Dual-target Search Research Articles

High task demand in dual-target paradigm redirects experimentally increased anxiety to uphold goal-directed attention.

Previous research has shown that state anxiety facilitates stimulus-driven attentional capture and impairs goal-directed attentional control by increasing sensitivity to salient distractors or threat cues or narrowing spatial attention. However, recent findings in this area have been mixed, and less is known about how state-dependent anxiety may affect attentional performance. Here, we employed a novel dual-target search paradigm to investigate this relationship. This paradigm allowed us to investigate attentional control and how focus narrows under different anxiety states. Participants watched a short movie-either anxiety-inducing or neutral-before engaging in the dual-target visual search task. We found that they performed faster and more accurately in trials without the salient distractor compared to those with distractors, and they performed better in tasks presented on the center than the periphery. However, despite a significant increase in self-reported anxiety in the anxiety-inducing session, participants' performance in terms of speed and accuracy remain comparable across both anxious and neutral sessions. This resilience is likely due to compensatory mechanisms that offset anxiety, a result of the high demands and working memory load inherent in the dual-target task.

The specificity of feature-based attentional guidance is equivalent under single- and dual-target search.

Individuals actively maintain attentional templates to prioritize target-matching inputs. While previous works have established that multiple templates can be held simultaneously, current understanding is limited with respect to the representational quality of such templates. We thus investigated: (a) whether the maintenance of two templates is limited to broad, coarse-grained representations, and if not, (b) whether there is nonetheless a decline in the achievable level of specificity when multiple attentional templates are held simultaneously. Using a spatial cueing procedure, we probed the breadth of attentional templates while participants maintained either one (Experiment 1) or two target colors (Experiment 2) under conditions of low- or high-similarity search and found specific template maintenance during high-similarity search for both single- and dual-target conditions. We then directly compared template specificity during single- and dual-target maintenance in Experiment 3, probing at the point of differentiation between target and nontarget feature values observed during single-target search. Here we found no difference in the selectivity of cue validity effects between single- and dual-target search, suggesting equivalent template specificity regardless of whether one or two features are relevant to search. Lastly, in Experiment 4, we established that such template specificity is dependent on access to visual working memory. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The allocation of working memory resources determines the efficiency of attentional templates in single- and dual-target search

The allocation of working memory resources determines the efficiency of attentional templates in single- and dual-target search

The allocation of working memory resources determines the efficiency of attentional templates in single- and dual-target search.

Attentional templates are representations of target features in working memory (WM). Although two attentional templates can guide visual search in dual-target search, search efficiency is reduced compared with one attentional template in single-target search. Here, we investigated whether the allocation of WM resources contributes to these differences. Participants always memorized two colors, but the use of the corresponding WM representations varied. In the blocked conditions, the two colors were either maintained as attentional templates for dual-target search or as simple WM representations for recall only. In the mixed condition, one color was maintained as an attentional template for single-target search and the other as a simple WM representation for recall only. Reaction times (RTs) were delayed and recall precision reduced with two attentional templates in the blocked condition compared with one attentional template in the mixed condition, indicating that search efficiency and WM resources decreased in dual- compared with single-target search. Moreover, the attentional template was always recalled more precisely than the simple WM representation in the mixed condition, despite lowered visual search frequency (Experiment 2) and retro-cueing (Experiment 3). Consistent with the existence of an "active" WM state, resources were strongly biased toward the attentional template in single-target search. In dual-target search, however, resources were balanced between two attentional templates and flexibly adjusted with retro-cues, as with two simple WM representations. Therefore, the allocation of WM resources goes beyond the traditional dichotomy between "active" and "accessory" WM states and explains how attentional templates guide visual search with variable efficiency. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Supplemental Material for The Allocation of Working Memory Resources Determines the Efficiency of Attentional Templates in Single- and Dual-Target Search

Supplemental Material for The Allocation of Working Memory Resources Determines the Efficiency of Attentional Templates in Single- and Dual-Target Search

Top-down influences on working memory representations of faces: Evidence from dual-target visual search.

Variability in appearance across different images of the same unfamiliar face often causes participants to perceive different faces. Because perceptual information is not sufficient to link these encounters, top-down guidance may be critical in the initial stages of face learning. Here, we examine the interaction between top-down guidance and perceptual information when forming memory representations of unfamiliar faces. In two experiments, we manipulated the names associated with images of a target face that participants had to find in a search array. In Experiment 1, wrongly labelling two images of the same face with different names resulted in more errors relative to when the faces were labelled correctly. In Experiment 2, we compared this cost of mislabelling with the established "dual-target search cost," where searching for two targets produces more search errors relative to one target. We found search costs when searching for two different faces, but not when searching for mislabelled images of the same face. Together, these results suggest that perceptual and semantic information interact when we form face memory representations. Mislabelling the identity of perceptually similar faces does not cause dual representations to be created, but rather it impedes the process of forming a single robust representation.

Dual target search: Attention tuned to relative features, both within and across feature dimensions.

Current models of attention propose that we can tune attention in a top-down controlled manner to a specific feature value (e.g., shape, color) to find specific items (e.g., a red car; feature-specific search). However, subsequent research has shown that attention is often tuned in a context-dependent manner to the relative features that distinguish a sought-after target from other surrounding nontarget items (e.g., larger, bluer, and faster; relational search). Currently, it is unknown whether search will be feature-specific or relational in search for multiple targets with different attributes. In the present study, observers had to search for 2 targets that differed either across 2 stimulus dimensions (color, motion; Experiment 1) or within the same stimulus dimension (color; Experiment 2: orange/redder or aqua/bluer). We distinguished between feature-specific and relational search by measuring eye movements to different types of irrelevant distractors (e.g., relatively matching vs. feature-matching). The results showed that attention was biased to the 2 relative features of the targets, both across different feature dimensions (i.e., motion and color) and within a single dimension (i.e., 2 colors; bluer and redder). The results were not due to automatic intertrial effects (dimension weighting or feature priming), and we found only small effects for valid precueing of the target feature, indicating that relational search for two targets was conducted with relative ease. This is the first demonstration that attention is top-down biased to the relative target features in dual target search, which shows that the relational account generalizes to multiple target search. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

The relationship between working memory and the dual-target cost in visual search guidance.

Searching for two targets produces a dual-target cost compared with single-target search, with reduced attentional guidance toward targets (Stroud, Menneer, Cave, & Donnelly, 2012). We explore the effect of holding a color in working memory (WM) on guidance in single-target search. In Experiments 1 and 2, participants searched for a T of a specific color while holding one of the following in WM: a color patch, a letter, a dot pattern, or an oriented bar. Only when holding a color in WM was guidance in single-target search affected as strongly as it is in dual-target search. In Experiment 3, the target changed color from trial to trial. A color in WM reduced guidance, but not to the extent of dual-target search. However, search and WM error rates were high, suggesting interference and incomplete engagement with the combined task. We conclude that the guidance cost in dual-target search is not solely due to attentional capture by the WM-color, because the WM-color can be effectively separated from search color, with little confusion between the two. However, WM load does cause substantial interference in guidance when both tasks involve color. These results illustrate the complex interactions between WM and attentional guidance. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The allocation of resources in visual working memory and multiple attentional templates.

In a visual search task, sensory input is matched to a representation of the search target in visual working memory (VWM). This representation is referred to as attentional template. We investigated the conditions that allow for more than a single attentional template. The attentional template of color targets was measured by means of the contingent attentional capture paradigm. We found that attentional templates did not differ between search with 1 and 2 memorized target colors, suggesting that dual target search allowed for multiple attentional templates. In the same paradigm, we asked participants to memorize target and distractor color with equal precision. Both were presented before the search task. An attentional template was set up for the target, but not for the distractor color, suggesting that keeping a color in VWM does not automatically result in the creation of multiple attentional templates. Importantly, the precision of recall of the distractor color was worse than the precision of recall of the target color, regardless of instructions, suggesting that participants always allocated fewer VWM resources to the distractor color. Thus, 2 attentional templates may be set up, but only when the 2 colors receive an equal amount of resources in VWM (i.e., in dual target search). In contrast, when 1 item is deprioritized because of task demands, it receives fewer resources in VWM and multiple attentional templates cannot be established. Thus, unequal roles in the search task prevented the simultaneous operation of multiple attentional templates in VWM. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Pressure sensitive paint image registration combined with gray level information

Pressure-sensitive paint technology is a wind tunnel pressure measurement frontier technology with high economical efficiency and high speed. In the wind tunnel test, due to the strong wind, the model will be distorted, making the wind image and the windless image difficult to register, which will seriously affect the pressure measurement accuracy. In response to this problem, this paper innovatively applies the two-dimensional non-rigid iterative closest point (ICP) algorithm to solve this problem. The point cloud method is used to make the image detail area to be effectively registered, and it is also conducive to the subsequent three-dimensional reconstruction work. However, due to the two-dimensional non-rigid ICP algorithm, only the two-dimensional coordinate positional relationship is considered. The correlation of the pixel grayscales of the pressure-sensitive paint image is neglected, so that the registration accuracy is not too high. However, if the three-dimensional non-rigid ICP algorithm is directly used, misregistration will occur. Therefore, in order to further improve the registration accuracy, this paper proposes a non-rigid ICP algorithm based on pixel-based search strategy. The algorithm designs a dual-target search strategy that takes 2D coordinates and pixel gray values into consideration and achieves accurate local matching, realizing point search and double goal optimization. The algorithm of this paper is compared with five registration algorithms on multiple sets of pressure sensitive paint images. The experimental results show that the proposed algorithm has the best registration accuracy. Compared to the suboptimal algorithm, the RMSE is improved by more than 15% and the NMI is increased by about 5%.

The Influence of Training with One or Two Faces on Dual-Target Face Search

The Influence of Training with One or Two Faces on Dual-Target Face Search

Dual Target Search is Neither Purely Simultaneous nor Purely Successive.

Previous research shows that visual search for two different targets is less efficient than search for a single target. Stroud, Menneer, Cave and Donnelly (2012) concluded that two target colours are represented separately based on modeling the fixation patterns. Although those analyses provide evidence for two separate target representations, they do not show whether participants search simultaneously for both targets, or first search for one target and then the other. Some studies suggest that multiple target representations are simultaneously active, while others indicate that search can be voluntarily simultaneous, or switching, or a mixture of both. Stroud et al.'s participants were not explicitly instructed to use any particular strategy. These data were revisited to determine which strategy was employed. Each fixated item was categorised according to whether its colour was more similar to one target or the other. Once an item similar to one target is fixated, the next fixated item is more likely to be similar to that target than the other, showing that at a given moment during search, one target is generally favoured. However, the search for one target is not completed before search for the other begins. Instead, there are often short runs of one or two fixations to distractors similar to one target, with each run followed by a switch to the other target. Thus, the results suggest that one target is more highly weighted than the other at any given time, but not to the extent that search is purely successive.

Dual-target cost in visual search for multiple unfamiliar faces.

The efficiency of visual search for one (single-target) and either of two (dual-target) unfamiliar faces was explored to understand the manifestations of capacity and guidance limitations in face search. The visual similarity of distractor faces to target faces was manipulated using morphing (Experiments 1 and 2) and multidimensional scaling (Experiment 3). A dual-target cost was found in all experiments, evidenced by slower and less accurate search in dual- than single-target conditions. The dual-target cost was unequal across the targets, with performance being maintained on one target and reduced on the other, which we label "preferred" and "non-preferred" respectively. We calculated the capacity for each target face and show reduced capacity for representing the non-preferred target face. However, results show that the capacity for the non-preferred target can be increased when the dual-target condition is conducted after participants complete the single-target conditions. Analyses of eye movements revealed evidence for weak guidance of fixations in single-target search, and when searching for the preferred target in dual-target search. Overall, the experiments show dual-target search for faces is capacity- and guidance-limited, leading to superior search for 1 face over the other in dual-target search. However, learning faces individually may improve capacity with the second face. (PsycINFO Database Record

Faster than the speed of rejection: Object identification processes during visual search for multiple targets.

When engaged in a visual search for two targets, participants are slower and less accurate in their responses, relative to their performance when searching for singular targets. Previous work on this "dual-target cost" has primarily focused on the breakdown of attentional guidance when looking for two items. Here, we investigated how object identification processes are affected by dual-target search. Our goal was to chart the speed at which distractors could be rejected, to assess whether dual-target search impairs object identification. To do so, we examined the capacity coefficient, which measures the speed at which decisions can be made, and provides a baseline of parallel performance against which to compare. We found that participants could search at or above this baseline, suggesting that dual-target search does not impair object identification abilities. We also found substantial differences in performance when participants were asked to search for simple versus complex images. Somewhat paradoxically, participants were able to reject complex images more rapidly than simple images. We suggest that this reflects the greater number of features that can be used to identify complex images, a finding that has important consequences for understanding object identification in visual search more generally.

Correction: Attentional Control via Parallel Target-Templates in Dual-Target Search

Correction: Attentional Control via Parallel Target-Templates in Dual-Target Search

Attentional control via parallel target-templates in dual-target search.

Simultaneous search for two targets has been shown to be slower and less accurate than independent searches for the same two targets. Recent research suggests this ‘dual-target cost’ may be attributable to a limit in the number of target-templates than can guide search at any one time. The current study investigated this possibility by comparing behavioural responses during single- and dual-target searches for targets defined by their orientation. The results revealed an increase in reaction times for dual- compared to single-target searches that was largely independent of the number of items in the display. Response accuracy also decreased on dual- compared to single-target searches: dual-target accuracy was higher than predicted by a model restricting search guidance to a single target-template and lower than predicted by a model simulating two independent single-target searches. These results are consistent with a parallel model of dual-target search in which attentional control is exerted by more than one target-template at a time. The requirement to maintain two target-templates simultaneously, however, appears to impose a reduction in the specificity of the memory representation that guides search for each target.

Visual Searches Need Their Own Personal Space: The Importance of Spacing Between Simultaneously Presented Search Arrays.

Visual search, the process of looking for targets amongst distractors, is an everyday activity executed in a variety of contexts. While searches are often mundane (e.g., looking for your keys) they can also be highly important (e.g., airport baggage screeners looking for contraband). Considerable research has examined the nature of visual search accuracy, but how well do the results generalize to real-world visual searches? For example, most cognitive psychology experiments present observers with a single search array and assess how quickly and accurately target(s) are found. However, airport baggage screeners often view displays that contain multiple search arrays (i.e., several bags on the same x-ray monitor), and these search arrays can be close together and/or appear physically connected (e.g., when passengers shove their bags into the x-ray machine). Here we investigated how accuracy is affected when multiple search arrays are simultaneously present, and whether spacing between arrays impacts performance. Experiment 1 presented 3 search arrays, either spaced close together (5-pixel separation) or far apart (100-pixel separation), and each array could contain 0, 1, or 2 targets. Trials progressed by having the arrays physically shift to the edge of the monitor as if on a conveyor belt, and participants were to only search the center array before advancing. Array spacing did not impact response time or accuracy on single- and no-target trials, but did affect dual-target trials: second target accuracy (after having found a first target in the same array) was significantly worse when the arrays were close together than far apart. Experiment 2 compared trials with 3 far-spaced arrays to trials with only a single array, and there were no response time or accuracy differences. Collectively, the results suggest that search array spacing can negatively impact accuracy for dual-target search, which is a particularly complex search process. Meeting abstract presented at VSS 2013

A unilateral field advantage in visual search and detection

Superior visual processing of information distributed across hemifields than in a single hemifield (bilateral field advantage) has been reported in tasks that require parallel processing (e.g. Sereno & Kosslyn, 1991). This study comprises a series of experiments exploring hemifield effects in visual search and detection. Experiment 1 explored the hemifield effect on dual-target search, in which subjects searched for two designated targets ("T" in two different orientations) among distractors (rotated "L"s). On each trial, subjects saw a crowded display (180 msec) of twenty items (see Figure 1) and reported the presence of each of the two targets. When both present, the two targets appeared in the same hemifield (unilateral) or in opposite hemifields (bilateral). Subjects were more likely to detect two targets simultaneously on unilateral trials, suggesting a unilateral field advantage (UFA) in searching for two targets. Experiment 2 examined if the UFA in Experiment 1 was due to the task demand of detecting two targets. Subjects performed a detection task in Experiment 2A, in which they reported the number of targets (rotated "T"s) present (0, 1 or 2), and performed an identification task in Experiment 2B, in which they identified the orientations of targets (rotated "T"s). In both tasks (see Figure 2, 3), each trial contained six items, spreading within a single hemifield (unilateral) or across hemifields (bilateral). UFA was found in detection but not in identification, and was evident only in detecting two targets. Experiment 3 replicated the findings in 2A’s detection task with 3D shaded cubes. The results suggest that UFA depends on the task demand of detecting multiple targets simultaneously. We demonstrated a UFA in visual search and detection of more than one target. We argue that this UFA is likely due to greater integration of target signal within the same hemifield than across hemifields. Meeting abstract presented at VSS 2012

Search for two categories of target produces fewer fixations to target-color items.

Searching simultaneously for metal threats (guns and knives) and improvised explosive devices (IEDs) in X-ray images is less effective than 2 independent single-target searches, 1 for metal threats and 1 for IEDs. The goals of this study were to (a) replicate this dual-target cost for categorical targets and to determine whether the cost remains when X-ray images overlap, (b) determine the role of attentional guidance in this dual-target cost by measuring eye movements, and (c) determine the effect of practice on guidance. Untrained participants conducted 5,376 trials of visual search of X-ray images, each specializing in single-target search for metal threats, single-target search for IEDs, or dual-target search for both. In dual-target search, only 1 target (metal threat or IED) at most appeared on any 1 trial. Eye movements, response time, and accuracy were compared across single-target and dual-target searches. Results showed a dual-target cost in response time, accuracy, and guidance, with fewer fixations to target-color objects and disproportionately more to non-target-color objects, compared with single-target search. Such reduction in guidance explains why targets are missed in dual-target search, which was particularly noticeable when objects overlapped. After extensive practice, accuracy, response time, and guidance remained better in single-target search than in dual-target search. The results indicate that, when 2 different target representations are required for search, both representations cannot be maintained as accurately as in separate single-target searches. They suggest that baggage X-ray security screeners should specialize in one type of threat, or be trained to conduct 2 independent searches, 1 for each threat item.

Interactions between Reward, Feedback, and Timing Structures on Dual-Target Search Performance

Individuals who conduct visual searches that can contain more than one target face many challenges. Such multiple-target visual searches can be especially error prone, as identification of one target often makes identification of a second target less likely. Given that many real-world searches can be multiple-target searches (e.g., radiological examinations, baggage screening, military searches), it is important to understand what can affect performance. Multiple-target search is particularly sensitive to top-down influences such as anticipatory anxiety (Cain, Dunsmoor, LaBar, & Mitroff, VSS 2011), and here we explore the impact of reward motivation. Participants completed a paradigm that reliably produces dual-target errors (Fleck, Samei, & Mitroff, 2010). When we simply motivated participants with a performance-based, ten-percent chance of winning an additional d50 in compensation (Experiment 1), the performance decline on dual-target trials was eliminated, while accuracy on single-target trials remained the same. Further, without monetary motivation, adding trial-by-trial feedback (Experiment 2) did not significantly improve dual-target accuracy; however, the presence of both monetary motivation and feedback (Experiment 3) resulted in substantial performance benefits for both single- and dual-target conditions compared to Experiments 1 and 2. Finally, in the presence of top-down monetary motivation, trial-based time limits (Experiment 4) did not affect performance (i.e., participants performed equivalently with or without a time limit). This is in contrast to prior data without monetary incentives (Fleck et al., 2010), in which time limits negatively affected performance. Collectively, these experiments demonstrate that (1) motivation alone is sufficient to enhance dual-target search performance, (2) such benefits are enhanced when paired with trial-by-trial feedback, and (3) time limits hurt performance in the absence of motivation but have no effect with motivation. These findings provide key information about the role of top-down motivation on performance and how this can successfully improve performance on critical dual-target searches.