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1

A Temporal Pattern Search Algorithm for Personal History Event Visualization  

E-print Network

1 A Temporal Pattern Search Algorithm for Personal History Event Visualization Taowei David Wang algorithm for searching for temporal patterns of events in historical personal histories. The traditional, it allows TPS to skip many unnecessary events in personal histories. We show that TPS's running time

Shneiderman, Ben

2

A Temporal Pattern Search Algorithm for Personal History Event Visualization  

E-print Network

1 A Temporal Pattern Search Algorithm for Personal History Event Visualization Taowei David Wang algorithm for searching for temporal patterns of events in historical personal histories. The traditional to skip many unnecessary events in personal histories. We show that TPS's running time is bounded by O(m2

Golbeck, Jennifer

3

A Temporal Pattern Search Algorithm for Personal History Event Visualization  

Microsoft Academic Search

We present Temporal Pattern Search (TPS), a novel algorithm for searching for temporal patterns of events in historical personal histories. The traditional method of searching for such patterns uses an automaton-based approach over a single array of events, sorted by time stamps. Instead, TPS operates on a set of arrays, where each array contains all events of the same type,

Taowei David Wang; Amol Deshpande; Ben Shneiderman

2012-01-01

4

Statistical patterns of visual search for hidden objects  

PubMed Central

The movement of the eyes has been the subject of intensive research as a way to elucidate inner mechanisms of cognitive processes. A cognitive task that is rather frequent in our daily life is the visual search for hidden objects. Here we investigate through eye-tracking experiments the statistical properties associated with the search of target images embedded in a landscape of distractors. Specifically, our results show that the twofold process of eye movement, composed of sequences of fixations (small steps) intercalated by saccades (longer jumps), displays characteristic statistical signatures. While the saccadic jumps follow a log-normal distribution of distances, which is typical of multiplicative processes, the lengths of the smaller steps in the fixation trajectories are consistent with a power-law distribution. Moreover, the present analysis reveals a clear transition between a directional serial search to an isotropic random movement as the difficulty level of the searching task is increased. PMID:23226829

Credidio, Heitor F.; Teixeira, Elisangela N.; Reis, Saulo D. S.; Moreira, Andre A.; Andrade Jr, Jose S.

2012-01-01

5

Changes in visual search patterns of pathology residents as they gain experience  

NASA Astrophysics Data System (ADS)

The goal of this study was to examine and characterize changes in the ways that pathology residents examine digital or "virtual" slides as they gain more experience. A series of 20 digitized breast biopsy virtual slides (half benign and half malignant) were shown to 6 pathology residents at three points in time - at the beginning of their first year of residency, at the beginning of the second year, and at the beginning of the third year. Their task was to examine each image and select three areas that they would most want to zoom on in order to view the diagnostic detail at higher resolution. Eye position was recorded as they scanned each image. The data indicate that with each successive year of experience, the residents' search patterns do change. Overall it takes significantly less time to view an individual slide and decide where to zoom, significantly fewer fixations are generated overall, and there is less examination of non-diagnostic areas. Essentially, the residents' search becomes much more efficient and after only one year closely resembles that of an expert pathologist. These findings are similar to those in radiology, and support the theory that an important aspect of the development of expertise is improved pattern recognition (taking in more information during the initial Gestalt or gist view) as well as improved allocation of attention and visual processing resources.

Krupinski, Elizabeth A.; Weinstein, Ronald S.

2011-03-01

6

NCI Visuals Online: Search  

Cancer.gov

Skip Navigation NCI Visuals Online Home About My Pictures Browse Search Quick Search Search Search for: Date Created: Any 1900 1920 1940 1960 1980 1990 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 to Any 1900 1920 1940 1960 1980 1990 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 Sort

7

Interrupted Visual Searches Reveal Volatile Search Memory  

ERIC Educational Resources Information Center

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…

Shen, Y. Jeremy; Jiang, Yuhong V.

2006-01-01

8

Visual Representation Determines Search Difficulty: Explaining Visual Search Asymmetries  

PubMed Central

In visual search experiments there exist a variety of experimental paradigms in which a symmetric set of experimental conditions yields asymmetric corresponding task performance. There are a variety of examples of this that currently lack a satisfactory explanation. In this paper, we demonstrate that distinct classes of asymmetries may be explained by virtue of a few simple conditions that are consistent with current thinking surrounding computational modeling of visual search and coding in the primate brain. This includes a detailed look at the role that stimulus familiarity plays in the determination of search performance. Overall, we demonstrate that all of these asymmetries have a common origin, namely, they are a consequence of the encoding that appears in the visual cortex. The analysis associated with these cases yields insight into the problem of visual search in general and predictions of novel search asymmetries. PMID:21808617

Bruce, Neil D. B.; Tsotsos, John K.

2011-01-01

9

Learning in repeated visual search  

PubMed Central

Visual search (e.g., finding a specific object in an array of other objects) is performed most effectively when people are able to ignore distracting nontargets. In repeated search, however, incidental learning of object identities may facilitate performance. In three experiments, with over 1,100 participants, we examined the extent to which search could be facilitated by object memory and by memory for spatial layouts. Participants searched for new targets (real-world, nameable objects) embedded among repeated distractors. To make the task more challenging, some participants performed search for multiple targets, increasing demands on visual working memory (WM). Following search, memory for search distractors was assessed using a surprise two-alternative forced choice recognition memory test with semantically matched foils. Search performance was facilitated by distractor object learning and by spatial memory; it was most robust when object identity was consistently tied to spatial locations and weakest (or absent) when object identities were inconsistent across trials. Incidental memory for distractors was better among participants who searched under high WM load, relative to low WM load. These results were observed when visual search included exhaustive-search trials (Experiment 1) or when all trials were self-terminating (Experiment 2). In Experiment 3, stimulus exposure was equated across WM load groups by presenting objects in a single-object stream; recognition accuracy was similar to that in Experiments 1 and 2. Together, the results suggest that people incidentally generate memory for nontarget objects encountered during search and that such memory can facilitate search performance. PMID:20601709

Hout, Michael C.; Goldinger, Stephen D.

2014-01-01

10

Evolutionary pattern search algorithms  

SciTech Connect

This paper defines a class of evolutionary algorithms called evolutionary pattern search algorithms (EPSAs) and analyzes their convergence properties. This class of algorithms is closely related to evolutionary programming, evolutionary strategie and real-coded genetic algorithms. EPSAs are self-adapting systems that modify the step size of the mutation operator in response to the success of previous optimization steps. The rule used to adapt the step size can be used to provide a stationary point convergence theory for EPSAs on any continuous function. This convergence theory is based on an extension of the convergence theory for generalized pattern search methods. An experimental analysis of the performance of EPSAs demonstrates that these algorithms can perform a level of global search that is comparable to that of canonical EAs. We also describe a stopping rule for EPSAs, which reliably terminated near stationary points in our experiments. This is the first stopping rule for any class of EAs that can terminate at a given distance from stationary points.

Hart, W.E.

1995-09-19

11

Computing visual target distinctness through selective filtering, statistical features, and visual patterns  

NASA Astrophysics Data System (ADS)

This paper presents three computational visual distinctness measures, computed from image representational models based on selective filtering, statistical features, and visual patterns, respectively. They are applied to quantify the visual distinctness of targets in complex natural scenes. The measure that applies a simple decision rule to the distances between segregated visual patterns is shown (1) to predict human observer performance in search and detection tasks on complex natural imagery, and (2) to correlate strongly with visual target distinctness estimated by human observers.

Fdez-Vidal, Xose R.; Toet, Alexander; Garcia, J. A.; Fdez-Valdivia, J.

2000-01-01

12

Statistical templates for visual search.  

PubMed

How do we find a target embedded in a scene? Within the framework of signal detection theory, this task is carried out by comparing each region of the scene with a "template," i.e., an internal representation of the search target. Here we ask what form this representation takes when the search target is a complex image with uncertain orientation. We examine three possible representations. The first is the matched filter. Such a representation cannot account for the ease with which humans can find a complex search target that is rotated relative to the template. A second representation attempts to deal with this by estimating the relative orientation of target and match and rotating the intensity-based template. No intensity-based template, however, can account for the ability to easily locate targets that are defined categorically and not in terms of a specific arrangement of pixels. Thus, we define a third template that represents the target in terms of image statistics rather than pixel intensities. Subjects performed a two-alternative, forced-choice search task in which they had to localize an image that matched a previously viewed target. Target images were texture patches. In one condition, match images were the same image as the target and distractors were a different image of the same textured material. In the second condition, the match image was of the same texture as the target (but different pixels) and the distractor was an image of a different texture. Match and distractor stimuli were randomly rotated relative to the target. We compared human performance to pixel-based, pixel-based with rotation, and statistic-based search models. The statistic-based search model was most successful at matching human performance. We conclude that humans use summary statistics to search for complex visual targets. PMID:24627458

Ackermann, John F; Landy, Michael S

2014-01-01

13

Beyond the Search Surface: Visual Search and Attentional Engagement  

Microsoft Academic Search

Treisman (1991) described a series of visual search studies testing feature integration theory against an alternative (Duncan & Humphreys, 1989) in which feature and conjunction search are basically similar. Here the latter account is noted to have 2 distinct levels: (a) a summary of search findings in terms of stimulus similarities, and (b) a theory of how visual attention is

John Duncan; Glyn Humphreys

1992-01-01

14

Fractal fluctuations in gaze speed visual search  

Microsoft Academic Search

Visual search involves a subtle coordination of visual memory and lower-order perceptual mechanisms. Specifically, the fluctuations\\u000a in gaze may provide support for visual search above and beyond what may be attributed to memory. Prior research indicates\\u000a that gaze during search exhibits fractal fluctuations, which allow for a wide sampling of the field of view. Fractal fluctuations\\u000a constitute a case of

Damian G. Stephen; Jason Anastas

2011-01-01

15

The development of organized visual search  

PubMed Central

Visual search plays an important role in guiding behavior. Children have more difficulty performing conjunction search tasks than adults. The present research evaluates whether developmental differences in children's ability to organize serial visual search (i.e., search organization skills) contribute to performance limitations in a typical conjunction search task. We evaluated 134 children between the ages of 2 and 17 on separate tasks measuring search for targets defined by a conjunction of features or by distinct features. Our results demonstrated that children organize their visual search better as they get older. As children's skills at organizing visual search improve they become more accurate at locating targets with conjunction of features amongst distractors, but not for targets with distinct features. Developmental limitations in children's abilities to organize their visual search of the environment are an important component of poor conjunction search in young children. In addition, our findings provide preliminary evidence that, like other visuospatial tasks, exposure to reading may influence children's spatial orientation to the visual environment when performing a visual search. PMID:23584560

Woods, Adam J.; Goksun, Tilbe; Chatterjee, Anjan; Zelonis, Sarah; Mehta, Anika; Smith, Sabrina E.

2013-01-01

16

Aurally and visually guided visual search in a virtual environment.  

PubMed

We investigated the time participants took to perform a visual search task for targets outside the visual field of view using a helmet-mounted display. We also measured the effectiveness of visual and auditory cues to target location. The auditory stimuli used to cue location were noise bursts previously recorded from the ear canals of the participants and were either presented briefly at the beginning of a trial or continually updated to compensate for head movements. The visual cue was a dynamic arrow that indicated the direction and angular distance from the instantaneous head position to the target. Both visual and auditory spatial cues reduced search time dramatically, compared with unaided search. The updating audio cue was more effective than the transient audio cue and was as effective as the visual cue in reducing search time. These data show that both spatial auditory and visual cues can markedly improve visual search performance. Potential applications for this research include highly visual environments, such as aviation, where there is risk of overloading the visual modality with information. PMID:9849104

Flanagan, P; McAnally, K I; Martin, R L; Meehan, J W; Oldfield, S R

1998-09-01

17

Visually inspecting the search behavior of Harmony Search and its variants with Viz3D  

Microsoft Academic Search

The aim of this study is to assess the Harmony Search (HS) meta-heuristic and some of its variants when submitted to benchmark continuous optimization problems to reveal whether and how such variants change the patterns of search behavior exhibited by the canonical version. For this purpose, a new Visual Mining tool based on the Viz3D algorithm was developed to aid

Marcelo Lotif; Andre L. V. Coelho

2011-01-01

18

Distributed Search and Pattern Matching  

NASA Astrophysics Data System (ADS)

Peer-to-peer (P2P) technology has triggered a wide range of distributed applications including file-sharing, distributed XML databases, distributed computing, server-less web publishing and networked resource/service sharing. Despite of the diversity in application, these systems share common requirements for searching due to transitory nodes population and content volatility. In such dynamic environment, users do not have the exact information about available resources. Queries are based on partial information. This mandates the search mechanism to be emphflexible. On the other hand, the search mechanism is required to be bandwidth emphefficient to support large networks. Variety of search techniques have been proposed to provide satisfactory solution to the conflicting requirements of search efficiency and flexibility. This chapter highlights the search requirements in large scale distributed systems and the ability of the existing distributed search techniques in satisfying these requirements. Representative search techniques from three application domains, namely, P2P content sharing, service discovery and distributed XML databases, are considered. An abstract problem formulation called Distributed Pattern Matching (DPM) is presented as well. The DPM framework can be used as a common ground for addressing the search problem in these three application domains.

Ahmed, Reaz; Boutaba, Raouf

19

Innate Visual Learning through Spontaneous Activity Patterns  

Microsoft Academic Search

Patterns of spontaneous activity in the developing retina, LGN, and cortex are necessary for the proper development of visual cortex. With these patterns intact, the primary visual cortices of many newborn animals develop properties similar to those of the adult cortex but without the training benefit of visual experience. Previous models have demonstrated how V1 responses can be initialized through

Mark V. Albert; Adam Schnabel; David J. Field

2008-01-01

20

Effects of Peripheral Visual Field Loss on Eye Movements During Visual Search  

PubMed Central

Natural vision involves sequential eye movements that bring the fovea to locations selected by peripheral vision. How peripheral visual field loss (PVFL) affects this process is not well understood. We examine how the location and extent of PVFL affects eye movement behavior in a naturalistic visual search task. Ten patients with PVFL and 13 normally sighted subjects with full visual fields (FVF) completed 30 visual searches monocularly. Subjects located a 4°?×?4° target, pseudo-randomly selected within a 26°?×?11° natural image. Eye positions were recorded at 50?Hz. Search duration, fixation duration, saccade size, and number of saccades per trial were not significantly different between PVFL and FVF groups (p?>?0.1). A ?2 test showed that the distributions of saccade directions for PVFL and FVL subjects were significantly different in 8 out of 10 cases (p?Visual Field pattern deviations for each subject were compared with the spatial distribution of eye movement directions. There were no significant correlations between saccade directional bias and visual field sensitivity across the 10 patients. Visual search performance was not significantly affected by PVFL. An analysis of eye movement directions revealed patients with PVFL show a biased directional distribution that was not directly related to the locus of vision loss, challenging feed-forward models of eye movement control. Consequently, many patients do not optimally compensate for visual field loss during visual search. PMID:23162511

Wiecek, Emily; Pasquale, Louis R.; Fiser, Jozsef; Dakin, Steven; Bex, Peter J.

2012-01-01

21

Visual Testing: Searching for Guidelines.  

ERIC Educational Resources Information Center

An experiment was conducted to investigate the influence of the variables "realism" and "context" on the performance of biology students on a visual test about the anatomy of a rat. The instruction was primarily visual with additional verbal information like Latin names and practical information about the learning task: dissecting a rat to gain…

Van Gendt, Kitty; Verhagen, Plon

22

BTC image coding with visual patterns  

Microsoft Academic Search

This paper presents a block truncation coding (BTC) scheme for image compression that employs visual patterns designed independently of the image to be coded. In this method, image blocks are first classified into three classes: uniform, gentle edge, and sharp edge, according to their variations. Design focus is on edge blocks, where two sets of patterns, namely, visual patterns and

Tak Po Chan; Bing Zeng; Ming L. Liou

1994-01-01

23

Automatization and training in visual search.  

PubMed

In several search tasks, the amount of practice on particular combinations of targets and distractors was equated in varied-mapping (VM) and consistent-mapping (CM) conditions. The results indicate the importance of distinguishing between memory and visual search tasks, and implicate a number of factors that play important roles in visual search and its learning. Visual search was studied in Experiment 1. VM and CM performance were almost equal, and slope reductions occurred during practice for both, suggesting the learning of efficient attentive search based on features, and no important role for automatic attention attraction. However, positive transfer effects occurred when previous CM targets were re-paired with previous CM distractors, even though these targets and distractors had not been trained together. Also, the introduction of a demanding simultaneous task produced advantages of CM over VM. These latter two results demonstrated the operation of automatic attention attraction. Visual search was further studied in Experiment 2, using novel characters for which feature overlap and similarity were controlled. The design and many of the findings paralleled Experiment 1. In addition, enormous search improvement was seen over 35 sessions of training, suggesting the operation of perceptual unitization for the novel characters. Experiment 3 showed a large, persistent advantage for CM over VM performance in memory search, even when practice on particular combinations of targets and distractors was equated in the two training conditions. A multifactor theory of automatization and attention is put forth to account for these findings and others in the literature. PMID:1621883

Czerwinski, M; Lightfoot, N; Shiffrin, R M

1992-01-01

24

Features in visual search combine linearly.  

PubMed

Single features such as line orientation and length are known to guide visual search, but relatively little is known about how multiple features combine in search. To address this question, we investigated how search for targets differing in multiple features (intensity, length, orientation) from the distracters is related to searches for targets differing in each of the individual features. We tested race models (based on reaction times) and co-activation models (based on reciprocal of reaction times) for their ability to predict multiple feature searches. Multiple feature searches were best accounted for by a co-activation model in which feature information combined linearly (r = 0.95). This result agrees with the classic finding that these features are separable i.e., subjective dissimilarity ratings sum linearly. We then replicated the classical finding that the length and width of a rectangle are integral features-in other words, they combine nonlinearly in visual search. However, to our surprise, upon including aspect ratio as an additional feature, length and width combined linearly and this model outperformed all other models. Thus, length and width of a rectangle became separable when considered together with aspect ratio. This finding predicts that searches involving shapes with identical aspect ratio should be more difficult than searches where shapes differ in aspect ratio. We confirmed this prediction on a variety of shapes. We conclude that features in visual search co-activate linearly and demonstrate for the first time that aspect ratio is a novel feature that guides visual search. PMID:24715328

Pramod, R T; Arun, S P

2014-01-01

25

Urban camouflage assessment through visual search and computational saliency  

NASA Astrophysics Data System (ADS)

We present a new method to derive a multiscale urban camouflage pattern from a given set of background image samples. We applied this method to design a camouflage pattern for a given (semi-arid) urban environment. We performed a human visual search experiment and a computational evaluation study to assess the effectiveness of this multiscale camouflage pattern relative to the performance of 10 other (multiscale, disruptive and monotonous) patterns that were also designed for deployment in the same operating theater. The results show that the pattern combines the overall lowest detection probability with an average mean search time. We also show that a frequency-tuned saliency metric predicts human observer performance to an appreciable extent. This computational metric can therefore be incorporated in the design process to optimize the effectiveness of camouflage patterns derived from a set of background samples.

Toet, Alexander; Hogervorst, Maarten A.

2013-04-01

26

Sources of Top-Down Control in Visual Search  

Microsoft Academic Search

Endogenous control of visual search can influence search guidance at the level of a supradimensional topographic saliency map [Wolfe, J. M. Guided Search 2.0: A revised model of visual search. Psychonomic Bulletin & Review, 1, 202–238, 1994], and modulate nonspatial mechanisms coding saliency in dimension-specific input modules [Müller, H. J., Reimann, B., & Krummenacher, J. Visual search for singleton feature

Ralph Weidner; Joseph Krummenacher; Brit Reimann; Hermann J. Müller; Gereon R. Fink

2009-01-01

27

Driving forces in free visual search: An ethology.  

PubMed

Visual search typically involves sequences of eye movements under the constraints of a specific scene and specific goals. Visual search has been used as an experimental paradigm to study the interplay of scene salience and top-down goals, as well as various aspects of vision, attention, and memory, usually by introducing a secondary task or by controlling and manipulating the search environment. An ethology is a study of an animal in its natural environment, and here we examine the fixation patterns of the human animal searching a series of challenging illustrated scenes that are well-known in popular culture. The search was free of secondary tasks, probes, and other distractions. Our goal was to describe saccadic behavior, including patterns of fixation duration, saccade amplitude, and angular direction. In particular, we employed both new and established techniques for identifying top-down strategies, any influences of bottom-up image salience, and the midlevel attentional effects of saccadic momentum and inhibition of return. The visual search dynamics that we observed and quantified demonstrate that saccades are not independently generated and incorporate distinct influences from strategy, salience, and attention. Sequential dependencies consistent with inhibition of return also emerged from our analyses. PMID:24385137

MacInnes, W Joseph; Hunt, Amelia R; Hilchey, Matthew D; Klein, Raymond M

2014-02-01

28

ASYNCHRONOUS PARALLEL PATTERN SEARCH FOR NONLINEAR OPTIMIZATION  

E-print Network

ASYNCHRONOUS PARALLEL PATTERN SEARCH FOR NONLINEAR OPTIMIZATION PATRICIA D. HOUGH, TAMARA G. KOLDA. 1, pp. 134­156 Abstract. We introduce a new asynchronous parallel pattern search (APPS). Parallel pattern search can be quite useful for engineering optimization problems characterized by a small number

Kolda, Tamara G.

29

ASYNCHRONOUS PARALLEL PATTERN SEARCH FOR NONLINEAR OPTIMIZATION #  

E-print Network

ASYNCHRONOUS PARALLEL PATTERN SEARCH FOR NONLINEAR OPTIMIZATION # PATRICIA D. HOUGH + , TAMARA G Mathematics Vol. 23, No. 1, pp. 134--156 Abstract. We introduce a new asynchronous parallel pattern search (APPS). Parallel pattern search can be quite useful for engineering optimization problems characterized

Kolda, Tamara G.

30

Attention and Visual Search: Active Robotic Vision Systems that Search  

Microsoft Academic Search

Visual attention is a multi-faceted phenomenon, playing different roles in different situations and for different processing mechanisms. Regardless, attention is a mechanism that optimizes the search processes inherent in vision. This perspective leads to a sound theoretical foundation for studies of attention in both machine and in the brain. The development of this foundation and the many ways in which

John K. Tsotsos; Ksenia Shubina

31

TMS effect on visual search task.  

PubMed

In this study, we examined the temporal aspects of the right posterior parietal cortex in easy feature and hard feature "pop-out" visual searches using transcranial magnetic stimulation (TMS). The transcranial magnetic stimulations were applied over the right posterior parietal cortex of subjects. Subjects received 4 tests which the TMS onset times were set as 100, 150, 200 and 250 msec after visual stimulus presentation. We found that, when SOA=150 msec, compared to no-TMS condition, There was a significant elevation in response time when the TMS pluses were applied. However for the other SOA cases, there was no significant difference between TMS and no-TMS conditions. Therefore, we considered that "pop-out" visual search was processed in the right posterior parietal cortex at about 150 msec after stimulus present. PMID:17946445

Ge, Sheng; Matsuoka, Akira; Ueno, Shoogo; Iramina, Keiji

2006-01-01

32

A visual tool for using design patterns as pattern languages  

Microsoft Academic Search

Design patterns document successful solutions to recurrent problems in a specific software development domain. However, finding the patterns you need can be difficult, often requiring the designer to comprehend a long narrative description to understand the benefits, implications and trade-offs of each pattern and of its relationships with others. In this paper we propose a visual notation supported by a

Paloma Díaz; Ignacio Aedo; Mary Beth Rosson; John M. Carroll

2010-01-01

33

Parallel Mechanisms for Visual Search in Zebrafish  

PubMed Central

Parallel visual search mechanisms have been reported previously only in mammals and birds, and not animals lacking an expanded telencephalon such as bees. Here we report the first evidence for parallel visual search in fish using a choice task where the fish had to find a target amongst an increasing number of distractors. Following two-choice discrimination training, zebrafish were presented with the original stimulus within an increasing array of distractor stimuli. We found that zebrafish exhibit no significant change in accuracy and approach latency as the number of distractors increased, providing evidence of parallel processing. This evidence challenges theories of vertebrate neural architecture and the importance of an expanded telencephalon for the evolution of executive function. PMID:25353168

Proulx, Michael J.; Parker, Matthew O.; Tahir, Yasser; Brennan, Caroline H.

2014-01-01

34

Parallel mechanisms for visual search in zebrafish.  

PubMed

Parallel visual search mechanisms have been reported previously only in mammals and birds, and not animals lacking an expanded telencephalon such as bees. Here we report the first evidence for parallel visual search in fish using a choice task where the fish had to find a target amongst an increasing number of distractors. Following two-choice discrimination training, zebrafish were presented with the original stimulus within an increasing array of distractor stimuli. We found that zebrafish exhibit no significant change in accuracy and approach latency as the number of distractors increased, providing evidence of parallel processing. This evidence challenges theories of vertebrate neural architecture and the importance of an expanded telencephalon for the evolution of executive function. PMID:25353168

Proulx, Michael J; Parker, Matthew O; Tahir, Yasser; Brennan, Caroline H

2014-01-01

35

Visual Field Screening System by Using Overlapped Fixation Patterns  

NASA Astrophysics Data System (ADS)

This study introduces a novel technique for estimating visual field by using overlapped fixation patterns obtained by amounts of displacement in voluntary eye movements during searching-tracking trials, as an alternative screening medical device for visual field examination. Proposed system was evaluated by glaucoma patients, in order to study whether or not the proposed system can be used as a visual field detection device for screening. As a result, the proposed system detected the visual field abnormality to a certain extent. However, there were some cases that detection of Mariotte blind spots was inaccurately performed. The experimental results revealed that there was room to reconsider our understanding regarding the effect of ptosis, overlapped with eye sight as well as calibration of the display position to the correct location to be examined. Results of the evaluation experiment indicated that this proposed system has a potential to be used as a visual field examination device for screening.

Kotani, Kentaro; Yoshikawa, Ryota; Tamura, Toshiki; Asao, Takafumi; Sugiyama, Tetsuya; Ueki, Mari; Kojima, Shota; Shibata, Maho; Ikeda, Tsunehiko

36

Mobile Visual Search: Architectures, Technologies, and the Emerging  

E-print Network

Mobile Visual Search: Architectures, Technologies, and the Emerging MPEG Standard Modern-era mobile to initiate search queries about objects in the user's visual proximity (see Figure 1). Such applications can, real estate, printed media, or art. First deploy- ments of mobile visual-search systems include Google

Girod, Bernd

37

Guided Text Search Using Adaptive Visual Analytics  

SciTech Connect

This research demonstrates the promise of augmenting interactive visualizations with semi- supervised machine learning techniques to improve the discovery of significant associations and insights in the search and analysis of textual information. More specifically, we have developed a system called Gryffin that hosts a unique collection of techniques that facilitate individualized investigative search pertaining to an ever-changing set of analytical questions over an indexed collection of open-source documents related to critical national infrastructure. The Gryffin client hosts dynamic displays of the search results via focus+context record listings, temporal timelines, term-frequency views, and multiple coordinate views. Furthermore, as the analyst interacts with the display, the interactions are recorded and used to label the search records. These labeled records are then used to drive semi-supervised machine learning algorithms that re-rank the unlabeled search records such that potentially relevant records are moved to the top of the record listing. Gryffin is described in the context of the daily tasks encountered at the US Department of Homeland Security s Fusion Center, with whom we are collaborating in its development. The resulting system is capable of addressing the analysts information overload that can be directly attributed to the deluge of information that must be addressed in the search and investigative analysis of textual information.

Steed, Chad A [ORNL; Symons, Christopher T [ORNL; Senter, James K [ORNL; DeNap, Frank A [ORNL

2012-10-01

38

Visualizing VDOT Traffic Pattern Data Old Dominion University 1  

E-print Network

Visualizing VDOT Traffic Pattern Data Old Dominion University 1 Visualizing VDOT Traffic Pattern Science Old Dominion University #12;Visualizing VDOT Traffic Pattern Data Old Dominion University 2 TABLE.................................................................... 29 #12;Visualizing VDOT Traffic Pattern Data Old Dominion University 3 Acknowledgment I feel

Weigle, Michele

39

Modeling spatial patterns in the visual cortex  

NASA Astrophysics Data System (ADS)

We propose a model for the formation of patterns in the visual cortex. The dynamical units of the model are Kuramoto phase oscillators that interact through a complex network structure embedded in two dimensions. In this way the strength of the interactions takes into account the geographical distance between units. We show that for different parameters, clustered or striped patterns emerge. Using the structure factor as an order parameter we are able to quantitatively characterize these patterns and present a phase diagram. Finally, we show that the model is able to reproduce patterns with cardinal preference, as observed in ferrets.

Daza C., Yudy Carolina; Tauro, Carolina B.; Tamarit, Francisco A.; Gleiser, Pablo M.

2014-10-01

40

Guided Visual Search in Individuals With Mental Retardation  

Microsoft Academic Search

The ability of individuals with mental retardation to focus on task-relevant elements of complex visual arrays and increase visual-search efficiency was investigated. Initial assess- ments of visual-search efficiency were conducted to identify pairs of features for the form and size dimensions for which each participant demonstrated serial search. Subsequently, color was added as a defining feature that could guide search

Michael T. Carlin; Sal A. Soraci; Nancy A. Dennis; Christina Strawbridge; Nicholas A. Chechile

2002-01-01

41

Software Design Patterns for Information Visualization  

Microsoft Academic Search

Despite a diversity of software architectures supporting information visualization, it is often difficult to identify, evaluate, and re-apply the design solutions implemented within such frameworks. One popular and effective approach for addressing such difficulties is to capture successful solutions in design patterns, abstract descriptions of interacting software components that can be customized to solve design problems within a particular context.

Jeffrey Heer; Maneesh Agrawala

2006-01-01

42

Perceptual Grouping and Motion Coherence in Visual Search  

Microsoft Academic Search

have a dramatic effect on search performance. We propose that this interaction between perceptual grouping and visual search is gov- erned by three general rules. Our data also provide convincing evi- dence of the preattentive organization of a visual display into surfaces defined by common motion. In the real world, different items compete for visual attention. How does one select

A. Kingstone; W. F. Bischof

1999-01-01

43

Temporal aspects of visual search studied by transcranial magnetic stimulation  

Microsoft Academic Search

Transcranial magnetic stimulation was applied over the parietal visual cortex of subjects while they were performing ‘popout’ or conjunction visual search tasks in arrays containing eight distractors. Magnetic stimulation had no detrimental effect on the performance of pop-out search, but did significantly increase reaction times on conjunction search when stimulation was applied over the right parietal cortex 100 msec after

Elisabeth Ashbridge; Vincent Walsh; Alan Cowey

1997-01-01

44

Recognition of Facially Expressed Emotions and Visual Search Strategies in Adults with Asperger Syndrome  

ERIC Educational Resources Information Center

Can the disadvantages persons with Asperger syndrome frequently experience with reading facially expressed emotions be attributed to a different visual perception, affecting their scanning patterns? Visual search strategies, particularly regarding the importance of information from the eye area, and the ability to recognise facially expressed…

Falkmer, Marita; Bjallmark, Anna; Larsson, Matilda; Falkmer, Torbjorn

2011-01-01

45

Anticipation and visual search behaviour in expert soccer goalkeepers  

Microsoft Academic Search

A novel methodological approach is presented to examine the visual search behaviours employed by expert goalkeepers during simulated penalty kick situations in soccer. Expert soccer goalkeepers were classified as successful or unsuccessful based on their performance on a film-based test of anticipation skill, thereby allowing an intra-group comparison of visual search behaviour on the task. The anticipation test required participants

Geert J. P. Savelsbergh; John Van der Kamp; A. Mark Williams; Paul Ward

2005-01-01

46

Texture segmentation and visual search for pop-out targets  

Microsoft Academic Search

‘Parallel’ visual search and effortless texture segmentation were believed to rely on similar mechanisms until Wolfe [Vis. Res. 32 (1992) 757] demonstrated that efficient visual search and effortless texture segmentation are not always the same thing. In a recent study, Meinecke and Donk [Perception 31 (2002) 591] varied display size in a pop-out task and found that, albeit stimulus elements

Anna Schubö; Erich Schröger; Cristina Meinecke

2004-01-01

47

Spatial Constraints on Learning in Visual Search: Modeling Contextual Cuing  

Microsoft Academic Search

Predictive visual context facilitates visual search, a benefit termed contextual cuing (M. M. Chun & Y. Jiang, 1998). In the original task, search arrays were repeated across blocks such that the spatial configuration (context) of all of the distractors in a display predicted an embedded target location. The authors modeled existing results using a connectionist architecture and then designed new

Timothy F. Brady; Marvin M. Chun

2007-01-01

48

Parallel visual search and rapid animal detection in natural scenes  

E-print Network

Parallel visual search and rapid animal detection in natural scenes Centre de Recherche Cerveau et, Giessen, GermanyKarl R. Gegenfurtner Human observers are capable of detecting animals within novel natural and efficient even when the animals are embedded in their natural backgrounds. Keywords: visual search, rapid

49

Visual Search Deficits Are Independent of Magnocellular Deficits in Dyslexia  

ERIC Educational Resources Information Center

The aim of this study was to investigate the theory that visual magnocellular deficits seen in groups with dyslexia are linked to reading via the mechanisms of visual attention. Visual attention was measured with a serial search task and magnocellular function with a coherent motion task. A large group of children with dyslexia (n = 70) had slower…

Wright, Craig M.; Conlon, Elizabeth G.; Dyck, Murray

2012-01-01

50

Spatial coding for the Simon effect in visual search.  

PubMed

Two experiments were conducted to examine the Simon effect (i.e., faster responding when irrelevant stimulus location corresponds with response location than when it does not) in visual search tasks. The search items were arranged in a 4 x 4 grid, and grid locations were coded into sets of four, two involving inner columns and two involving outer columns. In experiment 1, three different types of inefficient search tasks were used. The Simon effects were shown to be larger when the target appeared in one of the outer columns than in one of the inner columns ("laterality effect"). This pattern of results was not observed when distractors were absent, suggesting that the laterality effect depends on the operation of selective attention. In experiment 2, a pop-out search task was used, and no significant effect of target location on the Simon effect was found. Interpretations of the results based on the attention-shift account and referential-coding account were discussed. PMID:16900362

Zhang, Dexuan; Zhou, Xiaolin; di Pellegrino, Giuseppe; Ladavas, Elisabetta

2007-02-01

51

The Role of Categorization in Visual Search for Orientation  

Microsoft Academic Search

Visual search for 1 target orientation is fast and virtually independent of set size if all of the distractors are of a single, different orientation. However, in the presence of distractors of several orientations, search can become inefficient and strongly dependent on set size (Exp. 1). Search can be inefficient even if only 2 distractor orientations are used and even

Jeremy M. Wolfe; Stacia R. Friedman-Hill; Marion I. Stewart; Kathleen M. O’Connell

1992-01-01

52

Applying models of visual search to menu design  

Microsoft Academic Search

The Guided Search (GS) model, a quantitative model of visual search, was used to develop menu designs in a four-step process. First, a GS simulation model was defined for a menu search task. Second, model parameters were estimated to provide the best fit between model predictions and experimental data. Third, an optimization algorithm was used to identify the menu design

Baili Liu; Gregory Francis; Gavriel Salvendy

2002-01-01

53

Searching for intellectual turning points: Progressive knowledge domain visualization  

PubMed Central

This article introduces a previously undescribed method progressively visualizing the evolution of a knowledge domain's cocitation network. The method first derives a sequence of cocitation networks from a series of equal-length time interval slices. These time-registered networks are merged and visualized in a panoramic view in such a way that intellectually significant articles can be identified based on their visually salient features. The method is applied to a cocitation study of the superstring field in theoretical physics. The study focuses on the search of articles that triggered two superstring revolutions. Visually salient nodes in the panoramic view are identified, and the nature of their intellectual contributions is validated by leading scientists in the field. The analysis has demonstrated that a search for intellectual turning points can be narrowed down to visually salient nodes in the visualized network. The method provides a promising way to simplify otherwise cognitively demanding tasks to a search for landmarks, pivots, and hubs. PMID:14724295

Chen, Chaomei

2004-01-01

54

Pattern electroretinogram, visual evoked potential and psychophysical functions in maculopathy  

Microsoft Academic Search

To compare pattern electroretinograms and visual evoked potentials with psychophysical examinations, such as visual acuity, static (automated) perimetry and color vision in unilateral maculopathies of various origins, 20 patients with unilateral retinal diseases within the macula and the posterior pole were tested. Pattern electroretinography, visual evoked potential testing and static perimetry (Octopus program M1) were performed with three different test

Armin Junghardt; Hannes Wildberger; Béla Török

1995-01-01

55

Horizontal visual search in a large field by patients with unilateral spatial neglect.  

PubMed

In this study, we investigated the horizontal visual search ability and pattern of horizontal visual search in a large space performed by patients with unilateral spatial neglect (USN). Subjects included nine patients with right hemisphere damage caused by cerebrovascular disease showing left USN, nine patients with right hemisphere damage but no USN, and six healthy individuals with no history of brain damage who were age-matched to the groups with brain right hemisphere damage. The number of visual search tasks accomplished was recorded in the first experiment. Neck rotation angle was continuously measured during the task and quantitative data of the measurements were collected. There was a strong correlation between the number of visual search tasks accomplished and the total Behavioral Inattention Test Conventional Subtest (BITC) score in subjects with right hemisphere damage. In both USN and control groups, the head position during the visual search task showed a balanced bell-shaped distribution from the central point on the field to the left and right sides. Our results indicate that compensatory strategies, including cervical rotation, may improve visual search capability and achieve balance on the neglected side. PMID:23632293

Nakatani, Ken; Notoya, Masako; Sunahara, Nobuyuki; Takahashi, Shusuke; Inoue, Katsumi

2013-06-01

56

Asynchronous parallel pattern search for nonlinear optimization  

SciTech Connect

Parallel pattern search (PPS) can be quite useful for engineering optimization problems characterized by a small number of variables (say 10--50) and by expensive objective function evaluations such as complex simulations that take from minutes to hours to run. However, PPS, which was originally designed for execution on homogeneous and tightly-coupled parallel machine, is not well suited to the more heterogeneous, loosely-coupled, and even fault-prone parallel systems available today. Specifically, PPS is hindered by synchronization penalties and cannot recover in the event of a failure. The authors introduce a new asynchronous and fault tolerant parallel pattern search (AAPS) method and demonstrate its effectiveness on both simple test problems as well as some engineering optimization problems

P. D. Hough; T. G. Kolda; V. J. Torczon

2000-01-01

57

Visual Search Asymmetry with Uncertain Targets  

ERIC Educational Resources Information Center

The underlying mechanism of search asymmetry is still unknown. Many computational models postulate top-down selection of target-defining features as a crucial factor. This feature selection account implies, and other theories implicitly assume, that predefined target identity is necessary for search asymmetry. The authors tested the validity of…

Saiki, Jun; Koike, Takahiko; Takahashi, Kohske; Inoue, Tomoko

2005-01-01

58

Pip and Pop: Nonspatial Auditory Signals Improve Spatial Visual Search  

ERIC Educational Resources Information Center

Searching for an object within a cluttered, continuously changing environment can be a very time-consuming process. The authors show that a simple auditory pip drastically decreases search times for a synchronized visual object that is normally very difficult to find. This effect occurs even though the pip contains no information on the location…

Van der Burg, Erik; Olivers, Christian N. L.; Bronkhorst, Adelbert W.; Theeuwes, Jan

2008-01-01

59

Moray revisited: High-priority affective stimuli and visual search  

Microsoft Academic Search

Previous research offers conflicting suggestions about whether “high-priority” verbal stimuli such as an individual's own name or emotionally charged words automatically grab attention and\\/or can be detected without the usual capacity limitations. Nine experiments investigated this issue, using visual search through displays of words. In speeded search tasks, the subject's own name was detected more quickly than other targets, but

Christine R. Harris; Harold E. Pashler; Pashler Coburn

2004-01-01

60

Saccadic selection and crowding in visual search: stronger lateral masking leads to shorter search times  

Microsoft Academic Search

We investigated the role of crowding in saccadic selection during visual search. To guide eye movements, often information\\u000a from the visual periphery is used. Crowding is known to deteriorate the quality of peripheral information. In four search\\u000a experiments, we studied the role of crowding, by accompanying individual search elements by flankers. Varying the difference\\u000a between target and flankers allowed us

Jelmer P. de Vries; Ignace T. C. Hooge; Marco A. Wiering; Frans A. J. Verstraten

2011-01-01

61

Rapid compensation of visual search strategy in patients with chronic visual field defects  

PubMed Central

Introduction The aim of this study was to test the effect and specificity of a novel, compensatory eye movement training therapy designed to improve visual search performance in patients with homonymous visual field defects. Methods Seven patients with chronic homonymous visual field defects and six healthy control subjects were tested. All subjects completed the single training period (300 trials). Subjects were assessed on three different saccadic tasks (a visual search task, a rapid scanning task and a reading task) which were evaluated at three time points on the same day: two before and one after the training period. The computer-based training consisted of a novel ramp-step search paradigm that required subjects to pursue a stimulus (ramp phase) and then saccade to find its location when it suddenly jumped (step phase). Results Pre-therapy we confirmed that patients differed from controls on the visual search task. Post-training we demonstrated a clear improvement in terms of reaction time required to complete the visual search. This effect was confined to: (1) the patient group only; (2) targets presented to the blind visual field of the patients only; (3) the visual search task only and not the rapid scanning or reading task. Conclusion These results demonstrate that rapid, compensatory changes can occur in patients with visual field defects that impact on their ability to carry out efficient visual search. We plan to translate this therapy, along with appropriate testing materials, in a free-to-use, internet-based application based on this intervention. PMID:22626007

Jacquin-Courtois, Sophie; Bays, Paul M.; Salemme, Romeo; Leff, Alexander P.; Husain, Masud

2014-01-01

62

Hexagon-based search pattern for fast block motion estimation  

Microsoft Academic Search

In block motion estimation, a search pattern with a different shape or size has a very important impact on search speed and distortion performance. A square-shaped search pattern is adopted in many popular fast algorithms. Recently, a diamond-shaped search pattern was introduced in fast block motion estimation and has exhibited a faster search speed. Based on an in-depth examination of

Ce Zhu; Xiao Lin; Lap-pui Chau

2002-01-01

63

Parallel and Serial Processes in Visual Search  

ERIC Educational Resources Information Center

A long-standing issue in the study of how people acquire visual information centers around the scheduling and deployment of attentional resources: Is the process serial, or is it parallel? A substantial empirical effort has been dedicated to resolving this issue. However, the results remain largely inconclusive because the methodologies that have…

Thornton, Thomas L.; Gilden, David L.

2007-01-01

64

Algorithm 856: APPSPACK 4.0: Asynchronous Parallel Pattern Search  

E-print Network

Algorithm 856: APPSPACK 4.0: Asynchronous Parallel Pattern Search for Derivative-Free Optimization unconstrained and bound-constrained optimization problems. It implements an asynchronous parallel pattern search-free optimization, pattern search 1. INTRODUCTION APPSPACK is software for solving unconstrained and bound

Kolda, Tamara G.

65

ON THE CONVERGENCE OF ASYNCHRONOUS PARALLEL PATTERN SEARCH  

E-print Network

ON THE CONVERGENCE OF ASYNCHRONOUS PARALLEL PATTERN SEARCH TAMARA G. KOLDA AND VIRGINIA J. TORCZON­964 Abstract. In this paper we prove global convergence for asynchronous parallel pattern search. In standard pattern search, decisions regarding the update of the iterate and the step-length control parameter

Kolda, Tamara G.

66

RANK ORDERING AND POSITIVE BASES IN PATTERN SEARCH ALGORITHMS  

E-print Network

propose the term "methods of steep descent" to describe pattern search methods. Revision: 1.8 Date: 1998RANK ORDERING AND POSITIVE BASES IN PATTERN SEARCH ALGORITHMS ROBERT MICHAEL LEWIS AND VIRGINIA TORCZON Abstract. We present two new classes of pattern search algorithms for unconstrained mini

Torczon, Virginia

67

A summary statistic representation in peripheral vision explains visual search.  

PubMed

Vision is an active process: We repeatedly move our eyes to seek out objects of interest and explore our environment. Visual search experiments capture aspects of this process, by having subjects look for a target within a background of distractors. Search speed often correlates with target-distractor discriminability; search is faster when the target and distractors look quite different. However, there are notable exceptions. A given discriminability can yield efficient searches (where the target seems to "pop-out") as well as inefficient ones (where additional distractors make search significantly slower and more difficult). Search is often more difficult when finding the target requires distinguishing a particular configuration or conjunction of features. Search asymmetries abound. These puzzling results have fueled three decades of theoretical and experimental studies. We argue that the key issue in search is the processing of image patches in the periphery, where visual representation is characterized by summary statistics computed over a sizable pooling region. By quantifying these statistics, we predict a set of classic search results, as well as peripheral discriminability of crowded patches such as those found in search displays. PMID:22523401

Rosenholtz, Ruth; Huang, Jie; Raj, Alvin; Balas, Benjamin J; Ilie, Livia

2012-01-01

68

Video Google: Efficient Visual Search of Videos  

Microsoft Academic Search

We describe an approach to object retrieval which searches for and localizes all the occurrences of an object in a video, given a query image of the object. The object is represented by a set of viewpoint invariant region descriptors so that recognition can proceed successfully despite changes in viewpoint, illumination and partial occlusion. The temporal continuity of the video

Josef Sivic; Andrew Zisserman

2006-01-01

69

Anticipation and visual search behaviour in expert soccer goalkeepers.  

PubMed

A novel methodological approach is presented to examine the visual search behaviours employed by expert goalkeepers during simulated penalty kick situations in soccer. Expert soccer goalkeepers were classified as successful or unsuccessful based on their performance on a film-based test of anticipation skill, thereby allowing an intra-group comparison of visual search behaviour on the task. The anticipation test required participants to move a joystick in response to penalty kick situations presented on a large screen. The proportion of penalties saved was assessed as well as the frequency and time of initiation of joystick corrections. Visual search behaviour was examined using a portable eye movement registration system. The successful experts were more accurate in predicting the height and direction of the penalty kick, waited longer before initiating a response and appeared to spend longer periods of time fixating on the non-kicking leg compared with the non-successful experts. PMID:16338733

Savelsbergh, Geert J P; Van der Kamp, John; Williams, A Mark; Ward, Paul

70

Signal detection evidence for limited capacity in visual search.  

PubMed

The nature of capacity limits (if any) in visual search has been a topic of controversy for decades. In 30 years of work, researchers have attempted to distinguish between two broad classes of visual search models. Attention-limited models have proposed two stages of perceptual processing: an unlimited-capacity preattentive stage, and a limited-capacity selective attention stage. Conversely, noise-limited models have proposed a single, unlimited-capacity perceptual processing stage, with decision processes influenced only by stochastic noise. Here, we use signal detection methods to test a strong prediction of attention-limited models. In standard attention-limited models, performance of some searches (feature searches) should only be limited by a preattentive stage. Other search tasks (e.g., spatial configuration search for a "2" among "5"s) should be additionally limited by an attentional bottleneck. We equated average accuracies for a feature and a spatial configuration search over set sizes of 1-8 for briefly presented stimuli. The strong prediction of attention-limited models is that, given overall equivalence in performance, accuracy should be better on the spatial configuration search than on the feature search for set size 1, and worse for set size 8. We confirm this crossover interaction and show that it is problematic for at least one class of one-stage decision models. PMID:21901574

Palmer, Evan M; Fencsik, David E; Flusberg, Stephen J; Horowitz, Todd S; Wolfe, Jeremy M

2011-11-01

71

Perceptual load corresponds with factors known to influence visual search  

PubMed Central

One account of the early versus late selection debate in attention proposes that perceptual load determines the locus of selection. Attention selects stimuli at a late processing level under low-load conditions but selects stimuli at an early level under high-load conditions. Despite the successes of perceptual load theory, a non-circular definition of perceptual load remains elusive. We investigated the factors that influence perceptual load by using manipulations that have been studied extensively in visual search, namely target-distractor similarity and distractor-distractor similarity. Consistent with previous work, search was most efficient when targets and distractors were dissimilar and the displays contained homogeneous distractors; search became less efficient when target-distractor similarity increased irrespective of display heterogeneity. Importantly, we used these same stimuli in a typical perceptual load task that measured attentional spill-over to a task-irrelevant flanker. We found a strong correspondence between search efficiency and perceptual load; stimuli that generated efficient searches produced flanker interference effects, suggesting that such displays involved low perceptual load. Flanker interference effects were reduced in displays that produced less efficient searches. Furthermore, our results demonstrate that search difficulty, as measured by search intercept, has little bearing on perceptual load. These results suggest that perceptual load might be defined in part by well-characterized, continuous factors that influence visual search. PMID:23398258

Roper, Zachary J. J.; Cosman, Joshua D.; Vecera, Shaun P.

2014-01-01

72

Hemispheric differences in visual search of simple line arrays  

Microsoft Academic Search

The effects of perceptual organization on hemispheric visual-information processing were assessed with stimulus arrays composed of short lines arranged in columns. A visual-search task was employed in which subjects judged whether all the lines were vertical (same) or whether a single horizontal line was present (different). Stimulus-display organization was manipulated in two experiments by variation of line density, linear organization,

John Polich; David P. DeFrancesco; Joseph F. Garon; William Cohen

1990-01-01

73

Does linear separability really matter? Complex visual search is explained by simple search  

PubMed Central

Visual search in real life involves complex displays with a target among multiple types of distracters, but in the laboratory, it is often tested using simple displays with identical distracters. Can complex search be understood in terms of simple searches? This link may not be straightforward if complex search has emergent properties. One such property is linear separability, whereby search is hard when a target cannot be separated from its distracters using a single linear boundary. However, evidence in favor of linear separability is based on testing stimulus configurations in an external parametric space that need not be related to their true perceptual representation. We therefore set out to assess whether linear separability influences complex search at all. Our null hypothesis was that complex search performance depends only on classical factors such as target-distracter similarity and distracter homogeneity, which we measured using simple searches. Across three experiments involving a variety of artificial and natural objects, differences between linearly separable and nonseparable searches were explained using target-distracter similarity and distracter heterogeneity. Further, simple searches accurately predicted complex search regardless of linear separability (r = 0.91). Our results show that complex search is explained by simple search, refuting the widely held belief that linear separability influences visual search. PMID:24029822

Vighneshvel, T.; Arun, S. P.

2013-01-01

74

Predictive saccade target selection in superior colliculus during visual search.  

PubMed

Searching for a visual object naturally involves sequences of gaze fixations, during which the current foveal image is analyzed and the next object to inspect is selected as a saccade target. Fixation durations during such sequences are short, suggesting that saccades may be concurrently processed. Therefore, the selection of the next saccade target may occur before the current saccade target is acquired. To test this hypothesis, we trained four female rhesus monkeys (Macaca mulatta) to perform a multiple-fixation visual conjunction search task. We simultaneously recorded the activity of sensorimotor neurons in the midbrain superior colliculus (SC) in two monkeys. In this task, monkeys made multiple fixations before foveating the target. Fixation durations were significantly shorter than the latency of the initial responses to the search display, with approximately one-quarter being shorter than the shortest response latencies. The time at which SC sensorimotor activity discriminated the target from distracters occurred significantly earlier for the selection of subsequent fixations than for the selection of the first fixation. Target selection during subsequent fixations occurred even before the visual afferent delay in more than half of the neuronal sample, suggesting that the process of selection can encompass at least two future saccade targets. This predictive selection was present even when differences in saccade latencies were taken into account. Altogether, these findings demonstrate how neural representations on the visual salience map are processed in parallel, thus facilitating visual search. PMID:24741054

Shen, Kelly; Paré, Martin

2014-04-16

75

Functional MRI mapping of visual function and selective attention for performance assessment and presurgical planning using conjunctive visual search  

PubMed Central

Background Accurate mapping of visual function and selective attention using fMRI is important in the study of human performance as well as in presurgical treatment planning of lesions in or near visual centers of the brain. Conjunctive visual search (CVS) is a useful tool for mapping visual function during fMRI because of its greater activation extent compared with high-capacity parallel search processes. Aims The purpose of this work was to develop and evaluate a CVS that was capable of generating consistent activation in the basic and higher level visual areas of the brain by using a high number of distractors as well as an optimized contrast condition. Materials and methods Images from 10 healthy volunteers were analyzed and brain regions of greatest activation and deactivation were determined using a nonbiased decomposition of the results at the hemisphere, lobe, and gyrus levels. The results were quantified in terms of activation and deactivation extent and mean z-statistic. Results The proposed CVS was found to generate robust activation of the occipital lobe, as well as regions in the middle frontal gyrus associated with coordinating eye movements and in regions of the insula associated with task-level control and focal attention. As expected, the task demonstrated deactivation patterns commonly implicated in the default-mode network. Further deactivation was noted in the posterior region of the cerebellum, most likely associated with the formation of optimal search strategy. Conclusion We believe the task will be useful in studies of visual and selective attention in the neuroscience community as well as in mapping visual function in clinical fMRI. PMID:24683515

Parker, Jason G; Zalusky, Eric J; Kirbas, Cemil

2014-01-01

76

Visual search deficits in Williams-Beuren syndrome  

Microsoft Academic Search

Williams-Beuren syndrome (WBS) is a rare genetic condition characterized by several physical and mental traits, such as a poor visuo-spatial processing and a relative strength in language. In this study we investigated how WBS subjects search and scan their visual environment.We presented 10 search displays on a computer screen to WBS subjects as well as control subjects, with the instruction

I. Montfoort; M. A. Frens; I. Th. C. Hooge; G. C. Lagers-van Haselen; J. N. van der Geest

2007-01-01

77

Pip and pop: nonspatial auditory signals improve spatial visual search.  

PubMed

Searching for an object within a cluttered, continuously changing environment can be a very time-consuming process. The authors show that a simple auditory pip drastically decreases search times for a synchronized visual object that is normally very difficult to find. This effect occurs even though the pip contains no information on the location or identity of the visual object. The experiments also show that the effect is not due to general alerting (because it does not occur with visual cues), nor is it due to top-down cuing of the visual change (because it still occurs when the pip is synchronized with distractors on the majority of trials). Instead, we propose that the temporal information of the auditory signal is integrated with the visual signal, generating a relatively salient emergent feature that automatically draws attention. Phenomenally, the synchronous pip makes the visual object pop out from its complex environment, providing a direct demonstration of spatially nonspecific sounds affecting competition in spatial visual processing. PMID:18823194

Van der Burg, Erik; Olivers, Christian N L; Bronkhorst, Adelbert W; Theeuwes, Jan

2008-10-01

78

Visual exploratory search of relationship graphs on smartphones.  

PubMed

This paper presents a novel framework for Visual Exploratory Search of Relationship Graphs on Smartphones (VESRGS) that is composed of three major components: inference and representation of semantic relationship graphs on the Web via meta-search, visual exploratory search of relationship graphs through both querying and browsing strategies, and human-computer interactions via the multi-touch interface and mobile Internet on smartphones. In comparison with traditional lookup search methodologies, the proposed VESRGS system is characterized with the following perceived advantages. 1) It infers rich semantic relationships between the querying keywords and other related concepts from large-scale meta-search results from Google, Yahoo! and Bing search engines, and represents semantic relationships via graphs; 2) the exploratory search approach empowers users to naturally and effectively explore, adventure and discover knowledge in a rich information world of interlinked relationship graphs in a personalized fashion; 3) it effectively takes the advantages of smartphones' user-friendly interfaces and ubiquitous Internet connection and portability. Our extensive experimental results have demonstrated that the VESRGS framework can significantly improve the users' capability of seeking the most relevant relationship information to their own specific needs. We envision that the VESRGS framework can be a starting point for future exploration of novel, effective search strategies in the mobile Internet era. PMID:24223936

Ouyang, Jianquan; Zheng, Hao; Kong, Fanbin; Liu, Tianming

2013-01-01

79

Perceptual basis of redundancy gains in visual pop-out search.  

PubMed

The redundant-signals effect (RSE) refers to a speed-up of RT when the response is triggered by two, rather than just one, response-relevant target elements. Although there is agreement that in the visual modality RSEs observed with dimensionally redundant signals originating from the same location are generated by coactive processing architectures, there has been a debate as to the exact stage(s)--preattentive versus postselective--of processing at which coactivation arises. To determine the origin(s) of redundancy gains in visual pop-out search, the present study combined mental chronometry with electrophysiological markers that reflect purely preattentive perceptual (posterior-contralateral negativity [PCN]), preattentive and postselective perceptual plus response selection-related (stimulus-locked lateralized readiness potential [LRP]), or purely response production-related processes (response-locked LRP). As expected, there was an RSE on target detection RTs, with evidence for coactivation. At the electrophysiological level, this pattern was mirrored by an RSE in PCN latencies, whereas stimulus-locked LRP latencies showed no RSE over and above the PCN effect. Also, there was no RSE on the response-locked LRPs. This pattern demonstrates a major contribution of preattentive perceptual processing stages to the RSE in visual pop-out search, consistent with parallel-coactive coding of target signals in multiple visual dimensions [Müller, H. J., Heller, D., & Ziegler, J. Visual search for singleton feature targets within and across feature dimensions. PMID:20044891

Töllner, Thomas; Zehetleitner, Michael; Krummenacher, Joseph; Müller, Hermann J

2011-01-01

80

Measuring Search Efficiency in Complex Visual Search Tasks: Global and Local Clutter  

ERIC Educational Resources Information Center

Set size and crowding affect search efficiency by limiting attention for recognition and attention against competition; however, these factors can be difficult to quantify in complex search tasks. The current experiments use a quantitative measure of the amount and variability of visual information (i.e., clutter) in highly complex stimuli (i.e.,…

Beck, Melissa R.; Lohrenz, Maura C.; Trafton, J. Gregory

2010-01-01

81

Monitoring mechanisms in visual search: an fMRI study.  

PubMed

This fMRI study investigates the neural underpinning and the cognitive factors associated with monitoring in visual search. A visual search task was designed by pseudo-randomly mixing four experimental conditions, which were obtained through the factorial combination of salience (pop-out vs. non pop-out) and target presence (present vs. absent). The fastest responses were obtained when a salient target was presented, while responses were slowest with target-absent conditions, which required extensive evaluation of the visual scene. Partial Least Square multivariate analysis was used to analyze the fMRI data. The first Latent Variable revealed a set of fronto-parietal and occipital regions, which was cohesively activated especially when the presence of the target stimulus was not easy to discard, such as when all stimuli in the visual scene were non-targets or when one stimulus among the rest was salient (pop-out) but not a target. The most extensive and robust activation within this cohesive set of regions was located in the right inferior/middle frontal gyrus. This finding corroborates evidence in favor of a role of the right lateral prefrontal cortex, and associated regions, for evaluative operations, extending previous findings to the visual search domain. PMID:25046361

Vallesi, Antonino

2014-09-01

82

Bumblebee visual search for multiple learned target types.  

PubMed

Visual search is well studied in human psychology, but we know comparatively little about similar capacities in non-human animals. It is sometimes assumed that animal visual search is restricted to a single target at a time. In bees, for example, this limitation has been evoked to explain flower constancy, the tendency of bees to specialise on a single flower type. Few studies, however, have investigated bee visual search for multiple target types after extended learning and controlling for prior visual experience. We trained colour-naive bumblebees (Bombus terrestris) extensively in separate discrimination tasks to recognise two rewarding colours in interspersed block training sessions. We then tested them with the two colours simultaneously in the presence of distracting colours to examine whether and how quickly they were able to switch between the target colours. We found that bees switched between visual targets quickly and often. The median time taken to switch between targets was shorter than known estimates of how long traces last in bees' working memory, suggesting that their capacity to recall more than one learned target was not restricted by working memory limitations. Following our results, we propose a model of memory and learning that integrates our findings with those of previous studies investigating flower constancy. PMID:23948481

Nityananda, Vivek; Pattrick, Jonathan G

2013-11-15

83

Scanners and drillers: Characterizing expert visual search through volumetric images  

E-print Network

# $ Department of Surgery, Brigham and Women's Hospital, Boston, MA, USA Modern imaging methods like computed tomography) scan with, perhaps, 1,000 ``slices'' through the body. These high-resolution images allowScanners and drillers: Characterizing expert visual search through volumetric images Trafton Drew

84

Predicting Cognitive Strategies and Eye Movements in Hierarchical Visual Search  

E-print Network

Predicting Cognitive Strategies and Eye Movements in Hierarchical Visual Search Anthony J. Hornof and a priori predictive models of the eye movement data. The models are evaluated based on the eye movement sweep", in which the eyes move to capture everything in the high resolution foveal vision, which

Hornof, Anthony

85

Operator Choice Modeling for Collaborative UAV Visual Search Tasks  

E-print Network

Operator Choice Modeling for Collaborative UAV Visual Search Tasks Luca F. Bertuccelli Member, IEEE, and Mary L. Cummings Senior Member, IEEE Abstract--Unmanned Aerial Vehicles (UAVs) provide unprece- dented is expected to increase with envisaged future missions of one operator controlling mul- tiple UAVs

Cummings, Mary "Missy"

86

Statistical Templates for Visual Search John F. Ackermann1  

E-print Network

of target and match, and rotating the intensity-based template. No intensity-based template, however, can). It thus acts as a matched filter, i.e., a template for a rudimentary stimulus such as an edge, a lineStatistical Templates for Visual Search John F. Ackermann1 & Michael S. Landy1,2 1. Department

Landy, Michael S.

87

Enhancing visual search abilities of people with intellectual disabilities.  

PubMed

This study aimed to evaluate the effects of cueing in visual search paradigm for people with and without intellectual disabilities (ID). A total of 36 subjects (18 persons with ID and 18 persons with normal intelligence) were recruited using convenient sampling method. A series of experiments were conducted to compare guided cue strategies using either motion contrast or additional cue to basic search task. Repeated measure ANOVA and post hoc multiple comparison tests were used to compare each cue strategy. Results showed that the use of guided strategies was able to capture focal attention in an autonomic manner in the ID group (Pillai's Trace=5.99, p<0.0001). Both guided cue and guided motion search tasks demonstrated functionally similar effects that confirmed the non-specific character of salience. These findings suggested that the visual search efficiency of people with ID was greatly improved if the target was made salient using cueing effect when the complexity of the display increased (i.e. set size increased). This study could have an important implication for the design of the visual searching format of any computerized programs developed for people with ID in learning new tasks. PMID:18359188

Li-Tsang, Cecilia W P; Wong, Jackson K K

2009-01-01

88

Visualizing non-functional requirements patterns  

Microsoft Academic Search

Properly dealing with non-functional requirements (NFRs), such as security and trustworthiness, requires a large body of knowledge about NFRs. Such knowledge can be captured as NFR patterns for reuse. Since knowledge of NFRs can have potentially complex structures and rules, it becomes hard to capture and reuse NFR patterns when they are represented only textually. In this paper, we present

Sam Supakkul; Lawrence Chung

2010-01-01

89

Synchronized audio-visual transients drive efficient visual search for motion-in-depth.  

PubMed

In natural audio-visual environments, a change in depth is usually correlated with a change in loudness. In the present study, we investigated whether correlating changes in disparity and loudness would provide a functional advantage in binding disparity and sound amplitude in a visual search paradigm. To test this hypothesis, we used a method similar to that used by van der Burg et al. to show that non-spatial transient (square-wave) modulations of loudness can drastically improve spatial visual search for a correlated luminance modulation. We used dynamic random-dot stereogram displays to produce pure disparity modulations. Target and distractors were small disparity-defined squares (either 6 or 10 in total). Each square moved back and forth in depth in front of the background plane at different phases. The target's depth modulation was synchronized with an amplitude-modulated auditory tone. Visual and auditory modulations were always congruent (both sine-wave or square-wave). In a speeded search task, five observers were asked to identify the target as quickly as possible. Results show a significant improvement in visual search times in the square-wave condition compared to the sine condition, suggesting that transient auditory information can efficiently drive visual search in the disparity domain. In a second experiment, participants performed the same task in the absence of sound and showed a clear set-size effect in both modulation conditions. In a third experiment, we correlated the sound with a distractor instead of the target. This produced longer search times, indicating that the correlation is not easily ignored. PMID:22615939

Zannoli, Marina; Cass, John; Mamassian, Pascal; Alais, David

2012-01-01

90

Using Indexed-Sequential Geometric Glyphs to Explore Visual Patterns  

Microsoft Academic Search

\\u000a This paper presents a visualization tool called PolygonR&D for exploring visual tiling patterns. To facilitate the exploration\\u000a process, PolygonR&D uses dynamically-generated, interactive geometric glyph visualizations that intermediate reasoning between\\u000a the sequential textual code and the parallel visual structure of the tilings. Sequential textual code generates indexed-sequential\\u000a geometric glyphs. Not only does each glyph represent one procedure in the sequential code,

Jim Morey; Kamran Sedig

2004-01-01

91

Visual search, anticipation and expertise in soccer goalkeepers.  

PubMed

We used a novel methodological approach to examine skill-based differences in anticipation and visual search behaviour during the penalty kick in soccer. Expert and novice goalkeepers were required to move a joystick in response to penalty kicks presented on film. The proportion of penalties saved was assessed, as well as the frequency and time of initiation of joystick corrections. Visual search behaviour was examined using an eye movement registration system. Expert goalkeepers were generally more accurate in predicting the direction of the penalty kick, waited longer before initiating a response and made fewer corrective movements with the joystick. The expert goalkeepers used a more efficient search strategy involving fewer fixations of longer duration to less disparate areas of the display. The novices spent longer fixating on the trunk, arms and hips, whereas the experts found the kicking leg, non-kicking leg and ball areas to be more informative, particularly as the moment of foot-ball contact approached. No differences in visual search behaviour were observed between successful and unsuccessful penalties. The results have implications for improving anticipation skill at penalty kicks. PMID:11999482

Savelsbergh, Geert J P; Williams, A Mark; Van der Kamp, John; Ward, Paul

2002-03-01

92

Visual cluster analysis and pattern recognition methods  

DOEpatents

A method of clustering using a novel template to define a region of influence. Using neighboring approximation methods, computation times can be significantly reduced. The template and method are applicable and improve pattern recognition techniques.

Osbourn, Gordon Cecil (Albuquerque, NM); Martinez, Rubel Francisco (Albuquerque, NM)

2001-01-01

93

Visual Object Pattern Separation Varies in Older Adults  

ERIC Educational Resources Information Center

Young and nondemented older adults completed a visual object continuous recognition memory task in which some stimuli (lures) were similar but not identical to previously presented objects. The lures were hypothesized to result in increased interference and increased pattern separation demand. To examine variability in object pattern separation…

Holden, Heather M.; Toner, Chelsea; Pirogovsky, Eva; Kirwan, C. Brock; Gilbert, Paul E.

2013-01-01

94

MIME: A Framework for Interactive Visual Pattern Mining  

E-print Network

MIME: A Framework for Interactive Visual Pattern Mining Bart Goethals, Sandy Moens, and Jilles, using a toolbox consisting of interestingness measures, mining algorithms and post-processing algorithms to assist in identifying interesting patterns. By mining interactively, we enable the user to combine

Antwerpen, Universiteit

95

Macular degeneration affects eye movement behavior during visual search  

PubMed Central

Patients with a scotoma in their central vision (e.g., due to macular degeneration, MD) commonly adopt a strategy to direct the eyes such that the image falls onto a peripheral location on the retina. This location is referred to as the preferred retinal locus (PRL). Although previous research has investigated the characteristics of this PRL, it is unclear whether eye movement metrics are modulated by peripheral viewing with a PRL as measured during a visual search paradigm. To this end, we tested four MD patients in a visual search paradigm and contrasted their performance with a healthy control group and a healthy control group performing the same experiment with a simulated scotoma. The experiment contained two conditions. In the first condition the target was an unfilled circle hidden among c-shaped distractors (serial condition) and in the second condition the target was a filled circle (pop-out condition). Saccadic search latencies for the MD group were significantly longer in both conditions compared to both control groups. Results of a subsequent experiment indicated that this difference between the MD and the control groups could not be explained by a difference in target selection sensitivity. Furthermore, search behavior of MD patients was associated with saccades with smaller amplitudes toward the scotoma, an increased intersaccadic interval and an increased number of eye movements necessary to locate the target. Some of these characteristics, such as the increased intersaccadic interval, were also observed in the simulation group, which indicate that these characteristics are related to the peripheral viewing itself. We suggest that the combination of the central scotoma and peripheral viewing can explain the altered search behavior and no behavioral evidence was found for a possible reorganization of the visual system associated with the use of a PRL. Thus the switch from a fovea-based to a PRL-based reference frame impairs search efficiency. PMID:24027546

Van der Stigchel, Stefan; Bethlehem, Richard A. I.; Klein, Barrie P.; Berendschot, Tos T. J. M.; Nijboer, Tanja C. W.; Dumoulin, Serge O.

2013-01-01

96

Searching for Pulsars Using Image Pattern Recognition  

NASA Astrophysics Data System (ADS)

In the modern era of big data, many fields of astronomy are generating huge volumes of data, the analysis of which can sometimes be the limiting factor in research. Fortunately, computer scientists have developed powerful data-mining techniques that can be applied to various fields. In this paper, we present a novel artificial intelligence (AI) program that identifies pulsars from recent surveys by using image pattern recognition with deep neural nets—the PICS (Pulsar Image-based Classification System) AI. The AI mimics human experts and distinguishes pulsars from noise and interference by looking for patterns from candidate plots. Different from other pulsar selection programs that search for expected patterns, the PICS AI is taught the salient features of different pulsars from a set of human-labeled candidates through machine learning. The training candidates are collected from the Pulsar Arecibo L-band Feed Array (PALFA) survey. The information from each pulsar candidate is synthesized in four diagnostic plots, which consist of image data with up to thousands of pixels. The AI takes these data from each candidate as its input and uses thousands of such candidates to train its ~9000 neurons. The deep neural networks in this AI system grant it superior ability to recognize various types of pulsars as well as their harmonic signals. The trained AI's performance has been validated with a large set of candidates from a different pulsar survey, the Green Bank North Celestial Cap survey. In this completely independent test, the PICS ranked 264 out of 277 pulsar-related candidates, including all 56 previously known pulsars and 208 of their harmonics, in the top 961 (1%) of 90,008 test candidates, missing only 13 harmonics. The first non-pulsar candidate appears at rank 187, following 45 pulsars and 141 harmonics. In other words, 100% of the pulsars were ranked in the top 1% of all candidates, while 80% were ranked higher than any noise or interference. The performance of this system can be improved over time as more training data are accumulated. This AI system has been integrated into the PALFA survey pipeline and has discovered six new pulsars to date.

Zhu, W. W.; Berndsen, A.; Madsen, E. C.; Tan, M.; Stairs, I. H.; Brazier, A.; Lazarus, P.; Lynch, R.; Scholz, P.; Stovall, K.; Ransom, S. M.; Banaszak, S.; Biwer, C. M.; Cohen, S.; Dartez, L. P.; Flanigan, J.; Lunsford, G.; Martinez, J. G.; Mata, A.; Rohr, M.; Walker, A.; Allen, B.; Bhat, N. D. R.; Bogdanov, S.; Camilo, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J. S.; Desvignes, G.; Ferdman, R. D.; Freire, P. C. C.; Hessels, J. W. T.; Jenet, F. A.; Kaplan, D. L.; Kaspi, V. M.; Knispel, B.; Lee, K. J.; van Leeuwen, J.; Lyne, A. G.; McLaughlin, M. A.; Siemens, X.; Spitler, L. G.; Venkataraman, A.

2014-02-01

97

Sequential pattern data mining and visualization  

DOEpatents

One or more processors (22) are operated to extract a number of different event identifiers therefrom. These processors (22) are further operable to determine a number a display locations each representative of one of the different identifiers and a corresponding time. The display locations are grouped into sets each corresponding to a different one of several event sequences (330a, 330b, 330c. 330d, 330e). An output is generated corresponding to a visualization (320) of the event sequences (330a, 330b, 330c, 330d, 330e).

Wong, Pak Chung (Richland, WA); Jurrus, Elizabeth R. (Kennewick, WA); Cowley, Wendy E. (Benton City, WA); Foote, Harlan P. (Richland, WA); Thomas, James J. (Richland, WA)

2011-12-06

98

Sequential pattern data mining and visualization  

DOEpatents

One or more processors (22) are operated to extract a number of different event identifiers therefrom. These processors (22) are further operable to determine a number a display locations each representative of one of the different identifiers and a corresponding time. The display locations are grouped into sets each corresponding to a different one of several event sequences (330a, 330b, 330c. 330d, 330e). An output is generated corresponding to a visualization (320) of the event sequences (330a, 330b, 330c, 330d, 330e).

Wong, Pak Chung (Richland, WA); Jurrus, Elizabeth R. (Kennewick, WA); Cowley, Wendy E. (Benton City, WA); Foote, Harlan P. (Richland, WA); Thomas, James J. (Richland, WA)

2009-05-26

99

Aurally aided visual search in three-dimensional space.  

PubMed

We conducted an experiment to evaluate the effectiveness of spatial audio displays on target acquisition performance. Participants performed a visual search task with and without the aid of a spatial audio display. Potential target locations ranged between plus and minus 180 degrees in azimuth and from -70 degrees to +90 degrees in elevation. Independent variables included the number of visual distractors present (1, 5, 10, 25, 50) and the spatial audio condition (no spatial audio, free-field spatial audio, virtual spatial audio). Results indicated that both free-field and virtual audio cues engendered a significant decrease in search times. Potential applications of this research include the design of spatial audio displays for aircraft cockpits and ground combat vehicles. PMID:10774135

Bolia, R S; D'Angelo, W R; McKinley, R L

1999-12-01

100

Do the Contents of Visual Working Memory Automatically Influence Attentional Selection During Visual Search?  

Microsoft Academic Search

In many theories of cognition, researchers propose that working memory and perception operate interactively. For example, in previous studies researchers have suggested that sensory inputs matching the contents of working memory will have an automatic advantage in the competition for processing resources. The authors tested this hypothesis by requiring observers to perform a visual search task while concurrently maintaining object

Geoffrey F. Woodman; Steven J. Luck

2007-01-01

101

Visualizing and discovering web navigational patterns  

Microsoft Academic Search

Web site structures are complex to analyze. Cross-referencing the web structure with navigational behaviour adds to the complexity of the analysis. However, this convoluted analysis is necessary to discover useful patterns and understand the navigational behaviour of web site visitors, whether to improve web site structures, provide intelligent on-line tools or offer support to human decision makers. Moreover, interactive investigation

Jiyang Chen; Lisheng Sun; Osmar R. Zaïane; Randy Goebel

2004-01-01

102

Serial Attention Mechanisms in Visual Search: A Direct Behavioral Demonstration  

Microsoft Academic Search

In visual search, inefficient performance of human observers is typically characterized by a steady increase in reaction time with the number of array elementsthe so-called set-size effect. In general, set-size effects are taken to indicate that processing of the array elements depends on limited-capacity resources, that is, it involves attention. Contrasting theories have been proposed to account for this attentional

Emanuela Bricolo; Tiziana Gianesini; Alessandra Fanini; Claus Bundesen; Leonardo Chelazzi

2002-01-01

103

Visual search performance of patients with vision impairment: effect of JPEG image enhancement  

E-print Network

Visual search performance of patients with vision impairment: effect of JPEG image enhancement Gang & Peli E. Visual search performance of patients with vision impairment: effect of JPEG image enhancement, image enhancement, low vision rehabilitation, visual search Correspondence: Gang Luo E-mail address

Peli, Eli

104

PatternHunter: faster and more sensitive homology search  

Microsoft Academic Search

Motivation: Genomics and proteomics studies routinely depend on homology searches based on the strategy of finding short seed matches which are then extended. The exploding genomic data growth presents a dilemma for DNA homology search techniques: increasing seed size decreases sensitivity whereas decreasing seed size slows down computation. Results: We present a new homology search algorithm 'PatternHunter' that uses a

Bin Ma; John Tromp; Ming Li

2002-01-01

105

Image pattern recognition supporting interactive analysis and graphical visualization  

NASA Technical Reports Server (NTRS)

Image Pattern Recognition attempts to infer properties of the world from image data. Such capabilities are crucial for making measurements from satellite or telescope images related to Earth and space science problems. Such measurements can be the required product itself, or the measurements can be used as input to a computer graphics system for visualization purposes. At present, the field of image pattern recognition lacks a unified scientific structure for developing and evaluating image pattern recognition applications. The overall goal of this project is to begin developing such a structure. This report summarizes results of a 3-year research effort in image pattern recognition addressing the following three principal aims: (1) to create a software foundation for the research and identify image pattern recognition problems in Earth and space science; (2) to develop image measurement operations based on Artificial Visual Systems; and (3) to develop multiscale image descriptions for use in interactive image analysis.

Coggins, James M.

1992-01-01

106

The development of organized visual search Adam J. Woods a,c,  

E-print Network

, The Children's Hospital of Philadelphia, United States c Center for Cognitive Neuroscience, University orientation Conjunction search Visual search plays an important role in guiding behavior. Children have more developmental differences in children's ability to organize serial visual search (i.e., search organization

Chatterjee, Anjan

107

Intertrial Temporal Contextual Cuing: Association Across Successive Visual Search Trials Guides Spatial Attention  

Microsoft Academic Search

Contextual cuing refers to the facilitation of performance in visual search due to the repetition of the same displays. Whereas previous studies have focused on contextual cuing within single-search trials, this study tested whether 1 trial facilitates visual search of the next trial. Participants searched for a T among Ls. In the training phase, the spatial layout on trial N?1

Fuminori Ono; Yuhong Jiang; Jun-ichiro Kawahara

2005-01-01

108

Rapid searches for complex patterns in biological molecules.  

PubMed Central

The intrinsic redundancy of genetic information makes searching for patterns in biological sequences a difficult task. We have designed an interactive self-documenting computer program called QUEST that allows rapid searching of large DNA and protein data banks for highly redundant consensus sequences or character patterns. QUEST uses a concise language for specifying character patterns containing several levels of ambiguity and pattern arrangement. Examples of the use of this program for sequence data are given. Details of the algorithm and pattern optimization are explained. PMID:6546419

Abarbanel, R M; Wieneke, P R; Mansfield, E; Jaffe, D A; Brutlag, D L

1984-01-01

109

Visualizing the log-periodic pattern before crashes  

Microsoft Academic Search

:   We present a method for visualizing the pattern which we believe to be a precursor signature of financial crashes (or ruptures).\\u000a The log-periodicity of the pattern is investigated through the envelope function technique. Three periods of the Dow Jones\\u000a Industrial Average (DJIA) are investigated: 1982-1987, 1992-1997 and 1993-1998. The presence of a rupture in the end of 1998\\u000a is

N. Vandewalle; M. Ausloos; Ph. Boveroux; A. Minguet

1999-01-01

110

Recognizing patterns of visual field loss using unsupervised machine learning  

NASA Astrophysics Data System (ADS)

Glaucoma is a potentially blinding optic neuropathy that results in a decrease in visual sensitivity. Visual field abnormalities (decreased visual sensitivity on psychophysical tests) are the primary means of glaucoma diagnosis. One form of visual field testing is Frequency Doubling Technology (FDT) that tests sensitivity at 52 points within the visual field. Like other psychophysical tests used in clinical practice, FDT results yield specific patterns of defect indicative of the disease. We used Gaussian Mixture Model with Expectation Maximization (GEM), (EM is used to estimate the model parameters) to automatically separate FDT data into clusters of normal and abnormal eyes. Principal component analysis (PCA) was used to decompose each cluster into different axes (patterns). FDT measurements were obtained from 1,190 eyes with normal FDT results and 786 eyes with abnormal (i.e., glaucomatous) FDT results, recruited from a university-based, longitudinal, multi-center, clinical study on glaucoma. The GEM input was the 52-point FDT threshold sensitivities for all eyes. The optimal GEM model separated the FDT fields into 3 clusters. Cluster 1 contained 94% normal fields (94% specificity) and clusters 2 and 3 combined, contained 77% abnormal fields (77% sensitivity). For clusters 1, 2 and 3 the optimal number of PCA-identified axes were 2, 2 and 5, respectively. GEM with PCA successfully separated FDT fields from healthy and glaucoma eyes and identified familiar glaucomatous patterns of loss.

Yousefi, Siamak; Goldbaum, Michael H.; Zangwill, Linda M.; Medeiros, Felipe A.; Bowd, Christopher

2014-03-01

111

Adaptation improves performance on a visual search task  

PubMed Central

Temporal context, or adaptation, profoundly affects visual perception. Despite the strength and prevalence of adaptation effects, their functional role in visual processing remains unclear. The effects of spatial context and their functional role are better understood: these effects highlight features that differ from their surroundings and determine stimulus salience. Similarities in the perceptual and physiological effects of spatial and temporal context raise the possibility that they serve similar functions. We therefore tested the possibility that adaptation can enhance stimulus salience. We measured the effects of prolonged (40 s) adaptation to a counterphase grating on performance in a search task in which targets were defined by an orientation offset relative to a background of distracters. We found that, for targets with small orientation offsets, adaptation reduced reaction times and decreased the number of saccades made to find targets. Our results provide evidence that adaptation may function to highlight features that differ from the temporal context in which they are embedded. PMID:23390320

Wissig, Stephanie C.; Patterson, Carlyn A.; Kohn, Adam

2013-01-01

112

Model of visual contrast gain control and pattern masking  

E-print Network

Model of visual contrast gain control and pattern masking Andrew B. Watson NASA Ames Research Center, Moffett Field, California 94035-1000 Joshua A. Solomon Institute of Ophthalmology, Bath Street March 20, 1997 We have implemented a model of contrast gain control in human vision that incorporates

Watson, Andrew B.

113

Fatigue and Structural Change: Two Consequences of Visual Pattern Adaptation  

E-print Network

Fatigue and Structural Change: Two Consequences of Visual Pattern Adaptation Jeremy M. Wolfe-term fatigue, produced very quickly and (2) long-term structural change, requiring more extended adaptation reductions in the sensitivity of the mechanisms detecting the stimulus. Adaptation fatigues the mechanism

114

Implementation of visual languages using pattern-based specifications  

Microsoft Academic Search

SUMMARY The implementation of visual languages requires a wide range of conceptual and technical knowledge from issues of user interface design and graphical implementation to aspects of analysis and transformation for languages in general. We present a powerful toolset that incorporates such knowledge. Our toolset generates editors from high-level specifications. A language is specified by identifyingcertain patterns in the language

Carsten Schmidt; Uwe Kastens

2003-01-01

115

Visual pattern based colour image compression G. Schaefer+  

E-print Network

& Imaging Institute ++ School of Computing & Mathematics University of Derby, UK ABSTRACT A novel colour of predefined, universal visual patterns in a uniform colour space. Source coding and colour quantisation per pixel) needed to represent a digital image whilst trying to maintain high perceptual image quality

Aickelin, Uwe

116

Visual search strategies of experienced and nonexperienced swimming coaches.  

PubMed

The aim of this study consists of the application of an experimental protocol that allows information to be obtained about the visual search strategies elaborated by swimming coaches. 16 swimming coaches participated. The Experienced group (n=8) had 16.1 yr. (SD=8.2) of coaching experience and at least five years of experience in underwater vision. The Nonexperienced group in underwater vision (n= 8) had 4.2 yr. (SD= 4.0) of coaching experience. Participants were tested in a laboratory environment using a video-projected sample of the crawl stroke of an elite swimmer. This work discusses the main areas of the swimmer's body used by coaches to identify and analyse errors in technique from overhead and underwater perspectives. In front-underwater videos, body roll and mid-water were the locations of the display with higher percentages of fixation time. In the side-underwater slow videos, the upper body was the location with higher percentages of visual fixation time and was used to detect the low elbow fault. Side-overhead takes were not the best perspectives to pick up information directly about performance of the arms; coaches attended to the head as a reference for their visual search. The observation and technical analysis of the hands and arms were facilitated by an underwater perspective. Visual fixation on the elbow served as a reference to identify errors in the upper body. The side-underwater perspective may be an adequate way to identify correct knee angles in leg kicking and the alignment of a swimmer's body and leg actions. PMID:17326515

Moreno, Francisco J; Saavedra, José M; Sabido, Rafael; Luis, Vicente; Reina, Raúl

2006-12-01

117

A new hybrid optimization method for loading pattern search  

SciTech Connect

A new hybrid optimization method in reloading pattern search is presented in this paper, which mix genetic algorithm (GA) with tabu search (TS). The method combines global search of GA and local search of TS reasonably to enhance the search ability and computational efficiency. For verification and illustration of the advantage of this method, the proposed hybrid optimization method has been applied to the reactor reloading optimization calculation of Cartesian and hexagonal geometry core. The numerical results show that the hybrid method works faster and better than GA. (authors)

Tao, Wang [Shanghai Jiao Tong University, Shanghai 200030 (China); Zhongsheng, Xie [Xi'an Jiao Tong University, Xi'an 710049 (China)

2006-07-01

118

LOCAL DENSITY GUIDES VISUAL SEARCH: SPARSE GROUPS ARE FIRST AND FASTER  

E-print Network

LOCAL DENSITY GUIDES VISUAL SEARCH: SPARSE GROUPS ARE FIRST AND FASTER Tim Halverson and Anthony J modeling to investigate the effect of local density on the visual search of structured layouts of words to process words within a consistent visual angle regardless of density, but that they were more likely

Hornof, Anthony

119

Searching for Signs, Symbols, and Icons: Effects of Time of Day, Visual Complexity, and Grouping  

ERIC Educational Resources Information Center

Searching for icons, symbols, or signs is an integral part of tasks involving computer or radar displays, head-up displays in aircraft, or attending to road traffic signs. Icons therefore need to be designed to optimize search times, taking into account the factors likely to slow down visual search. Three factors likely to adversely affect visual

McDougall, Sine; Tyrer, Victoria; Folkard, Simon

2006-01-01

120

Object-based auditory facilitation of visual search for pictures and words with frequent and rare targets  

PubMed Central

Auditory and visual processes demonstrably enhance each other based on spatial and temporal coincidence. Our recent results on visual search have shown that auditory signals also enhance visual salience of specific objects based on multimodal experience. For example, we tend to see an object (e.g., a cat) and simultaneously hear its characteristic sound (e.g., “meow”), to name an object when we see it, and to vocalize a word when we read it, but we do not tend to see a word (e.g., cat) and simultaneously hear the characteristic sound (e.g., “meow”) of the named object. If auditory-visual enhancements occur based on this pattern of experiential associations, playing a characteristic sound (e.g., “meow”) should facilitate visual search for the corresponding object (e.g., an image of a cat), hearing a name should facilitate visual search for both the corresponding object and corresponding word, but playing a characteristic sound should not facilitate visual search for the name of the corresponding object. Our present and prior results together confirmed these experiential-association predictions. We also recently showed that the underlying object-based auditory-visual interactions occur rapidly (within 220 ms) and guide initial saccades towards target objects. If object-based auditory-visual enhancements are automatic and persistent, an interesting application would be to use characteristic sounds to facilitate visual search when targets are rare, such as during baggage screening. Our participants searched for a gun among other objects when a gun was presented on only 10% of the trials. The search time was speeded when a gun sound was played on every trial (primarily on gun-absent trials); importantly, playing gun sounds facilitated both gun-present and gun-absent responses, suggesting that object-based auditory-visual enhancements persistently increase the detectability of guns rather than simply biasing gun-present responses. Thus, object-based auditory-visual interactions that derive from experiential associations rapidly and persistently increase visual salience of corresponding objects. PMID:20864070

Iordanescu, Lucica; Grabowecky, Marcia; Suzuki, Satoru

2010-01-01

121

Vibrio coralliilyticus Search Patterns across an Oxygen Gradient  

PubMed Central

The coral pathogen, Vibrio coralliilyticus shows specific chemotactic search pattern preference for oxic and anoxic conditions, with the newly identified 3-step flick search pattern dominating the patterns used in oxic conditions. We analyzed motile V. coralliilyticus cells for behavioral changes with varying oxygen concentrations to mimic the natural coral environment exhibited during light and dark conditions. Results showed that 3-step flicks were 1.4× (P?=?0.006) more likely to occur in oxic conditions than anoxic conditions with mean values of 18 flicks (95% CI?=?0.4, n?=?53) identified in oxic regions compared to 13 (95% CI?=?0.5, n?=?38) at anoxic areas. In contrast, run and reverse search patterns were more frequent in anoxic regions with a mean value of 15 (95% CI?=?0.7, n?=?46), compared to a mean value of 10 (95% CI?=?0.8, n?=?29) at oxic regions. Straight swimming search patterns remained similar across oxic and anoxic regions with a mean value of 13 (95% CI?=?0.7, n?=?oxic: 13, anoxic: 14). V. coralliilyticus remained motile in oxic and anoxic conditions, however, the 3-step flick search pattern occurred in oxic conditions. This result provides an approach to further investigate the 3-step flick. PMID:23874480

Winn, Karina M.; Bourne, David G.; Mitchell, James G.

2013-01-01

122

Patterns in the sky: Natural visualization of aircraft flow fields  

NASA Technical Reports Server (NTRS)

The objective of the current publication is to present the collection of flight photographs to illustrate the types of flow patterns that were visualized and to present qualitative correlations with computational and wind tunnel results. Initially in section 2, the condensation process is discussed, including a review of relative humidity, vapor pressure, and factors which determine the presence of visible condensate. Next, outputs from computer code calculations are postprocessed by using water-vapor relationships to determine if computed values of relative humidity in the local flow field correlate with the qualitative features of the in-flight condensation patterns. The photographs are then presented in section 3 by flow type and subsequently in section 4 by aircraft type to demonstrate the variety of condensed flow fields that was visualized for a wide range of aircraft and flight maneuvers.

Campbell, James F.; Chambers, Joseph R.

1994-01-01

123

Searching for pulsars using image pattern recognition  

E-print Network

In this paper, we present a novel artificial intelligence (AI) program that identifies pulsars from recent surv eys using image pattern recognition with deep neural nets---the PICS(Pulsar Image-based Classification System) AI. The AI mimics human experts and distinguishes pulsars from noise and interferences by looking for patterns from candidate. The information from each pulsar candidate is synthesized in four diagnostic plots, which consist of up to thousands pixel of image data. The AI takes these data from each candidate as its input and uses thousands of such candidates to train its $\\sim$9000 neurons. Different from other pulsar selection programs which use pre-designed patterns, the PICS AI teaches itself the salient features of different pulsars from a set of human-labeled candidates through machine learning. The deep neural networks in this AI system grant it superior ability in recognizing various types of pulsars as well as their harmonic signals. The trained AI's performance has been validated wi...

Zhu, W W; Madsen, E C; Tan, M; Stairs, I H; Brazier, A; Lazarus, P; Lynch, R; Scholz, P; Stovall, K; Random, S M; Banaszak, S; Biwer, C M; Cohen, S; Dartez, L P; Flanigan, J; Lunsford, G; Matinez, J G; Mata, A; Rohr, M; Walker, A; Allen, B; Bhat, N D R; Bogdanov, S; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J S; Desvignes, G; Ferdman, R D; Hessels, J W T; Jenet, F A; Kaplan, D; Kaspi, V M; Knispel, B; Lee, K J; van Leeuwen, J; Lyne, A G; McLaughlin, M A; Spitler, L G

2014-01-01

124

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

PubMed

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. PMID:16634668

Beck, Melissa R; Peterson, Matthew S; Vomela, Miroslava

2006-04-01

125

How visual edge features influence cuttlefish camouflage patterning.  

PubMed

Rapid adaptive camouflage is the primary defense of soft-bodied cuttlefish. Previous studies have shown that cuttlefish body patterns are strongly influenced by visual edges in the substrate. The aim of the present study was to examine how cuttlefish body patterning is differentially controlled by various aspects of edges, including contrast polarity, contrast strength, and the presence or absence of "line terminators" introduced into a pattern when continuous edges are fragmented. Spatially high- and low-pass filtered white or black disks, as well as isolated, continuous and fragmented edges varying in contrast, were used to assess activation of cuttlefish skin components. Although disks of both contrast polarities evoked relatively weak disruptive body patterns, black disks activated different skin components than white disks, and high-frequency information alone sufficed to drive the responses to white disks whereas high- and low-frequency information were both required to drive responses to black disks. Strikingly, high-contrast edge fragments evoked substantially stronger body pattern responses than low-contrast edge fragments, whereas the body pattern responses evoked by high-contrast continuous edges were no stronger than those produced by low-contrast edges. This suggests that line terminators vs. continuous edges influence expression of disruptive body pattern components via different mechanisms that are controlled by contrast in different ways. PMID:23499977

Chiao, Chuan-Chin; Ulmer, Kimberly M; Siemann, Liese A; Buresch, Kendra C; Chubb, Charles; Hanlon, Roger T

2013-05-01

126

Case role filling as a side effect of visual search  

SciTech Connect

This paper addresses the problem of generating communicatively adequate extended responses in the absence of specific knowledge concerning the intentions of the questioner. The authors formulate and justify a heuristic for the selection of optional deep case slots not contained in the question as candidates for the additional information contained in an extended response. It is shown that, in a visually present domain of discourse, case role filling for the construction of an extended response can be regarded as a side effect of the visual search necessary to answer a question containing a locomotion verb. The paper describes the various representation constructions used in the German language dialog system HAM-ANS for dealing with the semantics of locomotion verbs and illustrates their use in generating extended responses. In particular, it outlines the structure of the geometrical scene description, the representation of events in a logic-oriented semantic representation language, the case-frame lexicon and the representation of the referential semantics based on the flavor system. The emphasis is on a detailed presentation of the application of object-oriented programming methods for coping with the semantics of locomotion verbs. The process of generating an extended response is illustrated by an extensively annotated trace. 13 references.

Marburger, H.; Wahlster, W.

1983-01-01

127

Spontaneous pattern formation and pinning in the visual cortex  

NASA Astrophysics Data System (ADS)

Bifurcation theory and perturbation theory can be combined with a knowledge of the underlying circuitry of the visual cortex to produce an elegant story explaining the phenomenon of visual hallucinations. A key insight is the application of an important set of ideas concerning spontaneous pattern formation introduced by Turing in 1952. The basic mechanism is a diffusion driven linear instability favoring a particular wavelength that determines the size of the ensuing stripe or spot periodicity of the emerging spatial pattern. Competition between short range excitation and longer range inhibition in the connectivity profile of cortical neurons provides the difference in diffusion length scales necessary for the Turing mechanism to occur and has been proven by Ermentrout and Cowan to be sufficient to explain the generation of a subset of reported geometric hallucinations. Incorporating further details of the cortical circuitry, namely that neurons are also weakly connected to other neurons sharing a particular stimulus orientation or spatial frequency preference at even longer ranges and the resulting shift-twist symmetry of the neuronal connectivity, improves the story. We expand this approach in order to be able to include the tuned responses of cortical neurons to additional visual stimulus features such as motion, color and disparity. We apply a study of nonlinear dynamics similar to the analysis of wave propagation in a crystalline lattice to demonstrate how a spatial pattern formed through the Turing instability can be pinned to the geometric layout of various feature preferences. The perturbation analysis is analogous to solving the Schrodinger equation in a weak periodic potential. Competition between the local isotropic connections which produce patterns of activity via the Turing mechanism and the weaker patchy lateral connections that depend on a neuron's particular set of feature preferences create long wavelength affects analogous to commensurate-incommensurate transitions found in fluid systems under a spatially periodic driving force. In this way we hope to better understand how the intrinsic architecture of the visual cortex can generate patterns of activity that underlie visual hallucinations.

Baker, Tanya I.

128

Visualization of oxygen distribution patterns caused by coral and algae.  

PubMed

Planar optodes were used to visualize oxygen distribution patterns associated with a coral reef associated green algae (Chaetomorpha sp.) and a hermatypic coral (Favia sp.) separately, as standalone organisms, and placed in close proximity mimicking coral-algal interactions. Oxygen patterns were assessed in light and dark conditions and under varying flow regimes. The images show discrete high oxygen concentration regions above the organisms during lighted periods and low oxygen in the dark. Size and orientation of these areas were dependent on flow regime. For corals and algae in close proximity the 2D optodes show areas of extremely low oxygen concentration at the interaction interfaces under both dark (18.4 ± 7.7 µmol O2 L(- 1)) and daylight (97.9 ± 27.5 µmol O2 L(- 1)) conditions. These images present the first two-dimensional visualization of oxygen gradients generated by benthic reef algae and corals under varying flow conditions and provide a 2D depiction of previously observed hypoxic zones at coral algae interfaces. This approach allows for visualization of locally confined, distinctive alterations of oxygen concentrations facilitated by benthic organisms and provides compelling evidence for hypoxic conditions at coral-algae interaction zones. PMID:23882443

Haas, Andreas F; Gregg, Allison K; Smith, Jennifer E; Abieri, Maria L; Hatay, Mark; Rohwer, Forest

2013-01-01

129

Is There a Limit to the Superiority of Individuals with ASD in Visual Search?  

ERIC Educational Resources Information Center

Superiority in visual search for individuals diagnosed with autism spectrum disorder (ASD) is a well-reported finding. We administered two visual search tasks to individuals with ASD and matched controls. One showed no difference between the groups, and one did show the expected superior performance for individuals with ASD. These results offer an…

Hessels, Roy S.; Hooge, Ignace T. C.; Snijders, Tineke M.; Kemner, Chantal

2014-01-01

130

Psychophysiological Evidence for Continuous Information Transmission Between Visual Search and Response Processes  

Microsoft Academic Search

This study was designed to test whether information transmission between the perceptual and motor levels occurs continuously or in discrete steps. Ss performed visual search across nontargets that shared visual features with one of two possible targets, each assigned to a different response. In addition to reaction time, psychophysiological measures were used to assess the duration of target search and

Henderikus G. O. M. Smid; Wiebo Lamain; Menno M. Hogeboom; Gijsbertus Mulder; Lambertus J. M. Mulder

1991-01-01

131

Neural Basis for Priming of Pop-Out during Visual Search Revealed with fMRI  

Microsoft Academic Search

Maljkovic and Nakayama first showed that visual search efficiency can be influenced by priming effects. Even ''pop-out'' targets (defined by unique color) are judged quicker if they appear at the same location and\\/or in the same color as on the preceding trial, in an unpredictable sequence. Here, we studied the potential neural correlates of such priming in human visual search

Arni Kristjansson; Patrik Vuilleumier; Sophie Schwartz; E. Macaluso; J. Driver

2006-01-01

132

Visual Working Memory Supports the Inhibition of Previously Processed Information: Evidence from Preview Search  

ERIC Educational Resources Information Center

In four experiments we assessed whether visual working memory (VWM) maintains a record of previously processed visual information, allowing old information to be inhibited, and new information to be prioritized. Specifically, we evaluated whether VWM contributes to the inhibition (i.e., visual marking) of previewed distractors in a preview search.…

Al-Aidroos, Naseem; Emrich, Stephen M.; Ferber, Susanne; Pratt, Jay

2012-01-01

133

The effect of search condition and advertising type on visual attention to Internet advertising.  

PubMed

This research was conducted to examine the level of consumers' visual attention to Internet advertising. It was predicted that consumers' search type would influence visual attention to advertising. Specifically, it was predicted that more attention to advertising would be attracted in the exploratory search condition than in the goal-directed search condition. It was also predicted that there would be a difference in visual attention depending on the advertisement type (advertising type: text vs. pictorial advertising). An eye tracker was used for measurement. Results revealed that search condition and advertising type influenced advertising effectiveness. PMID:20973730

Kim, Gho; Lee, Jang-Han

2011-05-01

134

Problem-Solving Models and Search Strategies for Pattern Recognition  

Microsoft Academic Search

Noting the major limitations of multivariate statistical classification and syntactic pattern recognition models, this paper presents an overview of some recent work using alternate representations for multistage and nearest neighbor multiclass classification, and for structural analysis and feature extraction. These alternate representations are based on generalizations of state-space and AND\\/OR graph models and search strategies developed in artificial intelligence (AI).

Laveen N. Kanal

1979-01-01

135

Query suggestions for mobile search: understanding usage patterns  

Microsoft Academic Search

Entering search terms on mobile phones is a time consuming and cumbersome task. In this paper, we explore the usage patterns of query entry interfaces that display suggestions. Our primary goal is to build a usage model of query suggestions in order to provide user interface guidelines for mobile text prediction interfaces. We find that users who were asked to

Maryam Kamvar; Shumeet Baluja

2008-01-01

136

Optimal asymmetrical SVM using pattern search. A health care application.  

PubMed

This paper considers the model selection problem for Support Vector Machines. A well-known derivative Pattern Search method, which aims to tune hyperparameter values using an empirical error estimate as a steering criterion, is proposed. This approach is experimentally evaluated on a health care problem which involves discriminating nosocomially infected patients from non-infected patients. The Hooke and Jeeves Pattern Search (HJPS) method is shown to improve the results achieved by Grid Search (GS) in terms of solution quality and computational efficiency. Unlike most other parameter tuning techniques, our approach does not require supplementary effort such as computation of derivatives, making them well suited for practical purposes. This method produces encouraging results: it exhibits good performance and convergence properties. PMID:21893810

Cohen, Gilles; Meyer, Rodolphe

2011-01-01

137

Bicycle accidents and drivers' visual search at left and right turns.  

PubMed

The accident data base of the City of Helsinki shows that when drivers cross a cycle path as they enter a non-signalized intersection, the clearly dominant type of car-cycle crashes is that in which a cyclist comes from the right and the driver is turning right, in marked contrast to the cases with drivers turning left (Pasanen 1992; City of Helsinki, Traffic Planning Department, Report L4). This study first tested an explanation that drivers turning right simply focus their attention on the cars coming from the left-those coming from the right posing no threat to them-and fail to see the cyclist from the right early enough. Drivers' scanning behavior was studied at two T-intersections. Two well-hidden video cameras were used, one to measure the head movements of the approaching drivers and the other one to measure speed and distance from the cycle crossroad. The results supported the hypothesis: the drivers turning right scanned the right leg of the T-intersection less frequently and later than those turning left. Thus, it appears that drivers develop a visual scanning strategy which concentrates on detection of more frequent and major dangers but ignores and may even mask visual information on less frequent dangers. The second part of the study evaluated different countermeasures, including speed humps, in terms of drivers' visual search behavior. The results suggested that speed-reducing countermeasures changed drivers' visual search patterns in favor of the cyclists coming from the right, presumably at least in part due to the fact that drivers were simply provided with more time to focus on each direction. PMID:8703272

Summala, H; Pasanen, E; Räsänen, M; Sievänen, J

1996-03-01

138

Exploiting visual search theory to infer social interactions  

NASA Astrophysics Data System (ADS)

In this paper we propose a new method to infer human social interactions using typical techniques adopted in literature for visual search and information retrieval. The main piece of information we use to discriminate among different types of interactions is provided by proxemics cues acquired by a tracker, and used to distinguish between intentional and casual interactions. The proxemics information has been acquired through the analysis of two different metrics: on the one hand we observe the current distance between subjects, and on the other hand we measure the O-space synergy between subjects. The obtained values are taken at every time step over a temporal sliding window, and processed in the Discrete Fourier Transform (DFT) domain. The features are eventually merged into an unique array, and clustered using the K-means algorithm. The clusters are reorganized using a second larger temporal window into a Bag Of Words framework, so as to build the feature vector that will feed the SVM classifier.

Rota, Paolo; Dang-Nguyen, Duc-Tien; Conci, Nicola; Sebe, Nicu

2013-03-01

139

Feature processing during visual search in normal aging: electrophysiological evidence.  

PubMed

Event-related potentials (ERPs) were recorded from healthy young and older subjects during the execution of a visual search task in which they were required to detect the presence of a target stimulus that differed from distractors in a salient feature (orientation). Apart from the orientation target, a task-irrelevant singleton defined by a different feature (color) was also presented without instruction. The effects of normal aging on the N2pc component, an electrophysiological correlate of the allocation of visuospatial attention, were evaluated for the first time. Behavioral results showed an increase in the mean reaction time (RT) and a reduction in the hit rates with age. Electrophysiological results showed a consistent N2pc for orientation target pop-outs but not for irrelevant color pop-outs in both age groups, suggesting that the irrelevant color singleton did not induce attentional capture. Furthermore, the N2pc component observed for orientation targets was significantly delayed and attenuated in older subjects compared to young subjects, suggesting a specific impairment of the allocation of visuospatial attention with advancing age. PMID:17346855

Lorenzo-López, Laura; Amenedo, Elena; Cadaveira, Fernando

2008-07-01

140

Animating streamlines with repeated asymmetric patterns for steady flow visualization  

NASA Astrophysics Data System (ADS)

Animation provides intuitive cueing for revealing essential spatial-temporal features of data in scientific visualization. This paper explores the design of Repeated Asymmetric Patterns (RAPs) in animating evenly-spaced color-mapped streamlines for dense accurate visualization of complex steady flows. We present a smooth cyclic variable-speed RAP animation model that performs velocity (magnitude) integral luminance transition on streamlines. This model is extended with inter-streamline synchronization in luminance varying along the tangential direction to emulate orthogonal advancing waves from a geometry-based flow representation, and then with evenly-spaced hue differing in the orthogonal direction to construct tangential flow streaks. To weave these two mutually dual sets of patterns, we propose an energy-decreasing strategy that adopts an iterative yet efficient procedure for determining the luminance phase and hue of each streamline in HSL color space. We also employ adaptive luminance interleaving in the direction perpendicular to the flow to increase the contrast between streamlines.

Yeh, Chih-Kuo; Liu, Zhanping; Lee, Tong-Yee

2012-01-01

141

Dynamic Analysis and Pattern Visualization of Forest Fires  

PubMed Central

This paper analyses forest fires in the perspective of dynamical systems. Forest fires exhibit complex correlations in size, space and time, revealing features often present in complex systems, such as the absence of a characteristic length-scale, or the emergence of long range correlations and persistent memory. This study addresses a public domain forest fires catalogue, containing information of events for Portugal, during the period from 1980 up to 2012. The data is analysed in an annual basis, modelling the occurrences as sequences of Dirac impulses with amplitude proportional to the burnt area. First, we consider mutual information to correlate annual patterns. We use visualization trees, generated by hierarchical clustering algorithms, in order to compare and to extract relationships among the data. Second, we adopt the Multidimensional Scaling (MDS) visualization tool. MDS generates maps where each object corresponds to a point. Objects that are perceived to be similar to each other are placed on the map forming clusters. The results are analysed in order to extract relationships among the data and to identify forest fire patterns. PMID:25137393

Lopes, Antonio M.; Tenreiro Machado, J. A.

2014-01-01

142

How fast can you change your mind? The speed of top-down guidance in visual search  

Microsoft Academic Search

Most laboratory visual search tasks involve many searches for the same target, while in the real world we typically change our target with each search (e.g. find the coffee cup, then the sugar). How quickly can the visual system be reconfigured to search for a new target? Here observers searched for targets specified by cues presented at different SOAs relative

Jeremy M. Wolfe; Todd S. Horowitz; Naomi Kenner; Megan Hyle; Nina Vasan

2004-01-01

143

The Lévy flight paradigm: random search patterns and mechanisms.  

PubMed

Over recent years there has been an accumulation of evidence from a variety of experimental, theoretical, and field studies that many organisms use a movement strategy approximated by Lévy flights when they are searching for resources. Lévy flights are random movements that can maximize the efficiency of resource searches in uncertain environments. This is a highly significant finding because it suggests that Lévy flights provide a rigorous mathematical basis for separating out evolved, innate behaviors from environmental influences. We discuss recent developments in random-search theory, as well as the many different experimental and data collection initiatives that have investigated search strategies. Methods for trajectory construction and robust data analysis procedures are presented. The key to prediction and understanding does, however, lie in the elucidation of mechanisms underlying the observed patterns. We discuss candidate neurological, olfactory, and learning mechanisms for the emergence of Lévy flight patterns in some organisms, and note that convergence of behaviors along such different evolutionary pathways is not surprising given the energetic efficiencies that Lévy flight movement patterns confer. PMID:19449680

Reynolds, A M; Rhodes, C J

2009-04-01

144

EVALUATION OF A VISUALLY CATEGORIZED SEARCH ENGINE Berrin Dogusoy, Kursat Cagiltay  

E-print Network

EVALUATION OF A VISUALLY CATEGORIZED SEARCH ENGINE Berrin Dogusoy, Kursat Cagiltay Department and the search engines are becoming an indispensable tool in order to find information in Internet. While web, the intensive workload requires that people should use the time properly. Using search engines effectively turns

Paris-Sud XI, Université de

145

Visualizing Evolving Searches with EvoBerry Edward Suvanaphen and Jonathan C. Roberts  

E-print Network

terms to create sub- sequent searches after viewing the results from the current terms. Various the query terms on suc- cessive searches to achieve their goal. Marchionini [11] extends this basic modelVisualizing Evolving Searches with EvoBerry Edward Suvanaphen and Jonathan C. Roberts Computing

Kent, University of

146

Pattern adaptation and cross-orientation interactions in the primary visual cortex  

Microsoft Academic Search

The responsiveness of neurons in the primary visual cortex (V1) is substantially reduced after a few seconds of visual stimulation with an effective pattern. This phenomenon, called pattern adaptation, is uniquely cortical and is the likely substrate of a variety of perceptual after-effects. While adaptation to a given pattern reduces the responses of V1 neurons to all subsequently viewed test

Matteo Carandini; J. Anthony Movshon; David Ferster

1998-01-01

147

Person, place, and past influence eye movements during visual search  

E-print Network

What is the role of an individual’s past experience in guiding gaze in familiar environments? Contemporary models of search guidance suggest high level scene context is a strong predictor of where observers search in ...

Hidalgo-Sotelo, Barbara Irene

148

Plans, Patterns, and Move Categories Guiding a Highly Selective Search  

Microsoft Academic Search

\\u000a In this paper we present our ideas for an Arimaa-playing program (also called a bot) that uses plans and pattern matching to guide a highly selective search. We restrict move generation to moves in certain\\u000a move categories to reduce the number of moves considered by the bot significantly. Arimaa is a modern board game that can\\u000a be played with a

Gerhard Trippen

2009-01-01

149

Visual search for features and conjunctions following declines in the useful field of view  

PubMed Central

Background/Study Context Typical measures for assessing the useful field (UFOV) of view involve many components of attention. The objective of the current experiment was to examine differences in visual search efficiency for older individuals with and without UFOV impairment. Methods The authors used a computerized screening instrument to assess the useful field of view and to characterize participants as having an impaired or normal UFOV. Participants also performed two visual search tasks, a feature search (e.g., search for a green target among red distractors) or a conjunction search (e.g., a green target with a gap on its left or right side among red distractors with gaps on the left or right and green distractors with gaps on the top or bottom). Results Visual search performance did not differ between UFOV impaired and unimpaired individuals when searching for a basic feature. However, search efficiency was lower for impaired individuals than unimpaired individuals when searching for a conjunction of features. Conclusion The results suggest that UFOV decline in normal aging is associated with conjunction search. This finding suggests that the underlying cause of UFOV decline may arise from an overall decline in attentional efficiency. Because the useful field of view is a reliable predictor of driving safety, the results suggest that decline in the everyday visual behavior of older adults might arise from attentional declines. PMID:22830667

Cosman, Joshua D.; Lees, Monica N.; Lee, John D.; Rizzo, Matthew; Vecera, Shaun P.

2013-01-01

150

Long-Term Memory Search across the Visual Brain  

PubMed Central

Signal transmission from the human retina to visual cortex and connectivity of visual brain areas are relatively well understood. How specific visual perceptions transform into corresponding long-term memories remains unknown. Here, I will review recent Blood Oxygenation Level-Dependent functional Magnetic Resonance Imaging (BOLD fMRI) in humans together with molecular biology studies (animal models) aiming to understand how the retinal image gets transformed into so-called visual (retinotropic) maps. The broken object paradigm has been chosen in order to illustrate the complexity of multisensory perception of simple objects subject to visual —rather than semantic— type of memory encoding. The author explores how amygdala projections to the visual cortex affect the memory formation and proposes the choice of experimental techniques needed to explain our massive visual memory capacity. Maintenance of the visual long-term memories is suggested to require recycling of GluR2-containing ?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR) and ?2-adrenoreceptors at the postsynaptic membrane, which critically depends on the catalytic activity of the N-ethylmaleimide-sensitive factor (NSF) and protein kinase PKM?. PMID:22900206

Fedurco, Milan

2012-01-01

151

Adaptive rood pattern search for fast block-matching motion estimation  

Microsoft Academic Search

We propose a novel and simple fast block-matching algorithm (BMA), called adaptive rood pattern search (ARPS), which consists of two sequential search stages: (1) initial search and (2) refined local search. For each macroblock (MB), the initial search is performed only once at the beginning in order to find a good starting point for the follow-up refined local search. By

Yao Nie; Kai-Kuang Ma

2002-01-01

152

Eye movement guidance in familiar visual scenes : a role for scene specific location priors in search  

E-print Network

Ecologically relevant search typically requires making rapid and strategic eye movements in complex, cluttered environments. Attention allocation is known to be influenced by low level image features, visual scene context, ...

Hidalgo-Sotelo, Barbara

2010-01-01

153

What are the shapes of response time distributions in visual search?  

E-print Network

Many visual search experiments measure response time (RT) as their primary dependent variable. Analyses typically focus on mean (or median) RT. However, given enough data, the RT distribution can be a rich source of ...

Palmer, Evan M.

154

A Study of Temporal Aspect of Posterior Parietal Cortex in Visual Search Using Transcranial Magnetic Stimulation  

NASA Astrophysics Data System (ADS)

It is known that the posterior parietal cortex (PPC) plays a dominant role in spatial processing during visual search. However, the temporal aspect of the PPC is unclear. In the present study, to investigate the temporal aspects of the PPC in feature search, we applied Transcranial Magnetic Stimulation (TMS) over the right PPC with the TMS stimulus onset asynchronies (SOAs) set at 100, 150, 200 and 250 ms after visual search stimulation. We found that when SOA was set at 150 ms, compared to the sham TMS condition, there was a significant elevation in response time when TMS pulses were applied. However, there was no significant difference between the TMS and sham TMS conditions for the other SOA settings. Therefore, we suggest that the spatial processing of feature search is probably processed in the posterior parietal cortex at about 150-170 ms after visual search stimuli presentation.

Ge, Sheng; Matsuoka, Akira; Ueno, Shoogo; Iramina, Keiji

155

Strategies of the honeybee Apis mellifera during visual search for vertical targets presented at various heights: a role for spatial attention?  

PubMed Central

When honeybees are presented with a colour discrimination task, they tend to choose swiftly and accurately when objects are presented in the ventral part of their frontal visual field. In contrast, poor performance is observed when objects appear in the dorsal part. Here we investigate if this asymmetry is caused by fixed search patterns or if bees can use alternative search mechanisms such as spatial attention, which allows flexible focusing on different areas of the visual field. We asked individual honeybees to choose an orange rewarded target among blue distractors. Target and distractors were presented in the ventral visual field, the dorsal field or both. Bees presented with targets in the ventral visual field consistently had the highest search efficiency, with rapid decisions, high accuracy and direct flight paths. In contrast, search performance for dorsally located targets was inaccurate and slow at the beginning of the test phase, but bees increased their search performance significantly after a few learning trials: they found the target faster, made fewer errors and flew in a straight line towards the target. However, bees needed thrice as long to improve the search for a dorsally located target when the target’s position changed randomly between the ventral and the dorsal visual field. We propose that honeybees form expectations of the location of the target’s appearance and adapt their search strategy accordingly. Different possible mechanisms of this behavioural adaptation are discussed. PMID:25254109

Morawetz, Linde; Chittka, Lars; Spaethe, Johannes

2014-01-01

156

Strategies of the honeybee Apis mellifera during visual search for vertical targets presented at various heights: a role for spatial attention?  

PubMed

When honeybees are presented with a colour discrimination task, they tend to choose swiftly and accurately when objects are presented in the ventral part of their frontal visual field. In contrast, poor performance is observed when objects appear in the dorsal part. Here we investigate if this asymmetry is caused by fixed search patterns or if bees can use alternative search mechanisms such as spatial attention, which allows flexible focusing on different areas of the visual field. We asked individual honeybees to choose an orange rewarded target among blue distractors. Target and distractors were presented in the ventral visual field, the dorsal field or both. Bees presented with targets in the ventral visual field consistently had the highest search efficiency, with rapid decisions, high accuracy and direct flight paths. In contrast, search performance for dorsally located targets was inaccurate and slow at the beginning of the test phase, but bees increased their search performance significantly after a few learning trials: they found the target faster, made fewer errors and flew in a straight line towards the target. However, bees needed thrice as long to improve the search for a dorsally located target when the target's position changed randomly between the ventral and the dorsal visual field. We propose that honeybees form expectations of the location of the target's appearance and adapt their search strategy accordingly. Different possible mechanisms of this behavioural adaptation are discussed. PMID:25254109

Morawetz, Linde; Chittka, Lars; Spaethe, Johannes

2014-01-01

157

The Role of Target-Distractor Relationships in Guiding Attention and the Eyes in Visual Search  

ERIC Educational Resources Information Center

Current models of visual search assume that visual attention can be guided by tuning attention toward specific feature values (e.g., particular size, color) or by inhibiting the features of the irrelevant nontargets. The present study demonstrates that attention and eye movements can also be guided by a relational specification of how the target…

Becker, Stefanie I.

2010-01-01

158

Priming of color and position during visual search in unilateral spatial neglect  

Microsoft Academic Search

We examined priming of visual search by repeated target location or color in two patients with left visual neglect and extinction, following strokes centered on the right inferior parietal lobe. Both patients, like the healthy controls we tested, showed intact priming, with performance speeded when either the location or color of a singleton target was repeated over successive trials in

A. Kristjansson; Patrik Vuilleumier; Paresh Malhotra; Masud Husain; Jon Driver

2005-01-01

159

The Effects of Presentation Method and Information Density on Visual Search Ability and Working Memory Load  

ERIC Educational Resources Information Center

This study investigates the effects of successive and simultaneous information presentation methods on learner's visual search ability and working memory load for different information densities. Since the processing of information in the brain depends on the capacity of visual short-term memory (VSTM), the limited information processing capacity…

Chang, Ting-Wen; Kinshuk; Chen, Nian-Shing; Yu, Pao-Ta

2012-01-01

160

Learning by Selection: Visual Search and Object Perception in Young Infants  

Microsoft Academic Search

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

Dima Amso; Scott P. Johnson

2006-01-01

161

Generalized Pattern Search Algorithm for Peptide Structure Prediction  

PubMed Central

Finding the near-native structure of a protein is one of the most important open problems in structural biology and biological physics. The problem becomes dramatically more difficult when a given protein has no regular secondary structure or it does not show a fold similar to structures already known. This situation occurs frequently when we need to predict the tertiary structure of small molecules, called peptides. In this research work, we propose a new ab initio algorithm, the generalized pattern search algorithm, based on the well-known class of Search-and-Poll algorithms. We performed an extensive set of simulations over a well-known set of 44 peptides to investigate the robustness and reliability of the proposed algorithm, and we compared the peptide conformation with a state-of-the-art algorithm for peptide structure prediction known as PEPstr. In particular, we tested the algorithm on the instances proposed by the originators of PEPstr, to validate the proposed algorithm; the experimental results confirm that the generalized pattern search algorithm outperforms PEPstr by 21.17% in terms of average root mean-square deviation, RMSD C?. PMID:18487293

Nicosia, Giuseppe; Stracquadanio, Giovanni

2008-01-01

162

Plans, Patterns, and Move Categories Guiding a Highly Selective Search  

NASA Astrophysics Data System (ADS)

In this paper we present our ideas for an Arimaa-playing program (also called a bot) that uses plans and pattern matching to guide a highly selective search. We restrict move generation to moves in certain move categories to reduce the number of moves considered by the bot significantly. Arimaa is a modern board game that can be played with a standard Chess set. However, the rules of the game are not at all like those of Chess. Furthermore, Arimaa was designed to be as simple and intuitive as possible for humans, yet challenging for computers. While all established Arimaa bots use alpha-beta search with a variety of pruning techniques and other heuristics ending in an extensive positional leaf node evaluation, our new bot, Rat, starts with a positional evaluation of the current position. Based on features found in the current position - supported by pattern matching using a directed position graph - our bot Rat decides which of a given set of plans to follow. The plan then dictates what types of moves can be chosen. This is another major difference from bots that generate "all" possible moves for a particular position. Rat is only allowed to generate moves that belong to certain categories. Leaf nodes are evaluated only by a straightforward material evaluation to help avoid moves that lose material. This highly selective search looks, on average, at only 5 moves out of 5,000 to over 40,000 possible moves in a middle game position.

Trippen, Gerhard

163

Scanners and drillers: Characterizing expert visual search through volumetric images  

PubMed Central

Modern imaging methods like computed tomography (CT) generate 3-D volumes of image data. How do radiologists search through such images? Are certain strategies more efficient? Although there is a large literature devoted to understanding search in 2-D, relatively little is known about search in volumetric space. In recent years, with the ever-increasing popularity of volumetric medical imaging, this question has taken on increased importance as we try to understand, and ultimately reduce, errors in diagnostic radiology. In the current study, we asked 24 radiologists to search chest CTs for lung nodules that could indicate lung cancer. To search, radiologists scrolled up and down through a “stack” of 2-D chest CT “slices.” At each moment, we tracked eye movements in the 2-D image plane and coregistered eye position with the current slice. We used these data to create a 3-D representation of the eye movements through the image volume. Radiologists tended to follow one of two dominant search strategies: “drilling” and “scanning.” Drillers restrict eye movements to a small region of the lung while quickly scrolling through depth. Scanners move more slowly through depth and search an entire level of the lung before moving on to the next level in depth. Driller performance was superior to the scanners on a variety of metrics, including lung nodule detection rate, percentage of the lung covered, and the percentage of search errors where a nodule was never fixated. PMID:23922445

Drew, Trafton; Vo, Melissa Le-Hoa; Olwal, Alex; Jacobson, Francine; Seltzer, Steven E.; Wolfe, Jeremy M.

2013-01-01

164

ON THE LOCAL CONVERGENCE OF PATTERN SEARCH ELIZABETH D. DOLAN, ROBERT MICHAEL LEWIS, AND VIRGINIA TORCZON  

E-print Network

ON THE LOCAL CONVERGENCE OF PATTERN SEARCH ELIZABETH D. DOLAN, ROBERT MICHAEL LEWIS, AND VIRGINIA­583 Abstract. We examine the local convergence properties of pattern search methods, comple- menting-length control parameter which appears in the definition of pattern search al- gorithms provides a reliable

Lewis, Robert Michael

165

ON THE LOCAL CONVERGENCE OF PATTERN SEARCH ELIZABETH D. DOLAN, ROBERT MICHAEL LEWIS, AND VIRGINIA TORCZON  

E-print Network

ON THE LOCAL CONVERGENCE OF PATTERN SEARCH ELIZABETH D. DOLAN, ROBERT MICHAEL LEWIS, AND VIRGINIA TORCZON Abstract. We examine the local convergence properties of pattern search methods, comple- menting-length control parameter which appears in the definition of pattern search al- gorithms provides a reliable

Torczon, Virginia

166

What Are the Shapes of Response Time Distributions in Visual Search?  

Microsoft Academic Search

Many visual search experiments measure response time (RT) as their primary dependent variable. Analyses typically focus on mean (or median) RT. However, given enough data, the RT distribution can be a rich source of information. For this paper, we collected about 500 trials per cell per observer for both target-present and target-absent displays in each of three classic search tasks:

Evan M. Palmer; Todd S. Horowitz; Antonio Torralba; Jeremy M. Wolfe

2011-01-01

167

On the roles of the human frontal eye fields and parietal cortex in visual search  

Microsoft Academic Search

Successful search for a target in a visual scene requires many cognitive operations, including orienting, detecting the target, and rejecting distractors. Performance in search is affected by a number of factors, including the number of targets and distractors, their similarity, motion in the display, location, and viewing history of the stimuli, etc. A task with so many stimulus variables and

Jacinta OShea; Neil G. Muggleton; Alan Cowey; Vincent Walsh

2006-01-01

168

Transformation of an Uncertain Video Search Pipeline to a Sketch-based Visual Analytics Loop  

E-print Network

Transformation of an Uncertain Video Search Pipeline to a Sketch-based Visual Analytics Loop Philip Chen Abstract-- Traditional sketch-based image or video search systems rely on machine learning since videos may not be semantically annotated sufficiently, there may be a lack of suitable training

Jones, Mark W.

169

Toward Real-Time Visually Augmented Navigation for Autonomous Search and Inspection of Ship Hulls  

E-print Network

Toward Real-Time Visually Augmented Navigation for Autonomous Search and Inspection of Ship Hulls Abstract This paper reports on current research to automate the task of ship hull inspection and search mapping framework and show how we are now applying that framework to the task of automated ship

Eustice, Ryan

170

An Efficient Index for Visual Search in Appearance-based SLAM Kiana Hajebi and Hong Zhang  

E-print Network

An Efficient Index for Visual Search in Appearance-based SLAM Kiana Hajebi and Hong Zhang Abstract the vocabulary is large. A BoW-based appearance SLAM needs to tackle this problem for an efficient real SLAM. We employ a graph-based nearest neighbor search (GNNS) algorithm to this aim, and experimentally

Zhang, Hong

171

How Temporal and Spatial Aspects of Presenting Visualizations Affect Learning about Locomotion Patterns  

ERIC Educational Resources Information Center

Two studies investigated the effectiveness of dynamic and static visualizations for a perceptual learning task (locomotion pattern classification). In Study 1, seventy-five students viewed either dynamic, static-sequential, or static-simultaneous visualizations. For tasks of intermediate difficulty, dynamic visualizations led to better…

Imhof, Birgit; Scheiter, Katharina; Edelmann, Jorg; Gerjets, Peter

2012-01-01

172

Patent semantics : analysis, search and visualization of large text corpora  

E-print Network

Patent Semantics is system for processing text documents by extracting features capturing their semantic content, and searching, clustering, and relating them by those same features. It is set apart from existing methodologies ...

Lucas, Christopher G

2004-01-01

173

Visualizing digital library search results with categorical and hierarchical axes  

Microsoft Academic Search

Digital library search results are usually shown as a textual list, with 10-20 items per page. Viewing several thousand search results at once on a two-dimensional display with continuous variables is a promising alternative. Since these displays can overwhelm some users, we created a simplified two-dimensional display that uses categorical and hierarchical axes, called hieraxes. Users appreciate the meaningful and

Ben Shneiderman; David Feldman; Anne Rose; Xavier Ferré Grau

2000-01-01

174

Neural Control of Visual Search by Frontal Eye Field: Effects of Unexpected Target Displacement on Visual Selection and Saccade Preparation  

PubMed Central

The dynamics of visual selection and saccade preparation by the frontal eye field was investigated in macaque monkeys performing a search-step task combining the classic double-step saccade task with visual search. Reward was earned for producing a saccade to a color singleton. On random trials the target and one distractor swapped locations before the saccade and monkeys were rewarded for shifting gaze to the new singleton location. A race model accounts for the probabilities and latencies of saccades to the initial and final singleton locations and provides a measure of the duration of a covert compensation process—target-step reaction time. When the target stepped out of a movement field, noncompensated saccades to the original location were produced when movement-related activity grew rapidly to a threshold. Compensated saccades to the final location were produced when the growth of the original movement-related activity was interrupted within target-step reaction time and was replaced by activation of other neurons producing the compensated saccade. When the target stepped into a receptive field, visual neurons selected the new target location regardless of the monkeys’ response. When the target stepped out of a receptive field most visual neurons maintained the representation of the original target location, but a minority of visual neurons showed reduced activity. Chronometric analyses of the neural responses to the target step revealed that the modulation of visually responsive neurons and movement-related neurons occurred early enough to shift attention and saccade preparation from the old to the new target location. These findings indicate that visual activity in the frontal eye field signals the location of targets for orienting, whereas movement-related activity instantiates saccade preparation. PMID:19261711

Murthy, Aditya; Ray, Supriya; Shorter, Stephanie M.; Schall, Jeffrey D.; Thompson, Kirk G.

2009-01-01

175

Neural control of visual search by frontal eye field: effects of unexpected target displacement on visual selection and saccade preparation.  

PubMed

The dynamics of visual selection and saccade preparation by the frontal eye field was investigated in macaque monkeys performing a search-step task combining the classic double-step saccade task with visual search. Reward was earned for producing a saccade to a color singleton. On random trials the target and one distractor swapped locations before the saccade and monkeys were rewarded for shifting gaze to the new singleton location. A race model accounts for the probabilities and latencies of saccades to the initial and final singleton locations and provides a measure of the duration of a covert compensation process-target-step reaction time. When the target stepped out of a movement field, noncompensated saccades to the original location were produced when movement-related activity grew rapidly to a threshold. Compensated saccades to the final location were produced when the growth of the original movement-related activity was interrupted within target-step reaction time and was replaced by activation of other neurons producing the compensated saccade. When the target stepped into a receptive field, visual neurons selected the new target location regardless of the monkeys' response. When the target stepped out of a receptive field most visual neurons maintained the representation of the original target location, but a minority of visual neurons showed reduced activity. Chronometric analyses of the neural responses to the target step revealed that the modulation of visually responsive neurons and movement-related neurons occurred early enough to shift attention and saccade preparation from the old to the new target location. These findings indicate that visual activity in the frontal eye field signals the location of targets for orienting, whereas movement-related activity instantiates saccade preparation. PMID:19261711

Murthy, Aditya; Ray, Supriya; Shorter, Stephanie M; Schall, Jeffrey D; Thompson, Kirk G

2009-05-01

176

A ground-like surface facilitates visual search in chimpanzees (Pan troglodytes)  

PubMed Central

Ground surfaces play an important role in terrestrial species' locomotion and ability to manipulate objects. In humans, ground surfaces have been found to offer significant advantages in distance perception and visual-search tasks (“ground dominance”). The present study used a comparative perspective to investigate the ground-dominance effect in chimpanzees, a species that spends time both on the ground and in trees. During the experiments chimpanzees and humans engaged in a search for a cube on a computer screen; the target cube was darker than other cubes. The search items were arranged on a ground-like or ceiling-like surface, which was defined by texture gradients and shading. The findings indicate that a ground-like, but not a ceiling-like, surface facilitated the search for a difference in luminance among both chimpanzees and humans. Our findings suggest the operation of a ground-dominance effect on visual search in both species. PMID:23917381

Imura, Tomoko; Tomonaga, Masaki

2013-01-01

177

Supplementary eye field during visual search: salience, cognitive control, and performance monitoring.  

PubMed

How supplementary eye field (SEF) contributes to visual search is unknown. Inputs from cortical and subcortical structures known to represent visual salience suggest that SEF may serve as an additional node in this network. This hypothesis was tested by recording action potentials and local field potentials (LFPs) in two monkeys performing an efficient pop-out visual search task. Target selection modulation, tuning width, and response magnitude of spikes and LFP in SEF were compared with those in frontal eye field. Surprisingly, only ?2% of SEF neurons and ?8% of SEF LFP sites selected the location of the search target. The absence of salience in SEF may be due to an absence of appropriate visual afferents, which suggests that these inputs are a necessary anatomical feature of areas representing salience. We also tested whether SEF contributes to overcoming the automatic tendency to respond to a primed color when the target identity switches during priming of pop-out. Very few SEF neurons or LFP sites modulated in association with performance deficits following target switches. However, a subset of SEF neurons and LFPs exhibited strong modulation following erroneous saccades to a distractor. Altogether, these results suggest that SEF plays a limited role in controlling ongoing visual search behavior, but may play a larger role in monitoring search performance. PMID:22836261

Purcell, Braden A; Weigand, Pauline K; Schall, Jeffrey D

2012-07-25

178

Acute exercise and aerobic fitness influence selective attention during visual search  

PubMed Central

Successful goal directed behavior relies on a human attention system that is flexible and able to adapt to different conditions of physiological stress. However, the effects of physical activity on multiple aspects of selective attention and whether these effects are mediated by aerobic capacity, remains unclear. The aim of the present study was to investigate the effects of a prolonged bout of physical activity on visual search performance and perceptual distraction. Two groups of participants completed a hybrid visual search flanker/response competition task in an initial baseline session and then at 17-min intervals over a 2 h 16 min test period. Participants assigned to the exercise group engaged in steady-state aerobic exercise between completing blocks of the visual task, whereas participants assigned to the control group rested in between blocks. The key result was a correlation between individual differences in aerobic capacity and visual search performance, such that those individuals that were more fit performed the search task more quickly. Critically, this relationship only emerged in the exercise group after the physical activity had begun. The relationship was not present in either group at baseline and never emerged in the control group during the test period, suggesting that under these task demands, aerobic capacity may be an important determinant of visual search performance under physical stress. The results enhance current understanding about the relationship between exercise and cognition, and also inform current models of selective attention.

Bullock, Tom; Giesbrecht, Barry

2014-01-01

179

An Enhanced Adaptive Rood Pattern Search Algorithm for Fast Block-Matching Motion Estimation  

Microsoft Academic Search

Based on adaptive rood pattern search (ARPS) algorithm, a new fast and efficient motion estimation algorithm called enhanced adaptive rood pattern search (E-ARPS) is proposed in this paper. Unlike ARPS, the E-ARPS utilizes spatial correlations to predict the initial search centre, then introduces a new initial search based on motion vector(MV) centre-biased distribution , and an adaptive unequal-arm rood search

Hui Zhao; Xin-bo Yu; Jia-hong Sun; Chang Sun; Hao-zhe Cong

2008-01-01

180

A Directional & Adaptive Diamond Search by Adaptive Pattern Switching with a Predicted Motion Vector  

Microsoft Academic Search

ABSTRACT Wepropose,a simple ,fast block-matching ,algorithm (BMA) based ,on the ,direction of the ,predicted motion vector called directional & adaptive diamond search by adaptive pattern switching (DADS-APS). The proposal method has two sequential search steps, including 1) an initial search, and 2) a refinement search for the local area. Adaptive pattern switching (APS) is proposed,for the initial search and a

Jong-ho Kim; Byung-gyu Kim; Suk-kyu Song; Chang-sik Cho

2006-01-01

181

Searching for Complex Human Activities with No Visual Examples  

Microsoft Academic Search

We describe a method of representing human ac- tivities that allows a collection of motions to be queried without examples, using a simple and effective query lan- guage. Our approach is based on units of activity at seg- ments of the body, that can be composed across space and across the body to produce complex queries. The presence of search

David A. Forsyth

2008-01-01

182

Visualizing Document Classification: A Search Aid for the Digital Library.  

ERIC Educational Resources Information Center

Discusses access to digital libraries on the World Wide Web via Web browsers and describes the design of a language-independent document classification system to help users of the Florida Center for Library Automation analyze search query results. Highlights include similarity scores, clustering, graphical representation of document similarity,…

Lieu, Yew-Huey; Dantzig, Paul; Sachs, Martin; Corey, James T.; Hinnebusch, Mark T.; Damashek, Marc; Cohen, Jonathan

2000-01-01

183

Mapping the Color Space of Saccadic Selectivity in Visual Search  

ERIC Educational Resources Information Center

Color coding is used to guide attention in computer displays for such critical tasks as baggage screening or air traffic control. It has been shown that a display object attracts more attention if its color is more similar to the color for which one is searching. However, what does "similar" precisely mean? Can we predict the amount of attention…

Xu, Yun; Higgins, Emily C.; Xiao, Mei; Pomplun, Marc

2007-01-01

184

Visualizing Spatial Proximity of Search Algorithms Mingxuan Sun Guy Lebanon  

E-print Network

attention users pay to top ranks over bottom ranks, (iv) computationally efficient, and (v) aggregate information over multiple queries in a mean- ingful way. We then use the measure with multi by search algorithms si(q), i = 1, . . . .l given a query q forms ordered lists i1, . . . , ik of subset

Lebanon, Guy

185

Visual Modeling of Business Problems: Workflow and Patterns  

Microsoft Academic Search

Computer-based business analysis relies on models, or algorithmic representations of the business process. Real-life business problems can become very complex, which creates difficulties in generation, analysis, testing, and the actual use of the models. The paper discusses a proposed solution: the visual modeling workflow. A diagram or a group of diagrams represent each step within this workflow. The visual modeling

Lev Virine; Jason Mcvean

2004-01-01

186

Predicting object features across saccades: Evidence from object recognition and visual search.  

PubMed

When we move our eyes, we process objects in the visual field with different spatial resolution due to the nonhomogeneity of our visual system. In particular, peripheral objects are only coarsely represented, whereas they are represented with high acuity when foveated. To keep track of visual features of objects across eye movements, these changes in spatial resolution have to be taken into account. Here, we develop and test a new framework proposing a visual feature prediction mechanism based on past experience to deal with changes in spatial resolution accompanying saccadic eye movements. In 3 experiments, we first exposed participants to an altered visual stimulation where, unnoticed by participants, 1 object systematically changed visual features during saccades. Experiments 1 and 2 then demonstrate that feature prediction during peripheral object recognition is biased toward previously associated postsaccadic foveal input and that this effect is particularly associated with making saccades. Moreover, Experiment 3 shows that during visual search, feature prediction is biased toward previously associated presaccadic peripheral input. Together, these findings demonstrate that the visual system uses past experience to predict how peripheral objects will look in the fovea, and what foveal search templates should look like in the periphery. As such, they support our framework based on ideomotor theory and shed new light on the mystery of why we are most of the time unaware of acuity limitations in the periphery and of our ability to locate relevant objects in the periphery. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24820249

Herwig, Arvid; Schneider, Werner X

2014-10-01

187

Analysis of microsaccades and pupil dilation reveals a common decisional origin during visual search.  

PubMed

During free viewing visual search, observers often refixate the same locations several times before and after target detection is reported with a button press. We analyzed the rate of microsaccades in the sequence of refixations made during visual search and found two important components. One related to the visual content of the region being fixated; fixations on targets generate more microsaccades and more microsaccades are generated for those targets that are more difficult to disambiguate. The other empathizes non-visual decisional processes; fixations containing the button press generate more microsaccades than those made on the same target but without the button press. Pupil dilation during the same refixations reveals a similar modulation. We inferred that generic sympathetic arousal mechanisms are part of the articulated complex of perceptual processes governing fixational eye movements. PMID:24333280

Privitera, Claudio M; Carney, Thom; Klein, Stanley; Aguilar, Mario

2014-02-01

188

Target features and target-distractor relation are both primed in visual search.  

PubMed

Intertrial priming in visual search is the finding that repeating target and distractor features from one trial to the next speeds up search, relative to when these features change. Recently, Becker (2008) reported evidence that it is not so much the repetition of absolute feature values that causes priming, but repetition of the relation between target and distractors. For example, in search for a unique size, the size of the search elements may change from trial to trial, but this does not hurt performance as long as the target remains consistently larger (or smaller) than the distractors. Becker (2008) concluded that such findings are difficult to reconcile with existing theory. Here, we replicate the findings in the dimensions of size, color, and luminance and show that these effects are not due to the magnitude of feature changes or to search strategies, as may be induced by blocking versus mixing different types of intertrial changes experienced by observers. However, we show that repeating a feature from one trial to the next does convey a benefit above and beyond repeating the target-distractor relation. We argue that both effects can be readily accounted for within current models of visual search. Priming of relations results when one assumes the existence of cardinal feature channels, as do most models of visual search. Additional priming of specific values results when one assumes broadly distributed, overlapping feature channels. PMID:24415176

Meeter, Martijn; Olivers, Christian N L

2014-04-01

189

White Matter Tract Integrity Predicts Visual Search Performance in Young and Older Adults  

PubMed Central

Functional imaging research has identified fronto-parietal attention networks involved in visual search, with mixed evidence regarding whether different networks are engaged when the search target differs from distracters by a single (elementary) versus multiple (conjunction) features. Neural correlates of visual search, and their potential dissociation, were examined here using integrity of white matter connecting the fronto-parietal networks. The effect of aging on these brain-behavior relationships was also of interest. Younger and older adults performed a visual search task and underwent diffusion tensor imaging (DTI) to reconstruct two fronto-parietal (superior and inferior longitudinal fasciculus, SLF and ILF) and two midline (genu, splenium) white matter tracts. As expected, results revealed age-related declines in conjunction, but not elementary, search performance; and in ILF and genu tract integrity. Importantly, integrity of the SLF, ILF, and genu tracts predicted search performance (conjunction and elementary), with no significant age group differences in these relationships. Thus, integrity of white matter tracts connecting fronto-parietal attention networks contributes to search performance in younger and older adults. PMID:21402431

Bennett, Ilana J.; Motes, Michael A.; Rao, Neena K.; Rypma, Bart

2011-01-01

190

The Visual Hemifield Asymmetry in the Spatial Blink during Singleton Search and Feature Search  

ERIC Educational Resources Information Center

The present study examined a visual field asymmetry in the contingent capture of attention that was previously observed by Du and Abrams (2010). In our first experiment, color singleton distractors that matched the color of a to-be-detected target produced a stronger capture of attention when they appeared in the left visual hemifield than in the…

Burnham, Bryan R.; Rozell, Cassandra A.; Kasper, Alex; Bianco, Nicole E.; Delliturri, Antony

2011-01-01

191

Rare, but obviously there: Effects of target frequency and salience on visual search accuracy.  

PubMed

Accuracy can be extremely important for many visual search tasks. However, numerous factors work to undermine successful search. Several negative influences on search have been well studied, yet one potentially influential factor has gone almost entirely unexplored-namely, how is search performance affected by the likelihood that a specific target might appear? A recent study demonstrated that when specific targets appear infrequently (i.e., once in every thousand trials) they were, on average, not often found. Even so, some infrequently appearing targets were actually found quite often, suggesting that the targets' frequency is not the only factor at play. Here, we investigated whether salience (i.e., the extent to which an item stands out during search) could explain why some infrequent targets are easily found whereas others are almost never found. Using the mobile application Airport Scanner, we assessed how individual target frequency and salience interacted in a visual search task that included a wide array of targets and millions of trials. Target frequency and salience were both significant predictors of search accuracy, although target frequency explained more of the accuracy variance. Further, when examining only the rarest target items (those that appeared on less than 0.15% of all trials), there was a significant relationship between salience and accuracy such that less salient items were less likely to be found. Beyond implications for search theory, these data suggest significant vulnerability for real-world searches that involve targets that are both infrequent and hard-to-spot. PMID:25226547

Biggs, Adam T; Adamo, Stephen H; Mitroff, Stephen R

2014-10-01

192

Pattern electroretinogram (PERG) and pattern visual evoked potential (PVEP) in the early stages of Alzheimer's disease.  

PubMed

Alzheimer's disease (AD) is one of the most common causes of dementia in the world. Patients with AD frequently complain of vision disturbances that do not manifest as changes in routine ophthalmological examination findings. The main causes of these disturbances are neuropathological changes in the visual cortex, although abnormalities in the retina and optic nerve cannot be excluded. Pattern electroretinogram (PERG) and pattern visual evoked potential (PVEP) tests are commonly used in ophthalmology to estimate bioelectrical function of the retina and optic nerve. The aim of this study was to determine whether retinal and optic nerve function, measured by PERG and PVEP tests, is changed in individuals in the early stages of AD with normal routine ophthalmological examination results. Standard PERG and PVEP tests were performed in 30 eyes of 30 patients with the early stages of AD. The results were compared to 30 eyes of 30 normal healthy controls. PERG and PVEP tests were recorded in accordance with the International Society for Clinical Electrophysiology of Vision (ISCEV) standards. Additionally, neural conduction was measured using retinocortical time (RCT)--the difference between P100-wave latency in PVEP and P50-wave implicit time in PERG. In PERG test, PVEP test, and RCT, statistically significant changes were detected. In PERG examination, increased implicit time of P50-wave (P < 0.03) and amplitudes reductions in P50- and N95-waves (P < 0.0001) were observed. In PVEP examination, increased latency of P100-wave (P < 0.0001) was found. A significant increase in RCT (P < 0.0001) was observed. The most prevalent features were amplitude reduction in N95-wave and increased latency of P100-wave which were seen in 56.7% (17/30) of the AD eyes. In patients with the early stages of AD and normal routine ophthalmological examination results, dysfunction of the retinal ganglion cells as well as of the optic nerve is present, as detected by PERG and PVEP tests. These dysfunctions, at least partially, explain the cause of visual disturbances observed in patients with the early stages of AD. PMID:20549299

Krasodomska, Kamila; Lubi?ski, Wojciech; Potemkowski, Andrzej; Honczarenko, Krystyna

2010-10-01

193

PATTERN MINING IN VISUAL CONCEPT STREAMS IBM T. J. Watson Research Center  

E-print Network

pattern min- ing in the large concept space. There are many promising directions to use concept miningPATTERN MINING IN VISUAL CONCEPT STREAMS Lexing Xie IBM T. J. Watson Research Center Shih-Fu Chang Columbia Univeristy ABSTRACT Pattern mining algorithms are often much easier applied than quan- titatively

Chang, Shih-Fu

194

Disturbance of visual search by stimulating to posterior parietal cortex in the brain using transcranial magnetic stimulation  

NASA Astrophysics Data System (ADS)

In this study, we applied a transcranial magnetic stimulation (TMS) to investigate the temporal aspect for the functional processing of visual attention. Although it has been known that right posterior parietal cortex (PPC) in the brain has a role in certain visual search tasks, there is little knowledge about the temporal aspect of this area. Three visual search tasks that have different difficulties of task execution individually were carried out. These three visual search tasks are the "easy feature task," the "hard feature task," and the "conjunction task." To investigate the temporal aspect of the PPC involved in the visual search, we applied various stimulus onset asynchronies (SOAs) and measured the reaction time of the visual search. The magnetic stimulation was applied on the right PPC or the left PPC by the figure-eight coil. The results show that the reaction times of the hard feature task are longer than those of the easy feature task. When SOA=150 ms, compared with no-TMS condition, there was a significant increase in target-present reaction time when TMS pulses were applied. We considered that the right PPC was involved in the visual search at about SOA=150 ms after visual stimulus presentation. The magnetic stimulation to the right PPC disturbed the processing of the visual search. However, the magnetic stimulation to the left PPC gives no effect on the processing of the visual search.

Iramina, Keiji; Ge, Sheng; Hyodo, Akira; Hayami, Takehito; Ueno, Shoogo

2009-04-01

195

Pattern-driven neighborhood search for biclustering of microarray data  

PubMed Central

Background Biclustering aims at finding subgroups of genes that show highly correlated behaviors across a subgroup of conditions. Biclustering is a very useful tool for mining microarray data and has various practical applications. From a computational point of view, biclustering is a highly combinatorial search problem and can be solved with optimization methods. Results We describe a stochastic pattern-driven neighborhood search algorithm for the biclustering problem. Starting from an initial bicluster, the proposed method improves progressively the quality of the bicluster by adjusting some genes and conditions. The adjustments are based on the quality of each gene and condition with respect to the bicluster and the initial data matrix. The performance of the method was evaluated on two well-known microarray datasets (Yeast cell cycle and Saccharomyces cerevisiae), showing that it is able to obtain statistically and biologically significant biclusters. The proposed method was also compared with six reference methods from the literature. Conclusions The proposed method is computationally fast and can be applied to discover significant biclusters. It can also used to effectively improve the quality of existing biclusters provided by other biclustering methods. PMID:22594997

2012-01-01

196

Priming of pop-out modulates attentional target selection in visual search: behavioural and electrophysiological evidence.  

PubMed

Previous behavioural studies have shown that the repetition of target or distractor features across trials speeds pop-out visual search. We obtained behavioural and event-related brain potential (ERP) measures in two experiments where participants searched for a colour singleton target among homogeneously coloured distractors. An ERP marker of spatially selective attention (N2pc component) was delayed when either target or distractor colours were swapped across successive trials, demonstrating that intertrial feature priming systematically affects the onset of focal-attentional target processing. Results support the hypothesis that priming of pop-out effects are primarily generated at early perceptual/attentional stages of visual processing. PMID:19895829

Eimer, Martin; Kiss, Monika; Cheung, Theodore

2010-06-25

197

Age-Related Preservation of Top-Down Control over Distraction in Visual Search  

PubMed Central

Visual search studies have demonstrated that older adults can have preserved or even increased top-down control over distraction. However, the results are mixed as to the extent of this age-related preservation. The present experiment assesses group differences in younger and older adults during visual search, with a task featuring two conditions offering varying degrees of top-down control over distraction. After controlling for generalized slowing, the analyses revealed that the age groups were equally capable of utilizing top-down control to minimize distraction. Furthermore, for both age groups, the distraction effect was manifested in a sustained manner across the reaction time distribution. PMID:20544447

Costello, Matthew C.; Madden, David J.; Shepler, Anne M.; Mitroff, Stephen R.; Leber, Andrew B.

2009-01-01

198

From parallel to serial processing: a computational study of visual search.  

PubMed

A novel computational model of a preattentive system performing visual search is presented. The model processes displays of lines, reproduced from Wolfe, Friedman-Hill, Stewart, and O'Connell's (1992) and Treisman and Sato's (1990) visual-search experiments. The response times measured in these experiments suggest that some of the displays are searched serially, whereas others are scanned in parallel. Our neural network model operates in two phases. First, the visual displays are compressed via standard methods (principal component analysis), to overcome assumed biological capacity limitations. Second, the compressed representations are further processed to identify a target in the display. The model succeeds in fast detection of targets in experimentally labeled parallel displays, but fails with serial ones. Analysis of the compressed internal representations reveals that compressed parallel displays contain global information that enables instantaneous target detection. However, in representations of serial displays, this global information is obscure, and hence, a target detection system should resort to a serial, attentional scan of local features across the display. Our analysis provides a numerical criterion that is strongly correlated with the experimental response time slopes and enables us to reformulate Duncan and Humphreys's (1989) search surface, using precise quantitative measures. Our findings provide further insight into the important debate concerning the dichotomous versus continuous views of parallel/serial visual search. PMID:10572471

Cohen, E; Ruppin, E

1999-10-01

199

Gene prediction by pattern recognition and homology search  

SciTech Connect

This paper presents an algorithm for combining pattern recognition-based exon prediction and database homology search in gene model construction. The goal is to use homologous genes or partial genes existing in the database as reference models while constructing (multiple) gene models from exon candidates predicted by pattern recognition methods. A unified framework for gene modeling is used for genes ranging from situations with strong homology to no homology in the database. To maximally use the homology information available, the algorithm applies homology on three levels: (1) exon candidate evaluation, (2) gene-segment construction with a reference model, and (3) (complete) gene modeling. Preliminary testing has been done on the algorithm. Test results show that (a) perfect gene modeling can be expected when the initial exon predictions are reasonably good and a strong homology exists in the database; (b) homology (not necessarily strong) in general helps improve the accuracy of gene modeling; (c) multiple gene modeling becomes feasible when homology exists in the database for the involved genes.

Xu, Y.; Uberbacher, E.C.

1996-05-01

200

Efficient "pop-out" visual search elicits sustained broadband ? activity in the dorsal attention network.  

PubMed

An object that differs markedly from its surrounding-for example, a red cherry among green leaves-seems to pop out effortlessly in our visual experience. The rapid detection of salient targets, independently of the number of other items in the scene, is thought to be mediated by efficient search brain mechanisms. It is not clear, however, whether efficient search is actually an "effortless" bottom-up process or whether it also involves regions of the prefrontal cortex generally associated with top-down sustained attention. We addressed this question with intracranial EEG (iEEG) recordings designed to identify brain regions underlying a classic visual search task and correlate neural activity with target detection latencies on a trial-by-trial basis with high temporal precision recordings of these regions in epileptic patients. The spatio-temporal dynamics of single-trial spectral analysis of iEEG recordings revealed sustained energy increases in a broad gamma band (50-150 Hz) throughout the duration of the search process in the entire dorsal attention network both in efficient and inefficient search conditions. By contrast to extensive theoretical and experimental indications that efficient search relies exclusively on transient bottom-up processes in visual areas, we found that efficient search is mediated by sustained gamma activity in the dorsal lateral prefrontal cortex and the anterior cingulate cortex, alongside the superior parietal cortex and the frontal eye field. Our findings support the hypothesis that active visual search systematically involves the frontal-parietal attention network and therefore, executive attention resources, regardless of target saliency. PMID:22399764

Ossandón, Tomas; Vidal, Juan R; Ciumas, Carolina; Jerbi, Karim; Hamamé, Carlos M; Dalal, Sarang S; Bertrand, Olivier; Minotti, Lorella; Kahane, Philippe; Lachaux, Jean-Philippe

2012-03-01

201

Emotional priming of pop-out in visual search.  

PubMed

When searching for a discrepant target along a simple dimension such as color or shape, repetition of the target feature substantially speeds search, an effect known as feature priming of pop-out (V. Maljkovic and K. Nakayama, 1994). The authors present the first report of emotional priming of pop-out. Participants had to detect the face displaying a discrepant expression of emotion in an array of four face photographs. On each trial, the target when present was either a neutral face among emotional faces (angry in Experiment 1 or happy in Experiment 2), or an emotional face among neutral faces. Target detection was faster when the target displayed the same emotion on successive trials. This effect occurred for angry and for happy faces, not for neutral faces. It was completely abolished when faces were inverted instead of upright, suggesting that emotional categories rather than physical feature properties drive emotional priming of pop-out. The implications of the present findings for theoretical accounts of intertrial priming and for the face-in-the-crowd phenomenon are discussed. PMID:18410189

Lamy, Dominique; Amunts, Liana; Bar-Haim, Yair

2008-04-01

202

The processing of coherent global form and motion patterns without visual awareness  

PubMed Central

In the present study we addressed whether the processing of global form and motion was dependent on visual awareness. Continuous flash suppression (CFS) was used to suppress from awareness global dot motion (GDM) and Glass pattern stimuli. We quantified the minimum time taken for both pattern types to break suppression with the signal coherence of the pattern (0, 25, 50, and 100% signal) and the type of global structure (rotational, and radial) as independent variables. For both form and motion patterns increasing signal coherence decreased the time required to break suppression. This was the same for both rotational and radial global patterns. However, GDM patterns broke suppression faster than Glass patterns. In a supplementary experiment, we confirmed that this difference in break times is not because of the temporal nature of GDM patterns in attracting attention. In Experiment 2, we examined whether the processing of dynamic Glass patterns were similarly dependent on visual awareness. The processing of dynamic Glass patterns is involves both motion and form systems, and we questioned whether the interaction of these two systems was dependent on visual awareness. The suppression of dynamic Glass patterns was also dependent on signal coherence and the time course of suppression break resembled the detection of global motion and not global form. In Experiment 3 we ruled out the possibility that faster suppression break times was because the visual system is more sensitive to highly coherent form and motion patterns. Here contrast changing GDM and Glass patterns were superimposed on the dynamic CFS mask, and the minimum time required for them to be detected was measured. We showed that there was no difference in detection times for patterns of 0 and 100% coherence. The advantage of highly coherent global motion and form patterns in breaking suppression indicated that the processing and interaction of global motion and form systems occur without visual awareness. PMID:24672494

Chung, Charles Y. L.; Khuu, Sieu K.

2014-01-01

203

Binocular saccade coordination in reading and visual search: a developmental study in typical reader and dyslexic children  

PubMed Central

Studies dealing with developmental aspects of binocular eye movement behavior during reading are scarce. In this study we have explored binocular strategies during reading and visual search tasks in a large population of dyslexic and typical readers. Binocular eye movements were recorded using a video-oculography system in 43 dyslexic children (aged 8–13) and in a group of 42 age-matched typical readers. The main findings are: (i) ocular motor characteristics of dyslexic children are impaired in comparison to those reported in typical children in reading task; (ii) a developmental effect exists in reading in control children, in dyslexic children the effect of development was observed only on fixation durations; and (iii) ocular motor behavior in the visual search tasks is similar for dyslexic children and for typical readers, except for the disconjugacy during and after the saccade: dyslexic children are impaired in comparison to typical children. Data reported here confirms and expands previous studies on children’s reading. Both reading skills and binocular saccades coordination improve with age in typical readers. The atypical eye movement’s patterns observed in dyslexic children suggest a deficiency in the visual attentional processing as well as an impairment of the ocular motor saccade and vergence systems interaction.

Seassau, Magali; Gerard, Christophe Loic; Bui-Quoc, Emmanuel; Bucci, Maria Pia

2014-01-01

204

Aging and performance on an everyday-based visual search task.  

PubMed

Research on aging and visual search often requires older people to search computer screens for target letters or numbers. The aim of this experiment was to investigate age-related differences using an everyday-based visual search task in a large participant sample (n=261) aged 20-88 years. Our results show that: (1) old-old adults have more difficulty with triple conjunction searches with one highly distinctive feature compared to young-old and younger adults; (2) age-related declines in conjunction searches emerge in middle age then progress throughout older age; (3) age-related declines are evident in feature searches on target absent trials, as older people seem to exhaustively and serially search the whole display to determine a target's absence. Together, these findings suggest that declines emerge in middle age then progress throughout older age in feature integration, guided search, perceptual grouping and/or spreading suppression processes. Discussed are implications for enhancing everyday functioning throughout adulthood. PMID:22664318

Potter, Lauren M; Grealy, Madeleine A; Elliott, Mark A; Andrés, Pilar

2012-07-01

205

Memory for found targets interferes with subsequent performance in multiple-target visual search.  

PubMed

Multiple-target visual searches--when more than 1 target can appear in a given search display--are commonplace in radiology, airport security screening, and the military. Whereas 1 target is often found accurately, additional targets are more likely to be missed in multiple-target searches. To better understand this decrement in 2nd-target detection, here we examined 2 potential forms of interference that can arise from finding a 1st target: interference from the perceptual salience of the 1st target (a now highly relevant distractor in a known location) and interference from a newly created memory representation for the 1st target. Here, we found that removing found targets from the display or making them salient and easily segregated color singletons improved subsequent search accuracy. However, replacing found targets with random distractor items did not improve subsequent search accuracy. Removing and highlighting found targets likely reduced both a target's visual salience and its memory load, whereas replacing a target removed its visual salience but not its representation in memory. Collectively, the current experiments suggest that the working memory load of a found target has a larger effect on subsequent search accuracy than does its perceptual salience. PMID:23163788

Cain, Matthew S; Mitroff, Stephen R

2013-10-01

206

Parafoveal Retinal Vascular Response to Pattern Visual Stimulation Assessed with OCT Angiography  

E-print Network

We used optical coherence tomography (OCT) angiography with a high-speed swept-source OCT system to investigate retinal blood flow changes induced by visual stimulation with a reversing checkerboard pattern. The split-spectrum ...

Wei, Eric

207

Aberrant Patterns of Visual Facial Information Usage in Schizophrenia Cameron M. Clark  

E-print Network

Aberrant Patterns of Visual Facial Information Usage in Schizophrenia Cameron M. Clark University emotion perception have been linked to poorer functional outcome in schizophrenia. However understand the nature of facial emotion perception deficits in schizophrenia, we used the Bubbles Facial

Gosselin, Frédéric

208

Transcranial magnetic stimulation reveals attentional feedback to area V1 during serial visual search.  

PubMed

Visual search tasks have been used to understand how, where and when attention influences visual processing. Current theories suggest the involvement of a high-level "saliency map" that selects a candidate location to focus attentional resources. For a parallel (or "pop-out") task, the first chosen location is systematically the target, but for a serial (or "difficult") task, the system may cycle on a few distractors before finally focusing on the target. This implies that attentional effects upon early visual areas, involving feedback from higher areas, should be visible at longer latencies during serial search. A previous study from Juan & Walsh (2003) had used Transcranial Magnetic Stimulation (TMS) to support this conclusion; however, only a few post-stimulus delays were compared, and no control TMS location was used. Here we applied TMS double-pulses (sub-threshold) to induce a transient inhibition of area V1 at every post-stimulus delay between 100 ms and 500 ms (50 ms steps). The search array was presented either at the location affected by the TMS pulses (previously identified by applying several pulses at supra-threshold intensity to induce phosphene perception), or in the opposite hemifield, which served as a retinotopically-defined control location. Two search tasks were used: a parallel (+ among Ls) and a serial one (T among Ls). TMS specifically impaired the serial, but not the parallel search. We highlight an involvement of V1 in serial search 300 ms after the onset; conversely, V1 did not contribute to parallel search at delays beyond 100 ms. This study supports the idea that serial search differs from parallel search by the presence of additional cycles of a select-and-focus iterative loop between V1 and higher-level areas. PMID:21611188

Dugué, Laura; Marque, Philippe; VanRullen, Rufin

2011-01-01

209

How visual edge features influence cuttlefish camouflage patterning Chuan-Chin Chiao a,b,  

E-print Network

Sepia officinalis a b s t r a c t Rapid adaptive camouflage is the primary defense of softHow visual edge features influence cuttlefish camouflage patterning Chuan-Chin Chiao a Cephalopod camouflage is the fastest changing and most versa- tile in the animal kingdom. These visually

California at Irvine, University of

210

Visualizing and Discovering Non-Trivial Patterns In Large Time Series Databases  

E-print Network

system based on augmenting suffix trees. VizTree visually summarizes both the global and local structures properties of patterns are mapped onto colors and other visual properties. We demonstrate the utility of our, the technicians use electronic strip charts similar to those used to record earthquake shock on paper rolls

Lonardi, Stefano

211

Exploration on Building of Visualization Platform to Innovate Business Operation Pattern of Supply Chain Finance  

NASA Astrophysics Data System (ADS)

Supply Chain Finance, as a new financing pattern, has been arousing general attentions of scholars at home and abroad since its publication. This paper describes the author's understanding towards supply chain finance, makes classification of its business patterns in China from different perspectives, analyzes the existing problems and deficiencies of the business patterns, and finally puts forward the notion of building a visualization platform to innovate the business operation patterns and risk control modes of domestic supply chain finance.

He, Xiangjun; Tang, Lingyun

212

Modeling cognitive effects on visual search for targets in cluttered backgrounds  

NASA Astrophysics Data System (ADS)

To understand how a human operator performs visual search in complex scenes, it is necessary to take into account top- down cognitive biases in addition to bottom-up visual saliency effects. We constructed a model to elucidate the relationship between saliency and cognitive effects in the domain of visual search for distant targets in photo- realistic images of cluttered scenes. In this domain, detecting targets is difficult and requires high visual acuity. Sufficient acuity is only available near the fixation point, i.e. in the fovea. Hence, the choice of fixation points is the most important determinant of whether targets get detected. We developed a model that predicts the 2D distribution of fixation probabilities directly from an image. Fixation probabilities were computed as a function of local contrast (saliency effect) and proximity to the horizon (cognitive effect: distant targets are more likely to be found c close to the horizon). For validation, the model's predictions were compared to ensemble statistics of subjects' actual fixation locations, collected with an eye- tracker. The model's predictions correlated well with the observed data. Disabling the horizon-proximity functionality of the model significantly degraded prediction accuracy, demonstrating that cognitive effects must be accounted for when modeling visual search.

Snorrason, Magnus; Ruda, Harald; Hoffman, James

1998-07-01

213

Minimum-contrast dominate visual search on complex-color background  

Microsoft Academic Search

As we know, the visual attention is greatly influenced by color salience although there are many other important factors such as orientation and spatial frequency. In this study, serial experiments of target search on complex background have been performed. As a result, all experiment results indicate that the response time (RT) is mainly dominated by the minimum-contrast rather than the

Xu Zhan-min; Zhan Quan

2010-01-01

214

Display size effects in visual search: Analyses of reaction time distributions as mixtures  

Microsoft Academic Search

In a reanalysis of data from Cousineau and Shiffrin (2004) and two new visual search experiments, we used a likelihood ratio test to examine the full distributions of reaction time (RT) for evidence that the display size effect is a mixture-type effect that occurs on only a proportion of trials, leaving RT in the remaining trials unaffected, as is predicted

Ann Reynolds; Jeff Miller

2009-01-01

215

"Self pop-out": agency enhances self-recognition in visual search.  

PubMed

In real-life situations, we are often required to recognize our own movements among movements originating from other people. In social situations, these movements are often correlated (for example, when dancing or walking with others) adding considerable difficulty to self-recognition. Studies from visual search have shown that visual attention can selectively highlight specific features to make them more salient. Here, we used a novel visual search task employing virtual reality and motion tracking to test whether visual attention can use efferent information to enhance self-recognition of one's movements among four or six moving avatars. Active movements compared to passive movements allowed faster recognition of the avatar moving like the subject. Critically, search slopes were flat for the active condition but increased for passive movements, suggesting efficient search for active movements. In a second experiment, we tested the effects of using the participants' own movements temporally delayed as distractors in a self-recognition discrimination task. We replicated the results of the first experiment with more rapid self-recognition during active trials. Importantly, temporally delayed distractors increased reaction times despite being more perceptually different than the spatial distractors. The findings demonstrate the importance of agency in self-recognition and self-other discrimination from movement in social settings. PMID:23665753

Salomon, R; Lim, M; Kannape, O; Llobera, J; Blanke, O

2013-07-01

216

Frontal eye field activity enhances object identification during covert visual search.  

PubMed

We investigated the link between neuronal activity in the frontal eye field (FEF) and the enhancement of visual processing associated with covert spatial attention in the absence of eye movements. We correlated activity recorded in the FEF of monkeys manually reporting the identity of a visual search target to performance accuracy and reaction time. Monkeys were cued to the most probable target location with a cue array containing a popout color singleton. Neurons exhibited spatially selective responses for the popout cue stimulus and for the target of the search array. The magnitude of activity related to the location of the cue prior to the presentation of the search array was correlated with trends in behavioral performance across valid, invalid, and neutral cue trial conditions. However, the speed and accuracy of the behavioral report on individual trials were predicted by the magnitude of spatial selectivity related to the target to be identified, not for the spatial cue. A minimum level of selectivity was necessary for target detection and a higher level for target identification. Muscimol inactivation of FEF produced spatially selective perceptual deficits in the covert search task that were correlated with the effectiveness of the inactivation and were strongest on invalid cue trials that require an endogenous attention shift. These results demonstrate a strong functional link between FEF activity and covert spatial attention and suggest that spatial signals from FEF directly influence visual processing during the time that a stimulus to be identified is being processed by the visual system. PMID:19828723

Monosov, Ilya E; Thompson, Kirk G

2009-12-01

217

Visual Search and Emotion: How Children with Autism Spectrum Disorders Scan Emotional Scenes  

ERIC Educational Resources Information Center

This study assessed visual search abilities, tested through the flicker task, in children diagnosed with autism spectrum disorders (ASDs). Twenty-two children diagnosed with ASD and 22 matched typically developing (TD) children were told to detect changes in objects of central interest or objects of marginal interest (MI) embedded in either…

Maccari, Lisa; Pasini, Augusto; Caroli, Emanuela; Rosa, Caterina; Marotta, Andrea; Martella, Diana; Fuentes, Luis J.; Casagrande, Maria

2014-01-01

218

Fusion of Multi-Sensor Imagery for Night Vision: Color Visualization, Target Learning and Search1  

E-print Network

Fusion of Multi-Sensor Imagery for Night Vision: Color Visualization, Target Learning and Search1 D sensors to create a color night vision capability. The fusion system architectures are based on biological ARTMAP neural network. Keywords: Sensor fusion, image fusion, night vision, real-time processing, data

219

Eye Movement and Visual Search: Are There Elementary Abnormalities in Autism?  

ERIC Educational Resources Information Center

Although atypical eye gaze is commonly observed in autism, little is known about underlying oculomotor abnormalities. Our review of visual search and oculomotor systems in the healthy brain suggests that relevant networks may be partially impaired in autism, given regional abnormalities known from neuroimaging. However, direct oculomotor evidence…

Brenner, Laurie A.; Turner, Katherine C.; Muller, Ralph-Axel

2007-01-01

220

Eye movements and attention in reading, scene perception, and visual search  

Microsoft Academic Search

Eye movements are now widely used to investigate cognitive processes during reading, scene perception, and visual search. In this article, research on the following topics is reviewed with respect to reading: (a) the perceptual span (or span of effective vision), (b) preview benefit, (c) eye movement control, and (d) models of eye movements. Related issues with respect to eye movements

Keith Rayner

2009-01-01

221

Controlling and investigating Cellular Automata behavior via interactive inversion and visualization of search space  

E-print Network

and visualization of search space F. Boschetti, CSIRO, Exploration and Mining. Abstract We use an Interactive Organised Map, enables the rapid on-line visualisation of the high dimensional parameter space and consequent control over the inversion itself. The insights into the topology of the parameter space offer

Boschetti, Fabio

222

Incorporating holistic visual search concepts into a SPECT myocardial perfusion imaging numerical observer  

Microsoft Academic Search

Previous Single Photon Emission Computed Tomography (SPECT) myocardial perfusion imaging (MPI) research has explored the utility of numerical observers. One previous study proposed that the model of holistic visual search of a myocardial perfusion image by an expert human observer might improve the development of a SPECT MPI numerical observer. Further examination of numerical processing techniques that seem to be

J. Michael O'Connor; Howard C. Gifford; Jovan G. Brankov; P. H. Pretorius

2011-01-01

223

Visual search in long-term cannabis users with early age of onset  

Microsoft Academic Search

The present research tested the hypothesis that there is a specific deficit in visual scanning in chronic users of cannabis with early onset of their drug consumption (age 14 to 16). 17 users and 20 control participants were asked to search for targets on a 5 × 5 stimulus array while their eye movements were monitored. Cannabis users showed less

Lynn Huestegge; Ralph Radach; Hans-Juergen Kunert; Dieter Heller

2002-01-01

224

Low Target Prevalence Is a Stubborn Source of Errors in Visual Search Tasks  

ERIC Educational Resources Information Center

In visual search tasks, observers look for targets in displays containing distractors. Likelihood that targets will be missed varies with target prevalence, the frequency with which targets are presented across trials. Miss error rates are much higher at low target prevalence (1%-2%) than at high prevalence (50%). Unfortunately, low prevalence is…

Wolfe, Jeremy M.; Horowitz, Todd S.; Van Wert, Michael J.; Kenner, Naomi M.; Place, Skyler S.; Kibbi, Nour

2007-01-01

225

Low Target Prevalence Is a Stubborn Source of Errors in Visual Search Tasks  

E-print Network

Low Target Prevalence Is a Stubborn Source of Errors in Visual Search Tasks Jeremy M. Wolfe and Todd S. Horowitz Brigham and Women's Hospital and Harvard Medical School Michael J. Van Wert, Naomi M with target prevalence, the frequency with which targets are presented across trials. Miss error rates

226

Effect of pattern complexity on the visual span for Chinese and alphabet characters  

PubMed Central

The visual span for reading is the number of letters that can be recognized without moving the eyes and is hypothesized to impose a sensory limitation on reading speed. Factors affecting the size of the visual span have been studied using alphabet letters. There may be common constraints applying to recognition of other scripts. The aim of this study was to extend the concept of the visual span to Chinese characters and to examine the effect of the greater complexity of these characters. We measured visual spans for Chinese characters and alphabet letters in the central vision of bilingual subjects. Perimetric complexity was used as a metric to quantify the pattern complexity of binary character images. The visual span tests were conducted with four sets of stimuli differing in complexity—lowercase alphabet letters and three groups of Chinese characters. We found that the size of visual spans decreased with increasing complexity, ranging from 10.5 characters for alphabet letters to 4.5 characters for the most complex Chinese characters studied. A decomposition analysis revealed that crowding was the dominant factor limiting the size of the visual span, and the amount of crowding increased with complexity. Errors in the spatial arrangement of characters (mislocations) had a secondary effect. We conclude that pattern complexity has a major effect on the size of the visual span, mediated in large part by crowding. Measuring the visual span for Chinese characters is likely to have high relevance to understanding visual constraints on Chinese reading performance. PMID:24993020

Wang, Hui; He, Xuanzi; Legge, Gordon E.

2014-01-01

227

The Pattern of Learned Visual Improvements in Adult Amblyopia  

E-print Network

, or occasion- ally both, eyes--despite full optical correction and no evident ocular pathology.1 It affects development--postnatal windows of experience-dependent neural plasticity.5 The neural site of the amblyopic of retaining any of the experience- dependent neural plasticity, which is so prominent during early visual

Nottingham, University of

228

Use Patterns of Visual Cues in Computer-Mediated Communication  

ERIC Educational Resources Information Center

Communication in the virtual environment can be challenging for participants because it lacks physical presence and nonverbal elements. Participants may have difficulties expressing their intentions and emotions in a primarily text-based course. Therefore, the use of visual communication elements such as pictographic and typographic marks can be…

Bolliger, Doris U.

2009-01-01

229

The scaling of spatial attention in visual search and its modification in healthy aging  

PubMed Central

A model of visual search (Greenwood & Parasuraman, 1999) postulating that visuospatial attention is composed of two processing components—shifting and scaling of a variable-gradient attentional focus—was tested in three experiments. Whereas young participants are able to dynamically constrict or expand the focus of visuospatial attention on the basis of prior information, in healthy aging individuals visuospatial attention becomes a poorly focused beam, unable to be constricted around one array element. In the present work, we sought to examine predictions of this view in healthy young and older participants. An attentional focus constricted in response to an element-sized precue had the strongest facilitatory effect on visual search. However, this was true only when the precue correctly indicated the location of a target fixed in size. When precues incorrectly indicated target location or when target size varied, the optimal spatial scale of attention for search was larger, encompassing a number of array elements. Healthy aging altered the deployment of attentional scaling: The benefit of valid precues on search initially (in participants 65–74 years of age) was increased but later (in those 75–85 years of age) was reduced. The results also provided evidence that cue size effects are attentional, not strategic. This evidence is consistent with the proposed model of attentional scaling in visual search. PMID:15095936

GREENWOOD, P. M.; PARASURAMAN, RAJA

2005-01-01

230

Centre-of-Gravity Fixations in Visual Search: When Looking at Nothing Helps to Find Something.  

PubMed

In visual search, some fixations are made between stimuli on empty regions, commonly referred to as "centre-of-gravity" fixations (henceforth: COG fixations). Previous studies have shown that observers with task expertise show more COG fixations than novices. This led to the view that COG fixations reflect simultaneous encoding of multiple stimuli, allowing more efficient processing of task-related items. The present study tested whether COG fixations also aid performance in visual search tasks with unfamiliar and abstract stimuli. Moreover, to provide evidence for the multiple-item processing view, we analysed the effects of COG fixations on the number and dwell times of stimulus fixations. The results showed that (1) search efficiency increased with increasing COG fixations even in search for unfamiliar stimuli and in the absence of special higher-order skills, (2) COG fixations reliably reduced the number of stimulus fixations and their dwell times, indicating processing of multiple distractors, and (3) the proportion of COG fixations was dynamically adapted to potential information gain of COG locations. A second experiment showed that COG fixations are diminished when stimulus positions unpredictably vary across trials. Together, the results support the multiple-item processing view, which has important implications for current theories of visual search. PMID:25002972

Venini, Dustin; Remington, Roger W; Horstmann, Gernot; Becker, Stefanie I

2014-01-01

231

The Importance of the Eye Area in Face Identification Abilities and Visual Search Strategies in Persons with Asperger Syndrome  

ERIC Educational Resources Information Center

Partly claimed to explain social difficulties observed in people with Asperger syndrome, face identification and visual search strategies become important. Previous research findings are, however, disparate. In order to explore face identification abilities and visual search strategies, with special focus on the importance of the eye area, 24…

Falkmer, Marita; Larsson, Matilda; Bjallmark, Anna; Falkmer, Torbjorn

2010-01-01

232

Visual cluster analysis and pattern recognition template and methods  

DOEpatents

A method of clustering using a novel template to define a region of influence is disclosed. Using neighboring approximation methods, computation times can be significantly reduced. The template and method are applicable and improve pattern recognition techniques. 30 figs.

Osbourn, G.C.; Martinez, R.F.

1999-05-04

233

Visual cluster analysis and pattern recognition template and methods  

DOEpatents

A method of clustering using a novel template to define a region of influence. Using neighboring approximation methods, computation times can be significantly reduced. The template and method are applicable and improve pattern recognition techniques.

Osbourn, Gordon Cecil (Albuquerque, NM); Martinez, Rubel Francisco (Albuquerque, NM)

1999-01-01

234

Visual cluster analysis and pattern recognition template and methods  

SciTech Connect

This invention is comprised of a method of clustering using a novel template to define a region of influence. Using neighboring approximation methods, computation times can be significantly reduced. The template and method are applicable and improve pattern recognition techniques.

Osbourn, G.C.; Martinez, R.F.

1993-12-31

235

Visualizing a High Recall Search Strategy Output for Undergraduates in an Exploration Stage of Researching a Term Paper.  

ERIC Educational Resources Information Center

Discusses high recall search strategies for undergraduates and how to overcome information overload that results. Highlights include word-based versus visual-based schemes; five summarization and visualization schemes for presenting information retrieval citation output; and results of a study that recommend visualization schemes geared toward…

Cole, Charles; Mandelblatt, Bertie; Stevenson, John

2002-01-01

236

Hypothesis Support Mechanism for Mid-Level Visual Pattern Recognition  

NASA Technical Reports Server (NTRS)

A method of mid-level pattern recognition provides for a pose invariant Hough Transform by parametrizing pairs of points in a pattern with respect to at least two reference points, thereby providing a parameter table that is scale- or rotation-invariant. A corresponding inverse transform may be applied to test hypothesized matches in an image and a distance transform utilized to quantify the level of match.

Amador, Jose J (Inventor)

2007-01-01

237

Query Suggestions for Mobile Search: Understanding Usage Patterns  

E-print Network

Inc 1600 Amphitheatre Parkway, Mountain View, CA shumeet@google.com ABSTRACT Entering search terms that users who were asked to enter queries on a search interface with query suggestions rated their workload heavily on suggestions if they are provided. Users who were asked to enter queries on a search interface

Tomkins, Andrew

238

Using Interactive Visualizations of WWW Log Data to Characterize Access Patterns and Inform Site Design  

E-print Network

that exceed those of traditional web log analysis tools. We introduce a series of interactive visualizations providers, understanding of user visit patterns is essential for effective design of sites involving online issues such as depth vs. breadth of tree structures, incidental learning patterns, utility of graphics

Shneiderman, Ben

239

Clustering and Symbolic Analysis of Cardiovascular Signals: Discovery and Visualization of Medically Relevant Patterns in  

E-print Network

of Medically Relevant Patterns in Long-Term Data Using Limited Prior Knowledge Presented by Dragana Veljkovic: Discovery and visualization of medically relevant patterns in long-term data using limited prior knowledge according to clusters Map to symbol by extracting information from the segment #12;Common representations

Tian, Qi

240

Visual search in hunting archerfish shares all hallmarks of human performance.  

PubMed

Archerfish are renowned for shooting down aerial prey with water jets, but nothing is known about how they spot prey items in their richly structured mangrove habitats. We trained archerfish to stably assign the categories 'target' and 'background' to objects solely on the basis of non-motion cues. Unlike many other hunters, archerfish are able to discriminate a target from its background in the complete absence of either self-motion or relative motion parallax cues and without using stored information about the structure of the background. This allowed us to perform matched tests to compare the ways fish and humans scan stationary visual scenes. In humans, visual search is seen as a doorway to cortical mechanisms of how attention is allocated. Fish lack a cortex and we therefore wondered whether archerfish would differ from humans in how they scan a stationary visual scene. Our matched tests failed to disclose any differences in the dependence of response time distributions, a most sensitive indicator of the search mechanism, on number and complexity of background objects. Median and range of response times depended linearly on the number of background objects and the corresponding effective processing time per item increased similarly - approximately fourfold - in both humans and fish when the task was harder. Archerfish, like humans, also systematically scanned the scenery, starting with the closest object. Taken together, benchmark visual search tasks failed to disclose any difference between archerfish - who lack a cortex - and humans. PMID:23619420

Rischawy, Ingo; Schuster, Stefan

2013-08-15

241

Production and perception rules underlying visual patterns: effects of symmetry and hierarchy.  

PubMed

Formal language theory has been extended to two-dimensional patterns, but little is known about two-dimensional pattern perception. We first examined spontaneous two-dimensional visual pattern production by humans, gathered using a novel touch screen approach. Both spontaneous creative production and subsequent aesthetic ratings show that humans prefer ordered, symmetrical patterns over random patterns. We then further explored pattern-parsing abilities in different human groups, and compared them with pigeons. We generated visual plane patterns based on rules varying in complexity. All human groups tested, including children and individuals diagnosed with autism spectrum disorder (ASD), were able to detect violations of all production rules tested. Our ASD participants detected pattern violations with the same speed and accuracy as matched controls. Children's ability to detect violations of a relatively complex rotational rule correlated with age, whereas their ability to detect violations of a simple translational rule did not. By contrast, even with extensive training, pigeons were unable to detect orientation-based structural violations, suggesting that, unlike humans, they did not learn the underlying structural rules. Visual two-dimensional patterns offer a promising new formally-grounded way to investigate pattern production and perception in general, widely applicable across species and age groups. PMID:22688636

Westphal-Fitch, Gesche; Huber, Ludwig; Gómez, Juan Carlos; Fitch, W Tecumseh

2012-07-19

242

Production and perception rules underlying visual patterns: effects of symmetry and hierarchy  

PubMed Central

Formal language theory has been extended to two-dimensional patterns, but little is known about two-dimensional pattern perception. We first examined spontaneous two-dimensional visual pattern production by humans, gathered using a novel touch screen approach. Both spontaneous creative production and subsequent aesthetic ratings show that humans prefer ordered, symmetrical patterns over random patterns. We then further explored pattern-parsing abilities in different human groups, and compared them with pigeons. We generated visual plane patterns based on rules varying in complexity. All human groups tested, including children and individuals diagnosed with autism spectrum disorder (ASD), were able to detect violations of all production rules tested. Our ASD participants detected pattern violations with the same speed and accuracy as matched controls. Children's ability to detect violations of a relatively complex rotational rule correlated with age, whereas their ability to detect violations of a simple translational rule did not. By contrast, even with extensive training, pigeons were unable to detect orientation-based structural violations, suggesting that, unlike humans, they did not learn the underlying structural rules. Visual two-dimensional patterns offer a promising new formally-grounded way to investigate pattern production and perception in general, widely applicable across species and age groups. PMID:22688636

Westphal-Fitch, Gesche; Huber, Ludwig; Gomez, Juan Carlos; Fitch, W. Tecumseh

2012-01-01

243

Visual ability and searching behavior of adult Laricobius nigrinus, a hemlock woolly adelgid predator.  

PubMed

Very little is known about the searching behavior and sensory cues that Laricobius spp. (Coleoptera: Derodontidae) predators use to locate suitable habitats and prey, which limits our ability to collect and monitor them for classical biological control of adelgids (Hemiptera: Adelgidae). The aim of this study was to examine the visual ability and the searching behavior of newly emerged L. nigrinus Fender, a host-specific predator of the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Phylloxeroidea: Adelgidae). In a laboratory bioassay, individual adults attempting to locate an uninfested eastern hemlock seedling under either light or dark conditions were observed in an arena. In another bioassay, individual adults searching for prey on hemlock seedlings (infested or uninfested) were continuously video-recorded. Beetles located and began climbing the seedling stem in light significantly more than in dark, indicating that vision is an important sensory modality. Our primary finding was that searching behavior of L. nigrinus, as in most species, was related to food abundance. Beetles did not fly in the presence of high A. tsugae densities and flew when A. tsugae was absent, which agrees with observed aggregations of beetles on heavily infested trees in the field. At close range of prey, slow crawling and frequent turning suggest the use of non-visual cues such as olfaction and contact chemoreception. Based on the beetles' visual ability to locate tree stems and their climbing behavior, a bole trap may be an effective collection and monitoring tool. PMID:22220637

Mausel, D L; Salom, S M; Kok, L T

2011-01-01

244

Activity in V4 Reflects the Direction, But Not the Latency, of Saccades During Visual Search  

PubMed Central

We constantly make eye movements to bring objects of interest onto the fovea for more detailed processing. Activity in area V4, a prestriate visual area, is enhanced at the location corresponding to the target of an eye movement. However, the precise role of activity in V4 in relation to these saccades and the modulation of other cortical areas in the oculomotor system remains unknown. V4 could be a source of visual feature information used to select the eye movement, or alternatively, it could reflect the locus of spatial attention. To test these hypotheses, we trained monkeys on a visual search task in which they were free to move their eyes. We found that activity in area V4 reflected the direction of the upcoming saccade but did not predict the latency of the saccade in contrast to activity in the lateral intraparietal area (LIP). We suggest that the signals in V4, unlike those in LIP, are not directly involved in the generation of the saccade itself but rather are more closely linked to visual perception and attention. Although V4 and LIP have different roles in spatial attention and preparing eye movements, they likely perform complimentary processes during visual search. PMID:20610790

Gee, Angela L.; Ipata, Anna E.

2010-01-01

245

The Influence of Caption Features on Clickthrough Patterns in Web Search  

E-print Network

The Influence of Caption Features on Clickthrough Patterns in Web Search Charles L. A. Clarke, and URL, to help users decide which search results to visit. Understanding the influence of features. In this paper we develop a methodology to use clickthrough logs from a commercial search engine to study user

Dumais, Susan

246

A Globally Convergent Augmented Lagrangian Pattern Search Algorithm for Optimization with General Constraints and Simple Bounds  

NASA Technical Reports Server (NTRS)

We give a pattern search adaptation of an augmented Lagrangian method due to Conn, Gould, and Toint. The algorithm proceeds by successive bound constrained minimization of an augmented Lagrangian. In the pattern search adaptation we solve this subproblem approximately using a bound constrained pattern search method. The stopping criterion proposed by Conn, Gould, and Toint for the solution of this subproblem requires explicit knowledge of derivatives. Such information is presumed absent in pattern search methods; however, we show how we can replace this with a stopping criterion based on the pattern size in a way that preserves the convergence properties of the original algorithm. In this way we proceed by successive, inexact, bound constrained minimization without knowing exactly how inexact the minimization is. So far as we know, this is the first provably convergent direct search method for general nonlinear programming.

Lewis, Robert Michael; Torczon, Virginia

1998-01-01

247

PATTERN REVERSAL VISUAL EVOKED POTENTIALS IN AWAKE RATS  

EPA Science Inventory

A method for recording pattern reversal evoked potentials (PREPs) from awake restrained rats has been developed. The procedure of Onofrj et al. was modified to eliminate the need for anesthetic, thereby avoiding possible interactions of the anesthetic with other manipulations of ...

248

The Dynamics of Visual Experience, an EEG Study of Subjective Pattern Formation  

PubMed Central

Background Since the origin of psychological science a number of studies have reported visual pattern formation in the absence of either physiological stimulation or direct visual-spatial references. Subjective patterns range from simple phosphenes to complex patterns but are highly specific and reported reliably across studies. Methodology/Principal Findings Using independent-component analysis (ICA) we report a reduction in amplitude variance consistent with subjective-pattern formation in ventral posterior areas of the electroencephalogram (EEG). The EEG exhibits significantly increased power at delta/theta and gamma-frequencies (point and circle patterns) or a series of high-frequency harmonics of a delta oscillation (spiral patterns). Conclusions/Significance Subjective-pattern formation may be described in a way entirely consistent with identical pattern formation in fluids or granular flows. In this manner, we propose subjective-pattern structure to be represented within a spatio-temporal lattice of harmonic oscillations which bind topographically organized visual-neuronal assemblies by virtue of low frequency modulation. PMID:22292053

Elliott, Mark A.; Twomey, Deirdre; Glennon, Mark

2012-01-01

249

Visual Search with Image Modification in Age-Related Macular Degeneration  

PubMed Central

Purpose. AMD results in loss of central vision and a dependence on low-resolution peripheral vision. While many image enhancement techniques have been proposed, there is a lack of quantitative comparison of the effectiveness of enhancement. We developed a natural visual search task that uses patients' eye movements as a quantitative and functional measure of the efficacy of image modification. Methods. Eye movements of 17 patients (mean age = 77 years) with AMD were recorded while they searched for target objects in natural images. Eight different image modification methods were implemented and included manipulations of local image or edge contrast, color, and crowding. In a subsequent task, patients ranked their preference of the image modifications. Results. Within individual participants, there was no significant difference in search duration or accuracy across eight different image manipulations. When data were collapsed across all image modifications, a multivariate model identified six significant predictors for normalized search duration including scotoma size and acuity, as well as interactions among scotoma size, age, acuity, and contrast (P < 0.05). Additionally, an analysis of image statistics showed no correlation with search performance across all image modifications. Rank ordering of enhancement methods based on participants' preference revealed a trend that participants preferred the least modified images (P < 0.05). Conclusions. There was no quantitative effect of image modification on search performance. A better understanding of low- and high-level components of visual search in natural scenes is necessary to improve future attempts at image enhancement for low vision patients. Different search tasks may require alternative image modifications to improve patient functioning and performance. PMID:22930725

Wiecek, Emily; Jackson, Mary Lou; Dakin, Steven C.; Bex, Peter

2012-01-01

250

Pattern Visualization for Software Comprehension Cognitive science emphasizes the strength of visual  

E-print Network

of the architectural constituents within the source code model is an indispensable aid for the guided evolution study example helps explicate and illustrate our work. Keywords: Design visualization, software that can preserve the history of both the initial design and the subsequent evolution of software. We be

Keller, Rudolf K.

251

Human Visual Search Does Not Maximize the Post-Saccadic Probability of Identifying Targets  

PubMed Central

Researchers have conjectured that eye movements during visual search are selected to minimize the number of saccades. The optimal Bayesian eye movement strategy minimizing saccades does not simply direct the eye to whichever location is judged most likely to contain the target but makes use of the entire retina as an information gathering device during each fixation. Here we show that human observers do not minimize the expected number of saccades in planning saccades in a simple visual search task composed of three tokens. In this task, the optimal eye movement strategy varied, depending on the spacing between tokens (in the first experiment) or the size of tokens (in the second experiment), and changed abruptly once the separation or size surpassed a critical value. None of our observers changed strategy as a function of separation or size. Human performance fell far short of ideal, both qualitatively and quantitatively. PMID:22319428

Morvan, Camille; Maloney, Laurence T.

2012-01-01

252

Local binary pattern based texture analysis for visual fire recognition  

Microsoft Academic Search

Color and shape features have difficulty to recognize fire from fire-colored, irregular-shaped and moving objects. An effective algorithm using texture analysis with the Local Binary Pattern (LBP) is proposed in our paper to help deal with this problem. Besides grayscale and rotation invariance, the ability of LBP operator for multi-resolution analysis is enhanced through multiple LBP operators with varying parameters

Jing Huang; Jianhui Zhao; Weiwei Gao; Chengjiang Long; Lu Xiong; Zhiyong Yuan; Shizhong Han

2010-01-01

253

A Pattern Recognition Feature Optimization Tool Using the Visual Empirical Region of Influence Algorithm  

SciTech Connect

This document is the second in a series that describe graphical user interface tools developed to control the Visual Empirical Region of Influence (VERI) algorithm. In this paper we describe a user interface designed to optimize the VERI algorithm results. The optimization mode uses a brute force method of searching through the combinations of features in a data set for features that produce the best pattern recognition results. With a small number of features in a data set an exact solution can be determined. However, the number of possible combinations increases exponentially with the number of features and an alternate means of finding a solution must be found. We developed and implemented a technique for finding solutions in data sets with both small and large numbers of features. This document illustrates step-by-step examples of how to use the interface and how to interpret the results. It is written in two parts, part I deals with using the interface to find the best combination from all possible sets of features, part II describes how to use the tool to find a good solution in data sets with a large number of features. The VERI Optimization Interface Tool was written using the Tcl/Tk Graphical User Interface (GUI) programming language, version 8.1. Although the Tcl/Tk packages are designed to run on multiple computer platforms, we have concentrated our efforts to develop a user interface for the ubiquitous DOS environment. The VERI algorithms are compiled, executable programs. The optimization interface executes the VERI algorithm in Leave-One-Out mode using the Euclidean metric. For a thorough description of the type of data analysis we perform, and for a general Pattern Recognition tutorial, refer to our website at: http://www.sandia.gov/imrl/XVisionScience/Xusers.htm.

MARTINEZ, RUBEL F.

2002-06-01

254

Sleep-Effects on Implicit and Explicit Memory in Repeated Visual Search  

PubMed Central

In repeated visual search tasks, facilitation of reaction times (RTs) due to repetition of the spatial arrangement of items occurs independently of RT facilitation due to improvements in general task performance. Whereas the latter represents typical procedural learning, the former is a kind of implicit memory that depends on the medial temporal lobe (MTL) memory system and is impaired in patients with amnesia. A third type of memory that develops during visual search is the observers’ explicit knowledge of repeated displays. Here, we used a visual search task to investigate whether procedural memory, implicit contextual cueing, and explicit knowledge of repeated configurations, which all arise independently from the same set of stimuli, are influenced by sleep. Observers participated in two experimental sessions, separated by either a nap or a controlled rest period. In each of the two sessions, they performed a visual search task in combination with an explicit recognition task. We found that (1) across sessions, MTL-independent procedural learning was more pronounced for the nap than rest group. This confirms earlier findings, albeit from different motor and perceptual tasks, showing that procedural memory can benefit from sleep. (2) Likewise, the sleep group compared with the rest group showed enhanced context-dependent configural learning in the second session. This is a novel finding, indicating that the MTL-dependent, implicit memory underlying contextual cueing is also sleep-dependent. (3) By contrast, sleep and wake groups displayed equivalent improvements in explicit recognition memory in the second session. Overall, the current study shows that sleep affects MTL-dependent as well as MTL-independent memory, but it affects different, albeit simultaneously acquired, forms of MTL-dependent memory differentially. PMID:23936363

Assumpcao, Leonardo; Gais, Steffen

2013-01-01

255

Visual supernova searching with the 40 inch telescope at Siding Spring Observatory  

NASA Astrophysics Data System (ADS)

Preliminary results are presented arising from the use of the 40 inch telescope at Siding Spring Observatory for visual supernova hunting over a period of about 18 months. The use of the telescope in this way is continuing. These results are compared with the performance of my 41 cm backyard telescope over the same 18-month period, and with recently announced results from the Perth Observatory's Automated Supernova Search using their 61 cm telescope over a three-year period.

Evans, R.

1997-08-01

256

Visual search for size is influenced by a background texture gradient  

Microsoft Academic Search

Research on the perception of texture gradients has relied heavily on the subjective reports of observers engaged in free-viewing. We asked whether these findings generalized to speeded performance. Experiment 1 showed that an important aspect of subjective perception—size- constancy scaling with perceived distance—also predicted the speed of pop-out visual search for cylinders viewed against a texture gradient. Experiment 2 showed

Deborah J. Aks; James T. Enns

1996-01-01

257

Color singleton pop-out does not always poop out: An alternative to visual search  

Microsoft Academic Search

Folk psychology suggests that when an observer views a scene, a unique item will stand out and draw attention to itself. This\\u000a belief stands in contrast to numerous studies in visual search that have found that a unique target item (e.g., a unique color)\\u000a is not identified more quickly than a nonunique target. We hypothesized that this finding is the

William Prinzmetal; Nadia Taylor

2006-01-01

258

A method to identify talent: visual search and locomotion behavior in young football players.  

PubMed

The present study examined differences in visual search and locomotor behavior among a group of skilled 10-12 year-old football players. The participants watched video clips of a 4-to-4 position game, presented on a large screen. The participants were asked to take part in the game by choosing the best position for the reception of the ball passed by one of the players in the clip. Participants' visual search and locomotor behavior were collected continuously throughout the presentation of the clip. A within-group comparison was made based upon the participants' interception score, i.e., more at the correct position. The findings show that the high-score group looked more to the ball area, while the players in the low-score group concentrated on the receiving player and on the hips/upper-body region of the passing player. The players in the high-score group covered a significantly greater distance compared to the low-score group. It was concluded that differences in visual search and locomotion behavior can be used as indicators for identifying talented junior football players. PMID:20728954

Savelsbergh, Geert J P; Haans, Sascha H A; Kooijman, Margit K; van Kampen, Paulien M

2010-10-01

259

Modeling the Effect of Selection History on Pop-Out Visual Search  

PubMed Central

While attentional effects in visual selection tasks have traditionally been assigned “top-down” or “bottom-up” origins, more recently it has been proposed that there are three major factors affecting visual selection: (1) physical salience, (2) current goals and (3) selection history. Here, we look further into selection history by investigating Priming of Pop-out (POP) and the Distractor Preview Effect (DPE), two inter-trial effects that demonstrate the influence of recent history on visual search performance. Using the Ratcliff diffusion model, we model observed saccadic selections from an oddball search experiment that included a mix of both POP and DPE conditions. We find that the Ratcliff diffusion model can effectively model the manner in which selection history affects current attentional control in visual inter-trial effects. The model evidence shows that bias regarding the current trial's most likely target color is the most critical parameter underlying the effect of selection history. Our results are consistent with the view that the 3-item color-oddball task used for POP and DPE experiments is best understood as an attentional decision making task. PMID:24595032

Tseng, Yuan-Chi; Glaser, Joshua I.; Caddigan, Eamon; Lleras, Alejandro

2014-01-01

260

Multimodal signals: enhancement and constraint of song motor patterns by visual display.  

PubMed

Many birds perform visual signals during their learned songs, but little is known about the interrelationship between visual and vocal displays. We show here that male brown-headed cowbirds (Molothrus ater) synchronize the most elaborate wing movements of their display with atypically long silent periods in their song, potentially avoiding adverse biomechanical effects on sound production. Furthermore, expiratory effort for song is significantly reduced when cowbirds perform their wing display. These results show a close integration between vocal and visual displays and suggest that constraints and synergistic interactions between the motor patterns of multimodal signals influence the evolution of birdsong. PMID:14739462

Cooper, Brenton G; Goller, Franz

2004-01-23

261

Visual search and emotion: how children with autism spectrum disorders scan emotional scenes.  

PubMed

This study assessed visual search abilities, tested through the flicker task, in children diagnosed with autism spectrum disorders (ASDs). Twenty-two children diagnosed with ASD and 22 matched typically developing (TD) children were told to detect changes in objects of central interest or objects of marginal interest (MI) embedded in either emotion-laden (positive or negative) or neutral real-world pictures. The results showed that emotion-laden pictures equally interfered with performance of both ASD and TD children, slowing down reaction times compared with neutral pictures. Children with ASD were faster than TD children, particularly in detecting changes in MI objects, the most difficult condition. However, their performance was less accurate than performance of TD children just when the pictures were negative. These findings suggest that children with ASD have better visual search abilities than TD children only when the search is particularly difficult and requires strong serial search strategies. The emotional-social impairment that is usually considered as a typical feature of ASD seems to be limited to processing of negative emotional information. PMID:24898908

Maccari, Lisa; Pasini, Augusto; Caroli, Emanuela; Rosa, Caterina; Marotta, Andrea; Martella, Diana; Fuentes, Luis J; Casagrande, Maria

2014-11-01

262

Training shortens search times in children with visual impairment accompanied by nystagmus  

PubMed Central

Perceptual learning (PL) can improve near visual acuity (NVA) in 4–9 year old children with visual impairment (VI). However, the mechanisms underlying improved NVA are unknown. The present study compares feature search and oculomotor measures in 4–9 year old children with VI accompanied by nystagmus (VI+nys [n = 33]) and children with normal vision (NV [n = 29]). Children in the VI+nys group were divided into three training groups: an experimental PL group, a control PL group, and a magnifier group. They were seen before (baseline) and after 6 weeks of training. Children with NV were only seen at baseline. The feature search task entailed finding a target E among distractor E's (pointing right) with element spacing varied in four steps: 0.04°, 0.5°, 1°, and 2°. At baseline, children with VI+nys showed longer search times, shorter fixation durations, and larger saccade amplitudes than children with NV. After training, all training groups showed shorter search times. Only the experimental PL group showed prolonged fixation duration after training at 0.5° and 2° spacing, p's respectively 0.033 and 0.021. Prolonged fixation duration was associated with reduced crowding and improved crowded NVA. One of the mechanisms underlying improved crowded NVA after PL in children with VI+nys seems to be prolonged fixation duration. PMID:25309473

Huurneman, Bianca; Boonstra, F. Nienke

2014-01-01

263

White matter hyperintensities are associated with visual search behavior independent of generalized slowing in aging.  

PubMed

A fundamental controversy is whether cognitive decline with advancing age can be entirely explained by decreased processing speed, or whether specific neural changes can elicit cognitive decline, independent of slowing. These hypotheses are anchored by studies of healthy older individuals where age is presumed the sole influence. Unfortunately, advancing age is also associated with asymptomatic brain white matter injury. We hypothesized that differences in white matter injury extent, manifest by MRI white matter hyperintensities (WMH), mediate differences in visual attentional control in healthy aging, beyond processing speed differences. We tested young and cognitively healthy older adults on search tasks indexing speed and attentional control. Increasing age was associated with generally slowed performance. WMH were also associated with slowed search times independent of processing speed differences. Consistent with evidence attributing reduced network connectivity to WMH, these results conclusively demonstrate that clinically silent white matter injury contributes to slower search performance indicative of compromised cognitive control, independent of generalized slowing of processing speed. PMID:24183716

Lockhart, Samuel N; Roach, Alexandra E; Luck, Steven J; Geng, Joy; Beckett, Laurel; Carmichael, Owen; DeCarli, Charles

2014-01-01

264

Model of visual contrast gain control and pattern masking  

NASA Technical Reports Server (NTRS)

We have implemented a model of contrast gain and control in human vision that incorporates a number of key features, including a contrast sensitivity function, multiple oriented bandpass channels, accelerating nonlinearities, and a devisive inhibitory gain control pool. The parameters of this model have been optimized through a fit to the recent data that describe masking of a Gabor function by cosine and Gabor masks [J. M. Foley, "Human luminance pattern mechanisms: masking experiments require a new model," J. Opt. Soc. Am. A 11, 1710 (1994)]. The model achieves a good fit to the data. We also demonstrate how the concept of recruitment may accommodate a variant of this model in which excitatory and inhibitory paths have a common accelerating nonlinearity, but which include multiple channels tuned to different levels of contrast.

Watson, A. B.; Solomon, J. A.

1997-01-01

265

Optimal protocol and trajectory visualization for conformational searches of peptides and proteins.  

PubMed

Conformational searches by molecular dynamics and different types of Monte Carlo or build-up methods usually aim to find the lowest-energy conformation. However, this is often misleading, as the energy functions used in conformational calculations are imprecise. For instance, though positions of local minima defined by the repulsive part of the Lennard-Jones potential are usually altered only slightly by functional modification, the relative depths of the minima could change significantly. Thus, the purpose of conformational searches and, correspondingly, performance criteria should be reformulated and appropriate methods found to extract different local minima from the search trajectory and allow visualization in the search space. Attempts at convergence to the lowest-energy structure should be replaced with efforts to visit a maximum number of different local energy minima with energies within a certain range. We use this quantitative criterion consistently to evaluate performances of different search procedures. To utilize information generated in the course of simulation, a "stack" of low energy conformations is created and stored. It keeps track of variables and visit numbers for the best representatives of different conformational families. To visualize the search, projection of multidimensional walks onto a principal plane defined by a set of reference structures is used. With Met-enkephalin as a structural example and a Monte Carlo procedure combined with energy minimization (MCM) as a basic search method, we analyzed the influence on search efficiency of different characteristics as temperature schedules, the step size for variable modification, constrained random step and response mechanisms to search difficulties. Simulated annealing MCM had comparable efficiency with MCM at constant and elevated temperature (about 600 K). Constraining the randomized choice of side-chain chi angles to optimal values (rotamers) on every MCM step did not improve, but rather worsened, the search efficiency. Two low-energy Met-enkephalin conformations with parallel Tyr1 and Phe4 rings, a gamma-turn around the Gly2 residue, and Phe4 and Met5 side-chains forming together a compact hydrophobic cluster were found and are suggested as possible structural candidates for interaction with a receptor or a membrane. PMID:1593634

Abagyan, R; Argos, P

1992-05-20

266

Patterned-String Tasks: Relation between Fine Motor Skills and Visual-Spatial Abilities in Parrots  

PubMed Central

String-pulling and patterned-string tasks are often used to analyse perceptual and cognitive abilities in animals. In addition, the paradigm can be used to test the interrelation between visual-spatial and motor performance. Two Australian parrot species, the galah (Eolophus roseicapilla) and the cockatiel (Nymphicus hollandicus), forage on the ground, but only the galah uses its feet to manipulate food. I used a set of string pulling and patterned-string tasks to test whether usage of the feet during foraging is a prerequisite for solving the vertical string pulling problem. Indeed, the two species used techniques that clearly differed in the extent of beak-foot coordination but did not differ in terms of their success in solving the string pulling task. However, when the visual-spatial skills of the subjects were tested, the galahs outperformed the cockatiels. This supports the hypothesis that the fine motor skills needed for advanced beak-foot coordination may be interrelated with certain visual-spatial abilities needed for solving patterned-string tasks. This pattern was also found within each of the two species on the individual level: higher motor abilities positively correlated with performance in patterned-string tasks. This is the first evidence of an interrelation between visual-spatial and motor abilities in non-mammalian animals. PMID:24376885

Krasheninnikova, Anastasia

2013-01-01

267

A Visualization System for Space-Time and Multivariate Patterns (VIS-STAMP)  

PubMed Central

The research reported here integrates computational, visual, and cartographic methods to develop a geovisual analytic approach for exploring and understanding spatio-temporal and multivariate patterns. The developed methodology and tools can help analysts investigate complex patterns across multivariate, spatial, and temporal dimensions via clustering, sorting, and visualization. Specifically, the approach involves a self-organizing map, a parallel coordinate plot, several forms of reorderable matrices (including several ordering methods), a geographic small multiple display, and a 2-dimensional cartographic color design method. The coupling among these methods leverages their independent strengths and facilitates a visual exploration of patterns that are difficult to discover otherwise. The visualization system we developed supports overview of complex patterns and, through a variety of interactions, enables users to focus on specific patterns and examine detailed views. We demonstrate the system with an application to the IEEE InfoVis 2005 Contest data set, which contains time-varying, geographically referenced, and multivariate data for technology companies in the US. PMID:17073369

Guo, Diansheng; Chen, Jin; MacEachren, Alan M.; Liao, Ke

2011-01-01

268

Visual-textual joint relevance learning for tag-based social image search.  

PubMed

Due to the popularity of social media websites, extensive research efforts have been dedicated to tag-based social image search. Both visual information and tags have been investigated in the research field. However, most existing methods use tags and visual characteristics either separately or sequentially in order to estimate the relevance of images. In this paper, we propose an approach that simultaneously utilizes both visual and textual information to estimate the relevance of user tagged images. The relevance estimation is determined with a hypergraph learning approach. In this method, a social image hypergraph is constructed, where vertices represent images and hyperedges represent visual or textual terms. Learning is achieved with use of a set of pseudo-positive images, where the weights of hyperedges are updated throughout the learning process. In this way, the impact of different tags and visual words can be automatically modulated. Comparative results of the experiments conducted on a dataset including 370+images are presented, which demonstrate the effectiveness of the proposed approach. PMID:22692911

Gao, Yue; Wang, Meng; Zha, Zheng-Jun; Shen, Jialie; Li, Xuelong; Wu, Xindong

2013-01-01

269

Pattern identification or 3D visualization? How best to learn topographic map comprehension  

NASA Astrophysics Data System (ADS)

Science, Technology, Engineering, and Mathematics (STEM) experts employ many representations that novices find hard to use because they require a critical STEM skill, interpreting two-dimensional (2D) diagrams that represent three-dimensional (3D) information. The current research focuses on learning to interpret topographic maps. Understanding topographic maps requires knowledge of how to interpret the conventions of contour lines, and skill in visualizing that information in 3D (e.g. shape of the terrain). Novices find both tasks difficult. The present study compared two interventions designed to facilitate understanding for topographic maps to minimal text-only instruction. The 3D Visualization group received instruction using 3D gestures and models to help visualize three topographic forms. The Pattern Identification group received instruction using pointing and tracing gestures to help identify the contour patterns associated with the three topographic forms. The Text-based Instruction group received only written instruction explaining topographic maps. All participants then completed a measure of topographic map use. The Pattern Identification group performed better on the map use measure than participants in the Text-based Instruction group, but no significant difference was found between the 3D Visualization group and the other two groups. These results suggest that learning to identify meaningful contour patterns is an effective strategy for learning how to comprehend topographic maps. Future research should address if learning strategies for how to interpret the information represented on a diagram (e.g. identify patterns in the contour lines), before trying to visualize the information in 3D (e.g. visualize the 3D structure of the terrain), also facilitates students' comprehension of other similar types of diagrams.

Atit, Kinnari

270

Pattern electroretinogram (PERG) and pattern visual evoked potential (PVEP) in the early stages of Alzheimer’s disease  

Microsoft Academic Search

Alzheimer’s disease (AD) is one of the most common causes of dementia in the world. Patients with AD frequently complain of\\u000a vision disturbances that do not manifest as changes in routine ophthalmological examination findings. The main causes of these\\u000a disturbances are neuropathological changes in the visual cortex, although abnormalities in the retina and optic nerve cannot\\u000a be excluded. Pattern electroretinogram

Kamila Krasodomska; Wojciech Lubi?ski; Andrzej Potemkowski; Krystyna Honczarenko

2010-01-01

271

Light propagation and visual patterns: Preinstruction learners' conceptions  

NSDL National Science Digital Library

This study formed part of a project aimed at revising the instructional approach for geometrical optics in the 10th grade. The instructional intervention was based on the extensive use of a diagrammatic representation as a descriptive, explanatory, and problem-solving tool in the domain. The purpose of this study was to elicit the conceptions and representations of light propagation, image formation, and sight typical to preinstruction learners, with special attention to identifying precursors of problematic features of postinstruction students' knowledge. The premise for this study was that the difficulties students have before, during, and after traditional instruction with respect to representing optical phenomena have their origins in the fragmented prescientific knowledge constructed on the basis of experience. We believe that the difficulties persist because the key factors leading to fragmentation are not usually addressed and remedied. The main findings of the study indicate that (a) preinstruction students display some familiarity with optical systems, light propagation, and illumination patterns; (b) student-generated graphical representations describing and explaining optical phenomena display some features of formal ray tracing; (c) preinstruction students have not developed a consistent descriptive and explanatory model for light propagation; and (d) the context of sight seems to have a confounding effect on the establishment of a unified prior model for optical phenomena.

Langley, Dorothy; Eylon, Bat-Sheva; Ronen, Miky

2005-11-22

272

Serial, Covert, Shifts of Attention during Visual Search are Reflected by the Frontal Eye Fields and Correlated with Population Oscillations  

E-print Network

Attention regulates the flood of sensory information into a manageable stream, and so understanding how attention is controlled is central to understanding cognition. Competing theories suggest visual search involves serial ...

Buschman, Timothy J.

273

Pattern drilling exploration: Optimum pattern types and hole spacings when searching for elliptical shaped targets  

Microsoft Academic Search

In this study the selection of the optimum type of drilling pattern to be used when exploring for elliptical shaped targets is examined. The rhombic pattern is optimal when the targets are known to have a preferred orientation. Situations can also be found where a rectangular pattern is as efficient as the rhombic pattern. A triangular or square drilling pattern

Lawrence J. Drew

1979-01-01

274

Color names, color categories, and color-cued visual search: Sometimes, color perception is not categorical  

PubMed Central

The relation between colors and their names is a classic case-study for investigating the Sapir-Whorf hypothesis that categorical perception is imposed on perception by language. Here, we investigate the Sapir-Whorf prediction that visual search for a green target presented among blue distractors (or vice versa) should be faster than search for a green target presented among distractors of a different color of green (or for a blue target among different blue distractors). Gilbert, Regier, Kay & Ivry (2006) reported that this Sapir-Whorf effect is restricted to the right visual field (RVF), because the major brain language centers are in the left cerebral hemisphere. We found no categorical effect at the Green|Blue color boundary, and no categorical effect restricted to the RVF. Scaling of perceived color differences by Maximum Likelihood Difference Scaling (MLDS) also showed no categorical effect, including no effect specific to the RVF. Two models fit the data: a color difference model based on MLDS and a standard opponent-colors model of color discrimination based on the spectral sensitivities of the cones. Neither of these models, nor any of our data, suggested categorical perception of colors at the Green|Blue boundary, in either visual field. PMID:21980188

Brown, Angela M; Lindsey, Delwin T; Guckes, Kevin M

2011-01-01

275

On Assisting a Visual-Facial Affect Recognition System with Keyboard-Stroke Pattern Information  

NASA Astrophysics Data System (ADS)

Towards realizing a multimodal affect recognition system, we are considering the advantages of assisting a visual-facial expression recognition system with keyboard-stroke pattern information. Our work is based on the assumption that the visual-facial and keyboard modalities are complementary to each other and that their combination can significantly improve the accuracy in affective user models. Specifically, we present and discuss the development and evaluation process of two corresponding affect recognition subsystems, with emphasis on the recognition of 6 basic emotional states, namely happiness, sadness, surprise, anger and disgust as well as the emotion-less state which we refer to as neutral. We find that emotion recognition by the visual-facial modality can be aided greatly by keyboard-stroke pattern information and the combination of the two modalities can lead to better results towards building a multimodal affect recognition system.

Stathopoulou, I.-O.; Alepis, E.; Tsihrintzis, G. A.; Virvou, M.

276

Families of stationary patterns producing illusory movement: insights into the visual system  

E-print Network

Families of stationary patterns producing illusory movement: insights into the visual system CORNELIA FERM¨ULLER, ROBERT PLESS and YIANNIS ALOIMONOS Computer Vision Laboratory, Center for Automation, College Park, MD 20742-3275, USA SUMMARY A computational explanation of the illusory movement experienced

Fermüller, Cornelia

277

Visualizing and Discovering Web Navigational Patterns Jiyang Chen, Lisheng Sun, Osmar R. Zaiane, Randy Goebel  

E-print Network

Visualizing and Discovering Web Navigational Patterns Jiyang Chen, Lisheng Sun, Osmar R. Za, lisheng, zaiane, goebel}@cs.ualberta.ca ABSTRACT Web site structures are complex to analyze. Cross-referencing the web structure with navigational behaviour adds to the complexity of the analysis. However

Zaiane, Osmar R.

278

Characteristics of Empirically Derived Subgroups Based on Intelligence and Visual-Motor Score Patterns.  

ERIC Educational Resources Information Center

Cluster-analyzed results from intelligence and visual-motor measures of children (N=1,204) referred for academic and/or behavior problems. Found five subgroups with three of the five showing more dysfunctional patterns than other two. Results suggest influence of physiological/developmental factors with development of learning difficulties.…

Snow, Jeffrey H.; Desch, Larry W.

1989-01-01

279

Package Patterns for Visual Architecture Recovery Mircea Lungu and Michele Lanza  

E-print Network

patterns for real-world systems by analyzing their frequency of occur- rence in six open-source software, visualization 1. Introduction Although the architecture of a system is usually docu- mented at the time of its- tems is an important asset for many software engineering tasks such as migrations, impact analysis

Lanza, Michele

280

Spatial patterns of visual cortical fast EEG during conditioned reflex in a rhesus monkey  

Microsoft Academic Search

A preliminary assay was made of the existence of time-space coherence patterns of fast EEG activity in the visual cortex of a Rhe- sus monkey. The primary intent of the present study was to evaluate the similarities and differences in relation to the olfactorybutb. where such eoherences have been described and have been demonstrated to be associated with behaviour. Segments

Walter J. Freeman; B VANDIJK

1987-01-01

281

Nurses' Behaviors and Visual Scanning Patterns May Reduce Patient Identification Errors  

ERIC Educational Resources Information Center

Patient identification (ID) errors occurring during the medication administration process can be fatal. The aim of this study is to determine whether differences in nurses' behaviors and visual scanning patterns during the medication administration process influence their capacities to identify patient ID errors. Nurse participants (n = 20)…

Marquard, Jenna L.; Henneman, Philip L.; He, Ze; Jo, Junghee; Fisher, Donald L.; Henneman, Elizabeth A.

2011-01-01

282

Nurses' Behaviors and Visual Scanning Patterns May Reduce Patient Identification Errors  

Microsoft Academic Search

Patient identification (ID) errors occurring during the medication administration process can be fatal. The aim of this study is to determine whether differences in nurses' behaviors and visual scanning patterns during the medication administration process influence their capacities to identify patient ID errors. Nurse participants (n = 20) administered medications to 3 patients in a simulated clinical setting, with 1

Jenna L. Marquard; Philip L. Henneman; Ze He; Junghee Jo; Donald L. Fisher; Elizabeth A. Henneman

2011-01-01

283

The Pattern of Ocular Dominance Columns in Macaque Visual Cortex Revealed by a Reduced Silver Stain  

E-print Network

The Pattern of Ocular Dominance Columns in Macaque Visual Cortex Revealed by a Reduced Silver Stain- face, were seen in tangential sections stained with a reduced silver method for normal fibers and were fixed, sectioned tangentially and stained with the silver method. All the lesions- a total of 12 -fell

Hubel, David

284

Action Patterns for the Incremental Specification of the Execution Semantics of Visual Languages  

Microsoft Academic Search

We present a new approach - based on graph transformation - to incremental specification of the operational (execution) semantics of visual languages. The approach combines editing rules with two meta-models: one to define the concrete syntax and one for the static semantics. We introduce the notion of action patterns, defining basic actions (e.g. consuming or producing a token in transition-based

Paolo Bottoni; Juan de Lara; E. Guerra

2007-01-01

285

Pattern electroretinogram and visual evoked potential amplitudes are influenced by different stimulus field sizes and scotomata  

Microsoft Academic Search

The pattern electroretinogram and the visual evoked potential were recorded simultaneously with various stimulus fields and artificial scotomata of increasing sizes. In contrast to an earlier study, a smaller check size (20') and two stimulus field sizes (20° × 20° and 10° × 10°) for the scotomata were used. With a concentric decreasing stimulus field, a reduction of both the

Armin Junghardt; Hannes Wildberger; Yves Robert; Bela Török

1993-01-01

286

STATIONARY PATTERN ADAPTATION AND THE EARLY COMPONENTS IN HUMAN VISUAL EVOKED POTENTIALS  

EPA Science Inventory

Pattern-onset visual evoked potentials were elicited from humans by sinusoidal gratings of 0.5., 1, 2 and 4 cpd (cycles/degree) following adaptation to a blank field or one of the gratings. The wave forms recorded after blank field adaptation showed an early positive component, P...

287

Experimental analysis and visualization of spatiotemporal patterns in spouted fluidized beds  

E-print Network

Experimental analysis and visualization of spatiotemporal patterns in spouted fluidized beds data of the spouting regime in a two-dimensional fluidized bed is presented. The aspect ratio revealed that the hy- drodynamics of fluidized beds exhibit many features as- sociated with low

288

The impact of clinical indications on visual search behaviour in skeletal radiographs  

NASA Astrophysics Data System (ADS)

The hazards associated with ionizing radiation have been documented in the literature and therefore justifying the need for X-ray examinations has come to the forefront of the radiation safety debate in recent years1. International legislation states that the referrer is responsible for the provision of sufficient clinical information to enable the justification of the medical exposure. Clinical indications are a set of systematically developed statements to assist in accurate diagnosis and appropriate patient management2. In this study, the impact of clinical indications upon fracture detection for musculoskeletal radiographs is analyzed. A group of radiographers (n=6) interpreted musculoskeletal radiology cases (n=33) with and without clinical indications. Radiographic images were selected to represent common trauma presentations of extremities and pelvis. Detection of the fracture was measured using ROC methodology. An eyetracking device was employed to record radiographers search behavior by analysing distinct fixation points and search patterns, resulting in a greater level of insight and understanding into the influence of clinical indications on observers' interpretation of radiographs. The influence of clinical information on fracture detection and search patterns was assessed. Findings of this study demonstrate that the inclusion of clinical indications result in impressionable search behavior. Differences in eye tracking parameters were also noted. This study also attempts to uncover fundamental observer search strategies and behavior with and without clinical indications, thus providing a greater understanding and insight into the image interpretation process. Results of this study suggest that availability of adequate clinical data should be emphasized for interpreting trauma radiographs.

Rutledge, A.; McEntee, M. F.; Rainford, L.; O'Grady, M.; McCarthy, K.; Butler, M. L.

2011-03-01

289

Searching for Truth: Internet Search Patterns as a Method of Investigating Online Responses to a Russian Illicit Drug Policy Debate  

PubMed Central

Background This is a methodological study investigating the online responses to a national debate over an important health and social problem in Russia. Russia is the largest Internet market in Europe, exceeding Germany in the absolute number of users. However, Russia is unusual in that the main search provider is not Google, but Yandex. Objective This study had two main objectives. First, to validate Yandex search patterns against those provided by Google, and second, to test this method's adequacy for investigating online interest in a 2010 national debate over Russian illicit drug policy. We hoped to learn what search patterns and specific search terms could reveal about the relative importance and geographic distribution of interest in this debate. Methods A national drug debate, centering on the anti-drug campaigner Egor Bychkov, was one of the main Russian domestic news events of 2010. Public interest in this episode was accompanied by increased Internet search. First, we measured the search patterns for 13 search terms related to the Bychkov episode and concurrent domestic events by extracting data from Google Insights for Search (GIFS) and Yandex WordStat (YaW). We conducted Spearman Rank Correlation of GIFS and YaW search data series. Second, we coded all 420 primary posts from Bychkov's personal blog between March 2010 and March 2012 to identify the main themes. Third, we compared GIFS and Yandex policies concerning the public release of search volume data. Finally, we established the relationship between salient drug issues and the Bychkov episode. Results We found a consistent pattern of strong to moderate positive correlations between Google and Yandex for the terms "Egor Bychkov" (r s = 0.88, P < .001), “Bychkov” (r s = .78, P < .001) and “Khimki”(r s = 0.92, P < .001). Peak search volumes for the Bychkov episode were comparable to other prominent domestic political events during 2010. Monthly search counts were 146,689 for “Bychkov” and 48,084 for “Egor Bychkov”, compared to 53,403 for “Khimki” in Yandex. We found Google potentially provides timely search results, whereas Yandex provides more accurate geographic localization. The correlation was moderate to strong between search terms representing the Bychkov episode and terms representing salient drug issues in Yandex–“illicit drug treatment” (r s = .90, P < .001), "illicit drugs" (r s = .76, P < .001), and "drug addiction" (r s = .74, P < .001). Google correlations were weaker or absent–"illicit drug treatment" (r s = .12, P = .58), “illicit drugs ” (r s = -0.29, P = .17), and "drug addiction" (r s = .68, P < .001). Conclusions This study contributes to the methodological literature on the analysis of search patterns for public health. This paper investigated the relationship between Google and Yandex, and contributed to the broader methods literature by highlighting both the potential and limitations of these two search providers. We believe that Yandex Wordstat is a potentially valuable, and underused data source for researchers working on Russian-related illicit drug policy and other public health problems. The Russian Federation, with its large, geographically dispersed, and politically engaged online population presents unique opportunities for studying the evolving influence of the Internet on politics and policy, using low cost methods resilient against potential increases in censorship. PMID:23238600

Gillespie, James A; Quinn, Casey

2012-01-01

290

Visual constraints in foraging bumblebees: flower size and color affect search time and flight behavior.  

PubMed

In optimal foraging theory, search time is a key variable defining the value of a prey type. But the sensory-perceptual processes that constrain the search for food have rarely been considered. Here we evaluate the flight behavior of bumblebees (Bombus terrestris) searching for artificial flowers of various sizes and colors. When flowers were large, search times correlated well with the color contrast of the targets with their green foliage-type background, as predicted by a model of color opponent coding using inputs from the bees' UV, blue, and green receptors. Targets that made poor color contrast with their backdrop, such as white, UV-reflecting ones, or red flowers, took longest to detect, even though brightness contrast with the background was pronounced. When searching for small targets, bees changed their strategy in several ways. They flew significantly slower and closer to the ground, so increasing the minimum detectable area subtended by an object on the ground. In addition, they used a different neuronal channel for flower detection. Instead of color contrast, they used only the green receptor signal for detection. We relate these findings to temporal and spatial limitations of different neuronal channels involved in stimulus detection and recognition. Thus, foraging speed may not be limited only by factors such as prey density, flight energetics, and scramble competition. Our results show that understanding the behavioral ecology of foraging can substantially gain from knowledge about mechanisms of visual information processing. PMID:11259668

Spaethe, J; Tautz, J; Chittka, L

2001-03-27

291

Color Channels, Not Color Appearance or Color Categories, Guide Visual Search for Desaturated Color Targets  

PubMed Central

In this article, we report that in visual search, desaturated reddish targets are much easier to find than other desaturated targets, even when perceptual differences between targets and distractors are carefully equated. Observers searched for desaturated targets among mixtures of white and saturated distractors. Reaction times were hundreds of milliseconds faster for the most effective (reddish) targets than for the least effective (purplish) targets. The advantage for desaturated reds did not reflect an advantage for the lexical category “pink,” because reaction times did not follow named color categories. Many pink stimuli were not found quickly, and many quickly found stimuli were not labeled “pink.” Other possible explanations (e.g., linear-separability effects) also failed. Instead, we propose that guidance of visual search for desaturated colors is based on a combination of low-level color-opponent signals that is different from the combinations that produce perceived color. We speculate that this guidance might reflect a specialization for human skin. PMID:20713637

Lindsey, Delwin T.; Brown, Angela M.; Reijnen, Ester; Rich, Anina N.; Kuzmova, Yoana I.; Wolfe, Jeremy M.

2011-01-01

292

User-assisted visual search and tracking across distributed multi-camera networks  

NASA Astrophysics Data System (ADS)

Human CCTV operators face several challenges in their task which can lead to missed events, people or associations, including: (a) data overload in large distributed multi-camera environments; (b) short attention span; (c) limited knowledge of what to look for; and (d) lack of access to non-visual contextual intelligence to aid search. Developing a system to aid human operators and alleviate such burdens requires addressing the problem of automatic re-identification of people across disjoint camera views, a matching task made difficult by factors such as lighting, viewpoint and pose changes and for which absolute scoring approaches are not best suited. Accordingly, we describe a distributed multi-camera tracking (MCT) system to visually aid human operators in associating people and objects effectively over multiple disjoint camera views in a large public space. The system comprises three key novel components: (1) relative measures of ranking rather than absolute scoring to learn the best features for matching; (2) multi-camera behaviour profiling as higher-level knowledge to reduce the search space and increase the chance of finding correct matches; and (3) human-assisted data mining to interactively guide search and in the process recover missing detections and discover previously unknown associations. We provide an extensive evaluation of the greater effectiveness of the system as compared to existing approaches on industry-standard i-LIDS multi-camera data.

Raja, Yogesh; Gong, Shaogang; Xiang, Tao

2011-11-01

293

Parietal substrates for dimensional effects in visual search: evidence from lesion-symptom mapping.  

PubMed

In visual search, the detection of pop-out targets is facilitated when the target-defining dimension remains the same compared with when it changes across trials. We tested the brain regions necessary for these dimensional carry-over effects using a voxel-based morphometry study with brain-lesioned patients. Participants had to search for targets defined by either their colour (red or blue) or orientation (right- or left-tilted), and the target dimension either stayed the same or changed on consecutive trials. Twenty-five patients were categorized according to whether they showed an effect of dimensional change on search or not. The two groups did not differ with regard to their performance on several working memory tasks, and the dimensional carry-over effects were not correlated with working memory performance. With spatial, sustained attention and working memory deficits as well as lesion volume controlled, damage within the right inferior parietal lobule (the angular and supramarginal gyri) extending into the intraparietal sulcus was associated with an absence of dimensional carry-over (P < 0.001, cluster-level corrected for multiple comparisons). The data suggest that these regions of parietal cortex are necessary to implement attention shifting in the context of visual dimensional change. PMID:23404335

Utz, Sandra; Humphreys, Glyn W; Chechlacz, Magdalena

2013-03-01

294

Revisiting Levy flight search patterns of wandering albatrosses, bumblebees and deer  

E-print Network

LETTERS Revisiting Le´vy flight search patterns of wandering albatrosses, bumblebees and deer about the search strategies of deer10 and bumblebees10 . These pioneering studies have triggered much weights19,20 . We apply this to the four original deer and bumblebee data sets10 , finding that none

Stanley, H. Eugene

295

Price Information Patterns in Web Search Advertising: An Empirical Case Study on Accommodation Industry  

E-print Network

Price Information Patterns in Web Search Advertising: An Empirical Case Study on Accommodation--Unlike advertising in traditional media, web search advertising content can be easily customized with little cost to the accommodation industry to empirically investigate how advertisers customize price information in their web

Pei, Jian

296

Optimization of boiling water reactor control rod patterns using linear search  

SciTech Connect

A computer program for searching the optimal control rod pattern has been developed. The program is able to find a control rod pattern where the resulting power distribution is optimal in the sense that it is the closest to the desired power distribution, and it satisfies all operational constraints. The search procedure consists of iterative uses of two steps: sensitivity analyses of local power and thermal margins using a three-dimensional reactor simulator for a simplified prediction model; linear search for the optimal control rod pattern with the simplified model. The optimal control rod pattern is found along the direction where the performance index gradient is the steepest. This program has been verified to find the optimal control rod pattern through simulations using operational data from the Oyster Creek Reactor.

Kiguchi, T.; Doi, K.; Fikuzaki, T.; Frogner, B.; Lin, C.; Long, A.B.

1984-10-01

297

Visual Signals Vertically Extend the Perceptual Span in Searching a Text: A Gaze-Contingent Window Study  

ERIC Educational Resources Information Center

This study investigated the effect of visual signals on perceptual span in text search and the kinds of signal information that facilitate the search. Participants were asked to find answers to specific questions in chapter-length texts in either a normal or a window condition, where the text disappeared beyond a vertical 3 degrees gaze-contingent…

Cauchard, Fabrice; Eyrolle, Helene; Cellier, Jean-Marie; Hyona, Jukka

2010-01-01

298

Errors in low prevalence visual search: Easy to produce,hard to cure Brigham and Women's Hospital  

E-print Network

Errors in low prevalence visual search: Easy to produce,hard to cure Brigham and Women's Hospital 1 V E R I TAS Harvard Medical School2 1 1,2 1 1,2 Michael J.Van Wert, Todd S.Horowitz, Skyler S 1 Experiment 2 Many socially important search tasks (e.g.,medical screening and airport security

299

On the origin of event-related potentials indexing covert attentional selection during visual search.  

PubMed

Despite nearly a century of electrophysiological studies recording extracranially from humans and intracranially from monkeys, the neural generators of nearly all human event-related potentials (ERPs) have not been definitively localized. We recorded an attention-related ERP component, known as the N2pc, simultaneously with intracranial spikes and local field potentials (LFPs) in macaques to test the hypothesis that an attentional-control structure, the frontal eye field (FEF), contributed to the generation of the macaque homologue of the N2pc (m-N2pc). While macaques performed a difficult visual search task, the search target was selected earliest by spikes from single FEF neurons, later by FEF LFPs, and latest by the m-N2pc. This neurochronometric comparison provides an empirical bridge connecting macaque and human experiments and a step toward localizing the neural generator of this important attention-related ERP component. PMID:19675287

Cohen, Jeremiah Y; Heitz, Richard P; Schall, Jeffrey D; Woodman, Geoffrey F

2009-10-01

300

Pattern of neuronal activity associated with conscious and unconscious processing of visual signals.  

PubMed

Following striate cortex damage in monkeys and humans there can be residual function mediated by parallel visual pathways. In humans this can sometimes be associated with a "feeling" that something has happened, especially with rapid movement or abrupt onset. For less transient events, discriminative performance may still be well above chance even when the subject reports no conscious awareness of the stimulus. In a previous study we examined parameters that yield good residual visual performance in the "blind" hemifield of a subject with unilateral damage to the primary visual cortex. With appropriate parameters we demonstrated good discriminative performance, both with and without conscious awareness of a visual event. These observations raise the possibility of imaging the brain activity generated in the "aware" and the "unaware" modes, with matched levels of discrimination performance, and hence of revealing patterns of brain activation associated with visual awareness. The intact hemifield also allows a comparison with normal vision. Here we report the results of a functional magnetic resonance imaging study on the same subject carried out under aware and unaware stimulus conditions. The results point to a shift in the pattern of activity from neocortex in the aware mode, to subcortical structures in the unaware mode. In the aware mode prestriate and dorsolateral prefrontal cortices (area 46) are active. In the unaware mode the superior colliculus is active, together with medial and orbital prefrontal cortical sites. PMID:9256495

Sahraie, A; Weiskrantz, L; Barbur, J L; Simmons, A; Williams, S C; Brammer, M J

1997-08-19

301

Maximizing over Multiple Pattern Databases Speeds up Heuristic Search  

E-print Network

multiple pattern databases. For example, the heuristic function used to solve Rubik's Cube in [17 various Preprint submitted to Elsevier Science 29 August 2006 #12;combinatorial puzzles such as Rubik's Cube [17], the sliding tile puzzles [6,19] and the 4-peg Towers of Hanoi problem [6,7] to be solved

Holte, Robert

302

A little bit of history repeating: Splitting up multiple-target visual searches decreases second-target miss errors.  

PubMed

Visual searches with several targets in a display have been shown to be particularly prone to miss errors in both academic laboratory searches and professional searches such as radiology and baggage screening. Specifically, finding 1 target in a display can reduce the likelihood of detecting additional targets. This phenomenon was originally referred to as "satisfaction of search," but is referred to here as "subsequent search misses" (SSMs). SSM errors have been linked to a variety of causes, and recent evidence supports a working memory deficit wherein finding a target consumes working memory resources that would otherwise aid subsequent search for additional targets (Cain & Mitroff, 2013). The current study demonstrated that dividing 1 multiple-target search into several single-target searches, separated by three to five unrelated trials, effectively freed the working memory resources used by the found target and eliminated SSM errors. This effect was demonstrated with both university community participants and with professional visual searchers from the Transportation Security Administration, suggesting it may be a generally applicable technique for improving multiple-target visual search accuracy. PMID:24708353

Cain, Matthew S; Biggs, Adam T; Darling, Elise F; Mitroff, Stephen R

2014-06-01

303

Intelligent technique to search for patterns within images in massive databases  

SciTech Connect

An image retrieval system for JET has been developed. The image database contains the images of the JET high speed visible camera. The system input is a pattern selected inside an image and the output is the group of frames (defined by their discharge numbers and time slices) that show patterns similar to the selected one. This approach is based on morphological pattern recognition and it should be emphasized that the pattern is found independently of its location in the frame. The technique encodes images into characters and, therefore, it transforms the pattern search into a character-matching problem.

Vega, J.; Murari, A.; Pereira, A.; Portas, A.; Castro, P. [JET-EFDA, Culham Science Center, OX14 3DB Abingdon (United Kingdom)

2008-10-15

304

Searching for patterns in remote sensing image databases using neural networks  

NASA Technical Reports Server (NTRS)

We have investigated a method, based on a successful neural network multispectral image classification system, of searching for single patterns in remote sensing databases. While defining the pattern to search for and the feature to be used for that search (spectral, spatial, temporal, etc.) is challenging, a more difficult task is selecting competing patterns to train against the desired pattern. Schemes for competing pattern selection, including random selection and human interpreted selection, are discussed in the context of an example detection of dense urban areas in Landsat Thematic Mapper imagery. When applying the search to multiple images, a simple normalization method can alleviate the problem of inconsistent image calibration. Another potential problem, that of highly compressed data, was found to have a minimal effect on the ability to detect the desired pattern. The neural network algorithm has been implemented using the PVM (Parallel Virtual Machine) library and nearly-optimal speedups have been obtained that help alleviate the long process of searching through imagery.

Paola, Justin D.; Schowengerdt, Robert A.

1995-01-01

305

Mining patterns in persistent surveillance systems with smart query and visual analytics  

NASA Astrophysics Data System (ADS)

In Persistent Surveillance Systems (PSS) the ability to detect and characterize events geospatially help take pre-emptive steps to counter adversary's actions. Interactive Visual Analytic (VA) model offers this platform for pattern investigation and reasoning to comprehend and/or predict such occurrences. The need for identifying and offsetting these threats requires collecting information from diverse sources, which brings with it increasingly abstract data. These abstract semantic data have a degree of inherent uncertainty and imprecision, and require a method for their filtration before being processed further. In this paper, we have introduced an approach based on Vector Space Modeling (VSM) technique for classification of spatiotemporal sequential patterns of group activities. The feature vectors consist of an array of attributes extracted from generated sensors semantic annotated messages. To facilitate proper similarity matching and detection of time-varying spatiotemporal patterns, a Temporal-Dynamic Time Warping (DTW) method with Gaussian Mixture Model (GMM) for Expectation Maximization (EM) is introduced. DTW is intended for detection of event patterns from neighborhood-proximity semantic frames derived from established ontology. GMM with EM, on the other hand, is employed as a Bayesian probabilistic model to estimated probability of events associated with a detected spatiotemporal pattern. In this paper, we present a new visual analytic tool for testing and evaluation group activities detected under this control scheme. Experimental results demonstrate the effectiveness of proposed approach for discovery and matching of subsequences within sequentially generated patterns space of our experiments.

Habibi, Mohammad S.; Shirkhodaie, Amir

2013-05-01

306

Temporal relationships between eye fixations and manual reactions in visual search.  

PubMed

Observers freely searched for, and manually responded to, the presence of a target in multistimulus displays. The stimuli were presented on a cinema screen such that each display subtended a large visual angle to encourage the use of eye movements. Times taken to initially fixate the target (T1Fs) were compared to manual response times (MRTs). The results of two experiments were qualitatively similar, despite different levels of difficulty between them. MRTs were a linear function of T1Fs, but only when fixations did not occur very early after the onset of the stimulus display. When fixations were made very soon after the onset of the display, T1Fs were independent of MRTs. The findings were described within the framework of a one-way synchronization model which was modified to accommodate attention effects in visual search. Finally, the methodology provides a novel means of quantifying the contributions of eye movements to manual acknowledgements in real-world vision-guided tasks. PMID:10100456

Greene, H H

1999-03-01

307

Geometrical illusions and the response of neurones in the cat's visual cortex to angle patterns  

PubMed Central

1. This report describes the responses of thirty-six single neurones in the primary visual area of the cat's neurologically isolated and unanaesthetized forebrain, to movements of thin white lines across the visual field. The experiments were designed to record the effects upon the response to a single test line of an added line, which was either parallel to the test line or joined it, making an angle-pattern of 30°. Unit responses were measured in terms of the peak probability of firing derived from a post-stimulus histogram. 2. All of the cortical neurones tested exhibited a preferred orientation for stimulation by the test line, i.e. an orientation of the line which produced a maximal response when the line passed through the centre of the unit's receptive field. 3. There was no evidence that the orientation of a single test line preferred by cortical neurones was different from that preferred by the same cell when excited by an angle pattern, one arm of which was the original test line. 4. The position of a test line (with preferred orientation) in the visual field that produced a maximal response from cortical neurones, was not always the same as the position for maximal response, when a second line was added to make either an angle pattern or to make a pattern of two parallel lines. 5. Where the two lines of these patterns were close together and separated by less than the radius of the receptive field, the position for maximal response to the test line was shifted towards the added line. Where the two lines were further apart than this but separated by less than a receptive field diameter, the optimal position for the test line was displaced away from the added line. 6. Some evidence was found of a lateral inhibition in the visual system, sufficient to account for the displacements described in paragraphs 4 and 5 above. 7. It is concluded that the tip of an angle pattern of 30° produces a distorted cortical image within the primary visual area. 8. This neural distortion of sensory information seems adequate to explain the well known illusions of orientation that are associated with human perception of patterns containing acute angles. PMID:5102531

Burns, B. Delisle; Pritchard, Roy

1971-01-01

308

Comparison of visualized turbine endwall secondary flows and measured heat transfer patterns  

NASA Technical Reports Server (NTRS)

Various flow visualization techniques were used to define the seondary flows near the endwall in a large heat transfer data. A comparison of the visualized flow patterns and the measured Stanton number distribution was made for cases where the inlet Reynolds number and exit Mach number were matched. Flows were visualized by using neutrally buoyant helium-filled soap bubbles, by using smoke from oil soaked cigars, and by a few techniques using permanent marker pen ink dots and synthetic wintergreen oil. Details of the horseshoe vortex and secondary flows can be directly compared with heat transfer distribution. Near the cascade entrance there is an obvious correlation between the two sets of data, but well into the passage the effect of secondary flow is not as obvious. Previously announced in STAR as N83-14435

Gaugler, R. E.; Russell, L. M.

1984-01-01

309

Comparison of visualized turbine endwall secondary flows and measured heat transfer patterns  

NASA Technical Reports Server (NTRS)

Various flow visualization techniques were used to define the secondary flows near the endwall in a large heat transfer data. A comparison of the visualized flow patterns and the measured Stanton number distribution was made for cases where the inlet Reynolds number and exit Mach number were matched. Flows were visualized by using neutrally buoyant helium-filled soap bubbles, by using smoke from oil soaked cigars, and by a few techniques using permanent marker pen ink dots and synthetic wintergreen oil. Details of the horseshoe vortex and secondary flows can be directly compared with heat transfer distribution. Near the cascade entrance there is an obvious correlation between the two sets of data, but well into the passage the effect of secondary flow is not as obvious.

Gaugler, R. E.; Russell, L. M.

1983-01-01

310

Serial, covert shifts of attention during visual search are reflected by the frontal eye fields and correlated with population oscillations.  

PubMed

Attention regulates the flood of sensory information into a manageable stream, and so understanding how attention is controlled is central to understanding cognition. Competing theories suggest visual search involves serial and/or parallel allocation of attention, but there is little direct, neural evidence for either mechanism. Two monkeys were trained to covertly search an array for a target stimulus under visual search (endogenous) and pop-out (exogenous) conditions. Here, we present neural evidence in the frontal eye fields (FEF) for serial, covert shifts of attention during search but not pop-out. Furthermore, attention shifts reflected in FEF spiking activity were correlated with 18-34 Hz oscillations in the local field potential, suggesting a "clocking" signal. This provides direct neural evidence that primates can spontaneously adopt a serial search strategy and that these serial covert shifts of attention are directed by the FEF. It also suggests that neuron population oscillations may regulate the timing of cognitive processing. PMID:19679077

Buschman, Timothy J; Miller, Earl K

2009-08-13

311

Serial, Covert, Shifts of Attention during Visual Search are Reflected by the Frontal Eye Fields and Correlated with Population Oscillations  

PubMed Central

Attention regulates the flood of sensory information into a manageable stream, and so understanding how attention is controlled is central to understanding cognition. Competing theories suggest visual search involves serial and/or parallel allocation of attention, but there is little direct, neural, evidence for either mechanism. Two monkeys were trained to covertly search an array for a target stimulus under visual search (endogenous) and pop-out (exogenous) conditions. Here we present neural evidence in the frontal eye fields (FEF) for serial, covert shifts of attention during search but not pop-out. Furthermore, attention shifts reflected in FEF spiking activity were correlated with 18–34 Hz oscillations in the local field potential, suggesting a ‘clocking’ signal. This provides direct neural evidence that primates can spontaneously adopt a serial search strategy and that these serial covert shifts of attention are directed by the FEF. It also suggests that neuron population oscillations may regulate the timing of cognitive processing. PMID:19679077

Buschman, Timothy J.; Miller, Earl K.

2009-01-01

312

Neurophysiological correlates of relatively enhanced local visual search in autistic adolescents  

PubMed Central

Previous studies found normal or even superior performance of autistic patients on visuospatial tasks requiring local search, like the Embedded Figures Task (EFT). A well-known interpretation of this is “weak central coherence”, i.e. autistic patients may show a reduced general ability to process information in its context and may therefore have a tendency to favour local over global aspects of information processing. An alternative view is that the local processing advantage in the EFT may result from a relative amplification of early perceptual processes which boosts processing of local stimulus properties but does not affect processing of global context. This study used functional magnetic resonance imaging (fMRI) in 12 autistic adolescents (9 Asperger and 3 high-functioning autistic patients) and 12 matched controls to help distinguish, on neurophysiological grounds, between these two accounts of EFT performance in autistic patients. Behaviourally, we found autistic individuals to be unimpaired during the EFT while they were significantly worse at performing a closely matched control task with minimal local search requirements. The fMRI results showed that activations specific for the local search aspects of the EFT were left-lateralised in parietal and premotor areas for the control group (as previously demonstrated for adults), whereas for the patients these activations were found in right primary visual cortex and bilateral extrastriate areas. These results suggest that enhanced local processing in early visual areas, as opposed to impaired processing of global context, is characteristic for performance of the EFT by autistic patients. PMID:17240169

Manjaly, Zina M.; Bruning, Nicole; Neufang, Susanne; Stephan, Klaas E.; Brieber, Sarah; Marshall, John C.; Kamp-Becker, Inge; Remschmidt, Helmut; Herpertz-Dahlmann, Beate; Konrad, Kerstin; Fink, Gereon R.

2007-01-01

313

Neural basis for priming of pop-out during visual search revealed with fMRI.  

PubMed

Maljkovic and Nakayama first showed that visual search efficiency can be influenced by priming effects. Even "pop-out" targets (defined by unique color) are judged quicker if they appear at the same location and/or in the same color as on the preceding trial, in an unpredictable sequence. Here, we studied the potential neural correlates of such priming in human visual search using functional magnetic resonance imaging (fMRI). We found that repeating either the location or the color of a singleton target led to repetition suppression of blood oxygen level-dependent (BOLD) activity in brain regions traditionally linked with attentional control, including bilateral intraparietal sulci. This indicates that the attention system of the human brain can be "primed," in apparent analogy to repetition-suppression effects on activity in other neural systems. For repetition of target color but not location, we also found repetition suppression in inferior temporal areas that may be associated with color processing, whereas repetition of target location led to greater reduction of activation in contralateral inferior parietal and frontal areas, relative to color repetition. The frontal eye fields were also implicated, notably when both target properties (color and location) were repeated together, which also led to further BOLD decreases in anterior fusiform cortex not seen when either property was repeated alone. These findings reveal the neural correlates for priming of pop-out search, including commonalities, differences, and interactions between location and color repetition. fMRI repetition-suppression effects may arise in components of the attention network because these settle into a stable "attractor state" more readily when the same target property is repeated than when a different attentional state is required. PMID:16959868

Kristjánsson, Arni; Vuilleumier, Patrik; Schwartz, Sophie; Macaluso, Emiliano; Driver, Jon

2007-07-01

314

Giant honeybees ( Apis dorsata) mob wasps away from the nest by directed visual patterns  

NASA Astrophysics Data System (ADS)

The open nesting behaviour of giant honeybees ( Apis dorsata) accounts for the evolution of a series of defence strategies to protect the colonies from predation. In particular, the concerted action of shimmering behaviour is known to effectively confuse and repel predators. In shimmering, bees on the nest surface flip their abdomens in a highly coordinated manner to generate Mexican wave-like patterns. The paper documents a further-going capacity of this kind of collective defence: the visual patterns of shimmering waves align regarding their directional characteristics with the projected flight manoeuvres of the wasps when preying in front of the bees' nest. The honeybees take here advantage of a threefold asymmetry intrinsic to the prey-predator interaction: (a) the visual patterns of shimmering turn faster than the wasps on their flight path, (b) they "follow" the wasps more persistently (up to 100 ms) than the wasps "follow" the shimmering patterns (up to 40 ms) and (c) the shimmering patterns align with the wasps' flight in all directions at the same strength, whereas the wasps have some preference for horizontal correspondence. The findings give evidence that shimmering honeybees utilize directional alignment to enforce their repelling power against preying wasps. This phenomenon can be identified as predator driving which is generally associated with mobbing behaviour (particularly known in selfish herds of vertebrate species), which is, until now, not reported in insects.

Kastberger, Gerald; Weihmann, Frank; Zierler, Martina; Hötzl, Thomas

2014-11-01

315

Giant honeybees (Apis dorsata) mob wasps away from the nest by directed visual patterns  

NASA Astrophysics Data System (ADS)

The open nesting behaviour of giant honeybees (Apis dorsata) accounts for the evolution of a series of defence strategies to protect the colonies from predation. In particular, the concerted action of shimmering behaviour is known to effectively confuse and repel predators. In shimmering, bees on the nest surface flip their abdomens in a highly coordinated manner to generate Mexican wave-like patterns. The paper documents a further-going capacity of this kind of collective defence: the visual patterns of shimmering waves align regarding their directional characteristics with the projected flight manoeuvres of the wasps when preying in front of the bees' nest. The honeybees take here advantage of a threefold asymmetry intrinsic to the prey-predator interaction: (a) the visual patterns of shimmering turn faster than the wasps on their flight path, (b) they "follow" the wasps more persistently (up to 100 ms) than the wasps "follow" the shimmering patterns (up to 40 ms) and (c) the shimmering patterns align with the wasps' flight in all directions at the same strength, whereas the wasps have some preference for horizontal correspondence. The findings give evidence that shimmering honeybees utilize directional alignment to enforce their repelling power against preying wasps. This phenomenon can be identified as predator driving which is generally associated with mobbing behaviour (particularly known in selfish herds of vertebrate species), which is, until now, not reported in insects.

Kastberger, Gerald; Weihmann, Frank; Zierler, Martina; Hötzl, Thomas

2014-08-01

316

Giant honeybees (Apis dorsata) mob wasps away from the nest by directed visual patterns.  

PubMed

The open nesting behaviour of giant honeybees (Apis dorsata) accounts for the evolution of a series of defence strategies to protect the colonies from predation. In particular, the concerted action of shimmering behaviour is known to effectively confuse and repel predators. In shimmering, bees on the nest surface flip their abdomens in a highly coordinated manner to generate Mexican wave-like patterns. The paper documents a further-going capacity of this kind of collective defence: the visual patterns of shimmering waves align regarding their directional characteristics with the projected flight manoeuvres of the wasps when preying in front of the bees' nest. The honeybees take here advantage of a threefold asymmetry intrinsic to the prey-predator interaction: (a) the visual patterns of shimmering turn faster than the wasps on their flight path, (b) they "follow" the wasps more persistently (up to 100 ms) than the wasps "follow" the shimmering patterns (up to 40 ms) and (c) the shimmering patterns align with the wasps' flight in all directions at the same strength, whereas the wasps have some preference for horizontal correspondence. The findings give evidence that shimmering honeybees utilize directional alignment to enforce their repelling power against preying wasps. This phenomenon can be identified as predator driving which is generally associated with mobbing behaviour (particularly known in selfish herds of vertebrate species), which is, until now, not reported in insects. PMID:25169944

Kastberger, Gerald; Weihmann, Frank; Zierler, Martina; Hötzl, Thomas

2014-11-01

317

3D pattern of brain abnormalities in Williams syndrome visualized using tensor-based morphometry  

Microsoft Academic Search

Williams syndrome (WS) is a neurodevelopmental disorder associated with deletion of ?20 contiguous genes in chromosome band 7q11.23. Individuals with WS exhibit mild to moderate mental retardation, but are relatively more proficient in specific language and musical abilities. We used tensor-based morphometry (TBM) to visualize the complex pattern of gray\\/white matter reductions in WS, based on fluid registration of structural

Ming-Chang Chiang; Allan L. Reiss; Agatha D. Lee; Ursula Bellugi; Albert M. Galaburda; Julie R. Korenberg; Debra L. Mills; Arthur W. Toga; Paul M. Thompson

2007-01-01

318

Using space-time visual analytic methods for exploring the dynamics of ethnic groups' residential patterns  

Microsoft Academic Search

In this article, we present a methodological framework, based on georeferenced house-level socio-demographic and infrastructure data, for investigating minority (or ethnic) group residential pattern dynamics in cities. This methodology, which uses visual analytical tools, is meant to help researchers examine how local land-use configurations shape minorities' residential dynamics and, thereby, affect the level of minority–majority segregation. This methodology responds to

Itzhak Omer; Peter Bak; Tobias Schreck

2010-01-01

319

Incidental learning speeds visual search by lowering response thresholds, not by improving efficiency: Evidence from eye movements  

PubMed Central

When observers search for a target object, they incidentally learn the identities and locations of “background” objects in the same display. This learning can facilitate search performance, eliciting faster reaction times for repeated displays (Hout & Goldinger, 2010). Despite these findings, visual search has been successfully modeled using architectures that maintain no history of attentional deployments; they are amnesic (e.g., Guided Search Theory; Wolfe, 2007). In the current study, we asked two questions: 1) under what conditions does such incidental learning occur? And 2) what does viewing behavior reveal about the efficiency of attentional deployments over time? In two experiments, we tracked eye movements during repeated visual search, and we tested incidental memory for repeated non-target objects. Across conditions, the consistency of search sets and spatial layouts were manipulated to assess their respective contributions to learning. Using viewing behavior, we contrasted three potential accounts for faster searching with experience. The results indicate that learning does not result in faster object identification or greater search efficiency. Instead, familiar search arrays appear to allow faster resolution of search decisions, whether targets are present or absent. PMID:21574743

Hout, Michael C.; Goldinger, Stephen D.

2011-01-01

320

The role of within-dimension singleton priming in visual search.  

PubMed

The authors report a newly identified intertrial priming phenomenon, within-dimension singleton priming, by which search for a target that happens to be a singleton on the current trial is faster when the target on the previous trial had also been a singleton on the same dimension rather than a nonsingleton. This effect was replicated in 6 experiments with different procedures, with singletons on various dimensions, when the featural contrast defining the singleton remained the same or changed within a dimension from one trial to the next, and when the target was a singleton on a target-defining dimension or on an irrelevant dimension. These findings cannot be explained by previously demonstrated intertrial repetition effects such as dimension-specific priming or priming of pop-out. Theoretical implications of the within-dimension singleton priming phenomenon are discussed relative to the dimension-weighting hypothesis, the role of stimulus-driven salience in feature-guided search, and the roles of intertrial priming and goal-directed factors in visual search. PMID:18377170

Lamy, Dominique; Bar-Anan, Yoav; Egeth, Howard E

2008-04-01

321

Salient collinear grouping diminishes local salience in visual search: an eye movement study.  

PubMed

Our eyes and attention are easily attracted to salient items in search displays. When a target is spatially overlapped with a salient distractor (overlapping target), it is usually detected more easily than when it is not (nonoverlapping target). Jingling and Tseng (2013), however, found that a salient distractor impaired visual search when the distractor was comprised of more than nine bars collinearly aligned to each other. In this study, we examined whether this search impairment is due to reduction of salience on overlapping targets. We used the short-latency saccades as an index for perceptual salience. Results showed that a long collinear distractor decreases perceptual salience of local overlapping targets in comparison to nonoverlapping targets, reflected by a smaller proportion of the short-latency saccades. Meanwhile, a salient noncollinear distractor increases salience of overlapping targets. Our results led us to conclude that a long collinear distractor diminishes the perceptual salience of the target, a factor which poses a counter-intuitive condition in which a target on a salient region becomes less salient. We discuss the possible causes for our findings, including crowding, the global precedence effect, and the filling-in of a collinear contour. PMID:24113088

Jingling, Li; Tang, Da-Lun; Tseng, Chia-Huei

2013-01-01

322

Optimised autonomous search pattern evaluation using the Cerberus framework  

NASA Astrophysics Data System (ADS)

There is an increasing emphasis on the intelligent use of multiple sensor assets within military applications which is driven by a number of factors. Firstly, the deployment of multiple, co-operative sensors can provide a much greater situational awareness which is a key factor in military decision making at both strategic and tactical levels. Secondly, through careful and timely asset management, military tempo and effectiveness can be maintained and even enhanced such that the mission objectives are optimally prosecuted. Thirdly, intrinsic limitations of individual sensors and their processing demands can be reduced or even eliminated. From a mission perspective, this renders the constraints and frailties of the associated with the sensor network transparent to the military end users. Underpinning all of these factors is the need to adaptively control and manipulate the various sensor search vectors in both space and time. Such a design and operational capability is provided through Cerberus, an advanced design tool developed by Waterfall Solutions Ltd. Within this paper, investigations into a range of different military applications using the Cerberus design environment are reported and assessed in terms of the associated military objectives. These applications include the use of both manned and uninhabited air vehicles as well as land and sea based sensor platforms. The use and benefits of available a priori knowledge such as digital terrain data and mission intelligence can also be exploited within the Cerberus environment to great military advantage.

Angell, C.; Bernhardt, M.

2008-04-01

323

Visual recognition based on temporal cortex cells: viewer-centred processing of pattern configuration.  

PubMed

A model of recognition is described based on cell properties in the ventral cortical stream of visual processing in the primate brain. At a critical intermediate stage in this system, 'Elaborate' feature sensitive cells respond selectively to visual features in a way that depends on size (+/- 1 octave), orientation (+/- 45 degrees) but does not depend on position within central vision (+/- 5 degrees). These features are simple conjunctions of 2-D elements (e.g. a horizontal dark area above a dark smoothly convex area). They can arise either as elements of an object's surface pattern or as a 3-D component bounded by an object's external contour. By requiring a combination of several such features without regard to their position within the central region of the visual image, 'Pattern' sensitive cells at higher levels can exhibit selectivity for complex configurations that typify objects seen under particular viewing conditions. Given that input features to such Pattern sensitive cells are specified in approximate size and orientation, initial cellular 'representations' of the visual appearance of object type (or object example) are also selective for orientation and size. At this level, sensitivity to object view (+/- 60 degrees) arises because visual features disappear as objects are rotated in perspective. Processing is thus viewer-centred and the neurones only respond to objects seen from particular viewing conditions or 'object instances'. Combined sensitivity to multiple features (conjunctions of elements) independent of their position, establishes selectivity for the configurations of object parts (from one view) because rearranged configurations of the same parts yield images lacking some of the 2-D visual features present in the normal configuration. Different neural populations appear to be selectively tuned to particular components of the same biological object (e.g. face, eyes, hands, legs), perhaps because the independent articulation of these components gives rise to correlated activity in different sets of input visual features. Generalisation over viewing conditions for a given object can be established by hierarchically pooling outputs of view-condition specific cells with pooling operations dependent on the continuity in experience across viewing conditions. Different object parts are seen together and different views are seen in succession when the observer walks around the object. The view specific coding that characterises the selectivity of cells in the temporal lobe can be seen as a natural consequence of selective experience of objects from particular vantage points. View specific coding for the face and body also has great utility in understanding complex social signals, a property that may not be feasible with object-centred processing. PMID:9755511

Perrett, D I; Oram, M W

1998-01-01

324

Multiscale pattern analysis of orientation-selective activity in the primary visual cortex  

PubMed Central

Although orientation columns are less than a millimeter in width, recent neuroimaging studies indicate that viewed orientations can be decoded from cortical activity patterns sampled at relatively coarse resolutions of several millimeters. One proposal is that these differential signals arise from random spatial irregularities in the columnar map. However, direct support for this hypothesis has yet to be obtained. Here, we used high-field, high-resolution functional magnetic resonance imaging (fMRI) and multivariate pattern analysis to determine the spatial scales at which orientation-selective information can be found in the primary visual cortex (V1) of cats and humans. We applied a multiscale pattern analysis approach in which fine- and coarse-scale signals were first removed by ideal spatial lowpass and highpass filters, and the residual activity patterns then analyzed by linear classifiers. Cat visual cortex, imaged at 0.3125mm resolution, showed a strong orientation signal at the scale of individual columns. Nonetheless, reliable orientation bias could still be found at spatial scales of several millimeters. In the human visual cortex, imaged at 1mm resolution, a majority of orientation information was found on scales of millimeters, with small contributions from global spatial biases exceeding ~1cm. Our high-resolution imaging results demonstrate a reliable millimeters-scale orientation signal, likely emerging from irregular spatial arrangements of orientation columns and their supporting vasculature. fMRI pattern analysis methods are thus likely to be sensitive to signals originating from other irregular columnar structures elsewhere in the brain. PMID:20053913

Swisher, Jascha D.; Gatenby, J. Christopher; Gore, John C.; Wolfe, Benjamin A.; Moon, Chan-Hong; Kim, Seong-Gi; Tong, Frank

2010-01-01

325

A Convergence Analysis of Unconstrained and Bound Constrained Evolutionary Pattern Search  

SciTech Connect

The authors present and analyze a class of evolutionary algorithms for unconstrained and bound constrained optimization on R{sup n}: evolutionary pattern search algorithms (EPSAs). EPSAs adaptively modify the step size of the mutation operator in response to the success of previous optimization steps. The design of EPSAs is inspired by recent analyses of pattern search methods. They show that EPSAs can be cast as stochastic pattern search methods, and they use this observation to prove that EpSAs have a probabilistic weak stationary point convergence theory. This work provides the first convergence analysis for a class of evolutionary algorithms that guarantees convergence almost surely to a stationary point of a nonconvex objective function.

Hart, W.E.

1999-04-22

326

Urinary oxytocin positively correlates with performance in facial visual search in unmarried males, without specific reaction to infant face.  

PubMed

The neuropeptide oxytocin plays a central role in prosocial and parental behavior in non-human mammals as well as humans. It has been suggested that oxytocin may affect visual processing of infant faces and emotional reaction to infants. Healthy male volunteers (N = 13) were tested for their ability to detect infant or adult faces among adult or infant faces (facial visual search task). Urine samples were collected from all participants before the study to measure the concentration of oxytocin. Urinary oxytocin positively correlated with performance in the facial visual search task. However, task performance and its correlation with oxytocin concentration did not differ between infant faces and adult faces. Our data suggests that endogenous oxytocin is related to facial visual cognition, but does not promote infant-specific responses in unmarried men who are not fathers. PMID:25120420

Saito, Atsuko; Hamada, Hiroki; Kikusui, Takefumi; Mogi, Kazutaka; Nagasawa, Miho; Mitsui, Shohei; Higuchi, Takashi; Hasegawa, Toshikazu; Hiraki, Kazuo

2014-01-01

327

Neural evidence for distracter suppression during visual search in real-world scenes  

PubMed Central

Selecting visual information from cluttered real-world scenes involves the matching of visual input to the observer’s attentional set -- an internal representation of objects that are relevant for current behavioral goals. When goals change, a new attentional set needs to be instantiated, requiring the suppression of the previous set to prevent distraction by objects that are no longer relevant. In the present fMRI study, we investigated how such suppression is implemented at the neural level. We measured human brain activity in response to natural scene photographs that could contain objects from (i) a currently relevant (target) category, and/or (ii) a previously but not presently relevant (distracter) category, and/or (iii) a never relevant (neutral) category. Across conditions, multi-voxel response patterns in object-selective cortex (OSC) carried information about objects present in the scenes. However, this information strongly depended on the task relevance of the objects. As expected, information about the target category was significantly increased relative to the neutral category, indicating top-down enhancement of task-relevant information. Importantly, information about the distracter category was significantly reduced relative to the neutral category, indicating that the processing of previously relevant objects was suppressed. Such active suppression at the level of high-order visual cortex may serve to prevent the erroneous selection of, or interference from, objects that are no longer relevant to ongoing behavior. We conclude that the enhancement of relevant information and the suppression of distracting information both contribute to the efficient selection of visual information from cluttered real-world scenes. PMID:22915122

Seidl, Katharina N.; Peelen, Marius V.; Kastner, Sabine

2012-01-01

328

HSI-Find: A Visualization and Search Service for Terascale Spectral Image Catalogs  

NASA Astrophysics Data System (ADS)

Imaging spectrometers are remote sensing instruments commonly deployed on aircraft and spacecraft. They provide surface reflectance in hundreds of wavelength channels, creating data cubes known as hyperspecrtral images. They provide rich compositional information making them powerful tools for planetary and terrestrial science. These data products can be challenging to interpret because they contain datapoints numbering in the thousands (Dawn VIR) or millions (AVIRIS-C). Cross-image studies or exploratory searches involving more than one scene are rare; data volumes are often tens of GB per image and typical consumer-grade computers cannot store more than a handful of images in RAM. Visualizing the information in a single scene is challenging since the human eye can only distinguish three color channels out of the hundreds available. To date, analysis has been performed mostly on single images using purpose-built software tools that require extensive training and commercial licenses. The HSIFind software suite provides a scalable distributed solution to the problem of visualizing and searching large catalogs of spectral image data. It consists of a RESTful web service that communicates to a javascript-based browser client. The software provides basic visualization through an intuitive visual interface, allowing users with minimal training to explore the images or view selected spectra. Users can accumulate a library of spectra from one or more images and use these to search for similar materials. The result appears as an intensity map showing the extent of a spectral feature in a scene. Continuum removal can isolate diagnostic absorption features. The server-side mapping algorithm uses an efficient matched filter algorithm that can process a megapixel image cube in just a few seconds. This enables real-time interaction, leading to a new way of interacting with the data: the user can launch a search with a single mouse click and see the resulting map in seconds. This allows the user to quickly explore each image, ascertain the main units of surface material, localize outliers, and develop an understanding of the various materials' spectral characteristics. The HSIFind software suite is currently in beta testing at the Planetary Science Institute and a process is underway to release it under an open source license to the broader community. We believe it will benefit instrument operations during remote planetary exploration, where tactical mission decisions demand rapid analysis of each new dataset. The approach also holds potential for public spectral catalogs where its shallow learning curve and portability can make these datasets accessible to a much wider range of researchers. Acknowledgements: The HSIFind project acknowledges the NASA Advanced MultiMission Operating System (AMMOS) and the Multimission Ground Support Services (MGSS). E. Palmer is with the Planetary Science Institute, Tucson, AZ. Other authors are with the Jet Propulsion Laboratory, Pasadena, CA. This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. Copyright 2013, California Institute of Technology.

Thompson, D. R.; Smith, A. T.; Castano, R.; Palmer, E. E.; Xing, Z.

2013-12-01

329

Structator: fast index-based search for RNA sequence-structure patterns  

PubMed Central

Background The secondary structure of RNA molecules is intimately related to their function and often more conserved than the sequence. Hence, the important task of searching databases for RNAs requires to match sequence-structure patterns. Unfortunately, current tools for this task have, in the best case, a running time that is only linear in the size of sequence databases. Furthermore, established index data structures for fast sequence matching, like suffix trees or arrays, cannot benefit from the complementarity constraints introduced by the secondary structure of RNAs. Results We present a novel method and readily applicable software for time efficient matching of RNA sequence-structure patterns in sequence databases. Our approach is based on affix arrays, a recently introduced index data structure, preprocessed from the target database. Affix arrays support bidirectional pattern search, which is required for efficiently handling the structural constraints of the pattern. Structural patterns like stem-loops can be matched inside out, such that the loop region is matched first and then the pairing bases on the boundaries are matched consecutively. This allows to exploit base pairing information for search space reduction and leads to an expected running time that is sublinear in the size of the sequence database. The incorporation of a new chaining approach in the search of RNA sequence-structure patterns enables the description of molecules folding into complex secondary structures with multiple ordered patterns. The chaining approach removes spurious matches from the set of intermediate results, in particular of patterns with little specificity. In benchmark experiments on the Rfam database, our method runs up to two orders of magnitude faster than previous methods. Conclusions The presented method's sublinear expected running time makes it well suited for RNA sequence-structure pattern matching in large sequence databases. RNA molecules containing several stem-loop substructures can be described by multiple sequence-structure patterns and their matches are efficiently handled by a novel chaining method. Beyond our algorithmic contributions, we provide with Structator a complete and robust open-source software solution for index-based search of RNA sequence-structure patterns. The Structator software is available at http://www.zbh.uni-hamburg.de/Structator. PMID:21619640

2011-01-01

330

Investigation of Attentional Bias in Obsessive Compulsive Disorder with and without Depression in Visual Search  

PubMed Central

Whether Obsessive Compulsive Disorder (OCD) is associated with an increased attentional bias to emotive stimuli remains controversial. Additionally, it is unclear whether comorbid depression modulates abnormal emotional processing in OCD. This study examined attentional bias to OC-relevant scenes using a visual search task. Controls, non-depressed and depressed OCD patients searched for their personally selected positive images amongst their negative distractors, and vice versa. Whilst the OCD groups were slower than healthy individuals in rating the images, there were no group differences in the magnitude of negative bias to concern-related scenes. A second experiment employing a common set of images replicated the results on an additional sample of OCD patients. Although there was a larger bias to negative OC-related images without pre-exposure overall, no group differences in attentional bias were observed. However, OCD patients subsequently rated the images more slowly and more negatively, again suggesting post-attentional processing abnormalities. The results argue against a robust attentional bias in OCD patients, regardless of their depression status and speak to generalized difficulties disengaging from negative valence stimuli. Rather, post-attentional processing abnormalities may account for differences in emotional processing in OCD. PMID:24260343

Morein-Zamir, Sharon; Papmeyer, Martina; Durieux, Alice; Fineberg, Naomi A.; Sahakian, Barbara J.; Robbins, Trevor W.

2013-01-01

331

Visual Search for Human Gaze Direction by a Chimpanzee (Pan troglodytes)  

PubMed Central

Background Humans detect faces with direct gazes among those with averted gazes more efficiently than they detect faces with averted gazes among those with direct gazes. We examined whether this “stare-in-the-crowd” effect occurs in chimpanzees (Pan troglodytes), whose eye morphology differs from that of humans (i.e., low-contrast eyes, dark sclera). Methodology/Principal Findings An adult female chimpanzee was trained to search for an odd-item target (front view of a human face) among distractors that differed from the target only with respect to the direction of the eye gaze. During visual-search testing, she performed more efficiently when the target was a direct-gaze face than when it was an averted-gaze face. This direct-gaze superiority was maintained when the faces were inverted and when parts of the face were scrambled. Subsequent tests revealed that gaze perception in the chimpanzee was controlled by the contrast between iris and sclera, as in humans, but that the chimpanzee attended only to the position of the iris in the eye, irrespective of head direction. Conclusion/Significance These results suggest that the chimpanzee can discriminate among human gaze directions and are more sensitive to direct gazes. However, limitations in the perception of human gaze by the chimpanzee are suggested by her inability to completely transfer her performance to faces showing a three-quarter view. PMID:20161750

Tomonaga, Masaki; Imura, Tomoko

2010-01-01

332

Short wavelength automated perimetry, frequency doubling technology perimetry, and pattern electroretinography for prediction of progressive glaucomatous standard visual field defects  

Microsoft Academic Search

PurposeTo evaluate the clinical use of a test battery of short wavelength automated perimetry (SWAP), frequency doubling technology perimetry (FDT), and pattern electroretinography (PERG) in predicting progressive glaucomatous visual field defects on standard automated perimetry (SAP).

Andreas U Bayer; Carl Erb

2002-01-01

333

Differential Roles of the Fan-Shaped Body and the Ellipsoid Body in "Drosophila" Visual Pattern Memory  

ERIC Educational Resources Information Center

The central complex is a prominent structure in the "Drosophila" brain. Visual learning experiments in the flight simulator, with flies with genetically altered brains, revealed that two groups of horizontal neurons in one of its substructures, the fan-shaped body, were required for "Drosophila" visual pattern memory. However, little is known…

Pan, Yufeng; Zhou, Yanqiong; Guo, Chao; Gong, Haiyun; Gong, Zhefeng; Liu, Li

2009-01-01

334

Visualization  

NSDL National Science Digital Library

Visualizing the Earth, its processes, and its evolution through time is a fundamental aspect of geoscience. The use of visualizations - diagrams, images, animations, maps, and more - is an essential tool in helping students to visualize the Earth and its processes. This site aggregates resources and results from two workshops on Teaching with Visualizations. The first, Teaching Geoscience with Visualizations: Using Images, Animations, and Models Effectively, was held at Carleton College in Northfield, MN in February, 2004. A follow-up workshop was held at the fall 2004 meeting of the American Geophysical Union in San Francisco, CA.

335

Visualization of flow patterns induced by an impinging jet issuing from a circular planform  

NASA Astrophysics Data System (ADS)

A four-jet impingement flow with application to high-performance VTOL aircraft is investigated. Flow visualization studies were conducted with water as the working medium. Photographs of different cross sections of the flow are presented to describe the properties of the fountain upwash and the stagnation-line patterns. The visualization technique involves the introduction of fluorescein-sodium, a fluorescent dye, into the jet flow and illumination by a sheet of light obtained by spreading a laser beam. Streak-line photographs were also taken using air bubbles as tracer particles. The strength and orientation of the fountain(s) were observed for different heights of the nozzle configuration above the ground and inclination angles of the forward nozzles.

Saripalli, K. R.

1983-12-01

336

Comparing the Performance of Learnable Evolution Model LEM and Pattern Search as a Function Optimizer  

Microsoft Academic Search

The underlying paper presents a comparison of the learnable evolution model LEM and Pattern Search PS techniques as a function optimizer. In contrast to conventional Darwinian type evolutionary computation algorithm that uses various forms of mutation and\\/or recombination operators, LEM uses machine learning to guide the process of generating new individuals. It employs the AQ learning to generate hypotheses discriminating

I. Talkhan; A. Atiya; H. Sallam; M. Ashour; A. M. Abd El Salam; C. Regazzoni

2006-01-01

337

Distinct spatial patterns of brain activity associated with memory storage and search  

E-print Network

Distinct spatial patterns of brain activity associated with memory storage and search Eric Zarahn Division of the Taub Institute, Columbia University College of Physicians and Surgeons, 630 West 168th College of Physicians and Surgeons, 630 West 168th Street, Columbia University, New York, NY 10032, USA c

338

APPSPACK 4.0: Parallel Pattern Search for Derivative-Free ...  

E-print Network

mization problems has several advantages: No derivative information is ... Additional Key Words and Phrases: parallel derivative-free optimization, pattern search. 1. ...... APPSPACK 4.0 can be found in the README file included with the software. ..... U.S. Geological Survey Techniques of Water Resources Investigations.

2005-12-14

339

Adaptation in the Visual Cortex: Influence of Membrane Trajectory and Neuronal Firing Pattern on Slow Afterpotentials  

PubMed Central

The input/output relationship in primary visual cortex neurons is influenced by the history of the preceding activity. To understand the impact that membrane potential trajectory and firing pattern has on the activation of slow conductances in cortical neurons we compared the afterpotentials that followed responses to different stimuli evoking similar numbers of action potentials. In particular, we compared afterpotentials following the intracellular injection of either square or sinusoidal currents lasting 20 seconds. Both stimuli were intracellular surrogates of different neuronal responses to prolonged visual stimulation. Recordings from 99 neurons in slices of visual cortex revealed that for stimuli evoking an equivalent number of spikes, sinusoidal current injection activated a slow afterhyperpolarization of significantly larger amplitude (8.5±3.3 mV) and duration (33±17 s) than that evoked by a square pulse (6.4±3.7 mV, 28±17 s; p<0.05). Spike frequency adaptation had a faster time course and was larger during plateau (square pulse) than during intermittent (sinusoidal) depolarizations. Similar results were obtained in 17 neurons intracellularly recorded from the visual cortex in vivo. The differences in the afterpotentials evoked with both protocols were abolished by removing calcium from the extracellular medium or by application of the L-type calcium channel blocker nifedipine, suggesting that the activation of a calcium-dependent current is at the base of this afterpotential difference. These findings suggest that not only the spikes, but the membrane potential values and firing patterns evoked by a particular stimulation protocol determine the responses to any subsequent incoming input in a time window that spans for tens of seconds to even minutes. PMID:25380063

Descalzo, Vanessa F.; Gallego, Roberto; Sanchez-Vives, Maria V.

2014-01-01

340

Gaze patterns predicting successful collision avoidance in patients with homonymous visual field defects.  

PubMed

Aim of the present study was to identify efficient compensatory gaze patterns applied by patients with homonymous visual field defects (HVFDs) under virtual reality (VR) conditions in a dynamic collision avoidance task. Thirty patients with HVFDs due to vascular brain lesions and 30 normal subjects performed a collision avoidance task with moving objects at an intersection under two difficulty levels. Based on their performance (i.e. the number of collisions), patients were assigned to either an "adequate" (HVFD(A)) or "inadequate" (HVFD(I)) subgroup by the median split method. Eye and head tracking data were available for 14 patients and 19 normal subjects. Saccades, fixations, mean number of gaze shifts, scanpath length and the mean gaze eccentricity, were compared between HVFD(A), HVFD(I) patients and normal subjects. For both difficulty levels, the gaze patterns of HVFD(A) patients (N=5) compared to HVFD(I) patients (N=9) were characterized by longer saccadic amplitudes towards both the affected and the intact side, larger mean gaze eccentricity, more gaze shifts, longer scanpaths and more fixations on vehicles but fewer fixations on the intersection. Both patient groups displayed more fixations in the affected compared to the intact hemifield. Fixation number, fixation duration, scanpath length, and number of gaze shifts were similar between HVFD(A) patients and normal subjects. Patients with HVFDs who adapt successfully to their visual deficit, display distinct gaze patterns characterized by increased exploratory eye and head movements, particularly towards moving objects of interest on their blind side. In the context of a dynamic environment, efficient compensation in patients with HVFDs is possible by means of gaze scanning. This strategy allows continuous update of the moving objects' spatial location and selection of the task-relevant ones, which will be represented in visual working memory. PMID:22721638

Papageorgiou, Eleni; Hardiess, Gregor; Mallot, Hanspeter A; Schiefer, Ulrich

2012-07-15

341

Visual search deficits in Parkinson's disease are attenuated by bottom-up target salience and top-down information  

Microsoft Academic Search

Patients with Parkinson's disease (PD), a degenerative disorder primarily affecting the nigrostriatal dopamine system, exhibit deficits in selecting task-relevant stimuli in the presence of irrelevant stimuli, such as in visual search tasks. However, results from previous studies suggest that these deficits may vary as a function of whether selection must rely primarily on the “bottom-up” salience of the target relative

Todd S. Horowitz; Won Yung Choi; Jon C. Horvitz; Lucien J. Côté; Jennifer A. Mangels

2006-01-01

342

How Prior Knowledge and Colour Contrast Interfere Visual Search Processes in Novice Learners: An Eye Tracking Study  

ERIC Educational Resources Information Center

This study investigates how prior content knowledge and prior exposure to microscope slides on the phases of mitosis effect students' visual search strategies and their ability to differentiate cells that are going through any phases of mitosis. Two different sets of microscope slide views were used for this purpose; with high and low colour…

Sonmez, Duygu; Altun, Arif; Mazman, Sacide Guzin

2012-01-01

343

Visual search and exploration in digital libraries, catalogues or multimedia databases User-centred document-and knowledge retrieval  

E-print Network

databases · User-centred document- and knowledge retrieval · Multiple application scenarios: libraries, e-commerce, desktop or intranet search, video-on-demand, media asset management ... · Visual interface and new.g. JPG, PDF, AVI, MP3, ...) · MedioVis explores innovative solutions for multimedia document storage

Reiterer, Harald

344

A Clash of Bottom-Up and Top-Down Processes in Visual Search: The Reversed Letter Effect Revisited  

ERIC Educational Resources Information Center

It is harder to find the letter "N" among its mirror reversals than vice versa, an inconvenient finding for bottom-up saliency accounts based on primary visual cortex (V1) mechanisms. However, in line with this account, we found that in dense search arrays, gaze first landed on either target equally fast. Remarkably, after first landing, gaze…

Zhaoping, Li; Frith, Uta

2011-01-01

345

Age-Related Occipito-Temporal Hypoactivation during Visual Search: Relationships between mN2pc Sources and Performance  

ERIC Educational Resources Information Center

Recently, an event-related potential (ERP) study (Lorenzo-Lopez et al., 2008) provided evidence that normal aging significantly delays and attenuates the electrophysiological correlate of the allocation of visuospatial attention (N2pc component) during a feature-detection visual search task. To further explore the effects of normal aging on the…

Lorenzo-Lopez, L.; Gutierrez, R.; Moratti, S.; Maestu, F.; Cadaveira, F.; Amenedo, E.

2011-01-01

346

The role of pattern recognition in creative problem solving: a case study in search of new mathematics for biology.  

PubMed

Rosen classified sciences into two categories: formalizable and unformalizable. Whereas formalizable sciences expressed in terms of mathematical theories were highly valued by Rutherford, Hutchins pointed out that unformalizable parts of soft sciences are of genuine interest and importance. Attempts to build mathematical theories for biology in the past century was met with modest and sporadic successes, and only in simple systems. In this article, a qualitative model of humans' high creativity is presented as a starting point to consider whether the gap between soft and hard sciences is bridgeable. Simonton's chance-configuration theory, which mimics the process of evolution, was modified and improved. By treating problem solving as a process of pattern recognition, the known dichotomy of visual thinking vs. verbal thinking can be recast in terms of analog pattern recognition (non-algorithmic process) and digital pattern recognition (algorithmic process), respectively. Additional concepts commonly encountered in computer science, operations research and artificial intelligence were also invoked: heuristic searching, parallel and sequential processing. The refurbished chance-configuration model is now capable of explaining several long-standing puzzles in human cognition: a) why novel discoveries often came without prior warning, b) why some creators had no ideas about the source of inspiration even after the fact, c) why some creators were consistently luckier than others, and, last but not least, d) why it was so difficult to explain what intuition, inspiration, insight, hunch, serendipity, etc. are all about. The predictive power of the present model was tested by means of resolving Zeno's paradox of Achilles and the Tortoise after one deliberately invoked visual thinking. Additional evidence of its predictive power must await future large-scale field studies. The analysis was further generalized to constructions of scientific theories in general. This approach is in line with Campbell's evolutionary epistemology. Instead of treating science as immutable Natural Laws, which already existed and which were just waiting to be discovered, scientific theories are regarded as humans' mental constructs, which must be invented to reconcile with observed natural phenomena. In this way, the pursuit of science is shifted from diligent and systematic (or random) searching for existing Natural Laws to firing up humans' imagination to comprehend Nature's behavioral pattern. The insights gained in understanding human creativity indicated that new mathematics that is capable of handling effectively parallel processing and human subjectivity is sorely needed. The past classification of formalizability vs. non-formalizability was made in reference to contemporary mathematics. Rosen's conclusion did not preclude future inventions of new biology-friendly mathematics. PMID:23597605

Hong, Felix T

2013-09-01

347

A Two-Stage Search of Visual Working Memory: Investigating Speed in the Change-Detection Paradigm  

PubMed Central

A popular procedure for investigating working memory processes has been the visual change-detection procedure. Models of performance in that procedure, however, tend to be based on performance accuracy and to treat working memory search as a one-step process, in which memory representations are compared to a test probe to determine if a match is present. To gain a clearer understanding of how search of these representations operate in the change-detection task, we examined reaction time in two experiments, with a single-item probe either located centrally or at the location of an array item. Contrary to current models of visual working memory capacity, our data point to a two-stage search process: a fast first step to check for the novelty of the probe and, in the absence of such novelty, a second, slower step to search exhaustively for a match between the test probe and a memory representation. In addition to these results, we found that participants tended not to use location information provided by the probe that theoretically could have abbreviated the search process. We suggest some basic revisions of current models of processing in this type of visual working memory task. PMID:25023891

Gilchrist, Amanda L.; Cowan, Nelson

2014-01-01

348

TMS of the right angular gyrus modulates priming of pop-out in visual search: combined TMS-ERP evidence.  

PubMed

During priming of pop-out, performance at discriminating a pop-out feature target in visual search is affected by whether the target on the previous trial was defined by the same feature as on the upcoming trial. Recent studies suggest that priming of pop-out relies on attentional processes. With the use of simultaneous, combined transcranial magnetic stimulation and event-related potential recording (TMS-ERP), we tested for any critical role of the right angular gyrus (rANG) and left and right frontal eye fields (FEFs)-key attentional sites-in modulating both performance and the ERPs evoked by such visual events. Intertrial TMS trains were applied while participants discriminated the orientation of a color pop-out element in a visual search array. rANG TMS disrupted priming of pop-out, reducing reaction time costs on switch trials and speeding responses when the color of the pop-out target switched. rANG TMS caused a negativity in the ERP elicited in response to the visual stimulus array, starting 210 ms after stimulus onset. Both behavioral and ERP effects were apparent only after rANG TMS, on switch trials, and when the target in the visual search array was presented in the left visual field, with no effects after left or right FEF TMS. These results provide evidence for an attentional reorienting mechanism, which originates in the rANG and is modulated by the implicit memory of the previous trial. The rANG plays a causal role on switch trials during priming of pop-out by interacting with visual processing, particularly in the ipsilateral hemisphere representing the contralateral hemifield. PMID:21880940

Taylor, Paul C J; Muggleton, Neil G; Kalla, Roger; Walsh, Vincent; Eimer, Martin

2011-12-01

349

Implementation of the three-dimensional-pattern search problem on Hopfield-like neural networks.  

PubMed

The three-dimensional (3D)-pattern search problem can be summarized as finding, in a molecule, the subset of atoms that have the most similar spatial arrangement as those of a given 3D pattern. For this NP-complete combinatorial optimization problem we propose, by analogy to the travelling salesman problem, a new method taking advantage of the capability of Hopfield-like neural networks to carry out combinatorial optimization of an objective function. This objective function is built from the sum of the differences of interatomic distances in the pattern and the molecule. Here we present the implementation we have found of the 3D-pattern search problem on Hopfield-like neural networks. Initial tests indicate that this approach not only successfully retrieves a given pattern, but can also suggest partial solutions having one or two atoms less than the given pattern, an interesting feature in the case of local conformational flexibility of the molecule. The distributed representation of the problem on Hopfield-like neural networks offers a good perspective for parallel implementation. PMID:8790627

Feuilleaubois, E; Fabart, V; Doucet, J P

1993-01-01

350

Scavengers on the Move: Behavioural Changes in Foraging Search Patterns during the Annual Cycle  

PubMed Central

Background Optimal foraging theory predicts that animals will tend to maximize foraging success by optimizing search strategies. However, how organisms detect sparsely distributed food resources remains an open question. When targets are sparse and unpredictably distributed, a Lévy strategy should maximize foraging success. By contrast, when resources are abundant and regularly distributed, simple Brownian random movement should be sufficient. Although very different groups of organisms exhibit Lévy motion, the shift from a Lévy to a Brownian search strategy has been suggested to depend on internal and external factors such as sex, prey density, or environmental context. However, animal response at the individual level has received little attention. Methodology/Principal Findings We used GPS satellite-telemetry data of Egyptian vultures Neophron percnopterus to examine movement patterns at the individual level during consecutive years, with particular interest in the variations in foraging search patterns during the different periods of the annual cycle (i.e. breeding vs. non-breeding). Our results show that vultures followed a Brownian search strategy in their wintering sojourn in Africa, whereas they exhibited a more complex foraging search pattern at breeding grounds in Europe, including Lévy motion. Interestingly, our results showed that individuals shifted between search strategies within the same period of the annual cycle in successive years. Conclusions/Significance Results could be primarily explained by the different environmental conditions in which foraging activities occur. However, the high degree of behavioural flexibility exhibited during the breeding period in contrast to the non-breeding period is challenging, suggesting that not only environmental conditions explain individuals' behaviour but also individuals' cognitive abilities (e.g., memory effects) could play an important role. Our results support the growing awareness about the role of behavioural flexibility at the individual level, adding new empirical evidence about how animals in general, and particularly scavengers, solve the problem of efficiently finding food resources. PMID:23372712

Lopez-Lopez, Pascual; Benavent-Corai, Jose; Garcia-Ripolles, Clara; Urios, Vicente

2013-01-01

351

Feasibility study on Compton imaging for visualization of flow patterns using radiotracers  

NASA Astrophysics Data System (ADS)

The radiotracer technique could be used in studies on multiphase flow systems by three-dimensional visualization of flow patterns, and, relatedly, there have been attempts to develop an industrial-purpose single photon emission computed tomography (SPECT) system. Compton cameras also have a great potential for industrial applications, due specifically to their inherent three-dimensional imaging capability, multi-tracing capability, and higher imaging sensitivity than imaging devices based on mechanical collimation. In the present study, the feasibility of Compton imaging for visualization of detailed flow patterns was determined using a Geant4 Monte Carlo simulation toolkit. The Compton camera considered is a double-scattering type consisting of three gamma-ray detectors: two double-sided silicon strip detectors (DSSDs) as scatterer detectors and one NaI(Tl) scintillation detector as an absorber detector. The results showed that the three-dimensional source distributions can be determined with the Compton camera under various source conditions, including a point source at the center, and two cylinderial volume sources of different dimensions or energies.

Seo, H.; Park, J. H.; Park, J. G.; Ushakov, A.; Kim, C. H.; Lee, J. H.; Lee, C. S.; Lee, J. S.

2011-01-01

352

The effects of action video game experience on the time course of inhibition of return and the efficiency of visual search  

Microsoft Academic Search

The ability to efficiently search the visual environment is a critical function of the visual system, and recent research has shown that experience playing action video games can influence visual selective attention. The present research examined the similarities and differences between video game players (VGPs) and non-video game players (NVGPs) in terms of the ability to inhibit attention from returning

Alan D. Castel; Jay Pratt; Emily Drummond

2005-01-01

353

IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS, VOL. 12, NO. 5, SEPTEMBER/OCTOBER 2006 Software Design Patterns for Information Visualization  

E-print Network

, evaluate, and re-apply the design solutions implemented within such frameworks. One popular and effective descriptions of interacting software components that can be customized to solve design problems within software, we present a series of design patterns for the domain of information visualization. We discuss

Heer, Jeffrey

354

The effect of flower-like and non-flower-like visual properties on choice of unrewarding patterns by bumblebees  

NASA Astrophysics Data System (ADS)

How do distinct visual stimuli help bumblebees discover flowers before they have experienced any reward outside of their nest? Two visual floral properties, type of a pattern (concentric vs radial) and its position on unrewarding artificial flowers (central vs peripheral on corolla), were manipulated in two experiments. Both visual properties showed significant effects on floral choice. When pitted against each other, pattern was more important than position. Experiment 1 shows a significant effect of concentric pattern position, and experiment 2 shows a significant preference towards radial patterns regardless of their position. These results show that the presence of markings at the center of a flower are not so important as the presence of markings that will direct bees there.

Orbán, Levente L.; Plowright, Catherine M. S.

2013-07-01

355

More target features in visual working memory leads to poorer search guidance: Evidence from contralateral delay activity  

PubMed Central

The visual-search literature has assumed that the top-down target representation used to guide search resides in visual working memory (VWM). We directly tested this assumption using contralateral delay activity (CDA) to estimate the VWM load imposed by the target representation. In Experiment 1, observers previewed four photorealistic objects and were cued to remember the two objects appearing to the left or right of central fixation; Experiment 2 was identical except that observers previewed two photorealistic objects and were cued to remember one. CDA was measured during a delay following preview offset but before onset of a four-object search array. One of the targets was always present, and observers were asked to make an eye movement to it and press a button. We found lower magnitude CDA on trials when the initial search saccade was directed to the target (strong guidance) compared to when it was not (weak guidance). This difference also tended to be larger shortly before search-display onset and was largely unaffected by VWM item-capacity limits or number of previews. Moreover, the difference between mean strong- and weak-guidance CDA was proportional to the increase in search time between mean strong-and weak-guidance trials (as measured by time-to-target and reaction-time difference scores). Contrary to most search models, our data suggest that trials resulting in the maintenance of more target features results in poor search guidance to a target. We interpret these counterintuitive findings as evidence for strong search guidance using a small set of highly discriminative target features that remain after pruning from a larger set of features, with the load imposed on VWM varying with this feature-consolidation process. PMID:24599946

Schmidt, Joseph; MacNamara, Annmarie; Proudfit, Greg Hajcak; Zelinsky, Gregory J.

2014-01-01

356

The hard-won benefits of familiarity in visual search: naturally familiar brand logos are found faster.  

PubMed

Familiar items are found faster than unfamiliar ones in visual search tasks. This effect has important implications for cognitive theory, because it may reveal how mental representations of commonly encountered items are changed by experience to optimize performance. It remains unknown, however, whether everyday items with moderate levels of exposure would show benefits in visual search, and if so, what kind of experience would be required to produce them. Here, we tested whether familiar product logos were searched for faster than unfamiliar ones, and also familiarized subjects with previously unfamiliar logos. Subjects searched for preexperimentally familiar and unfamiliar logos, half of which were familiarized in the laboratory, amongst other, unfamiliar distractor logos. In three experiments, we used an N-back-like familiarization task, and in four others we used a task that asked detailed questions about the perceptual aspects of the logos. The number of familiarization exposures ranged from 30 to 84 per logo across experiments, with two experiments involving across-day familiarization. Preexperimentally familiar target logos were searched for faster than were unfamiliar, nonfamiliarized logos, by 8 % on average. This difference was reliable in all seven experiments. However, familiarization had little or no effect on search speeds; its average effect was to improve search times by 0.7 %, and its effect was significant in only one of the seven experiments. If priming, mere exposure, episodic memory, or relatively modest familiarity were responsible for familiarity's effects on search, then performance should have improved following familiarization. Our results suggest that the search-related advantage of familiar logos does not develop easily or rapidly. PMID:24510424

Qin, Xiaoyan Angela; Koutstaal, Wilma; Engel, Stephen A

2014-05-01

357

Assessment of prostate cancer detection with a visual-search human model observer  

NASA Astrophysics Data System (ADS)

Early staging of prostate cancer (PC) is a significant challenge, in part because of the small tumor sizes in- volved. Our long-term goal is to determine realistic diagnostic task performance benchmarks for standard PC imaging with single photon emission computed tomography (SPECT). This paper reports on a localization receiver operator characteristic (LROC) validation study comparing human and model observers. The study made use of a digital anthropomorphic phantom and one-cm tumors within the prostate and pelvic lymph nodes. Uptake values were consistent with data obtained from clinical In-111 ProstaScint scans. The SPECT simulation modeled a parallel-hole imaging geometry with medium-energy collimators. Nonuniform attenua- tion and distance-dependent detector response were accounted for both in the imaging and the ordered-subset expectation-maximization (OSEM) iterative reconstruction. The observer study made use of 2D slices extracted from reconstructed volumes. All observers were informed about the prostate and nodal locations in an image. Iteration number and the level of postreconstruction smoothing were study parameters. The results show that a visual-search (VS) model observer correlates better with the average detection performance of human observers than does a scanning channelized nonprewhitening (CNPW) model observer.

Sen, Anando; Kalantari, Faraz; Gifford, Howard C.

2014-03-01

358

The influence of working memory on visual search for emotional facial expressions.  

PubMed

In visual search tasks, an angry face surrounded by happy faces is more rapidly detected compared with a happy face surrounded by angry faces. This is called the anger superiority effect. The anger superiority effect has been mainly related to automatic attentional effects, but top-down mechanisms may also influence this effect. In a series of studies, we investigated the influence of holding emotional information in working memory (WM) on the anger superiority effect. In multiple experiments, participants were generally faster to find an angry target with happy distractors compared to a happy target with angry distractors. However, this anger superiority effect was diminished when holding angry information in WM, whereas the effect was still observed when holding happy information. These effects were not observed when participants did not remember emotional information other than the color of the emotional stimuli. The data indicate that enhanced processing of distractor facial expressions was observed when they matched the content of WM, facilitating target detection. However, when the contents of WM and distractor faces differed, the processing of distractor faces and detection of a target face were delayed. These results suggest that the anger superiority effect is modulated by top-down effects of WM and that interactions between contents of WM and perception of facial expressions determine the enhancement or reduction of the anger superiority effect. PMID:24999613

Moriya, Jun; Koster, Ernst H W; De Raedt, Rudi

2014-10-01

359

Computer-aided methods to recover strategies for visual search and navigation  

NASA Astrophysics Data System (ADS)

A series of methods developed to recover strategies for visual search and navigation to support image analysis and classification in the case of uncertainty is presented. We used optimal filtering for better imaging of informative features, along with expert descriptions of processed images by the expert in terms of observed features. We collected these data in a database. Expert-guided analysis of the data in the database was applied to find discriminative features important for image interpretation. A formal decision rule was worked out for computer-aided image classification. The developed formal decision rule presented an effective strategy for image analysis and interpretation, orienting the user to look for specific features, and also showing how to classify the image on the basis of observed features. The methods were tested in the task of early peripheral lung cancer diagnosis. Experiments with more than 600 lung tomogram showed that an application of the methods gives essential (by 10% - 16%) improvement of diagnostic accuracy for physicians of different qualifications.

Belikova, Tatjana P.; Stenina, Irina I.; Yashunskaya, Nadezsda I.

2000-04-01

360

Response variability of frontal eye field neurons modulates with sensory input and saccade preparation but not visual search salience  

PubMed Central

Discharge rate modulation of frontal eye field (FEF) neurons has been identified with a representation of visual search salience (physical conspicuity and behavioral relevance) and saccade preparation. We tested whether salience or saccade preparation are evident in the trial-to-trial variability of discharge rate. We quantified response variability via the Fano factor in FEF neurons recorded in monkeys performing efficient and inefficient visual search tasks. Response variability declined following stimulus presentation in most neurons, but despite clear discharge rate modulation, variability did not change with target salience. Instead, we found that response variability was modulated by stimulus luminance and the number of items in the visual field independently of attentional demands. Response variability declined to a minimum before saccade initiation, and presaccadic response variability was directionally tuned. In addition, response variability was correlated with the response time of memory-guided saccades. These results indicate that the trial-by-trial response variability of FEF neurons reflects saccade preparation and the strength of sensory input, but not visual search salience or attentional allocation. PMID:22956785

Purcell, Braden A.; Heitz, Richard P.; Cohen, Jeremiah Y.

2012-01-01

361

How do the regions of the visual field contribute to object search in real-world scenes? Evidence from eye movements.  

PubMed

An important factor constraining visual search performance is the inhomogeneity of the visual system. Engaging participants in a scene search task, the present study explored how the different regions of the visual field contribute to search. Gaze-contingent Blindspots and Spotlights were implemented to determine the absolute and relative importance of the different visual regions for object-in-scene search. Three Blindspot/Spotlight radii (1.6°, 2.9°, and 4.1°) were used to differentiate between foveal, parafoveal, and peripheral vision. When searching the scene with artificially impaired foveal or central vision (Blindspots), search performance was surprisingly unimpaired. Foveal vision was not necessary to attain normal search performance. When high-resolution scene information was withheld in both foveal and parafoveal vision (4.1° Blindspot), target localization was unimpaired but it took longer to verify the identity of the target. Artificially impairing extrafoveal scene analysis (Spotlights) affected attentional selection and visual processing; shrinking the Spotlight of high resolution led to longer search times, shorter saccades, and more and longer fixations. The 4.1° radius was identified as the crossover point of equal search times in Blindspot and Spotlight conditions. However, a gaze-data based decomposition of search times into behaviorally defined epochs revealed differences in particular subprocesses of search. PMID:23937216

Nuthmann, Antje

2014-02-01

362

Hybrid General Pattern Search and Simulated Annealing for Industrail Production Planning Problems  

NASA Astrophysics Data System (ADS)

In this paper, the hybridization of GPS (General Pattern Search) method and SA (Simulated Annealing) incorporated in the optimization process in order to look for the global optimal solution for the fitness function and decision variables as well as minimum computational CPU time. The real strength of SA approach been tested in this case study problem of industrial production planning. This is due to the great advantage of SA for being easily escaping from trapped in local minima by accepting up-hill move through a probabilistic procedure in the final stages of optimization process. Vasant [1] in his Ph. D thesis has provided 16 different techniques of heuristic and meta-heuristic in solving industrial production problems with non-linear cubic objective functions, eight decision variables and 29 constraints. In this paper, fuzzy technological problems have been solved using hybrid techniques of general pattern search and simulated annealing. The simulated and computational results are compared to other various evolutionary techniques.

Vasant, P.; Barsoum, N.

2010-06-01

363

Measuring the impact of health policies using Internet search patterns: the case of abortion  

PubMed Central

Background Internet search patterns have emerged as a novel data source for monitoring infectious disease trends. We propose that these data can also be used more broadly to study the impact of health policies across different regions in a more efficient and timely manner. Methods As a test use case, we studied the relationships between abortion-related search volume, local abortion rates, and local abortion policies available for study. Results Our initial integrative analysis found that, both in the US and internationally, the volume of Internet searches for abortion is inversely proportional to local abortion rates and directly proportional to local restrictions on abortion. Conclusion These findings are consistent with published evidence that local restrictions on abortion lead individuals to seek abortion services outside of their area. Further validation of these methods has the potential to produce a timely, complementary data source for studying the effects of health policies. PMID:20738850

2010-01-01

364

Parafoveal Retinal Vascular Response to Pattern Visual Stimulation Assessed with OCT Angiography  

PubMed Central

We used optical coherence tomography (OCT) angiography with a high-speed swept-source OCT system to investigate retinal blood flow changes induced by visual stimulation with a reversing checkerboard pattern. The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to quantify blood flow as measured with parafoveal flow index (PFI), which is proportional to the density of blood vessels and the velocity of blood flow in the parafoveal region of the macula. PFI measurements were taken in 15 second intervals during a 4 minute period consisting of 1 minute of baseline, 2 minutes with an 8 Hz reversing checkerboard pattern stimulation, and 1 minute without stimulation. PFI measurements increased 6.1±4.7% (p?=?.001) during the first minute of stimulation, with the most significant increase in PFI occurring 30 seconds into stimulation (p<0.001). These results suggest that pattern stimulation induces a change to retinal blood flow that can be reliably measured with OCT angiography. PMID:24312549

Wei, Eric; Jia, Yali; Tan, Ou; Potsaid, Benjamin; Liu, Jonathan J.; Choi, WooJhon; Fujimoto, James G.; Huang, David

2013-01-01

365

Image processing and 3D visualization in the interpretation of patterned injury of the skin  

NASA Astrophysics Data System (ADS)

The use of image processing is becoming increasingly important in the evaluation of violent crime. While much work has been done in the use of these techniques for forensic purposes outside of forensic pathology, its use in the pathologic examination of wounding has been limited. We are investigating the use of image processing in the analysis of patterned injuries and tissue damage. Our interests are currently concentrated on 1) the use of image processing techniques to aid the investigator in observing and evaluating patterned injuries in photographs, 2) measurement of the 3D shape characteristics of surface lesions, and 3) correlation of patterned injuries with deep tissue injury as a problem in 3D visualization. We are beginning investigations in data-acquisition problems for performing 3D scene reconstructions from the pathology perspective of correlating tissue injury to scene features and trace evidence localization. Our primary tool for correlation of surface injuries with deep tissue injuries has been the comparison of processed surface injury photographs with 3D reconstructions from antemortem CT and MRI data. We have developed a prototype robot for the acquisition of 3D wound and scene data.

Oliver, William R.; Altschuler, Bruce R.

1995-09-01

366

Peripheral Vision of Youths with Low Vision: Motion Perception, Crowding, and Visual Search  

E-print Network

Low Vision Peripheral Vision of Youths with Low Vision: Motion Perception, Crowding, and Visual. Effects of low vision on peripheral visual function are poorly understood, especially in children whose visual functions in youths with typical and low vision. Of specific interest was the extent to which

Tadin, Duje

367

Visual constraints in foraging bumblebees: Flower size and color affect search time and flight behavior  

Microsoft Academic Search

In optimal foraging theory, search time is a key variable defining the value of a prey type. But the sensory-perceptual processes that constrain the search for food have rarely been considered. Here we evaluate the flight behavior of bumblebees (Bombus terrestris) searching for artificial flowers of various sizes and colors. When flowers were large, search times correlated well with the

J. Spaethe; J. Tautz; L. Chittka

2001-01-01

368

Neural correlates of inter-trial priming and role-reversal in visual search.  

PubMed

Studies of priming of visual perception demonstrate that observers respond more quickly to targets in a field of distractors when relevant features are repeated versus novel or role-reversed. In a recent brain imaging study by Kristjánsson et al. (2007), participants were presented with two items of one color and a single item in a different color with the task of reporting the orientation of the uniquely colored item. Consistent with previous behavioral reports, they found that observers were faster to respond when the target and distractor colors were identical to the previous trial than when they were reversed. They found reduced BOLD activity in brain areas linked with attentional control on trials where the target and distractor colors were repeated relative to reversed, which they interpreted as reflecting response suppression (decreased BOLD signal for repeated stimuli). However, since their design only compared repeated versus reversed task demands, it is logically possible that this pattern reflects increased BOLD signal for role-reversed stimuli: activity required to inhibit previously facilitated information and select previously inhibited information. We explored this possibility with a task where we contrasted the signal generated by repeated, reversed, and novel features. Our data suggest that the majority of the change in neural signal elicited by priming of pop-out reflects increased activation when selection criteria are reversed. PMID:22144956

Rorden, Christopher; Kristjansson, Arni; Revill, Kathleen Pirog; Saevarsson, Styrmir

2011-01-01

369

Identifying Shared Genetic Structure Patterns among Pacific Northwest Forest Taxa: Insights from Use of Visualization Tools and Computer Simulations  

PubMed Central

Background Identifying causal relationships in phylogeographic and landscape genetic investigations is notoriously difficult, but can be facilitated by use of multispecies comparisons. Methodology/Principal Findings We used data visualizations to identify common spatial patterns within single lineages of four taxa inhabiting Pacific Northwest forests (northern spotted owl: Strix occidentalis caurina; red tree vole: Arborimus longicaudus; southern torrent salamander: Rhyacotriton variegatus; and western white pine: Pinus monticola). Visualizations suggested that, despite occupying the same geographical region and habitats, species responded differently to prevailing historical processes. S. o. caurina and P. monticola demonstrated directional patterns of spatial genetic structure where genetic distances and diversity were greater in southern versus northern locales. A. longicaudus and R. variegatus displayed opposite patterns where genetic distances were greater in northern versus southern regions. Statistical analyses of directional patterns subsequently confirmed observations from visualizations. Based upon regional climatological history, we hypothesized that observed latitudinal patterns may have been produced by range expansions. Subsequent computer simulations confirmed that directional patterns can be produced by expansion events. Conclusions/Significance We discuss phylogeographic hypotheses regarding historical processes that may have produced observed patterns. Inferential methods used here may become increasingly powerful as detailed simulations of organisms and historical scenarios become plausible. We further suggest that inter-specific comparisons of historical patterns take place prior to drawing conclusions regarding effects of current anthropogenic change within landscapes. PMID:21060824

Miller, Mark P.; Haig, Susan M.

2010-01-01

370

A visual-search model observer for multislice-multiview SPECT images  

PubMed Central

Purpose: Mathematical model observers are intended for efficient assessment of diagnostic image quality, but model-observer studies often are not representative of clinical realities. Model observers based on a visual-search (VS) paradigm may allow for greater clinical relevance. The author has compared the performances of several VS model observers with those of human observers and an existing scanning model observer for a study involving nodule detection and localization in simulated Tc-99m single-photon emission computed tomography (SPECT) lung volumes. Methods: A localization receiver operating characteristic (LROC) study compared two iterative SPECT reconstruction strategies: an all-corrections (AllC) strategy with compensations for attenuation, scatter, and distance-dependent camera resolution and an “RC” strategy with resolution compensation only. Nodules in the simulation phantom were of three different relative contrasts. Observers in the study had access to the coronal, sagittal, and transverse displays of the reconstructed volumes. Three human observers each read 50 training volumes and 100 test volumes per reconstruction strategy. The same images were analyzed by a channelized nonprewhitening (CNPW) scanning observer and two VS observers. The VS observers implemented holistic search processes that identified focal points of Tc-99m uptake for subsequent analysis by the CNPW scanning model. The level of prior knowledge about the background structure in the images was a study variable for the model observers. Performance was scored by area under the LROC curve. Results: The average human-observer performances were respectively 0.67 ± 0.04 and 0.61 ± 0.03 for the RC and AllC strategies. Given approximate knowledge about the background structure, both VS models scored 0.69 ± 0.08 (RC) and 0.66 ± 0.08 (AllC). The scanning observer reversed the strategy ranking in scoring 0.73 ± 0.08 with the AllC strategy and 0.64 ± 0.08 with the RC strategy. The VS observers exhibited less sensitivity to variations in background knowledge compared to the scanning observer. Conclusions: The VS framework has the potential to increase the clinical similitude of model-observer studies and to enhance the ability of existing model observers to quantitatively predict human-observer performance. PMID:24007181

Gifford, Howard C.

2013-01-01

371

Perceptual Factors Influence Visual Search for Meaningful Symbols In Individuals with Intellectual Disabilities and Down Syndrome or Autism Spectrum Disorders  

PubMed Central

Augmentative and alternative communication (AAC) systems often supplement oral communication of individuals with intellectual and communication disabilities. Research with nondisabled preschoolers has demonstrated that two visual perceptual factors influence speed and/or accuracy of finding a target - the internal color and spatial organization of symbols. Twelve participants with Down syndrome and 12 with ASD underwent two search tasks. In one, the symbols were clustered by internal color; in the other the identical symbols had no arrangement cue. Visual search was superior in participants with ASD compared to those with Down syndrome. In both groups, responses were significantly faster when the symbols were clustered by internal color. Construction of aided AAC displays may benefit from attention to their physical/perceptual features. PMID:24245729

Wilkinson, Krista M.; McIlvane, William J.

2013-01-01

372

Discovering patterns of correlation and similarities in software project data with the Circos visualization tool  

E-print Network

Software cost estimation based on multivariate data from completed projects requires the building of efficient models. These models essentially describe relations in the data, either on the basis of correlations between variables or of similarities between the projects. The continuous growth of the amount of data gathered and the need to perform preliminary analysis in order to discover patterns able to drive the building of reasonable models, leads the researchers towards intelligent and time-saving tools which can effectively describe data and their relationships. The goal of this paper is to suggest an innovative visualization tool, widely used in bioinformatics, which represents relations in data in an aesthetic and intelligent way. In order to illustrate the capabilities of the tool, we use a well known dataset from software engineering projects.

Kosti, Makrina Viola; Bourazani, Nikoleta; Angelis, Lefteris

2011-01-01

373

Increasing robustness against background noise: visual pattern recognition by a neocognitron.  

PubMed

The neocognitron is a hierarchical multi-layered neural network capable of robust visual pattern recognition. It has been demonstrated that recent versions of the neocognitron exhibit excellent performance for recognizing handwritten digits. When characters are written on a noisy background, however, recognition rate was not always satisfactory. To find out the causes of vulnerability to noise, this paper analyzes the behavior of feature-extracting S-cells. It then proposes the use of subtractive inhibition to S-cells from V-cells, which calculate the average of input signals to the S-cells with a root-mean-square. Together with this, several modifications have also been applied to the neocognitron. Computer simulation shows that the new neocognitron is much more robust against background noise than the conventional ones. PMID:21482455

Fukushima, Kunihiko

2011-09-01

374

Pattern-reversal visual-evoked potential in patients with occult macular dystrophy  

PubMed Central

Purpose: Occult macular dystrophy (OMD) is a hereditary retinal disease characterized by a normal fundus, normal full-field electroretinograms (ERGs), progressive decrease of visual acuity, and abnormal focal macular ERGs. The purpose of this study was to report pattern-reversal visual-evoked potential (pVEPs) findings in OMD patients. Patients and method: The pVEPs recorded from four patients with OMD (aged 42–61 years; 2 men and 2 women) were reviewed. The visual acuities ranged from 20/200 to 20/30. The amplitudes of the N-75 and P-100 (P2 amplitude) and the latency of the N-75 components (N1 latency) were analyzed. Results: The mean (±SD) P2 amplitude was 2.7 ± 1.9 ?V for the 5?, 4.8 ± 2.9 ?V for the 10?, 3.2 ± 2.1 ?V for the 20?, and 4.4 ± 3.5 ?V for the 40? checkerboard stimuli. The N1 latency was 122.2 ± 6.4 ms for the 5?, 105.0 ± 11.5 ms for the 10?, 97.7 ± 10.0 ms for the 20?, and 91.0 ± 13.7 ms for the 40? checkerboard stimuli. The mean P2 amplitude was reduced and the N1 latency was delayed in comparison with the laboratory standard for the Keio University Hospital. Conclusions: The delayed latency and reduced amplitude suggest a major contribution of the central cone pathway to the pVEPs. PMID:21191449

Hanazono, Gen; Ohde, Hisao; Shinoda, Kei; Tsunoda, Kazushige; Tsubota, Kazuo; Miyake, Yozo

2010-01-01

375

Intracellular Trafficking in Drosophila Visual System Development: A Basis for Pattern Formation Through Simple Mechanisms  

PubMed Central

Intracellular trafficking underlies cellular functions ranging from membrane remodeling to receptor activation. During multicellular organ development, these basic cell biological functions are required as both passive machinery and active signaling regulators. Exocytosis, endocytosis, and recycling of several key signaling receptors have long been known to actively regulate morphogenesis and pattern formation during Drosophila eye development. Hence, intracellular membrane trafficking not only sets the cell biological stage for receptor-mediated signaling but also actively controls signaling through spatiotemporally regulated receptor localization. In contrast to eye development, the role of intracellular trafficking for the establishment of the eye-to-brain connectivity map has only recently received more attention. It is still poorly understood how guidance receptors are spatiotemporally regulated to serve as meaningful synapse formation signals. Yet, the Drosophila visual system provides some of the most striking examples for the regulatory role of intracellular trafficking during multicellular organ development. In this review we will first highlight the experimental and conceptual advances that motivate the study of intracellular trafficking during Drosophila visual system development. We will then illuminate the development of the eye, the eye-to-brain connectivity map and the optic lobe from the perspective of cell biological dynamics. Finally, we provide a conceptual framework that seeks to explain how the interplay of simple genetically encoded intracellular trafficking events governs the seemingly complex cellular behaviors, which in turn determine the developmental product. PMID:21714102

Chan, Chih-Chiang; Epstein, Daniel; Hiesinger, P. Robin

2012-01-01

376

Breast screening: visual search as an aid for digital mammographic interpretation training  

NASA Astrophysics Data System (ADS)

Digital mammography is gradually being introduced across all breast screening centres in the UK during 2010. This provides increased training opportunities using lower resolution, lower cost and more widely available devices, in addition to the clinical digital mammography workstations. This study examined how experienced breast screening personnel performed when they examined sets of difficult DICOM two-view screening cases in three conditions: on GE digital mammography workstations, on a standard LCD monitor (using a DICOM viewer) and an iPhone (running Osirix software). In each condition they either viewed the full images unaided or were permitted to use the post-processing manipulations of pan, zoom and window level/width adjustments. For each case they had to report the feature type, rate their confidence on the presence of abnormality, classify the case and specify case density. Their visual search behaviour was recorded throughout using a head mounted eye tracker. Additionally aspects of their real life screening performance and performance on a national self assessment scheme were examined. Data indicate that screening experience plays a major role in doing well on the self assessment scheme. Task performance was best on the clinical workstation. However, the data also suggest that a DICOM viewer that runs on a PC or laptop with a standard LCD display allows viewing digital images in full resolution support impressive cancer detection performance. The iPhone is not ideal for examining full images due to the amount of scrolling and zooming required. Overall, the results indicate that low cost devices could be used to provide additional tailored training as long as device resolution and HCI aspects are carefully considered.

Chen, Yan; Turnbull, Ann; James, Jonathan; Gale, Alastair; Scott, Hazel

2010-02-01

377

The Role of Fear-Relevant Stimuli in Visual Search: A Comparison of Phylogenetic and Ontogenetic Stimuli  

Microsoft Academic Search

It has been argued that phylogenetic fear-relevant stimuli elicit preattentive capture of attention. To distinguish between fear relevance and time of appearance in evolutionary history, the authors compare phylogenetic and ontogenetic fear-relevant and fear-irrelevant stimuli in a visual search task. The authors found no evidence for a special role of phylogenetic fear-relevant stimuli; it seems that fear relevance in general

Tobias Brosch; Dinkar Sharma

2005-01-01

378

Effects of 10 h time zone changes on female flight attendants' circadian rhythms of body temperature, alertness, and visual search  

Microsoft Academic Search

The aim of the study was to analyse the effects of rapid time zone changes on the circadian rhythms of flight attendants. The mean age of the 40 female subjects was 30·0 (SD=6·9) years. Measurements of oral temperature, alertness, and visual search were performed at two hour intervals two days before the flight from Helsinki to Los Angeles, during the

S. SUVANTO; M. HÄRMÄ; J. ILMARINEN; M. PARTINEN

1993-01-01

379

Visualization and Phospholipid Identification (VaLID): online integrated search engine capable of identifying and visualizing glycerophospholipids with given mass  

PubMed Central

Motivation: Establishing phospholipid identities in large lipidomic datasets is a labour-intensive process. Where genomics and proteomics capitalize on sequence-based signatures, glycerophospholipids lack easily definable molecular fingerprints. Carbon chain length, degree of unsaturation, linkage, and polar head group identity must be calculated from mass to charge (m/z) ratios under defined mass spectrometry (MS) conditions. Given increasing MS sensitivity, many m/z values are not represented in existing prediction engines. To address this need, Visualization and Phospholipid Identification is a web-based application that returns all theoretically possible phospholipids for any m/z value and MS condition. Visualization algorithms produce multiple chemical structure files for each species. Curated lipids detected by the Canadian Institutes of Health Research Training Program in Neurodegenerative Lipidomics are provided as high-resolution structures. Availability: VaLID is available through the Canadian Institutes of Health Research Training Program in Neurodegenerative Lipidomics resources web site at https://www.med.uottawa.ca/lipidomics/resources.html. Contacts: lipawrd@uottawa.ca Supplementary Information: Supplementary data are available at Bioinformatics online. PMID:23162086

Figeys, Daniel; Fai, Stephen; Bennett, Steffany A. L.

2013-01-01

380

Accuracy of Using Visual Identification of White Sharks to Estimate Residency Patterns  

PubMed Central

Determining the residency of an aquatic species is important but challenging and it remains unclear what is the best sampling methodology. Photo-identification has been used extensively to estimate patterns of animals' residency and is arguably the most common approach, but it may not be the most effective approach in marine environments. To examine this, in 2005, we deployed acoustic transmitters on 22 white sharks (Carcharodon carcharias) in Mossel Bay, South Africa to quantify the probability of detecting these tagged sharks by photo-identification and different deployment strategies of acoustic telemetry equipment. Using the data collected by the different sampling approaches (detections from an acoustic listening station deployed under a chumming vessel versus those from visual sightings and photo-identification), we quantified the methodologies' probability of detection and determined if the sampling approaches, also including an acoustic telemetry array, produce comparable results for patterns of residency. Photo-identification had the lowest probability of detection and underestimated residency. The underestimation is driven by various factors primarily that acoustic telemetry monitors a large area and this reduces the occurrence of false negatives. Therefore, we propose that researchers need to use acoustic telemetry and also continue to develop new sampling approaches as photo-identification techniques are inadequate to determine residency. Using the methods presented in this paper will allow researchers to further refine sampling approaches that enable them to collect more accurate data that will result in better research and more informed management efforts and policy decisions. PMID:22514662

Delaney, David G.; Johnson, Ryan; Bester, Marthan N.; Gennari, Enrico

2012-01-01

381

The emergence of duality of patterning through iterated learning: Precursors to phonology in a visual lexicon  

PubMed Central

Duality of Patterning, one of Hockett’s (1960) proposed design features unique to human language, refers in part to the arrangements of a relatively small stock of distinguishable meaningless sounds which are combined to create a potentially infinite set of morphemes. Literature regarding the emergence of this design feature is less abundant than that exploring other levels of structure as focus is more often given to the emergence of syntax. In an effort to explore where combinatorial structure of meaningless elements arises the results of two pilot experiments are presented within which we observe human participants modifying a small lexicon of visual symbols through a process of iterated learning. As this lexicon evolves there is evidence that it becomes simpler and more learnable, more easily transmitted. I argue that these features are a consequence of spontaneous emergence of combinatorial, sub-lexical structure in the lexicon, that the pattern of emergence is more complex than the most widely espoused explanation suggests, and I propose ways in which future work can build on what we learn from these pilot experiments to confirm this hypothesis. PMID:23205149

Giudice, Alex Del

2012-01-01

382

Right fusiform response patterns reflect visual object identity rather than semantic similarity.  

PubMed

We previously reported the neuropsychological consequences of a lesion confined to the middle and posterior part of the right fusiform gyrus (case JA) causing a partial loss of knowledge of visual attributes of concrete entities in the absence of category-selectivity (animate versus inanimate). We interpreted this in the context of a two-step model that distinguishes structural description knowledge from associative-semantic processing and implicated the lesioned area in the former process. To test this hypothesis in the intact brain, multi-voxel pattern analysis was used in a series of event-related fMRI studies in a total of 46 healthy subjects. We predicted that activity patterns in this region would be determined by the identity of rather than the conceptual similarity between concrete entities. In a prior behavioral experiment features were generated for each entity by more than 1000 subjects. Based on a hierarchical clustering analysis the entities were organised into 3 semantic clusters (musical instruments, vehicles, tools). Entities were presented as words or pictures. With foveal presentation of pictures, cosine similarity between fMRI response patterns in right fusiform cortex appeared to reflect both the identity of and the semantic similarity between the entities. No such effects were found for words in this region. The effect of object identity was invariant for location, scaling, orientation axis and color (grayscale versus color). It also persisted for different exemplars referring to a same concrete entity. The apparent semantic similarity effect however was not invariant. This study provides further support for a neurobiological distinction between structural description knowledge and processing of semantic relationships and confirms the role of right mid-posterior fusiform cortex in the former process, in accordance with previous lesion evidence. PMID:23811413

Bruffaerts, Rose; Dupont, Patrick; De Grauwe, Sophie; Peeters, Ronald; De Deyne, Simon; Storms, Gerrit; Vandenberghe, Rik

2013-12-01

383

Unequal-arm Adaptive Rood Pattern Search with Early Terminations For Fast Block-matching Motion Estimation on H.264  

Microsoft Academic Search

Based on a rood-shaped pattern of the motion-vector displacement distribution inherently resulted from block-matching motion estimation, a series of adaptive rood pattern search (ARPS) algorithms have been introduced. Among them, the unequal-arm ARPS has achieved superior performance on many accounts while maintaining a fairly close rate-distortion performance compared with that of the full search. In this paper, an enhanced version

Bin Li; Kai-kuang Ma

2006-01-01

384

PROSPECT improves cis-acting regulatory element prediction by integrating expression profile data with consensus pattern searches  

Microsoft Academic Search

Consensus pattern and matrix-based searches designed to predict cis-acting transcriptional regula- tory sequences have historically been subject to large numbers of false positives. We sought to decrease false positives by incorporating expression profile data into a consensus pattern-based search method. We have systematically analyzed the expression phenotypes of over 6000 yeast genes, across 121 expression profile experiments, and correlated them

Wataru Fujibuchi; John S. J. Anderson; David Landsman

385

Iso-orientation domains in cat visual cortex are arranged in pinwheel-like patterns  

NASA Astrophysics Data System (ADS)

THE mammalian cortex is organized in a columnar fashion: neurons lying below each other from the pia to the white matter usually share many functional properties. Across the cortical surface, cells with similar response properties are also clustered together, forming elongated bands or patches. Some response properties, such as orientation preference in the visual cortex, change gradually across the cortical surface forming 'orientation maps'. To determine the precise layout of iso-orientation domains, knowledge of responses not only to one but to many stimulus orientations is essential. Therefore, the exact depiction of orientation maps has been hampered by technical difficulties and remained controversial for almost thirty years. Here we use in vivo optical imaging based on intrinsic signals to gather information on the responses of a piece of cortex to gratings in many different orientations. This complete set of responses then provides detailed information on the structure of the orientation map in a large patch of cortex from area 18 of the cat. We find that cortical regions that respond best to one orientation form highly ordered patches rather than elongated bands. These iso-orientation patches are organized around 'orientation centres', producing pinwheel-like patterns in which the orientation preference of cells is changing continuously across the cortex. We have also analysed our data for fast changes in orientation preference and find that these 'fractures' are limited to the orientation centres. The pinwheels and orientation centres are such a prominent organizational feature that it should be important to understand their development as well as their function in the processing of visual information.

Bonhoeffer, Tobias; Grinvald, Amiram

1991-10-01

386

APPSPACK 4.0 : asynchronous parallel pattern search for derivative-free optimization.  

SciTech Connect

APPSPACK is software for solving unconstrained and bound constrained optimization problems. It implements an asynchronous parallel pattern search method that has been specifically designed for problems characterized by expensive function evaluations. Using APPSPACK to solve optimization problems has several advantages: No derivative information is needed; the procedure for evaluating the objective function can be executed via a separate program or script; the code can be run in serial or parallel, regardless of whether or not the function evaluation itself is parallel; and the software is freely available. We describe the underlying algorithm, data structures, and features of APPSPACK version 4.0 as well as how to use and customize the software.

Gray, Genetha Anne; Kolda, Tamara Gibson

2004-12-01

387

Search Patterns and Absorptive Capacity: A Comparison of Low and High-Technology Firms from Thirteen European Countries  

Microsoft Academic Search

Searching for externally available knowledge has been characterised as a vital part of the innovation process. Previous research has, however, almost exclusively focused on hightechnology environments, largely ignoring the substantial low- and medium-technology sectors of modern economies. We argue that low- and high-technology firms differ in their search patterns and that these moderate the relationship between innovation inputs and outputs.

Christoph Grimpe; Wolfgang Sofka

2007-01-01

388

Social and Non-Social Visual Attention Patterns and Associative Learning in Infants at Risk for Autism  

ERIC Educational Resources Information Center

Background: Social inattention is common in children with autism whereas associative learning capabilities are considered a relative strength. Identifying early precursors of impairment associated with autism could lead to earlier identification of this disorder. The present study compared social and non-social visual attention patterns as well as…

Bhat, A. N.; Galloway, J. C.; Landa, R. J.

2010-01-01

389

Spatio-temporal patterns of antennal movements in the searching cockroach.  

PubMed

To characterize the spatio-temporal patterns of antennal behavior in insects, the voluntary movement of both right and left antennae was examined in the cockroach Periplaneta americana. The position of the tip of the antenna (flagellum) is controlled by two mobile joints at its base (the scape and the pedicel) and by the neck. Horizontal and vertical components of movement at the antennal basal joints exhibited rhythmic activities during locomotory (walking) and non-locomotory (pausing) states in the searching animal. In both states, the horizontal component was slower than vertical one. Joint-manipulation experiments suggested that the faster vertical component is due mainly to movements of the scape-pedicel joint, while the slower horizontal component may originate from the head-scape joint. Large horizontal deflections of the antenna corresponded consistently with the yaw component of head movement. The trajectories of the antennae showed little patterned regularity in most animals. In a few cases, however, loop-like patterns appeared. The area scanned by an antenna was narrower in the walking state than in the pausing state, mainly because of a decrease in the horizontal angular range. Cross-correlation analyses revealed that the coupling between right and left horizontal antennal motor systems and that for the vertical systems were both significantly stronger in the walking state than during pausing. These results indicate that the spatio-temporal pattern of antennal movements changes dynamically depending on the animal's behavioral state. PMID:15371477

Okada, Jiro; Toh, Yoshihiro

2004-10-01

390

Learning about Locomotion Patterns from Visualizations: Effects of Presentation Format and Realism  

ERIC Educational Resources Information Center

The rapid development of computer graphics technology has made possible an easy integration of dynamic visualizations into computer-based learning environments. This study examines the relative effectiveness of dynamic visualizations, compared either to sequentially or simultaneously presented static visualizations. Moreover, the degree of realism…

Imhof, Birgit; Scheiter, Katharina; Gerjets, Peter

2011-01-01

391

Effects of Scleral Search Coil Wear on Visual Function Elizabeth L. Irving,1  

E-print Network

were taken for both eyes: tonometry (noncontact), corneal topography, biomicroscopic examination, buckling of the iris, grade 2 and 3 corneal stain- ing, and reduction in visual acuity. Effects appeared

Allison, Robert

392

Parasite Lost: Chemical and Visual Cues Used by Pseudacteon in Search of Azteca instabilis  

Microsoft Academic Search

An undescribed species of phorid fly (genus: Pseudacteon) parasitizes the ant Azteca instabilis F Smith, by first locating these ants through the use of both chemical and visual cues. Experiments were performed in Chiapas,\\u000a Mexico to examine a) the anatomical source of phorid attractants, b) the specific chemicals produced that attract phorids,\\u000a and c) the nature of the visual cues

Kaitlyn A. Mathis; Stacy M. Philpott; Rayane F. Moreira

2011-01-01

393

More than Just Finding Color: Strategy in Global Visual Search Is Shaped by Learned Target Probabilities  

ERIC Educational Resources Information Center

In 2 experiments, eye movements were examined during searches in which elements were grouped into four 9-item clusters. The target (a red or blue "T") was known in advance, and each cluster contained different numbers of target-color elements. Rather than color composition of a cluster invariantly guiding the order of search though clusters, the…

Williams, Carrick C.; Pollatsek, Alexander; Cave, Kyle R.; Stroud, Michael J.

2009-01-01

394

Combining Propagation Information and Search Tree Visualization using ILOG OPL Studio  

Microsoft Academic Search

In this paper we give an overview of the current state of the graphical features provided by ILOG OPL Studio for debugging and performance tuning of OPL programs or external ILOG Solver based applications. This paper focuses on combining propagation and search information using the Search Tree view and the Propagation Spy. A new synthetic view is presented: the Christmas

Christiane Bracchi; Christophe Gefflot; Frederic Paulin

2001-01-01

395

Three-dimensional visualization and image processing in the evaluation of patterned injuries. The AFIP/UNC experience in the Rodney King case.  

PubMed

We used image processing to elucidate patterned injuries in a case of assault with a police baton. Three-dimensional visualization techniques were then used to correlate the location of patterned injuries with subjacent fracture and soft tissue damage. The visualization methods are discussed. PMID:9095293

Oliver, W R; Boxwala, A; Rosenman, J; Cullip, T; Symon, J; Wagner, G

1997-03-01

396

Further evaluation of the Walter Reed Visual Assessment Scale: correlation with curve pattern and radiological deformity  

PubMed Central

Background The Walter Reed Visual Assessment Scale (WRVAS) was designed to measure physical deformity as perceived by patients with idiopathic scoliosis. Previous studies have shown that the instrument has excellent internal consistency and a high correlation with the radiological magnitude of scoliotic curves. Nonetheless, it is not known whether the scale can discriminate between the various curve patterns of the deformity, or whether the deformities represented in the scale's drawings relate to the corresponding radiological deformities. Methods This study included 101 patients (86 women and 15 men; mean age 19.4 years) with idiopathic scoliosis. In a single visit, patients underwent standing PA radiography of the spine and completed the WRVAS. X-ray measurements included: 1) magnitude (Cobb angle) of the proximal thoracic curve (PT), main thoracic curve (MT), and thoracolumbar/lumbar curve (TL/L); 2) difference in shoulder level; 3) T1 offset from the central sacral line (T1-CSL); 4) apical vertebra (apV) rotation at the MT and TL/L curves and 5) apical vertebra offset of the MT and TL/L curves from the central sacral line. A variable designated Cobbmax was defined as the largest angle of the three curves (PT, MT or TL/L). Patients were grouped onto three patterns: Thoracic (TH Group)(n = 30, mean MT 42.1°, TL/L 20.9°); double major (DM Group) (n = 39, mean MT 38.6°, TL/L 34.4°) and thoracolumbar (TL Group)(n = 32, mean MT 14.3°, TL/L 25.5°). The magnitude of the curves in the TL Group was significantly smaller than in the other groups (P < 0.05). The Spearman partial correlation coefficient was determined between the score for each WRVAS question and the curve pattern, adjusting for the Cobbmax variable. The Spearman correlation coefficient was determined between the WRVAS items and shoulder imbalance, T1-CSL offset, MT Cobb angle, MT apV rotation, MT apV offset, PT Cobb, TL/L Cobb, TL/L apV rotation and TL/L apV offset. Results The median (interquartile range) of the total WRVAS score was 14 (IQR 6). No correlation was found between the curve pattern and the various scores on the scale (partial correlation coefficients ranged from -0.16 to 0.12). WRVAS drawings for items 1, 2, 4 and 7 correlated satisfactorily with the corresponding radiological measurements (correlation coefficients, 0.62, 0.3, 0.48 and 0.53, respectively). Items 3, 5 and 6 did not correlate with the radiological measurements (correlation coefficients -0.06, -0.07 and 0.05, respectively). Conclusion The profile of the individual WRVAS scores does not differentiate among specific curve patterns (thoracic, double major and thoracolumbar/lumbar). Moreover, some of the drawings (items 3, 5 and 6) do not correlate with the radiological deformity they were designed to measure. PMID:17888178

Bago, Juan; Climent, Jose M; Pineda, Sonia; Gilperez, Carmen

2007-01-01

397

Relationship between BOLD amplitude and pattern classification of orientation-selective activity in the human visual cortex.  

PubMed

Orientation-selective responses can be decoded from fMRI activity patterns in the human visual cortex, using multivariate pattern analysis (MVPA). To what extent do these feature-selective activity patterns depend on the strength and quality of the sensory input, and might the reliability of these activity patterns be predicted by the gross amplitude of the stimulus-driven BOLD response? Observers viewed oriented gratings that varied in luminance contrast (4, 20 or 100%) or spatial frequency (0.25, 1.0 or 4.0 cpd). As predicted, activity patterns in early visual areas led to better discrimination of orientations presented at high than low contrast, with greater effects of contrast found in area V1 than in V3. A second experiment revealed generally better decoding of orientations at low or moderate as compared to high spatial frequencies. Interestingly however, V1 exhibited a relative advantage at discriminating high spatial frequency orientations, consistent with the finer scale of representation in the primary visual cortex. In both experiments, the reliability of these orientation-selective activity patterns was well predicted by the average BOLD amplitude in each region of interest, as indicated by correlation analyses, as well as decoding applied to a simple model of voxel responses to simulated orientation columns. Moreover, individual differences in decoding accuracy could be predicted by the signal-to-noise ratio of an individual's BOLD response. Our results indicate that decoding accuracy can be well predicted by incorporating the amplitude of the BOLD response into simple simulation models of cortical selectivity; such models could prove useful in future applications of fMRI pattern classification. PMID:22917989

Tong, Frank; Harrison, Stephenie A; Dewey, John A; Kamitani, Yukiyasu

2012-11-15

398

Predicting Glycerophosphoinositol Identities in Lipidomic Datasets Using VaLID (Visualization and Phospholipid Identification)--An Online Bioinformatic Search Engine  

PubMed Central

The capacity to predict and visualize all theoretically possible glycerophospholipid molecular identities present in lipidomic datasets is currently limited. To address this issue, we expanded the search-engine and compositional databases of the online Visualization and Phospholipid Identification (VaLID) bioinformatic tool to include the glycerophosphoinositol superfamily. VaLID v1.0.0 originally allowed exact and average mass libraries of 736,584 individual species from eight phospholipid classes: glycerophosphates, glyceropyrophosphates, glycerophosphocholines, glycerophosphoethanolamines, glycerophosphoglycerols, glycerophosphoglycerophosphates, glycerophosphoserines, and cytidine 5?-diphosphate 1,2-diacyl-sn-glycerols to be searched for any mass to charge value (with adjustable tolerance levels) under a variety of mass spectrometry conditions. Here, we describe an update that now includes all possible glycerophosphoinositols, glycerophosphoinositol monophosphates, glycerophosphoinositol bisphosphates, and glycerophosphoinositol trisphosphates. This update expands the total number of lipid species represented in the VaLID v2.0.0 database to 1,473,168 phospholipids. Each phospholipid can be generated in skeletal representation. A subset of species curated by the Canadian Institutes of Health Research Training Program in Neurodegenerative Lipidomics (CTPNL) team is provided as an array of high-resolution structures. VaLID is freely available and responds to all users through the CTPNL resources web site. PMID:24701584

McDowell, Graeme S. V.; Taylor, Graeme P.; Fai, Stephen; Bennett, Steffany A. L.

2014-01-01

399

Predicting glycerophosphoinositol identities in lipidomic datasets using VaLID (Visualization and Phospholipid Identification)--an online bioinformatic search engine.  

PubMed

The capacity to predict and visualize all theoretically possible glycerophospholipid molecular identities present in lipidomic datasets is currently limited. To address this issue, we expanded the search-engine and compositional databases of the online Visualization and Phospholipid Identification (VaLID) bioinformatic tool to include the glycerophosphoinositol superfamily. VaLID v1.0.0 originally allowed exact and average mass libraries of 736,584 individual species from eight phospholipid classes: glycerophosphates, glyceropyrophosphates, glycerophosphocholines, glycerophosphoethanolamines, glycerophosphoglycerols, glycerophosphoglycerophosphates, glycerophosphoserines, and cytidine 5'-diphosphate 1,2-diacyl-sn-glycerols to be searched for any mass to charge value (with adjustable tolerance levels) under a variety of mass spectrometry conditions. Here, we describe an update that now includes all possible glycerophosphoinositols, glycerophosphoinositol monophosphates, glycerophosphoinositol bisphosphates, and glycerophosphoinositol trisphosphates. This update expands the total number of lipid species represented in the VaLID v2.0.0 database to 1,473,168 phospholipids. Each phospholipid can be generated in skeletal representation. A subset of species curated by the Canadian Institutes of Health Research Training Program in Neurodegenerative Lipidomics (CTPNL) team is provided as an array of high-resolution structures. VaLID is freely available and responds to all users through the CTPNL resources web site. PMID:24701584

McDowell, Graeme S V; Blanchard, Alexandre P; Taylor, Graeme P; Figeys, Daniel; Fai, Stephen; Bennett, Steffany A L

2014-01-01

400

PseudoBase++: an extension of PseudoBase for easy searching, formatting and visualization of pseudoknots  

PubMed Central

Pseudoknots have been recognized to be an important type of RNA secondary structures responsible for many biological functions. PseudoBase, a widely used database of pseudoknot secondary structures developed at Leiden University, contains over 250 records of pseudoknots obtained in the past 25 years through crystallography, NMR, mutational experiments and sequence comparisons. To promptly address the growing analysis requests of the researchers on RNA structures and bring together information from multiple sources across the Internet to a single platform, we designed and implemented PseudoBase++, an extension of PseudoBase for easy searching, formatting and visualization of pseudoknots. PseudoBase++ (http://pseudobaseplusplus.utep.edu) maps the PseudoBase dataset into a searchable relational database including additional functionalities such as pseudoknot type. PseudoBase++ links each pseudoknot in PseudoBase to the GenBank record of the corresponding nucleotide sequence and allows scientists to automatically visualize RNA secondary structures with PseudoViewer. It also includes the capabilities of fine-grained reference searching and collecting new pseudoknot information. PMID:18988624

Taufer, Michela; Licon, Abel; Araiza, Roberto; Mireles, David; van Batenburg, F. H. D.; Gultyaev, Alexander P.; Leung, Ming-Ying

2009-01-01

401

Age-Dependant Behavioral Strategies in a Visual Search Task in Baboons (Papio papio) and Their Relation to Inhibitory Control  

PubMed Central

A computerized visual search task was presented to 18 guinea baboons (Papio papio) ranging from 2.7 to 14.3 years of age. The task, inspired from Hick’s (1952) task, required detection of a target among a variable number of distractors equidistant to a start button. The reaction times (RTs) and movement times both increased with the number of distractors expressed in bits of information. However, the slope of RT per bit function correlated positively with age, whereas a negative correlation was found for the movement time slopes. In Experiment 2, the same baboons were required to inhibit an ongoing manual pointing toward a target stimulus, to reengage in a new point as a consequence of a change in target location. Results revealed a more accurate performance in the adults, suggesting that differences in behavioral strategies in Experiment 1 can be accounted for by a greater inhibitory control of the adult participants. Implications of these results are discussed regarding the relation between attention, inhibitory control, and behavioral strategies in monkeys, and the general significance of RT slopes in visual search tasks. PMID:22142038

Fagot, Joel; Bonte, Elodie; Hopkins, William D.

2014-01-01

402

Reliability of Macaque Frontal Eye Field Neurons Signaling Saccade Targets during Visual Search  

Microsoft Academic Search

Although many studies have explored the neural correlates of visual attention and selection, few have examined the reliability with which neurons represent relevant information. We moni- tored activity in the frontal eye field (FEF) of monkeys trained to make a saccade to a target defined by the conjunction of color and shape or to a target defined by color differences.

Narcisse P. Bichot; Kirk G. Thompson; S. Chenchal Rao; Jeffrey D. Schall

2001-01-01

403

A Visual Search Inspired Computational Model for Ship Detection in Optical Satellite Images  

Microsoft Academic Search

In this letter, we propose a novel computational model for automatic ship detection in optical satellite images. The model first selects salient candidate regions across entire detection scene by using a bottom-up visual attention mechanism. Then, two complementary types of top-down cues are employed to discriminate the selected ship candidates. Specifically, in addition to the detailed appearance analysis of candidates,

Fukun Bi; Bocheng Zhu; Lining Gao; Mingming Bian

2012-01-01

404

Transcranial Magnetic Stimulation Reveals Attentional Feedback to Area V1 during Serial Visual Search  

E-print Network

Transcranial Magnetic Stimulation Reveals Attentional Feedback to Area V1 during Serial Visual study from Juan & Walsh (2003) had used Transcranial Magnetic Stimulation (TMS) to support, Marque P, VanRullen R (2011) Transcranial Magnetic Stimulation Reveals Attentional Feedback to Area V1

Paris-Sud XI, Université de

405

Application of pattern recognition in molecular spectroscopy: Automatic line search in high-resolution spectra  

NASA Astrophysics Data System (ADS)

An expert system has been developed for the initial analysis of a recorded spectrum, namely, for the line search and the determination of line positions and intensities. The expert system is based on pattern recognition algorithms. Object recognition learning allows the system to achieve the needed flexibility and automatically detect groups of overlapping lines, whose profiles should be fit together. Gauss, Lorentz, and Voigt profiles are used as model profiles to which spectral lines are fit. The expert system was applied to processing of the Fourier transform spectrum of the D2O molecule in the region 3200-4200 cm-1, and it detected 4670 lines in the spectrum, which consisted of 439000 dots. No one experimentally observed line exceeding the noise level was missed.

Bykov, A. D.; Pshenichnikov, A. M.; Sinitsa, L. N.; Shcherbakov, A. P.

2004-07-01

406

Distinguishing between target and nontarget fixations in a visual search task using fixation-related potentials.  

PubMed

The P300 event-related potential (ERP) can be used to infer whether an observer is looking at a target or not. Common practice in P300 experiments and applications is that observers are asked to fixate their eyes while stimuli are presented. We investigated the possibility to differentiate between single target and nontarget fixations in a target search task involving eye movements by using EEG epochs synchronized to fixation onset (fixation-related potentials: FRPs). Participants systematically scanned search displays consisting of six small Landolt Cs in search of Cs with a particular orientation. After each search display, they indicated whether and where target Cs had been presented. As expected, an FRP component consistent with the P300 reliably distinguished between target and nontarget fixations. It was possible to classify single FRPs into target and nontarget FRPs above chance (on average 62% correct, where 50% would be chance). These results are the first step to practical applications such as covertly monitoring observers' interests and supporting search tasks. PMID:23863335

Brouwer, Anne-Marie; Reuderink, Boris; Vincent, Joris; van Gerven, Marcel A J; van Erp, Jan B F

2013-01-01

407

Pattern shift visual evoked potentials in abstinent cocaine-dependent, alcohol-dependent, and cross-dependent patients  

Microsoft Academic Search

The present study evaluated pattern shift visual evoked potential (VEP) amplitudes and latencies in four groups of adult subjects, characterized by the presence\\/absence of a recent history of alcohol dependence factorially crossed with the presence\\/absence of a recent history of cocaine dependence. All of the subjects were healthy and uncomplicated by histories of serious head injury, seizures (including drug-related seizures),

Lance O. Bauer; Caroline Easton

1996-01-01

408

Identifying Shared Genetic Structure Patterns among Pacific Northwest Forest Taxa: Insights from Use of Visualization Tools and Computer Simulations  

Microsoft Academic Search

BackgroundIdentifying causal relationships in phylogeographic and landscape genetic investigations is notoriously difficult, but can be facilitated by use of multispecies comparisons.Methodology\\/Principal FindingsWe used data visualizations to identify common spatial patterns within single lineages of four taxa inhabiting Pacific Northwest forests (northern spotted owl: Strix occidentalis caurina; red tree vole: Arborimus longicaudus; southern torrent salamander: Rhyacotriton variegatus; and western white pine:

Mark P. Miller; Susan M. Haig

2010-01-01

409

Scan Patterns Predict Sentence Production in the Cross-Modal Processing of Visual Scenes  

ERIC Educational Resources Information Center

Most everyday tasks involve multiple modalities, which raises the question of how the processing of these modalities is coordinated by the cognitive system. In this paper, we focus on the coordination of visual attention and linguistic processing during speaking. Previous research has shown that objects in a visual scene are fixated before they…

Coco, Moreno I.; Keller, Frank

2012-01-01

410

Introducing a New Interface for the Online MagIC Database by Integrating Data Uploading, Searching, and Visualization  

NASA Astrophysics Data System (ADS)

The Magnetics Information Consortium (MagIC) is dedicated to supporting the paleomagnetic, geomagnetic, and rock magnetic communities through the development and maintenance of an online database (http://earthref.org/MAGIC/), data upload and quality control, searches, data downloads, and visualization tools. While MagIC has completed importing some of the IAGA paleomagnetic databases (TRANS, PINT, PSVRL, GPMDB) and continues to import others (ARCHEO, MAGST and SECVR), further individual data uploading from the community contributes a wealth of easily-accessible rich datasets. Previously uploading of data to the MagIC database required the use of an Excel spreadsheet using either a Mac or PC. The new method of uploading data utilizes an HTML 5 web interface where the only computer requirement is a modern browser. This web interface will highlight all errors discovered in the dataset at once instead of the iterative error checking process found in the previous Excel spreadsheet data checker. As a web service, the community will always have easy access to the most up-to-date and bug free version of the data upload software. The filtering search mechanism of the MagIC database has been changed to a more intuitive system where the data from each contribution is displayed in tables similar to how the data is uploaded (http://earthref.org/MAGIC/search/). Searches themselves can be saved as a permanent URL, if desired. The saved search URL could then be used as a citation in a publication. When appropriate, plots (equal area, Zijderveld, ARAI, demagnetization, etc.) are associated with the data to give the user a quicker understanding of the underlying dataset. The MagIC database will continue to evolve to meet the needs of the paleomagnetic, geomagnetic, and rock magnetic communities.

Jarboe, N.; Minnett, R.; Constable, C.; Koppers, A. A.; Tauxe, L.

2013-12-01

411

Fusion of multi-sensor imagery for night vision: color visualization, target learning and search  

Microsoft Academic Search

We present methods and results for fusion of imagery from multiple sensors to create a color night vision capability. The fusion system architectures are based on biological models of the spatial and opponent-color processes in the human retina and visual cortex, implemented as shunting center-surround feed-forward neural networks. Real-time implementation of the dual-sensor fusion system combines imagery from either a

D. A. Fay; A. M. Waxman; M. Aguilar; D. B. Ireland; J. P. Racamato; W. D. Ross; W. W. Streilein; M. I. Braun

2000-01-01

412

Feature asymmetries in visual search: Effects of display duration, target eccentricity, orientation and spatial frequency  

Microsoft Academic Search

In Experiments 1–3 we monitored search performance as a function of target eccentricity under display durations that either allowed or precluded eye movements. The display was present either until observers responded, for 104 msec, or for 62 msec. In all three experiments an orientation asymmetry emerged: observers detected a tilted target among vertical distributers more efficiently than a vertical target

Marisa Carrasco; Tracy L. McLean; Svetlana M. Katz; Karen S. Frieder

1998-01-01

413

Search Path Mapping: A Versatile Approach for Visualizing Problem-Solving Behavior.  

ERIC Educational Resources Information Center

Computer-based problem-solving examinations in immunology generate graphic representations of students' search paths, allowing evaluation of how organized and focused their knowledge is, how well their organization relates to critical concepts in immunology, where major misconceptions exist, and whether proper knowledge links exist between content…

Stevens, Ronald H.

1991-01-01

414

Lévy flight and Brownian search patterns of a free-ranging predator reflect different prey field characteristics.  

PubMed

1. Search processes play an important role in physical, chemical and biological systems. In animal foraging, the search strategy predators should use to search optimally for prey is an enduring question. Some models demonstrate that when prey is sparsely distributed, an optimal search pattern is a specialised random walk known as a Lévy flight, whereas when prey is abundant, simple Brownian motion is sufficiently efficient. These predictions form part of what has been termed the Lévy flight foraging hypothesis (LFF) which states that as Lévy flights optimise random searches, movements approximated by optimal Lévy flights may have naturally evolved in organisms to enhance encounters with targets (e.g. prey) when knowledge of their locations is incomplete. 2. Whether free-ranging predators exhibit the movement patterns predicted in the LFF hypothesis in response to known prey types and distributions, however, has not been determined. We tested this using vertical and horizontal movement data from electronic tagging of an apex predator, the great white shark Carcharodon carcharias, across widely differing habitats reflecting different prey types. 3. Individual white sharks exhibited movement patterns that predicted well the prey types expected under the LFF hypothesis. Shark movements were best approximated by Brownian motion when hunting near abundant, predictable sources of prey (e.g. seal colonies, fish aggregations), whereas movements approximating truncated Lévy flights were present when searching for sparsely distributed or potentially difficult-to-detect prey in oceanic or shelf environments, respectively. 4. That movement patterns approximated by truncated Lévy flights and Brownian behaviour were present in the predicted prey fields indicates search strategies adopted by white sharks appear to be the most efficient ones for encountering prey in the habitats where such patterns are observed. This suggests that C. carcharias appears capable of exhibiting search patterns that are approximated as optimal in response to encountered changes in prey type and abundance, and across diverse marine habitats, from the surf zone to the deep ocean. 5. Our results provide some support for the LFF hypothesis. However, it is possible that the observed Lévy patterns of white sharks may not arise from an adaptive behaviour but could be an emergent property arising from simple, straight-line movements between complex (e.g. fractal) distributions of prey. Experimental studies are needed in vertebrates to test for the presence of Lévy behaviour patterns in the absence of complex prey distributions. PMID:22004140

Sims, David W; Humphries, Nicolas E; Bradford, Russell W; Bruce, Barry D

2012-03-01

415

User experience (UX) patterns for audio-visual networked applications: inspirations for design  

Microsoft Academic Search

This paper summarizes best practices for improving user experience (UX) of audio-visual networked applications such as YouTube, Flickr, or Facebook. Designing for a good UX is becoming increasingly important within the HCI community. However, there is still a lack of empirically based knowledge on how to design audio-visual networked applications for an optimal UX. Based on studies with more than

Marianna Obrist; Daniela Wurhofer; Elke Beck; Amela Karahasanovic; Manfred Tscheligi

2010-01-01

416

The Development of Visual Search in Infants and Very Young Children  

Microsoft Academic Search

In two experiments, 90 1- to 3-year-olds were trained in a new nonverbal task to touch a video screen that displayed a unique target resembling a popular television character. The target appeared among varying numbers of distractors that resembled another familiar television character and was either a uniquely colored shape (the feature search task) or a unique color-shape combination (the

Peter Gerhardstein; Carolyn Rovee-Collier

2002-01-01

417

When and why might a Computer Aided Detection (CAD) system interfere with visual search? An eye-tracking study  

PubMed Central

Rational and Objectives Computer Aided Detection (CAD) systems are intended to improve performance. This study investigates how CAD might actually interfere with a visual search task. This is a laboratory study with implications for clinical use of CAD. Methods 47 naïve observers in two studies were asked to search for a target, embedded in 1/f2.4 noise while we monitored their eye-movements. For some observers, a CAD system marked 75% of targets and 10% of distractors while other observers completed the study without CAD. In Experiment 1, the CAD system’s primary function was to tell observers where the target might be. In Experiment 2, CAD provided information about target identity. Results In Experiment 1, there was a significant enhancement of observer sensitivity in the presence of CAD (t(22)=4.74, p<.001), but there was also a substantial cost. Targets that were not marked by the CAD system were missed more frequently than equivalent targets in No CAD blocks of the experiment (t(22)=7.02, p<.001). Experiment 2 showed no behavioral benefit from CAD, but also no significant cost on sensitivity to unmarked targets (t(22)=0.6, p=n.s.). Finally, in both experiments, CAD produced reliable changes in eye-movements: CAD observers examined a lower total percentage of the search area than the No CAD observers (Ex 1: t(48)=3.05, p<.005; Ex 2: t(50)=7.31, p<.001). Conclusions CAD signals do not combine with observers’ unaided performance in a straight-forward manner. CAD can engender a sense of certainty that can lead to incomplete search and elevated chances of missing unmarked stimuli. PMID:22958720

Drew, Trafton; Cunningham, Corbin; Wolfe, Jeremy

2012-01-01

418

Using Geographic Information System to Visualize Travel Patterns and Market Research Data  

Microsoft Academic Search

Travel pattern data collected from a rural county in western North Carolina, United States, was analyzed using a geographic information system. Travel pattern data are valuable to destination marketers as it highlights potential regional promotions and development partners. Geographic information systems (GIS) can easily display in map form spatially oriented concepts such as travel patterns and provides easy viewing of

Charles Chancellor; Shu Cole

2008-01-01

419

Effect of head circumference on parameters of pattern reversal visual evoked potential in healthy adults of central India.  

PubMed

Visual evoked response testing has been one of the most exciting clinical tools to be developed from neurophysiologic research in recent years and has provided us with an objective method of identifying abnormalities of the afferent visual pathways. Investigation were carried out to see whether the head circumference influence the pattern reversal visual evoked potential (PRVEP) parameters. The study comprised of pattern reversal visual evoked potential (PRVEP) recordings in 400 eyes of 200 normal subjects. Two hundred fourty eight eyes were males and 152 eyes were from 76 female subjects recruited from the Central Indian population in the age range of 40-79 years. Visual evoked potential (VEP) recordings were performed in accordance to the standardized methodology of International Federation of Clinical Neurophysiology (IFCN) Committee Recommendations and International Society for Clinical Electrophysiology of Vision (ISCEV) Guidelines and montages were kept as per 10-20 International System of EEG Electrode placements. The stimulus configuration in this study consisted of the transient pattern reversal method in which a black and white checker board was generated (full field) and displayed on a VEP Monitor by an electronic pattern regenerator inbuilt in an Evoked Potential Recorder (RMS EMG EP MARK II). VEP latencies, duration and amplitude were measured in all subjects and the data were analyzed. The correlation of all the electrophysiological parameters with head circumference was evaluated by Pearson's correlation co-efficient (r) and its statistical significance was evaluated. The prediction equations for all the VEP parameters with respect to head circumference were derived. We found a positive correlation of P 100 latency and N 155 latency with mean head circumference, while a highly significant negative correlation were noted of P 100 amplitude with head circumference. N 70 latency was significantly correlated with head circumference. P 100 duration showed in negative correlation with head circumference. These findings suggest that VEP latencies, duration and amplitude are influenced by the head circumference of the individual in a sample of healthy subjects and head circumference can be a useful predictor of VEP peak latencies, amplitude and duration. PMID:23671950

Kothari, R; Singh, R; Singh, S; Bokariya, P

2012-06-01

420

Prediction for traffic accident severity: comparing the artificial neural network, genetic algorithm, combined genetic algorithm and pattern search methods  

Microsoft Academic Search

This paper focuses on predicting the severity of freeway traffic accidents by employing twelve accident-related parameters in a genetic algorithm (GA), pattern search and artificial neural network (ANN) modelling methods. The models were developed using the input parameters of driver's age and gender, the use of a seat belt, the type and safety of a vehicle, weather conditions, road surface,

Mehmet Metin Kunt; Iman Aghayan; Nima Noii

2011-01-01

421

Identification and functional characterization of two patterning genes, Zic4 and Ten_m3, in topographic map formation of the visual pathway  

E-print Network

A central feature of visual pathway development is its organization into retinotopic maps. The developmental process by which these maps form involves a transition from early patterning cues to arrays of axonal guidance ...

Horng, Sam H

2010-01-01

422

Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory  

E-print Network

Energy-dependent patterns in the arrival directions of cosmic rays are searched for using data of the Pierre Auger Observatory. We investigate local regions around the highest-energy cosmic rays with $E \\geq 6 \\cdot 10^{19}$ eV by analyzing cosmic rays with energies above $E = 5 \\cdot 10^{18}$ eV arriving within an angular separation of approximately $15{\\deg}$. We characterize the energy distributions inside these regions by two independent methods, one searching for angular dependence of energy-energy correlations and one searching for collimation of energy along the local system of principal axes of the energy distribution. No significant patterns are found with this analysis. The comparison of these measurements with astrophysical scenarios can therefore be used to obtain constraints on related model parameters such as strength of cosmic-ray deflection and density of point sources.

,

2014-01-01

423

In search of proteins that are important for synaptic functions in Drosophila visual system.  

PubMed

This is the second of two reviews that include some of the studies we, members of the Pak laboratory and collaborators, did from 2000 to 2010 on the mutants that affect synaptic transmission in the Drosophila visual system. Of the five mutants we discuss, two turned out to also play roles in the larval neuromuscular junction. This review complements the one on phototransduction to give a fairly complete account of what we focused on during the 10-year period, although we also did some studies on photoreceptor degeneration in the early part of the decade. Besides showing the power of using a genetic approach to the study of synaptic transmission, the review contains some unexpected results that illustrate the serendipitous nature of research. PMID:22283835

Kim, Eunju; Shino, Shikoh; Yoon, Jaeseung; Leung, Hung-Tat

2012-06-01

424

Effects of Symbol Brightness Cueing on Attention During a Visual Search of a Cockpit Display of Traffic Information  

NASA Technical Reports Server (NTRS)

This study investigated visual search performance for target aircraft symbols on a Cockpit Display of Traffic Information (CDTI). Of primary interest was the influence of target brightness (intensity) and highlighting validity (search directions) on the ability to detect a target aircraft among distractor aircraft. Target aircraft were distinguished by an airspace course that conflicted with Ownship (that is, the participant's aircraft). The display could present all (homogeneous) bright aircraft, all (homogeneous) dim aircraft, or mixed bright and dim aircraft, with the target aircraft being either bright or dim. In the mixed intensity condition, participants may or may not have been instructed whether the target was bright or dim. Results indicated that highlighting validity facilitated better detection times. However, instead of bright targets being detected faster, dim targets were found to be detected more slowly in the mixed intensity display than in the homogeneous display. This relative slowness may be due to a delay in confirming the dim aircraft to be a target when it it was among brighter distractor aircraft. This hypothesis will be tested in future research. Funding for this work was provided by the Advanced Air Transportation Technologies Project of NASA's Airspace Operation Systems Program.

Johnson, Walter W.; Liao, Min-Ju; Granada, Stacie

2003-01-01

425

Visual acts for goal-directed vision  

NASA Astrophysics Data System (ADS)

Humans use their senses, particularly vision, to interrogate the environment in search of information pertinent to the performance of a task. We say that the user has `visual goals', and we associate `visual acts' with these goals. Visual acts are patterns of `looking' displayed in acquiring the information. In this paper we present a model for visual acts which is based on known features of the human visual perception system and to illustrate the model we use as a case study a task which is typical of mechanical manipulation operations. The model is based on human perceptual discrimination and is motivated by a query-based model of the observer.

McKee, Gerard T.; Schenker, Paul S.

1994-10-01

426

Line Bisection in Parkinson's Disease: Investigation of Contributions of Visual Field, Retinal Vision, and Scanning Patterns to Visuospatial Function  

PubMed Central

Parkinson’s disease (PD) is characterized by disorders of visuospatial function that can impact everyday functioning. Visuospatial difficulties are more prominent in those whose motor symptoms begin on the left body side (LPD) than the right body side (RPD) and have mainly been attributed to parietal dysfunction. The source of visuospatial dysfunction is unclear, as in addition to subcortical–cortical changes, there are irregularities of visual scanning and potentially of retinal-level vision in PD. To assess these potential contributors, performance on a visuospatial task—line bisection—was examined together with retinal structure (nerve fiber layer thickness, measured by optical coherence tomography [OCT]), retinal function (contrast sensitivity, measured by frequency-doubling technology [FDT]), and visual scanning patterns. Participants included 20 nondemented patients (10 LPD, 10 RPD) and 11 normal control (NC) adults. Relative to the other groups, LPD were expected to show rightward bias on horizontal line bisection, especially within the left visual hemispace, and downward bias on vertical bisection. LPD relative rightward bias was confirmed, though not mainly within the left hemispace and not correlated with retinal structure or function. Retinal thinning was seen in LPD relative to RPD. Qualitative visualization of eye movements suggested greater LPD exploration of the right than left side of the line during horizontal bisection, and some overall compression of scanning range in RPD (both orientations) and LPD (primarily vertical). Results indicated that rightward visuospatial bias in our LPD sample arose not from abnormalities at the retinal level but potentially from attentional biases, reflected in eye movement patterns. PMID:23356329

Laudate, Thomas M.; Neargarder, Sandy; Cronin-Golomb, Alice

2013-01-01

427

Visual assessment of dopaminergic degeneration pattern in 123I-FP-CIT SPECT differentiates patients with atypical parkinsonian syndromes and idiopathic Parkinson's disease.  

PubMed

The aim of this study was to investigate whether visual assessment of (123)I-N-?-fluoropropyl-2?-carbomethoxy-3?-(4-iodophenyl)nortropan ((123)I-FP-CIT) single photon emission computed tomography (SPECT) in addition to quantitative analyses can help to differentiate idiopathic Parkinson's disease (PD) from atypical parkinsonian syndromes (APS). From a consecutive series of patients examined with (123)I-FP-CIT SPECT (n = 190) over a three-year period we identified 165 patients with a clinical diagnosis of PD (n = 120) or APS (n = 45). (123)I-FP-CIT SPECT results were analysed visually and quantitatively and compared for PD and APS and for the subgroup of patients with early PD and APS (disease duration <5 years). According to predefined visual patterns of dopaminergic degeneration the results were graded as normal (grade 5) or abnormal (grade 1-4), distinguishing a posterior-anterior degeneration pattern ("egg shape") from a global and severe degeneration pattern ("burst striatum"). Visual assessment of (123)I-FP-CIT SPECT showed significant different dopaminergic degeneration patterns for PD and APS patients. A grade 1 ("burst striatum") degeneration pattern was predominantly associated with APS patients. In contrast to that, a grade 2 (egg shape) degeneration pattern was the characteristic finding in PD patients. In a subgroup of patients with early disease, visual assessment with identification of the burst striatum degeneration pattern provided 90% positive predictive value and 99% specificity for the diagnosis of APS. Quantitative analysis of striatal binding ratios failed to depict these different degeneration patterns in PD and APS patients. Visual assessment of the pattern of dopaminergic loss in (123)I-FP-CIT SPECT shows different patterns of dopaminergic degeneration for PD and APS patients. Therefore, it could provide valuable information to distinguish APS from PD patients, especially in early stages of disease. Within the first 5 years of disease, the occurrence of a burst striatum degeneration pattern has a high positive predictive value of APS. PMID:21750954

Kahraman, Deniz; Eggers, Carsten; Schicha, Harald; Timmermann, Lars; Schmidt, Matthias

2012-02-01

428

JOB SEARCH PATTERNS OF COLLEGE GRADUATES: THE ROLE OF SOCIAL CAPITAL  

E-print Network

search. Key findings from this research indicate that the utility of educational credentials depends largely on social capital, suggesting that (1) social capital facilitates the job search; (2) the use of social capital varies because some graduates...

Coonfield, Emily Suzanne

2012-12-31

429

Understanding Patterns of User Visits to Web Sites: Interactive Star eld Visualizations of WWW Log Data  

E-print Network

those of traditional web log analysis tools. We in- troduce a series of interactive star eld providers, understanding of user visit patterns is essential for e ective design of sites involving online issues such as depth vs. breadth of tree structures, incidental learning patterns, utilityofgraphics

Shneiderman, Ben

430

Visualizing Interaction Patterns in Online Discussions and Indices of Cognitive Presence  

ERIC Educational Resources Information Center

This paper discusses Mapping Temporal Relations of Discussions Software (MTRDS), a Web-based application that visually represents the temporal relations of online discussions. MTRDS was used to observe interaction characteristics of three online discussions. In addition, the research employed the Practical Inquiry Model to identify indices of…

Gibbs, William J.

2006-01-01

431

Using Interactive Visualizations of WWW Log Data to Characterize Access Patterns and Inform Site Design  

E-print Network

that exceed those of traditional web log analysis tools. We introduce a series of interactive visualizations for effective design of sites involving online communities, government services, digital libraries, and electronic commerce. Such understanding helps