Visual Change With Moving Displays: More Evidence for Color Feature Map Inhibition During Preview Search.

Preview search with moving stimuli was investigated. The stimuli moved in multiple directions, and preview items could change either their color or their shape before onset of the new (search) displays. In Experiments 1 and 2, the authors found that (a) a preview benefit occurred even when more than 5 moving items had to be ignored, and (b) color change, but not shape change, disrupted preview search in moving stimuli. In contrast, shape change, but not color change, disrupted preview search in static stimuli (Experiments 3 and 4). Results suggest that preview search with moving displays is influenced by inhibition of a color map, whereas preview search with static displays is influenced by inhibition of locations of old distractors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual marking and visual change.

Five experiments investigated the types of changes that disrupt the preview effect--the benefit gained in difficult search tasks from presenting some distractors earlier in time. A shape change with or without an overall luminance change at the location of an old item was found to disrupt the preview effect, whereas an equivalent luminance change alone or an isoluminant color change was not disruptive. Results suggest that (a) relatively low-level visual changes may not be sufficient to abolish the benefit, (b) the benefit most likely occurs through inhibition applied to locations within a location master map, and (c) inhibition need not be applied to surface features of objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Initial scene representations facilitate eye movement guidance in visual search.

What role does the initial glimpse of a scene play in subsequent eye movement guidance? In 4 experiments, a brief scene preview was followed by object search through the scene via a small moving window that was tied to fixation position. Experiment 1 demonstrated that the scene preview resulted in more efficient eye movements compared with a control preview. Experiments 2 and 3 showed that this scene preview benefit was not due to the conceptual category of the scene or identification of the target object in the preview. Experiment 4 demonstrated that the scene preview benefit was unaffected by changing the size of the scene from preview to search. Taken together, the results suggest that an abstract (size invariant) visual representation is generated in an initial scene glimpse and that this representation can be retained in memory and used to guide subsequent eye movements. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual marking and facial affect: Can an emotional face be ignored?

Previewing a set of distractors allows them to be ignored in a subsequent visual search task (Watson & Humphreys, 1997). Seven experiments investigated whether this preview benefit can be obtained with emotional faces, and whether negative and positive facial expressions differ in the extent to which they can be ignored. Experiments 1–5 examined the preview benefit with neutral, negative, and positive previewed faces. These results showed that a partial preview benefit occurs with face stimuli, but that the valence of the previewed faces has little impact. Experiments 6 and 7 examined the time course of the preview benefit with valenced faces. These showed that negative faces were more difficult to ignore than positive faces, but only at short preview durations. Furthermore, a full preview benefit was not obtained with face stimuli even when the preview duration was extended up to 3 s. The findings are discussed in terms of the processes underlying the preview benefit, their ecological sensitivity, and the role of emotional valence in attentional capture and guidance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When a reappearance is old news: Visual marking survives occlusion.

Performance in a visual search task becomes more efficient if half of the distractors are presented before the rest of the stimuli. This "preview benefit" may partly be due to inhibition of the old (previewed) items. The preview effect is abolished, however, if the old items offset briefly before reappearing (D. G. Watson & G. W. Humphreys, 1997). The authors examined whether this offset effect still occurred if the old item undergo occlusion. Results show that a preview benefit was found when the old items were occluded but not otherwise, consistent with the idea of top-down attentional inhibition being applied to the old items. The preview benefit is attenuated, however, by movement of the irrelevant stimuli in the displays. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatiotemporal Segregation in Visual Search: Evidence From Parietal Lesions.

The mechanisms underlying segmentation and selection of visual stimuli over time were investigated in patients with posterior parietal damage. In a modified visual search task, a preview of old objects preceded search of a new set for a target while the old items remained. In Experiment 1, control participants ignored old and prioritized new items, but patients had severe difficulties finding the target (especially on the contralesional side). In Experiment 2, simplified displays yielded analogous results, ruling out search ease as a crucial factor in poor preview search. In Experiment 3, outlines around distractor groups (to aid segmentation) improved conjunction but not preview search, suggesting a specific deficit in spatiotemporal segmentation. Experiment 4 ruled out spatial disengagement problems as a factor. The data emphasize the role of spatiotemporal segmentation cues in preview search and the parietal lobe in the role of these cues to prioritize search of new stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual marking: Dissociating effects of new and old set size.

Visual marking makes it possible to ignore old items during search. In a typical study, old items are previewed 1 s before adding an equal number of new items, one of which is the target. Previewing half of the items reduces the search slope relating response time (RT) to overall set size by half. However, this manipulation sometimes only reduces overall RT but not search slope (Experiment 1). By orthogonally varying the numbers of old and new items, Experiment 2 shows that old and new set sizes interactively affect visual marking. Given a constant new set size, the size of the old set has negligible effect on RT. However, increasing the new set size reduces the preview benefit in overall RT. Experiment 3 shows that this reduction may be restricted to paradigms that use temporal segregation cues. Studies should vary old and new set size orthogonally to avoid missing a visual marking effect where one may be present. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Interrupted visual searches reveal volatile search memory.

This study investigated memory from interrupted visual searches. Participants conducted a change detection search task on polygons overlaid on scenes. Search was interrupted by various disruptions, including unfilled delay, passive viewing of other scenes, and additional search on new displays. Results showed that performance was unaffected by short intervals of unfilled delay or passive viewing, but it was impaired by additional search tasks. Across delays, memory for the spatial layout of the polygons was retained for future use, but memory for polygon shapes, background scene, and absolute polygon locations was not. The authors suggest that spatial memory aids interrupted visual searches, but the use of this memory is easily disrupted by additional searches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preview Search and Contextual Cuing.

We investigated the effect of contextual cuing (M. M. Chun & Y. Jiang, 1998) within the preview paradigm (D. G. Watson & G. W. Humphreys, 1997). Contextual cuing was shown with a 10-item letter search but not with more crowded 20-item displays. However, contextual learning did occur in a preview procedure in which 10 preview items were followed by 10 new items. Repeating the new items alone did not generate contextual learning, but repeating the preview items alone did, as long as they had a consistent spatial relation with the target. This was not merely due to the onset of the preview items being associated with the target location. No learning effect took place with a preview of homogeneous items that competed less for selection with new stimuli. The results provide evidence for old items being processed in preview search and providing a context for subsequent search of new items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual marking and change blindness: Moving occluders and transient masks neutralize shape changes to ignored objects.

Visual search efficiency improves by presenting (previewing) one set of distractors before the target and remaining distractor items (D. G. Watson & G. W. Humphreys, 1997). Previous work has shown that this preview benefit is abolished if the old items change their shape when the new items are added (e.g., D. G. Watson & G. W. Humphreys, 2002). Here we present 5 experiments that examined whether such object changes are still effective in recapturing attention if the changes occur while the previewed objects are occluded or masked. Overall, the findings suggest that masking transients are effective in preventing both object changes and the presentation of new objects from capturing attention in time-based visual search conditions. The findings are discussed in relation to theories of change blindness, new object capture, and the ecological properties of time-based visual selection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual marking: Selective attention to asynchronous temporal groups.

In visual search, when a subset of distractors is previewed 1 s before the target and the remaining distractors, search speed is independent of the number of previewed items. This is visual marking. What allows old items to be marked? Four experiments show that marking is disrupted if the onset of the new items is accompanied by synchronous changes to the old items, but it is not disrupted by changes restricted to the background or by asynchronous changes to the old items. Further, behaviorally relevant old items can be prioritized over new items. Visual marking is based on temporal asynchrony between new and old items, which allows segregation of these items into 2 temporal groups. Attention is then selectively applied to 1 group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Superior visual search in autism.

Children with a diagnosis of autism and normally developing children, matched for age and general ability, were tested on a series of visual search tasks in 2 separate experiments. The children with autism performed better than the normally developing children on difficult visual search tasks,. This result occurred regardless of whether the target was uniquely defined by a single feature or a conjunction of features, as long as ceiling effects did not mask the difference. Superior visual search performance in autism can be seen as analogous to other reports of enhanced unique item detection in autism. Unique item detection in autism is discussed in the light of mechanisms proposed to be involved in normal visual search performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Parallel Processing in Visual Search Asymmetry.

The difficulty of visual search may depend on assignment of the same visual elements as targets and distractors-search asymmetry. Easy C-in-O searches and difficult O-in-C searches are often associated with parallel and serial search, respectively. Here, the time course of visual search was measured for both tasks with speed-accuracy methods. The time courses of the 2 tasks were similar and independent of display size. New probabilistic parallel and serial search models and sophisticated-guessing variants made predictions about time course and accuracy of visual search. The probabilistic parallel model provided an excellent account of the data, but the serial model did not. Asymptotic search accuracies and display size effects were consistent with a signal-detection analysis, with lower variance encoding of Cs than Os. In the absence of eye movements, asymmetric visual search, long considered an example of serial deployment of covert attention, is qualitatively and quantitatively consistent with parallel search processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Active control of locomotion facilitates nonvisual navigation.

In some navigation tasks, participants are more accurate if they view the environment beforehand. To characterize the benefits associated with visual previews, 32 blindfolded participants were guided along simple paths and asked to walk unassisted to a specified destination (e.g., the origin). Paths were completed without vision, with or without a visual preview of the environment. Previews did not necessarily improve nonvisual navigation. When previewed landmarks stood near the origin or at off-path locations, they provided little benefit; by contrast, when they specified intermediate destinations (thereby increasing the degree of active control), performance was greatly enhanced. The results suggest that the benefit of a visual preview stems from the information it supplies for actively controlled locomotion. Accuracy in reaching the final destination, however, is strongly contingent upon the destination's location during the preview. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for where, but not what, is used during visual search.

Although the role of memory in visual search is debatable, most researchers agree with a limited-capacity model of memory in visual search. The authors demonstrate the role of memory by replicating previous findings showing that visual search is biased away from old items (previously examined items) and toward new items (nonexamined items). Furthermore, the authors examined the type of memory representations used to bias search by changing an item's individuating feature or location during search. Changing the individuating feature of an item did not disrupt normal search biases. However, when the location of an item changed, normal search biases were disrupted. These results suggest that memory used in visual search is based on items' locations rather than their identity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search in a multi-element asynchronous dynamic (MAD) world.

In visual search tasks participants search for a target among distractors in strictly controlled displays. We show that visual search principles observed in these tasks do not necessarily apply in more ecologically valid search conditions, using dynamic and complex displays. A multi-element asynchronous dynamic (MAD) visual search was developed in which the stimuli could either be moving, stationary, and/or changing in luminance. The set sizes were high and participants did not know the specific target template. Experiments 1 through 4 showed that, contrary to previous studies, search for moving items was less efficient than search for static items and targets were missed a high percentage of the time. However, error rates were reduced when participants knew the exact target template (Experiment 5) and the difference in search efficiency for moving and stationary targets disappeared when lower set sizes were used (Experiment 6). In all experiments there was no benefit to finding targets defined by a luminance change. The data show that visual search principles previously shown in the literature do not apply to these more complex and “realistically” driven displays. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Attentional resources in timing: interference effects in concurrent temporal and nontemporal working memory tasks

Three experiments examined interference effects in concurrent temporal and nontemporal tasks. The timing task in each experiment required subjects to generate a series of 2- or 5-sec temporal productions. The nontemporal tasks were pursuit rotor tracking (Experiment 1), visual search (Experiment 2), and mental arithmetic (Experiment 3). Each nontemporal task had two levels of difficulty. All tasks were performed under both single- and dual-task conditions. A simple attentional allocation model predicts bidirectional interference between concurrent tasks. The main results showed the classic interference effect in timing. That is, the concurrent nontemporal tasks caused temporal productions to become longer (longer productions represent a shortening of perceived time) and/or more variable than did timing-only conditions. In general, the difficult version of each nontemporal task disrupted timing more than the easier version. The timing data also exhibited a serial lengthening effect, in which temporal productions became longer across trials. Nontemporal task performance showed a mixed pattern. Tracking and visual search were essentially unaffected by the addition of a timing task, whereas mental arithmetic was disrupted by concurrent timing. These results call for a modification of the attentional allocation model to incorporate the idea of specialized processing resources. Two major theoretical frameworks--multiple resource theory and the working memory model--are critically evaluated with respect to the resource demands of timing and temporal/nontemporal dual-task performance.     

The preattentive emperor has no clothes: A dynamic redressing.

Preattentive models of early vision have not been supported by the evidence. Instead, an input filtering system, which is dynamically reconfigured so as to optimize performance on the task at hand, is proposed. As a case in point, the authors examined Sagi and Julesz's (1985a) claim that detection tasks are processed preattentively and efficiently (shallow search slopes), whereas discrimination tasks require focal attention and yield inefficient steep slopes. In 5 visual search experiments, efficiency was found to depend not on the nature of the task but on whether the task is single or dual. The second component of a dual task, whether detection or discrimination, is performed inefficiently if it does not fit the configuration of the input system, which had been set optimally for the first component. But, even the second component is processed efficiently if there is enough time to reconfigure the system after processing the first component. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fast color grouping and slow color inhibition: Evidence for distinct temporal windows for separate processes in preview search.

The authors report 4 experiments that examined color grouping and negative carryover effects in preview search via a probe detection task (J. J. Braithwaite, G. W. Humphreys, & J. Hodsoll, 2003). In Experiment 1, there was evidence of a negative color carryover from the preview to new items, using both search and probe detection measures. There was also a negative bias against probes on old items that carried the majority color in the preview. With a short preview duration (150 ms) carryover effects to new items were greatly reduced, but probe detection remained biased against the majority color in the old items. Experiments 2 and 4 showed that the color bias effects on old items could be reduced when these items had to be prioritized relative to being ignored. Experiment 3 tested and rejected the idea that variations in the probability of whether minority or majority colors were probed were crucial. These results show that the time course of color carryover effects can be separated from effects of early color grouping in the preview display: Color grouping is fast, and inhibitory color carryover effects are slow. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prioritized Selection in Visual Search Through Onset Capture and Color Inhibition: Evidence From a Probe-Dot Detection Task.

Observers performed a preview search task in which, on some trials, they had to indicate the presence of a briefly presented probe-dot. Probes could be presented on locations corresponding to old or new elements and prior to or after the presentation of the new elements. After the presentation of the new elements, probes were generally detected faster on new than on old locations, indicating prioritized selection of new elements. Prior to the presentation of the new elements, probes were detected faster on new than on old locations only when old and new elements differed in color. These results suggest that prioritized selection of new elements is mediated not by visual marking but by onset capture. Additionally, observers may apply color-based inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)