loci of the display set size effect (dilution effect) and the task-relevant set size effect (perceptual load effect) on distractor interference. A tone discrimination task (Task 1), in which a response was made to the pitch of the target tone, was followed by a letter discrimination task (Task 2) in which different types of visual target display were used. In Experiment 1, in which display set size was manipulated to examine the nature of the display set size effect on distractor interference in Task 2, the modulation of the congruency effect by display set size was observed at both short and long stimulus-onset asynchronies (SOAs), indicating that the display set size effect occurred after the target was selected for processing in the focused attention stage. In Experiment 2, in which task-relevant set size was manipulated to examine the nature of the task-relevant set size effect on distractor interference in Task 2, the effects of task-relevant set size increased with SOA, suggesting that the target selection efficiency in the preattentive stage was impaired with increasing task-relevant set size. These results suggest that display set size and task-relevant set size modulate distractor processing in different ways.

Generating a taxonomy of spatially cued attention for visual discrimination: effects of judgment precision and set size on attention.

Attention precues improve the performance of perceptual tasks in many but not all circumstances. These spatial attention effects may depend upon display set size or workload, and have been variously attributed to external noise filtering, stimulus enhancement, contrast gain, or response gain, or to uncertainty or other decision effects. In this study, we document systematically different effects of spatial attention in low- and high-precision judgments, with and without external noise, and in different set sizes in order to contribute to the development of a taxonomy of spatial attention. An elaborated perceptual template model (ePTM) provides an integrated account of a complex set of effects of spatial attention with just two attention factors: a set-size dependent exclusion or filtering of external noise and a narrowing of the perceptual template to focus on the signal stimulus. These results are related to the previous literature by classifying the judgment precision and presence of external noise masks in those experiments, suggesting a taxonomy of spatially cued attention in discrimination accuracy.

Task probability and report of feature information: What you know about what you ‘see’ depends on what you expect to need

We investigated the influence of dimensional set on report of object feature information using an immediate memory probe task. Participants viewed displays containing up to 36 coloured geometric shapes which were presented for several hundred milliseconds before one item was abruptly occluded by a probe. A cue presented simultaneously with the probe instructed participants to report either about the colour or shape of the probe item. A dimensional set towards the colour or shape of the presented items was induced by manipulating task probability — the relative probability with which the two feature dimensions required report. This was done across two participant groups: One group was given trials where there was a higher report probability of colour, the other a higher report probability of shape. Two experiments showed that features were reported most accurately when they were of high task probability, though in both cases the effect was largely driven by the colour dimension. Importantly the task probability effect did not interact with display set size. This is interpreted as tentative evidence that this manipulation influences feature processing in a global manner and at a stage prior to visual short term memory.

Perceptual load vs. dilution: the roles of attentional focus, stimulus category, and target predictability.

Many studies have shown that increasing the number of neutral stimuli in a display decreases distractor interference. This result has been interpreted within two different frameworks; a perceptual load account, based on a reduction in spare resources, and a dilution account, based on a degradation in distractor representation and/or an increase in crosstalk between the distractor and the neutral stimuli that contain visually similar features. In four experiments, we systematically manipulated the extent of attentional focus, stimulus category, and preknowledge of the target to examine how these factors would interact with the display set size to influence the degree of distractor processing. Display set size did not affect the degree of distractor processing in all situations. Increasing the number of neutral items decreased distractor processing only when a task induced a broad attentional focus that included the neutral stimuli, when the neutral stimuli were in the same category as the target and distractor, and when the preknowledge of the target was insufficient to guide attention to the target efficiently. These results suggest that the effect of neutral stimuli on the degree of distractor processing is more complex than previously assumed. They provide new insight into the competitive interactions between bottom-up and top-down processes that govern the efficiency of visual selective attention.

Set size and mask duration do not interact in object-substitution masking.

Object-substitution masking (OSM) occurs when a mask, such as four dots that surround a brief target item, onsets simultaneously with the target and offsets a short time after the target, rather than simultaneously with it. OSM is a reduction in accuracy of reporting the target with the temporally trailing mask, compared with the simultaneously offsetting mask. It has been thought that OSM occurs only if attention cannot be rapidly focused, or prefocused, on the target location. One line of evidence for this is a reported interaction between target display set size and the duration of the trailing mask. We analyze the evidence for this interaction and suggest it occurs only as an artifact of data being compressed by a ceiling effect. We report six experiments that support this interpretation by showing that the interaction is always absent unless a ceiling effect is induced. We go on to analyze other evidence to support the notion that attention modulates OSM, and argue that in each case, the data either reflect a ceiling effect or can be explained in another way. Our data and our analyses of the existing literature have strong implications for how OSM should be conceptualized.

Dilution, not load, affects distractor processing.

Lavie and Tsal (1994) proposed that spare attentional capacity is allocated involuntarily to the processing of irrelevant stimuli, thereby enabling interference. Under this view, when task demands increase, spare capacity should decrease and distractor interference should decrease. In support, Lavie and Cox (1997) found that increasing perceptual load by increasing search set size decreased interference from an irrelevant distractor. In three experiments, we manipulated the cue set size (number of cued locations) independently of the display set size (number of letters presented). Increasing the display set size reduced distractor interference regardless of whether the additional letters were relevant to the task. In contrast, increasing the cue set size increased distractor interference. Both findings are inconsistent with the load explanation, but are consistent with a proposed two-stage dilution account.

Visual working memory for simple and complex visual stimuli

Does the magical number “four” characterize our visual working memory (VWM) capacity for all kinds of objects, or is the capacity of VWM inversely related to the perceptual complexity of those objects? To find out how perceptual complexity affects VWM and whether the observed performance limitation in change detection reflected a limitation in the perceptual or memory process, we measured the slope of visual search RT as a function of display set size to independently quantify the informational load and used a change detection task to measure VWM capacity for six types of stimuli of different complexity: colors, letters, polygons, squiggles, cubes, and faces. We found that the estimated capacity decreased for more complex stimuli, suggesting that perceptual complexity was an important factor in determining VWM capacity. However, the considerable correlation between perceptual complexity and VWM capacity declined significantly if subjects were allowed to view the sample memory display longer. Although Alvarez and Cavanagh (2004) found that informational load was an excellent predictor of change detection performance, with a correlation coefficient of .996 between visual search slope and estimated VWM capacity, our findings show that informational load only accounted for 32% of the variance in VWM capacity with a memory display duration of 3 seconds or longer, indicating that informational load was a better predictor of the estimated VWM capacity at shorter durations. Because informational load should have a constant influence on the hypothetical VWM capacity, the increased correlation suggests that at shorter presentation durations, performance was additionally limited by perception. We conclude that when encoding limitations are minimized, perceptual complexity affects, but does not determine, VWM capacity.

Frontal–parietal synchrony in elderly EEG for visual search

Aging involves selective changes in attentional control. However, its precise effect on visual attention is difficult to discern from behavioural studies alone. In this paper, we employ a recently developed phase-locking measure of synchrony as an indicator of top-down/bottom-up control of attention to assess attentional control in the elderly. Fourteen participants (63–74 years) searched for a target item (coloured, oriented rectangular bar) among a display set of distractors. For the feature search condition, where none of the distractors shared a feature with the target, search time did not increase with display set size (two, or four items). For the conjunctive search condition, where each distractor shared either a colour or orientation feature with the target, search time increased with display size. Phase-locking analysis revealed a significant increase in high gamma-band (36–56 Hz) synchrony indicating greater bottom-up control for feature than conjunctive search. In view of our earlier study on younger (21–32 years) adults (Phillips and Takeda, 2009), these results suggest that older participants are more likely to use bottom-up control of attention, possibly triggered by their greater susceptibility to attentional capture, than younger participants.

Early ERP effects on the scaling of spatial attention in visual search

This article describes the examination of the spatial ‘scaling’ effect of visual attention with the technique of event-related potential (ERP). Eighteen participants were involved in a visual search task in which the cue-target paradigm was used. The search array was three concentric circles consisting of randomly selected English letters that were equally distributed in each circle. The behavioral and ERP data were recorded, respectively. The behavioral results showed that the response time increased and the response accuracy decreased with the increase of precue size. The ERPs amplitude of P1 and N1 components evoked by search array increased with the reduction of precue size. However, the latencies of these ERP components did not show significant differences between conditions. The hierarchical data of both behavioral assessment and ERPs provided evidence for the spatial ‘scaling’ effect of visual attention. The amplitudes of P1 and N1 components may be used as indices to examine the effect of spatial ‘scaling’. In different tasks, the display-set size of stimuli and the task complexity may be important factors that affect the attention allocation.

Retinal Encoding of Ultrabrief Shape Recognition Cues

Shape encoding mechanisms can be probed by the sequential brief display of dots that mark the boundary of the shape, and delays of less that a millisecond between successive dots can impair recognition. It is not entirely clear whether this is accomplished by preserving stimulus timing in the signal being sent to the brain, or calls for a retinal binding mechanism. Two experiments manipulated the degree of simultaneity among and within dot pairs, requiring also that the pair members be in the same half of the visual field or on opposite halves, i.e., across the midline from one another. Recognition performance was impaired the same for these two conditions. The results make it likely that simultaneity of cues is being registered within the retina. A potential mechanism is suggested, calling for linkage of stimulated sites through activation of PA1 cells. A third experiment confirmed a prior finding that the overall level of recognition deficit is partly a function of display-set size, and affirmed submillisecond resolution in binding dot pairs into effective shape-recognition cues.

Changing features do not guide attention in change detection: Evidence from a spatial cuing paradigm

Smilek, Eastwood, and Merikle (2000) demonstrated that the detection of change was facilitated when the target character changed in many rather than few of its features. Specifically, the function relating search response time to display set size was shallower when more features changed than when fewer features changed. The researchers interpreted these results as indicating that large feature changes provide preattentive guidance of focal attention to the location of the change. We tested this preattentive guidance hypothesis by examining change detection performance in the context of a spatial cuing paradigm. The hypothesis predicts that (1) the cost on invalidly cued trials should be less when more features change than when fewer features change, and (2) the features manipulation should have no effect on validly cued trials. In contrast to these predictions, our results show that cuing effects are equivalent across all levels of feature change and that a robust effect of the features manipulation is observable for both validly and invalidly cued trials. We argue that large feature changes do not provide preattentive guidance and in fact can be detected more readily after attention is already in place at the target location.

Attention capacity and task difficulty in visual search

When a visual search task is very difficult (as when a small feature difference defines the target), even detection of a unique element may be substantially slowed by increases in display set size. This has been attributed to the influence of attentional capacity limits. We examined the influence of attentional capacity limits on three kinds of search task: difficult feature search (with a subtle featural difference), difficult conjunction search, and spatial-configuration search. In all 3 tasks, each trial contained sixteen items, divided into two eight-item sets. The two sets were presented either successively or simultaneously. Comparison of accuracy in successive versus simultaneous presentations revealed that attentional capacity limitations are present only in the case of spatial-configuration search. While the other two types of task were inefficient (as reflected in steep search slopes), no capacity limitations were evident. We conclude that the difficulty of a visual search task affects search efficiency but does not necessarily introduce attentional capacity limits.

Unconscious Familiarity and Local Context Effects on Low-Level Face Processing: A Reconstruction Hypothesis

A common view in face recognition research holds that there is a stored representation specific to each known face. It is also posited that semantic or memory-based information cannot influence low-level face processing. The two experiments reported in this article investigate the nature of this representation and the flow of face information processing. Participants had to search for a particular primed face among other faces. In Experiment 1, the search was done in a context where distractors had either a different degree of fame or the same degree of fame. In Experiment 2, the target face was primed either with semantic information or without any information. Both experiments demonstrated that increasing the display set size lengthened face detection time. However, the lengthening was a function of face fame. The search context also had an effect on the slope of the famous face detection. The results are explained in terms of the idea that face representations are reconstructed and that high- and low-level information are integrated into the processing. The integration process is not a conscious one.

Attention in Visual Search: Distinguishing Four Causes of a Set-Size Effect

Visual search is a common task both in naturalistic settings and in the laboratory. Outside the labora tory, one might look for a car in a parking lot, a name in text, or a nav igation marker on the horizon. In the laboratory, search is simplified in several ways; commonly, the sub ject views a set of distinct objects and is asked to detect the presence of a particular object (the target) among a set of distractors. Two ex amples are shown in Figure 1. The top two panels illustrate the contrast increment task, in which the target is a disk of high luminance and the dis tractors are disks of lower lumi nance; the bottom two panels illus trate the line bisection task, in which the target is a rotated L and the dis tractors are rotated Ts. One of the most studied aspects of visual search is the effect on per formance of the number of objects, here referred to as the display set size. Display set sizes of 2 and 24 are illustrated in Figure 1. In the top panels, the target pops out?even for a large display set size. More pre cisely, display set size has little or no effect on search time or accuracy when the target is much brighter than the distractors. In contrast, in the bottom panels, finding the target requires scrutiny for the large set size. Display set size has a large ef feet on both search time and accu

Perceptual load as a necessary condition for selective attention.

The early and late selection debate may be resolved if perceptual load of relevant information determines the selective processing of irrelevant information. This hypothesis was tested in 3 studies; all used a variation of the response competition paradigm to measure irrelevant processing when load in the relevant processing was varied. Perceptual load was manipulated by relevant display set size or by different processing requirements for identical displays. These included the requirement to process conjunctions versus isolated features and the requirement to perform simple detection of a character's presence versus difficult identification of its size and position. Distractors' interference was found only under low-load conditions. Because the distractor was usually clearly distinct from the target, it is concluded that physical separation is not a sufficient condition for selective perception; overloading perception is also required. This allows a compromise between early and late selection views and resolves apparent discrepancies in previous work.