Does contextual cuing guide the deployment of attention?

Contextual cuing experiments show that when displays are repeated, reaction times to find a target decrease over time even when observers are not aware of the repetition. It has been thought that the context of the display guides attention to the target. The authors tested this hypothesis by comparing the effects of guidance in a standard search task with the effects of contextual cuing. First, in standard search, an improvement in guidance causes search slopes (derived from Reaction Time × Set Size functions) to decrease. In contrast, the authors found that search slopes in contextual cuing did not become more efficient over time (Experiment 1). Second, when guidance was optimal (e.g., in easy feature search), they still found a small but reliable contextual cuing effect (Experiments 2a and 2b), suggesting that other factors, such as response selection, contribute to the effect. Experiment 3 supported this hypothesis by showing that the contextual cuing effect disappeared when the authors added interference to the response selection process. Overall, the data suggest that the relationship between guidance and contextual cuing is weak and that response selection can account for part of the effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thinking about the weather: How display salience and knowledge affect performance in a graphic inference task.

Three experiments examined how bottom-up and top-down processes interact when people view and make inferences from complex visual displays (weather maps). Bottom-up effects of display design were investigated by manipulating the relative visual salience of task-relevant and task-irrelevant information across different maps. Top-down effects of domain knowledge were investigated by examining performance and eye fixations before and after participants learned relevant meteorological principles. Map design and knowledge interacted such that salience had no effect on performance before participants learned the meteorological principles; however, after learning, participants were more accurate if they viewed maps that made task-relevant information more visually salient. Effects of display design on task performance were somewhat dissociated from effects of display design on eye fixations. The results support a model in which eye fixations are directed primarily by top-down factors (task and domain knowledge). They suggest that good display design facilitates performance not just by guiding where viewers look in a complex display but also by facilitating processing of the visual features that represent task-relevant information at a given display location. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Input control processes in rapid serial visual presentations: Target selection and distractor inhibition.

The attentional blink refers to the finding that the 2nd of 2 targets embedded in a stream of rapidly presented distractors is often missed. Whereas most theories of the attentional blink focus on limited-capacity processes that occur after target selection, the present work investigates the selection process itself. Identifying a target letter caused an attentional blink for the enumeration of subsequent dot patterns, but this blink was reduced when the dots shared their color with the target letter. In contrast, performance worsened when the color of the dots matched that of the remaining distractors in the stream. Similarity between the targets also affected competition between different sets of dots presented simultaneously within a single display. The authors conclude that the selection of targets from a rapid serial visual presentation stream is mediated by both excitatory and inhibitory attentional control mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serial and parallel attentive visual searches: Evidence from cumulative distribution functions of response times.

Participants searched a visual display for a target among distractors. Each of 3 experiments tested a condition proposed to require attention and for which certain models propose a serial search. Serial versus parallel processing was tested by examining effects on response time means and cumulative distribution functions. In 2 conditions, the results suggested parallel rather than serial processing, even though the tasks produced significant set-size effects. Serial processing was produced only in a condition with a difficult discrimination and a very large set-size effect. The results support C. Bundesen's (1990) claim that an extreme set-size effect leads to serial processing. Implications for parallel models of visual selection are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual search performance among persons with schizophrenia as a function of target eccentricity.

The current study investigated one possible mechanism of impaired visual attention among patients with schizophrenia: a reduced visual span. Visual span is the region of the visual field from which one can extract information during a single eye fixation. This study hypothesized that schizophrenia-related visual search impairment is mediated, in part, by a smaller visual span. To test this hypothesis, 23 patients with schizophrenia and 22 healthy controls completed a visual search task where the target was pseudorandomly presented at different distances from the center of the display. Response times were analyzed as a function of search condition (feature vs. conjunctive), display size, and target eccentricity. Consistent with previous reports, patient search times were more adversely affected as the number of search items increased in the conjunctive search condition. It was important however, that patients’ conjunctive search times were also impacted to a greater degree by target eccentricity. Moreover, a significant impairment in patients’ visual search performance was only evident when targets were more eccentric and their performance was more similar to healthy controls when the target was located closer to the center of the search display. These results support the hypothesis that a narrower visual span may underlie impaired visual search performance among patients with schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When visual marking meets the attentional blink: More evidence for top-down, limited-capacity inhibition.

An attentional blink (AB) paradigm was used to investigate the attentional resources necessary for visual marking. The results showed that distractors presented inside the AB cannot easily be ignored despite participants anticipating a future target display. This supports the hypothesis that attentional resources are required for visual marking. In addition, probe dots were better detected on blinked distractors than on successfully ignored distractors, but only when the task required new items to be prioritized. In a final experiment, a stronger negative carry-over effect on search occurred for targets identical to distractors presented outside rather than inside the AB. This suggests that at least part of the inhibitory processes involved in visual marking are nonspatial. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evidence against early selection: Stimulus quality effects in previewed displays.

H. Pashler (see record 1985-05791-001) reported that when Ss identified a probed letter in a display of 8 characters, the effect of stimulus quality on reaction time (RT) persisted full blown even when Ss had 300 msec to preprocess the display. Pashler argued that these results are incompatible with theories of late selection but that they are naturally accommodated by the ones of early selection. The authors report 14 experiments using Pashler's methodology in which the effects of stimulus quality were reliably attenuated with a preview of the letter array. Pashler's results were also replicated, but only under a narrow set of conditions. Several "early selection" accounts of the interaction of probe delay with stimulus quality were examined and rejected in favor of a late selection account. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute and critical care in neurology

When subjects select a prime from a visual display while leaving a distractor prime unselected, response time (RT) or response accuracy to a subsequent probe may be impeded if the distractor prime and probe are identical, or if they are related to one another. This phenomenon, negative priming (NP), has obvious implications for understanding perceptual selection. However, it is not known whether NP results from other kinds of selection processes. The present studies were designed to investigate whether NP occurs when primes are selected from working memory rather than from a visual display. In the two experiments, the subjects memorized two primes, selected one prime for further processing, and classified the contents of a probe display. Significant NP occurred in both Experiments. In Experiment 2, however, NP occurred only under easy-selection conditions; the effect was reversed under difficult-selection conditions. The findings indicate a role for NP in memory processing, but contrast with the results from perceptual selection studies showing greater NP under difficult-selection than under easy-selection conditions. The present finding suggests a complex and perhaps strategy-dependent relationship between memory selection difficulty and NP.     

Underlying Processes in the Implicit Association Test: Dissociating Salience From Associations.

The authors investigated whether effects of the Implicit Association Test (IAT) are influenced by salience asymmetries, independent of associations. Two series of experiments analyzed unique effects of salience by using nonassociated, neutral categories that differed in salience. In a 3rd series, salience asymmetries were manipulated experimentally while holding associations between categories constant. In a 4th series, valent associations of the target categories were manipulated experimentally while holding salience asymmetries constant. Throughout, IAT effects were found to depend on salience asymmetries. Additionally, salience asymmetries between categories were assessed directly with a visual search task to tionally, provide an independent criterion of salience asymmetries. Salience asymmetries corresponded to IAT effects and also accounted for common variance in IAT effects and explicit measures of attitudes or the self-concept. (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)     

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)     

Priming reveals attentional modulation of human motion sensitivity

Although recent fMRI and single unit recording studies have shown that attention modulates neural activity in motion sensitive areas of extrastriate cortex, these approaches cannot reveal qualitative or quantitative effects of attention on perception of motion. To investigate this, we asked observers to select one of two orthogonal directions in a brief, transparent dot display (prime) and then measured their sensitivity to global directional motion in a second uni-directional dot display (probe) presented a short time later. When probe direction matched the attended prime direction, sensitivity was degraded. But, when probe direction matched the ignored prime direction, sensitivity was enhanced, even though both components were of equal physical strength. Sensitivity was unchanged for directions opposite to either previously seen direction. Neither sensory adaptation nor opponent direction mechanisms can account for these data. Rather, processes initiated by visual selection must underlie these dramatic changes in motion sensitivity.     

Learning by selection: Visual search and object perception in young infants.

The authors examined how visual selection mechanisms may relate to developing cognitive functions in infancy. Twenty-two 3-month-old infants were tested in 2 tasks on the same day: perceptual completion and visual search. In the perceptual completion task, infants were habituated to a partly occluded moving rod and subsequently presented with unoccluded broken and complete rod test stimuli. In the visual search task, infants viewed displays in which single targets of varying levels of salience were cast among homogeneous static vertical distractors. Infants whose posthabituation preference indicated unity perception in the completion task provided evidence of a functional visual selective attention mechanism in the search task. The authors discuss the implications of the efficiency of attentional mechanisms for information processing and learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Role of Stimulus-Driven and Goal-Driven Control in Saccadic Visual Selection.

Four experiments were conducted to investigate the role of stimulus-driven and goal-driven control in saccadic eye movements. Participants were required to make a speeded saccade toward a predefined target presented concurrently with multiple nontargets and possibly 1 distractor. Target and distractor were either equally salient (Experiments 1 and 2) or not (Experiments 3 and 4). The results uniformly demonstrated that fast eye movements were completely stimulus driven, whereas slower eye movements were goal driven. These results are in line with neither a bottom-up account nor a top-down notion of visual selection. Instead, they indicate that visual selection is the outcome of 2 independent processes, one stimulus driven and the other goal driven, operating in different time windows. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How many locations can be selected at once?

The visual system uses several tools to select only the most relevant visual information for further processing, including selection by location. In the present study, the authors explored how many locations can be selected at once. Although past evidence from several visual tasks suggests that the visual system can operate on a fixed number of 4 objects or locations at once, the authors found that this capacity varies widely in response to the precision of selection required by the task. When the authors required precise selection regions, only 2-3 locations could be selected. But when the selection regions could be coarser, up to 6-7 locations could be selected. The authors discuss potential mechanisms underlying the selection of multiple locations and review the evidence for fixed limits in visual attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory for Timing Visual and Auditory Signals in Albino and Pigmented Rats.

The authors hypothesized that during a gap in a timed signal, the time accumulated during the pregap interval decays at a rate proportional to the perceived salience of the gap, influenced by sensory acuity and signal intensity. When timing visual signals, albino (Sprague-Dawley) rats, which have poor visual acuity, stopped timing irrespective of gap duration, whereas pigmented (Long-Evans) rats, which have good visual acuity, stopped timing for short gaps but reset timing for long gaps. Pigmented rats stopped timing during a gap in a low-intensity visual signal and reset after a gap in a high-intensity visual signal, suggesting that memory for time in the gap procedure varies with the perceived salience of the gap, possibly through an attentional mechanism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Online response preparation in a rapid serial visual search task.

Online response preparation was assessed in a visual search task using rapid serial visual presentation. In each trial, a series of letters was presented sequentially, and participants were instructed to make a target-present response if a prespecified target letter was presented or a target-absent response if it was not. Measurements of response preparation using both probe reaction time and the lateralized readiness potential indicated that preparation of the target-absent response increased near the end of the sequence. Most of the increase appeared to be due to direct priming of the target-absent response by nontarget letters, but part was due to the increased conditional probability of this response near the end of the sequence. These results extend previous studies of response preparation by showing online response preparation during a temporally extended reaction time task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Crossmodal semantic priming by naturalistic sounds and spoken words enhances visual sensitivity.

We propose a multisensory framework based on Glaser and Glaser's (1989) general reading-naming interference model to account for the semantic priming effect by naturalistic sounds and spoken words on visual picture sensitivity. Four experiments were designed to investigate two key issues: First, can auditory stimuli enhance visual sensitivity when the sound leads the picture as well as when they are presented simultaneously? And, second, do naturalistic sounds (e.g., a dog's “woofing”) and spoken words (e.g., /d?g/) elicit similar semantic priming effects? Here, we estimated participants' sensitivity and response criterion using signal detection theory in a picture detection task. The results demonstrate that naturalistic sounds enhanced visual sensitivity when the onset of the sounds led that of the picture by 346 ms (but not when the sounds led the pictures by 173 ms, nor when they were presented simultaneously, Experiments 1-3A). At the same SOA, however, spoken words did not induce semantic priming effects on visual detection sensitivity (Experiments 3B and 4A). When using a dual picture detection/identification task, both kinds of auditory stimulus induced a similar semantic priming effect (Experiment 4B). Therefore, we suggest that there needs to be sufficient processing time for the auditory stimulus to access its associated meaning to modulate visual perception. Besides, the interactions between pictures and the two types of sounds depend not only on their processing route to access semantic representations, but also on the response to be made to fulfill the requirements of the task. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Identification and localization in tachistoscopic recognition: The effects of data- and resource-limitations.

Examined the effects of data- and resource-limits on mislocation and intrusion errors in a visual probe task. Mislocation errors were defined as responses to any letter that appeared in the test display but not in the position cued; intrusions were responses with letters that did not appear in the test display. Ss were 42 undergraduates with normal vision. Exp I manipulated the data-limits by changing both luminance and duration, and confirmed that decreasing stimulus energy increases intrusions and decreases the benefit of selective attention instructions. Exps II and III manipulated resource-limits by varying display size and the size of a defined subset of a display and showed that this manipulation primarily affected mislocation errors. Exp IV tested a minor point pertaining to the cue used in the previous studies. Results suggest that these errors may reflect 2 different processing operations, and that complete recognition of any visual stimulus involves both processes. (French abstract) (38 ref) (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)