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Sample records for visual search patterns

  1. Priming cases disturb visual search patterns in screening mammography

    NASA Astrophysics Data System (ADS)

    Lewis, Sarah J.; Reed, Warren M.; Tan, Alvin N. K.; Brennan, Patrick C.; Lee, Warwick; Mello-Thoms, Claudia

    2015-03-01

    Rationale and Objectives: To investigate the effect of inserting obvious cancers into a screening set of mammograms on the visual search of radiologists. Previous research presents conflicting evidence as to the impact of priming in scenarios where prevalence is naturally low, such as in screening mammography. Materials and Methods: An observer performance and eye position analysis study was performed. Four expert breast radiologists were asked to interpret two sets of 40 screening mammograms. The Control Set contained 36 normal and 4 malignant cases (located at case # 9, 14, 25 and 37). The Primed Set contained the same 34 normal and 4 malignant cases (in the same location) plus 2 "primer" malignant cases replacing 2 normal cases (located at positions #20 and 34). Primer cases were defined as lower difficulty cases containing salient malignant features inserted before cases of greater difficulty. Results: Wilcoxon Signed Rank Test indicated no significant differences in sensitivity or specificity between the two sets (P > 0.05). The fixation count in the malignant cases (#25, 37) in the Primed Set after viewing the primer cases (#20, 34) decreased significantly (Z = -2.330, P = 0.020). False-Negatives errors were mostly due to sampling in the Primed Set (75%) in contrast to in the Control Set (25%). Conclusion: The overall performance of radiologists is not affected by the inclusion of obvious cancer cases. However, changes in visual search behavior, as measured by eye-position recording, suggests visual disturbance by the inclusion of priming cases in screening mammography.

  2. Mining compact bag-of-patterns for low bit rate mobile visual search.

    PubMed

    Ji, Rongrong; Duan, Ling-Yu; Chen, Jie; Huang, Tiejun; Gao, Wen

    2014-07-01

    Visual patterns, i.e., high-order combinations of visual words, contributes to a discriminative abstraction of the high-dimensional bag-of-words image representation. However, the existing visual patterns are built upon the 2D photographic concurrences of visual words, which is ill-posed comparing with their real-world 3D concurrences, since the words from different objects or different depth might be incorrectly bound into an identical pattern. On the other hand, designing compact descriptors from the mined patterns is left open. To address both issues, in this paper, we propose a novel compact bag-of-patterns (CBoPs) descriptor with an application to low bit rate mobile landmark search. First, to overcome the ill-posed 2D photographic configuration, we build up a 3D point cloud from the reference images of each landmark, therefore more accurate pattern candidates can be extracted from the 3D concurrences of visual words. A novel gravity distance metric is then proposed to mine discriminative visual patterns. Second, we come up with compact image description by introducing a CBoPs descriptor. CBoP is figured out by sparse coding over the mined visual patterns, which maximally reconstructs the original bag-of-words histogram with a minimum coding length. We developed a low bit rate mobile landmark search prototype, in which CBoP descriptor is directly extracted and sent from the mobile end to reduce the query delivery latency. The CBoP performance is quantized in several large-scale benchmarks with comparisons to the state-of-the-art compact descriptors, topic features, and hashing descriptors. We have reported comparable accuracy to the million-scale bag-of-words histogram over the million scale visual words, with high descriptor compression rate (approximately 100-bits) than the state-of-the-art bag-of-words compression scheme. PMID:24835227

  3. 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 2015 to Any 1900 1920 1940 1960 1980 1990 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Image

  4. Situating visual search.

    PubMed

    Nakayama, Ken; Martini, Paolo

    2011-07-01

    Visual search attracted great interest because its ease under certain circumstances seemed to provide a way to understand how properties of early visual cortical areas could explain complex perception without resorting to higher order psychological or neurophysiological mechanisms. Furthermore, there was the hope that properties of visual search itself might even reveal new cortical features or dimensions. The shortcomings of this perspective suggest that we abandon fixed canonical elementary particles of vision as well as a corresponding simple to complex cognitive architecture for vision. Instead recent research has suggested a different organization of the visual brain with putative high level processing occurring very rapidly and often unconsciously. Given this outlook, we reconsider visual search under the broad category of recognition tasks, each having different trade-offs for computational resources, between detail and scope. We conclude noting recent trends showing how visual search is relevant to a wider range of issues in cognitive science, in particular to memory, decision making, and reward. PMID:20837042

  5. Evolutionary pattern search algorithms

    SciTech Connect

    Hart, W.E.

    1995-09-19

    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.

  6. Development of a Computerized Visual Search Test

    ERIC Educational Resources Information Center

    Reid, Denise; Babani, Harsha; Jon, Eugenia

    2009-01-01

    Visual attention and visual search are the features of visual perception, essential for attending and scanning one's environment while engaging in daily occupations. This study describes the development of a novel web-based test of visual search. The development information including the format of the test will be described. The test was designed…

  7. Eye-hand coordination during visual search on geographic displays

    E-print Network

    Çöltekin, Arzu

    : eye tracking, mouse tracking, visual search, trajectory anal- ysis 1 Introduction Our eyes and hands the gaze patterns in relation to mouse use. ET4S 2014, September 23, 2014, Vienna, Austria Copyright © 2014 in evaluating visual displays [3], obtaining them is (still) expensive and eye tracking process has various

  8. Statistical templates for visual search.

    PubMed

    Ackermann, John F; Landy, Michael S

    2014-01-01

    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

  9. Searching social networks for subgraph patterns

    NASA Astrophysics Data System (ADS)

    Ogaard, Kirk; Kase, Sue; Roy, Heather; Nagi, Rakesh; Sambhoos, Kedar; Sudit, Moises

    2013-06-01

    Software tools for Social Network Analysis (SNA) are being developed which support various types of analysis of social networks extracted from social media websites (e.g., Twitter). Once extracted and stored in a database such social networks are amenable to analysis by SNA software. This data analysis often involves searching for occurrences of various subgraph patterns (i.e., graphical representations of entities and relationships). The authors have developed the Graph Matching Toolkit (GMT) which provides an intuitive Graphical User Interface (GUI) for a heuristic graph matching algorithm called the Truncated Search Tree (TruST) algorithm. GMT is a visual interface for graph matching algorithms processing large social networks. GMT enables an analyst to draw a subgraph pattern by using a mouse to select categories and labels for nodes and links from drop-down menus. GMT then executes the TruST algorithm to find the top five occurrences of the subgraph pattern within the social network stored in the database. GMT was tested using a simulated counter-insurgency dataset consisting of cellular phone communications within a populated area of operations in Iraq. The results indicated GMT (when executing the TruST graph matching algorithm) is a time-efficient approach to searching large social networks. GMT's visual interface to a graph matching algorithm enables intelligence analysts to quickly analyze and summarize the large amounts of data necessary to produce actionable intelligence.

  10. Cue Search and Comparison Processes in Visual Search for

    E-print Network

    Logan, Gordon D.

    processes may function concurrently. When people search through arrays for a particular target letterCue Search and Comparison Processes in Visual Search for Letters* GORDON D. LOGAN Erindale College, subjects searched four- and eight-letter arrays for the presence of a T or an F. The position of the target

  11. Aurally and visually guided visual search in a virtual environment.

    PubMed

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

    1998-09-01

    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

  12. Distributed Search and Pattern Matching

    NASA Astrophysics Data System (ADS)

    Ahmed, Reaz; Boutaba, Raouf

    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.

  13. Words, shape, visual search and visual working memory in 3-year-old children

    PubMed Central

    Vales, Catarina; Smith, Linda B.

    2014-01-01

    Do words cue children’s visual attention, and if so, what are the relevant mechanisms? Across four experiments, 3-year-old children (N = 163) were tested in visual search tasks in which targets were cued with only a visual preview versus a visual preview and a spoken name. The experiments were designed to determine whether labels facilitated search times and to examine one route through which labels could have their effect: By influencing the visual working memory representation of the target. The targets and distractors were pictures of instances of basic-level known categories and the labels were the common name for the target category. We predicted that the label would enhance the visual working memory representation of the target object, guiding attention to objects that better matched the target representation. Experiments 1 and 2 used conjunctive search tasks, and Experiment 3 varied shape discriminability between targets and distractors. Experiment 4 compared the effects of labels to repeated presentations of the visual target, which should also influence the working memory representation of the target. The overall pattern fits contemporary theories of how the contents of visual working memory interact with visual search and attention, and shows that even in very young children heard words affect the processing of visual information. PMID:24720802

  14. Temporal Stability of Visual Search-Driven Biometrics

    SciTech Connect

    Yoon, Hong-Jun; Carmichael, Tandy; Tourassi, Georgia

    2015-01-01

    Previously, we have shown the potential of using an individual s visual search pattern as a possible biometric. That study focused on viewing images displaying dot-patterns with different spatial relationships to determine which pattern can be more effective in establishing the identity of an individual. In this follow-up study we investigated the temporal stability of this biometric. We performed an experiment with 16 individuals asked to search for a predetermined feature of a random-dot pattern as we tracked their eye movements. Each participant completed four testing sessions consisting of two dot patterns repeated twice. One dot pattern displayed concentric circles shifted to the left or right side of the screen overlaid with visual noise, and participants were asked which side the circles were centered on. The second dot-pattern displayed a number of circles (between 0 and 4) scattered on the screen overlaid with visual noise, and participants were asked how many circles they could identify. Each session contained 5 untracked tutorial questions and 50 tracked test questions (200 total tracked questions per participant). To create each participant s "fingerprint", we constructed a Hidden Markov Model (HMM) from the gaze data representing the underlying visual search and cognitive process. The accuracy of the derived HMM models was evaluated using cross-validation for various time-dependent train-test conditions. Subject identification accuracy ranged from 17.6% to 41.8% for all conditions, which is significantly higher than random guessing (1/16 = 6.25%). The results suggest that visual search pattern is a promising, fairly stable personalized fingerprint of perceptual organization.

  15. Temporal stability of visual search-driven biometrics

    NASA Astrophysics Data System (ADS)

    Yoon, Hong-Jun; Carmichael, Tandy R.; Tourassi, Georgia

    2015-03-01

    Previously, we have shown the potential of using an individual's visual search pattern as a possible biometric. That study focused on viewing images displaying dot-patterns with different spatial relationships to determine which pattern can be more effective in establishing the identity of an individual. In this follow-up study we investigated the temporal stability of this biometric. We performed an experiment with 16 individuals asked to search for a predetermined feature of a random-dot pattern as we tracked their eye movements. Each participant completed four testing sessions consisting of two dot patterns repeated twice. One dot pattern displayed concentric circles shifted to the left or right side of the screen overlaid with visual noise, and participants were asked which side the circles were centered on. The second dot-pattern displayed a number of circles (between 0 and 4) scattered on the screen overlaid with visual noise, and participants were asked how many circles they could identify. Each session contained 5 untracked tutorial questions and 50 tracked test questions (200 total tracked questions per participant). To create each participant's "fingerprint", we constructed a Hidden Markov Model (HMM) from the gaze data representing the underlying visual search and cognitive process. The accuracy of the derived HMM models was evaluated using cross-validation for various time-dependent train-test conditions. Subject identification accuracy ranged from 17.6% to 41.8% for all conditions, which is significantly higher than random guessing (1/16 = 6.25%). The results suggest that visual search pattern is a promising, temporally stable personalized fingerprint of perceptual organization.

  16. Cascade category-aware visual search.

    PubMed

    Zhang, Shiliang; Tian, Qi; Huang, Qingming; Gao, Wen; Rui, Yong

    2014-06-01

    Incorporating image classification into image retrieval system brings many attractive advantages. For instance, the search space can be narrowed down by rejecting images in irrelevant categories of the query. The retrieved images can be more consistent in semantics by indexing and returning images in the relevant categories together. However, due to their different goals on recognition accuracy and retrieval scalability, it is hard to efficiently incorporate most image classification works into large-scale image search. To study this problem, we propose cascade category-aware visual search, which utilizes weak category clue to achieve better retrieval accuracy, efficiency, and memory consumption. To capture the category and visual clues of an image, we first learn category-visual words, which are discriminative and repeatable local features labeled with categories. By identifying category-visual words in database images, we are able to discard noisy local features and extract image visual and category clues, which are hence recorded in a hierarchical index structure. Our retrieval system narrows down the search space by: 1) filtering the noisy local features in query; 2) rejecting irrelevant categories in database; and 3) preforming discriminative visual search in relevant categories. The proposed algorithm is tested on object search, landmark search, and large-scale similar image search on the large-scale LSVRC10 data set. Although the category clue introduced is weak, our algorithm still shows substantial advantages in retrieval accuracy, efficiency, and memory consumption than the state-of-the-art. PMID:24760907

  17. Visual Templates in Pattern Generalization Activity

    ERIC Educational Resources Information Center

    Rivera, F. D.

    2010-01-01

    In this research article, I present evidence of the existence of visual templates in pattern generalization activity. Such templates initially emerged from a 3-week design-driven classroom teaching experiment on pattern generalization involving linear figural patterns and were assessed for existence in a clinical interview that was conducted four…

  18. Pattern Search Algorithms for Bound Constrained Minimization

    NASA Technical Reports Server (NTRS)

    Lewis, Robert Michael; Torczon, Virginia

    1996-01-01

    We present a convergence theory for pattern search methods for solving bound constrained nonlinear programs. The analysis relies on the abstract structure of pattern search methods and an understanding of how the pattern interacts with the bound constraints. This analysis makes it possible to develop pattern search methods for bound constrained problems while only slightly restricting the flexibility present in pattern search methods for unconstrained problems. We prove global convergence despite the fact that pattern search methods do not have explicit information concerning the gradient and its projection onto the feasible region and consequently are unable to enforce explicitly a notion of sufficient feasible decrease.

  19. Visual Circuit Development Requires Patterned Activity Mediated

    E-print Network

    Contractor, Anis

    Neuron Article Visual Circuit Development Requires Patterned Activity Mediated by Retinal ordered neural circuits is an integral feature of the developing vertebrate nervous system. In sen- sory, assayed in vivo, that demon- strate a causal link between retinal waves and visual circuit refinement. We

  20. The Search for Optimal Visual Stimuli

    NASA Technical Reports Server (NTRS)

    Watson, Andrew B.; Ellis, Stephen R. (Technical Monitor)

    1997-01-01

    In 1983, Watson, Barlow and Robson published a brief report in which they explored the relative visibility of targets that varied in size, shape, spatial frequency, speed, and duration (referred to subsequently here as WBR). A novel aspect of that paper was that visibility was quantified in terms of threshold contrast energy, rather than contrast. As they noted, this provides a more direct measure of the efficiency with which various patterns are detected, and may be more edifying as to the underlying detection machinery. For example, under certain simple assumptions, the waveform of the most efficiently detected signal is an estimate of the receptive field of the visual system's most efficient detector. Thus one goal of their experiment Basuto search for the stimulus that the 'eye sees best'. Parenthetically, the search for optimal stimuli may be seen as the most general and sophisticated variant of the traditional 'subthreshold summation' experiment, in which one measures the effect upon visibility of small probes combined with a base stimulus.

  1. Extending Morphological Signatures for Visual Pattern Recognition

    E-print Network

    Lefèvre, Sébastien

    techniques are very dependent on the accuracy of the image features they rely on. The image analysis if it can be used directly to solve various pattern recognition problems related to image data, the simple Introduction When applied on visual information such as digital images, pattern recognition and data mining

  2. Feature correlation guidance in category visual search.

    PubMed

    Wu, Rachel; Pruitt, Zoe; Runkle, Megan; Meyer, Kristen; Scerif, Gaia; Aslin, Richard

    2015-09-01

    Compared to objects with uncorrelated features (e.g., jelly beans come in many colors), objects with correlated features (e.g., bananas tend to be yellow) enable more robust object and category representations (e.g., Austerweil & Griffiths, 2011; Wu et al., 2011; Younger & Cohen, 1986). It is unknown whether these more robust representations impact attentional templates (i.e., working memory representations guiding visual search). Adults participated in four visual search tasks (2x2 design) where targets were defined as either one item (a specific alien) or a category (any alien) with correlated features (e.g., circle belly shape, circle back spikes) or uncorrelated features (e.g., circle belly shape, triangle back spikes). We measured behavioral responses and the N2pc component, an event-related potential (ERP) marker for target selection. Behavioral responses were better for correlated items than uncorrelated items for both exemplar and category search. While the N2pc amplitude was larger for exemplar search compared to category search, the amplitude only differed based on feature correlation for category search: The N2pc was present for category search with correlated features, and not present in search for uncorrelated features. Our ERP results demonstrate that correlated (and not uncorrelated) features for novel categories provide a robust category representation that can guide visual search. Meeting abstract presented at VSS 2015. PMID:26326614

  3. Fractal analysis of radiologists' visual scanning pattern in screening mammography

    NASA Astrophysics Data System (ADS)

    Alamudun, Folami T.; Yoon, Hong-Jun; Hudson, Kathy; Morin-Ducote, Garnetta; Tourassi, Georgia

    2015-03-01

    Several researchers have investigated radiologists' visual scanning patterns with respect to features such as total time examining a case, time to initially hit true lesions, number of hits, etc. The purpose of this study was to examine the complexity of the radiologists' visual scanning pattern when viewing 4-view mammographic cases, as they typically do in clinical practice. Gaze data were collected from 10 readers (3 breast imaging experts and 7 radiology residents) while reviewing 100 screening mammograms (24 normal, 26 benign, 50 malignant). The radiologists' scanpaths across the 4 mammographic views were mapped to a single 2-D image plane. Then, fractal analysis was applied on the composite 4- view scanpaths. For each case, the complexity of each radiologist's scanpath was measured using fractal dimension estimated with the box counting method. The association between the fractal dimension of the radiologists' visual scanpath, case pathology, case density, and radiologist experience was evaluated using fixed effects ANOVA. ANOVA showed that the complexity of the radiologists' visual search pattern in screening mammography is dependent on case specific attributes (breast parenchyma density and case pathology) as well as on reader attributes, namely experience level. Visual scanning patterns are significantly different for benign and malignant cases than for normal cases. There is also substantial inter-observer variability which cannot be explained only by experience level.

  4. Pattern Search Methods for Linearly Constrained Minimization

    NASA Technical Reports Server (NTRS)

    Lewis, Robert Michael; Torczon, Virginia

    1998-01-01

    We extend pattern search methods to linearly constrained minimization. We develop a general class of feasible point pattern search algorithms and prove global convergence to a Karush-Kuhn-Tucker point. As in the case of unconstrained minimization, pattern search methods for linearly constrained problems accomplish this without explicit recourse to the gradient or the directional derivative. Key to the analysis of the algorithms is the way in which the local search patterns conform to the geometry of the boundary of the feasible region.

  5. Visual search under scotopic lighting conditions.

    PubMed

    Paulun, Vivian C; Schütz, Alexander C; Michel, Melchi M; Geisler, Wilson S; Gegenfurtner, Karl R

    2015-08-01

    When we search for visual targets in a cluttered background we systematically move our eyes around to bring different regions of the scene into foveal view. We explored how visual search behavior changes when the fovea is not functional, as is the case in scotopic vision. Scotopic contrast sensitivity is significantly lower overall, with a functional scotoma in the fovea. We found that in scotopic search, for a medium- and a low-spatial-frequency target, individuals made longer lasting fixations that were not broadly distributed across the entire search display but tended to peak in the upper center, especially for the medium-frequency target. The distributions of fixation locations are qualitatively similar to those of an ideal searcher that has human scotopic detectability across the visual field, and interestingly, these predicted distributions are different from those predicted by an ideal searcher with human photopic detectability. We conclude that although there are some qualitative differences between human and ideal search behavior, humans make principled adjustments in their search behavior as ambient light level decreases. PMID:25988753

  6. Dynamic Prototypicality Effects in Visual Search

    ERIC Educational Resources Information Center

    Kayaert, Greet; Op de Beeck, Hans P.; Wagemans, Johan

    2011-01-01

    In recent studies, researchers have discovered a larger neural activation for stimuli that are more extreme exemplars of their stimulus class, compared with stimuli that are more prototypical. This has been shown for faces as well as for familiar and novel shape classes. We used a visual search task to look for a behavioral correlate of these…

  7. Guidance of Visual Search by Preattentive Information

    E-print Network

    , an observer will use color information to guide covert attention as well as overt movements of eye and hand red car in the parking lot, we select red cars to examine, not blue cars. If we accept this set and dimensions are on the list on the basis of rather few data. Much evidence comes from visual search tasks

  8. Similarity relations in visual search predict rapid visual categorization

    PubMed Central

    Mohan, Krithika; Arun, S. P.

    2012-01-01

    How do we perform rapid visual categorization?It is widely thought that categorization involves evaluating the similarity of an object to other category items, but the underlying features and similarity relations remain unknown. Here, we hypothesized that categorization performance is based on perceived similarity relations between items within and outside the category. To this end, we measured the categorization performance of human subjects on three diverse visual categories (animals, vehicles, and tools) and across three hierarchical levels (superordinate, basic, and subordinate levels among animals). For the same subjects, we measured their perceived pair-wise similarities between objects using a visual search task. Regardless of category and hierarchical level, we found that the time taken to categorize an object could be predicted using its similarity to members within and outside its category. We were able to account for several classic categorization phenomena, such as (a) the longer times required to reject category membership; (b) the longer times to categorize atypical objects; and (c) differences in performance across tasks and across hierarchical levels. These categorization times were also accounted for by a model that extracts coarse structure from an image. The striking agreement observed between categorization and visual search suggests that these two disparate tasks depend on a shared coarse object representation. PMID:23092947

  9. Visual abstraction of complex motion patterns

    NASA Astrophysics Data System (ADS)

    Janetzko, Halldór; Jäckle, Dominik; Deussen, Oliver; Keim, Daniel A.

    2013-12-01

    Today's tracking devices allow high spatial and temporal resolutions and due to their decreasing size also an ever increasing number of application scenarios. However, understanding motion over time is quite difficult as soon as the resulting trajectories are getting complex. Simply plotting the data may obscure important patterns since trajectories over long time periods often include many revisits of the same place which creates a high degree of over-plotting. Furthermore, important details are often hidden due to a combination of large-scale transitions with local and small-scale movement patterns. We present a visualization and abstraction technique for such complex motion data. By analyzing the motion patterns and displaying them with visual abstraction techniques a synergy of aggregation and simplification is reached. The capabilities of the method are shown in real-world applications for tracked animals and discussed with experts from biology. Our proposed abstraction techniques reduce visual clutter and help analysts to understand the movement patterns that are hidden in raw spatiotemporal data.

  10. Investigation of Neural Strategies of Visual Search

    NASA Technical Reports Server (NTRS)

    Krauzlis, Richard J.

    2003-01-01

    The goal of this project was to measure how neurons in the superior colliculus (SC) change their activity during a visual search task. Specifically, we proposed to measure how the activity of these neurons was altered by the discriminability of visual targets and to test how these changes might predict the changes in the subjects performance. The primary rationale for this study was that understanding how the information encoded by these neurons constrains overall search performance would foster the development of better models of human performance. Work performed during the period supported by this grant has achieved these aims. First, we have recorded from neurons in the superior colliculus (SC) during a visual search task in which the difficulty of the task and the performance of the subject was systematically varied. The results from these single-neuron physiology experiments shows that prior to eye movement onset, the difference in activity across the ensemble of neurons reaches a fixed threshold value, reflecting the operation of a winner-take-all mechanism. Second, we have developed a model of eye movement decisions based on the principle of winner-take-all . The model incorporates the idea that the overt saccade choice reflects only one of the multiple saccades prepared during visual discrimination, consistent with our physiological data. The value of the model is that, unlike previous models, it is able to account for both the latency and the percent correct of saccade choices.

  11. LoyalTracker: Visualizing Loyalty Dynamics in Search Engines.

    PubMed

    Shi, Conglei; Wu, Yingcai; Liu, Shixia; Zhou, Hong; Qu, Huamin

    2014-12-01

    The huge amount of user log data collected by search engine providers creates new opportunities to understand user loyalty and defection behavior at an unprecedented scale. However, this also poses a great challenge to analyze the behavior and glean insights into the complex, large data. In this paper, we introduce LoyalTracker, a visual analytics system to track user loyalty and switching behavior towards multiple search engines from the vast amount of user log data. We propose a new interactive visualization technique (flow view) based on a flow metaphor, which conveys a proper visual summary of the dynamics of user loyalty of thousands of users over time. Two other visualization techniques, a density map and a word cloud, are integrated to enable analysts to gain further insights into the patterns identified by the flow view. Case studies and the interview with domain experts are conducted to demonstrate the usefulness of our technique in understanding user loyalty and switching behavior in search engines. PMID:26356887

  12. Parallel Mechanisms for Visual Search in Zebrafish

    PubMed Central

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

    2014-01-01

    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

  13. Adding a visualization feature to web search engines: it's time.

    PubMed

    Wong, Pak Chung

    2008-01-01

    It's widely recognized that all Web search engines today are almost identical in presentation layout and behavior. In fact, the same presentation approach has been applied to depicting search engine results pages (SERPs) since the first Web search engine launched in 1993. In this Visualization Viewpoints article, I propose to add a visualization feature to Web search engines and suggest that the new addition can improve search engines' performance and capabilities, which in turn lead to better Web search technology. PMID:19004680

  14. The impact of item clustering on visual search: It all depends on the nature of the visual search

    E-print Network

    Xu, Yaoda

    people search for a target item among distractor items have always avoided item clustering. Instead people search for a target item among distractor items have avoided item clustering. Instead, researchersThe impact of item clustering on visual search: It all depends on the nature of the visual search

  15. Circuit Optimization Using Efficient Parallel Pattern Search 

    E-print Network

    Narasimhan, Srinath S.

    2011-08-08

    evaluations and difficulty in getting explicit sensitivity information make these problems intractable to standard optimization methods. We propose to explore the recently developed asynchronous parallel pattern search (APPS) method for efficient driver size...

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

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  17. Visual memory for natural scenes: Evidence from change detection and visual search

    E-print Network

    Hollingworth, Andrew

    short-term memory and visual long-term memory. In addition, I review evidence that memoryVisual memory for natural scenes: Evidence from change detection and visual search Andrew memory in scene perception and visual search. Recent theories in these literatures have held

  18. Guided Text Search Using Adaptive Visual Analytics

    SciTech Connect

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

    2012-10-01

    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.

  19. When is stereopsis useful in visual search?

    PubMed

    Josephs, Emilie; Cain, Matthew; Hidalgo-Sotelo, Barbara; Cook, Gregory; Chang, Nelson; Ehinger, Krista; Oliva, Aude; Wolfe, Jeremy

    2015-09-01

    Does stereoscopic information improve visual search? We know that attention can be guided efficiently by stereopsis, for example, to the near target among far distractors (Nakayama and Silverman, 1986), but, when searching through a real scene, does it help if that scene is presented stereoscopically? Certainly, scenes appear to be more vividly real in 3D. However, we present three experiments in which the addition of stereo did not alter scene search very much. In Experiment 1, 12 observers searched twice for 10 target objects in each of 18 photographic scenes (a 'repeated' search task). Note that observers were not cued to search for a target at a specific depth, stereopsis simply added to the vividness of the scene. Reaction time and accuracy did not differ significantly in stereoscopic and monoscopic conditions. In Experiment 2, using similar images, we found no differences between 2D and 3D conditions on time to first fixation on the target or on the average length of saccades. However, gaze durations were significantly shorter in 3D scenes. Since gaze durations are typically taken to measure processing time, this may suggest that it was easier to disambiguate surfaces and/or objects in 3D, although this advantage did not translate to benefits in search times. In a final experiment, we reduced the stimulus array to a set of colored rendered objects distributed in depth against a plain background. In this task, the addition of stereo produced shorter reaction times, even though stereo information was not predictive of target location. Our real scenes may have contained such a rich array of cues to target location that the addition of stereo may not have contributed much additional information. It may be in more difficult searches, including more challenging real world tasks, that stereopsis will be an asset. Meeting abstract presented at VSS 2015. PMID:26327049

  20. Transition between different search patterns in human online search behavior

    NASA Astrophysics Data System (ADS)

    Wang, Xiangwen; Pleimling, Michel

    2015-03-01

    We investigate the human online search behavior by analyzing data sets from different search engines. Based on the comparison of the results from several click-through data-sets collected in different years, we observe a transition of the search pattern from a Lévy-flight-like behavior to a Brownian-motion-type behavior as the search engine algorithms improve. This result is consistent with findings in animal foraging processes. A more detailed analysis shows that the human search patterns are more complex than simple Lévy flights or Brownian motions. Notable differences between the behaviors of different individuals can be observed in many quantities. This work is in part supported by the US National Science Foundation through Grant DMR-1205309.

  1. Vocal Dynamic Visual Pattern for voice characterization

    NASA Astrophysics Data System (ADS)

    Dajer, M. E.; Andrade, F. A. S.; Montagnoli, A. N.; Pereira, J. C.; Tsuji, D. H.

    2011-12-01

    Voice assessment requires simple and painless exams. Modern technologies provide the necessary resources for voice signal processing. Techniques based on nonlinear dynamics seem to asses the complexity of voice more accurately than other methods. Vocal dynamic visual pattern (VDVP) is based on nonlinear methods and provides qualitative and quantitative information. Here we characterize healthy and Reinke's edema voices by means of perturbation measures and VDVP analysis. VDPD and jitter show different results for both groups, while amplitude perturbation has no difference. We suggest that VDPD analysis improve and complement the evaluation methods available for clinicians.

  2. Long-term visual search: Examining trial-by-trial learning over extended visual search experiences.

    PubMed

    Ericson, Justin; Biggs, Adam; Winkle, Jonathan; Gancayco, Christina; Mitroff, Stephen

    2015-09-01

    Airport security personnel search for a large number of prohibited items that vary in size, shape, color, category-membership, and more. This highly varied search set creates challenges for search accuracy, including how searchers are trained in identifying a myriad of potential targets. This challenge has both practical and theoretical implications (i.e., determining how best to obtain high accuracy, and how large memory sets interact with visual search performance, respectively). Recent research on "hybrid visual and memory search" (e.g., Wolfe, 2012) has begun to address such issues, but many questions remain. The current study addressed a difficult problem for traditional laboratory-based research-how does trial-by-trial learning develop over time for a large number of target types? This issue, which we call "long-term visual search," is key for understanding how reoccurring information in retained in memory so that it can aid future searches. Through the use of "big data" from the mobile application Airport Scanner (Kedlin Co.), it is possible to address such previously intractable questions. Airport Scanner is a game where players serve as an airport security officers looking for prohibited items in simulated bags. The game has over 7 million downloads and provides a powerful tool for psychological research (Mitroff et al., 2014 JEP:HPP). Trial-by-trial learning for multiple different targets was addressed by analyzing data from 50,000 participants. Distinct learning curves for each specific target revealed that accuracy rises asymptotically across trials without deteriorating to initially low starting levels. Additionally, an investigation into the number of to-be-searched-for target items indicated that performance accuracy remained high even as the memorized set size increased. The results suggest that items stored in memory generate their own item-specific template that is reinforced from repeated exposures. These findings offer insight into how novices develop into experts at target detection over the course of training. Meeting abstract presented at VSS 2015. PMID:26326796

  3. Words, Shape, Visual Search and Visual Working Memory in 3-Year-Old Children

    ERIC Educational Resources Information Center

    Vales, Catarina; Smith, Linda B.

    2015-01-01

    Do words cue children's visual attention, and if so, what are the relevant mechanisms? Across four experiments, 3-year-old children (N = 163) were tested in visual search tasks in which targets were cued with only a visual preview versus a visual preview and a spoken name. The experiments were designed to determine whether labels facilitated…

  4. Eye Movements Reveal How Task Difficulty Moulds Visual Search

    ERIC Educational Resources Information Center

    Young, Angela H.; Hulleman, Johan

    2013-01-01

    In two experiments we investigated the relationship between eye movements and performance in visual search tasks of varying difficulty. Experiment 1 provided evidence that a single process is used for search among static and moving items. Moreover, we estimated the functional visual field (FVF) from the gaze coordinates and found that its size…

  5. Global Statistical Learning in a Visual Search Task

    ERIC Educational Resources Information Center

    Jones, John L.; Kaschak, Michael P.

    2012-01-01

    Locating a target in a visual search task is facilitated when the target location is repeated on successive trials. Global statistical properties also influence visual search, but have often been confounded with local regularities (i.e., target location repetition). In two experiments, target locations were not repeated for four successive trials,…

  6. Spatial Constraints on Learning in Visual Search: Modeling Contextual Cuing

    ERIC Educational Resources Information Center

    Brady, Timothy F.; Chun, Marvin M.

    2007-01-01

    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…

  7. Visual search behaviour during laparoscopic cadaveric procedures

    NASA Astrophysics Data System (ADS)

    Dong, Leng; Chen, Yan; Gale, Alastair G.; Rees, Benjamin; Maxwell-Armstrong, Charles

    2014-03-01

    Laparoscopic surgery provides a very complex example of medical image interpretation. The task entails: visually examining a display that portrays the laparoscopic procedure from a varying viewpoint; eye-hand coordination; complex 3D interpretation of the 2D display imagery; efficient and safe usage of appropriate surgical tools, as well as other factors. Training in laparoscopic surgery typically entails practice using surgical simulators. Another approach is to use cadavers. Viewing previously recorded laparoscopic operations is also a viable additional approach and to examine this a study was undertaken to determine what differences exist between where surgeons look during actual operations and where they look when simply viewing the same pre-recorded operations. It was hypothesised that there would be differences related to the different experimental conditions; however the relative nature of such differences was unknown. The visual search behaviour of two experienced surgeons was recorded as they performed three types of laparoscopic operations on a cadaver. The operations were also digitally recorded. Subsequently they viewed the recording of their operations, again whilst their eye movements were monitored. Differences were found in various eye movement parameters when the two surgeons performed the operations and where they looked when they simply watched the recordings of the operations. It is argued that this reflects the different perceptual motor skills pertinent to the different situations. The relevance of this for surgical training is explored.

  8. Effects of Early Pattern Deprivation on Visual Development

    E-print Network

    Maurer, Daphne M.

    * ABSTRACT Studies of children treated for dense cataract shed light on the extent to which pattern deprivation has been treated by surgical removal of the cataractous lens, the interactions between the aphakic: visual deprivation, cataract, infants, children, visual outcome, sensitive periods, normal visual

  9. Investigating attention in complex visual search.

    PubMed

    Kovach, Christopher K; Adolphs, Ralph

    2015-11-01

    How we attend to and search for objects in the real world is influenced by a host of low-level and higher-level factors whose interactions are poorly understood. The vast majority of studies approach this issue by experimentally controlling one or two factors in isolation, often under conditions with limited ecological validity. We present a comprehensive regression framework, together with a matlab-implemented toolbox, which allows concurrent factors influencing saccade targeting to be more clearly distinguished. Based on the idea of gaze selection as a point process, the framework allows each putative factor to be modeled as a covariate in a generalized linear model, and its significance to be evaluated with model-based hypothesis testing. We apply this framework to visual search for faces as an example and demonstrate its power in detecting effects of eccentricity, inversion, task congruency, emotional expression, and serial fixation order on the targeting of gaze. Among other things, we find evidence for multiple goal-related and goal-independent processes that operate with distinct visuotopy and time course. PMID:25499190

  10. Visual search using realistic camouflage: countershading is highly effective at deterring search.

    PubMed

    Penacchio, Olivier; Lovell, George; Sanghera, Simon; Cuthill, Innes; Ruxton, Graeme; Harris, Julie

    2015-09-01

    One of the most widespread patterns of colouration in the animal kingdom is countershading, a gradation of colour in which body parts that face a higher light intensity are darker. Countershading may help counterbalance the shadowing created by directional light, and, hence, reduce 3D object recognition via shape-from-shading. There is evidence that other animals, as well as humans, derive information on shape from shading. Here, we assessed experimentally the effect of optimising countershading camouflage on detection speed and accuracy, to explore whether countershading needs to be fine-tuned to achieve crypsis. We used a computational 3D world that included ecologically realistic lighting patterns. We defined 3D scenes with elliptical 'distractor' leaves and an ellipsoid target object. The scenes were rendered with different types of illumination and the target objects were endowed with different levels of camouflage: none at all, a countershading pattern optimized for the light distribution of the scene and target orientation in space, or optimized for a different illuminant. Participants (N=12) were asked to detect the target 3D object in the scene as fast as possible. The results showed a very significant effect of countershading camouflage on detection rate and accuracy. The extent to which the countershading pattern departed from the optimal pattern for the actual lighting condition and orientation of the target object had a strong effect on detection performance. This experiment showed that appropriate countershading camouflage strongly interferes with visual search by decreasing detection rate and accuracy. A field predation experiment using birds, based on similar stimuli, showed similar effects. Taken together, this suggests that countershading obstructs efficient visual search across species and reduces visibility, thus enhancing survival in prey animals that adopt it. Meeting abstract presented at VSS 2015. PMID:26326656

  11. Asynchronous parallel pattern search for nonlinear optimization

    SciTech Connect

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

    2000-01-01

    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

  12. Memory is Necessary in Visual Search with Limited Guidance.

    PubMed

    Peltier, Chad; Becker, Mark

    2015-09-01

    There has been an ongoing debate in the visual search literature on whether or not visual search has memory. One manipulation to test if memory is used in visual search has been to randomize the location of stimuli in an image every 111ms, which prevents observers from tracking the locations of previously inspected items. Horowitz and Wolfe (1998) used this method and found no significant differences in search slopes between static and random conditions, leading to the conclusion that visual search has no memory. Here we revisit this claim. We reason that memory in search should only be necessary for a search where there is little guidance. Thus search may appear memoryless when the search task allows for adequate guidance, but search may rely on memory in more difficult search tasks when guidance is ineffective. In Experiment 1 we replicated Horowitz and Wolfe's findings when observers searched for a T among Ls. But when we made the task a search for the same T among offset Ls observers in the random presentation condition were very close to chance performance, making it difficult to interpret search slopes. However, error rates suggest that presentation type (static v. random) interacted with stimulus type (easy v. hard) suggesting a role for memory with the harder search. In Experiment 2 we sought to increase overall accuracy to avoid chance performance. We decreased the set sizes in Experiment 2 from 8, 12, and 16, to 4, 6, and 8, while increasing the stimulus presentation duration from 111 to 160ms. Again we found that poorer accuracy in the difficult stimuli condition is moderated by the presentation type. The data suggest that memory is not necessary in searches where guidance to the target is efficient, but memory is necessary for high performance in searches with limited guidance. Meeting abstract presented at VSS 2015. PMID:26327045

  13. Visualizing Design Patterns in Their Applications and Compositions

    E-print Network

    Zhang, Kang

    Visualizing Design Patterns in Their Applications and Compositions Jing Dong, Member, IEEE, Sheng Yang, Member, IEEE, and Kang Zhang, Senior Member, IEEE Abstract--Design patterns are generic design. It is hard for a designer to find the design patterns used in an application design. Consequently

  14. Visual Search in Learning Disabled and Hyperactive Boys.

    ERIC Educational Resources Information Center

    McIntyre, Curtis W.; And Others

    1981-01-01

    To test the suggestion that a deficit in selective attention is characteristic of learning disabled (LD) but not hyperactive (H) children, 72 students (12 LDH, 12 H, and 36 normal Ss) were timed on visual search tasks. (Author)

  15. Performance of Process Schizophrenics on Tasks Involving Visual Search

    ERIC Educational Resources Information Center

    Russell, Paul N.; Knight, Robert G.

    1977-01-01

    The response times of 32 process schizophrenics and 16 nonhospitalized controls were compared on three visual search tasks. Results suggest that process schizophrenics are not abnormally slow when extracting information from visual displays, and they appear to perform similar operations and strategies to those of normals when doing so. (Editor/RK)

  16. A Minimal Model for Predicting Visual Search in Human-Computer Interaction

    E-print Network

    Hornof, Anthony

    -computer interaction. It is critical that we build theory about how people visually search displays in order to better modeling of the perceptual, strategic, and oculomotor processes people used in a visual search task users and many tasks, information is obtained through visual search. The visual search processes people

  17. Towards a Flexible, Reusable Model for Predicting Eye Movements During Visual Search of Text

    E-print Network

    Hornof, Anthony

    : cognitive modeling; visual search; EPIC; eye movements Introduction The visual search strategies people amount of research has been done on visual search strategies people use. For example, Shen, Reingold, and Pomplun (2003) found that people tend to shift their visual search strategy very quickly based on which

  18. Visual Empirical Region of Influence (VERI) Pattern Recognition Algorithms

    Energy Science and Technology Software Center (ESTSC)

    2002-05-01

    We developed new pattern recognition (PR) algorithms based on a human visual perception model. We named these algorithms Visual Empirical Region of Influence (VERI) algorithms. To compare the new algorithm's effectiveness against othe PR algorithms, we benchmarked their clustering capabilities with a standard set of two-dimensional data that is well known in the PR community. The VERI algorithm succeeded in clustering all the data correctly. No existing algorithm had previously clustered all the pattens inmore »the data set successfully. The commands to execute VERI algorithms are quite difficult to master when executed from a DOS command line. The algorithm requires several parameters to operate correctly. From our own experiences we realized that if we wanted to provide a new data analysis tool to the PR community we would have to provide a new data analysis tool to the PR community we would have to make the tool powerful, yet easy and intuitive to use. That was our motivation for developing graphical user interfaces (GUI's) to the VERI algorithms. We developed GUI's to control the VERI algorithm in a single pass mode and in an optimization mode. We also developed a visualization technique that allows users to graphically animate and visually inspect multi-dimensional data after it has been classified by the VERI algorithms. The visualization technique that allows users to graphically animate and visually inspect multi-dimensional data after it has been classified by the VERI algorithms. The visualization package is integrated into the single pass interface. Both the single pass interface and optimization interface are part of the PR software package we have developed and make available to other users. The single pass mode only finds PR results for the sets of features in the data set that are manually requested by the user. The optimization model uses a brute force method of searching through the cominations 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. The VERI interface tools were written using the Tcl/Tk 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 interfaces run the VERI algorithms in Leave-One-Out mode using the Euclidean metric.« less

  19. Changing Perspective: Zooming in and out during Visual Search

    ERIC Educational Resources Information Center

    Solman, Grayden J. F.; Cheyne, J. Allan; Smilek, Daniel

    2013-01-01

    Laboratory studies of visual search are generally conducted in contexts with a static observer vantage point, constrained by a fixation cross or a headrest. In contrast, in many naturalistic search settings, observers freely adjust their vantage point by physically moving through space. In two experiments, we evaluate behavior during free vantage…

  20. Predicting Cognitive Strategies and Eye Movements in Hierarchical Visual Search

    E-print Network

    Hornof, Anthony

    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 the target group, and then confine their search within that group. Predicted and Observed Eye Movements Eye

  1. Visual search speed is influenced by differences in shape arbitrariness.

    PubMed

    Leshinskaya, Anna; Caramazza, Alfonso

    2015-09-01

    We hypothesized that the visual system is particularly tuned to those features which correlate with behaviorally relevant dimensions, and compared a few possibilities: how man-made an object is (naturalness), how often an object is eaten (edibility), how often an object is manipulated (manipulability), and the degree to which an object's shape is arbitrary (shape arbitrariness; Prasada, 2001). For example, the shape of a hammer is more constrained by the kind of thing that it is (i.e., is less arbitrary) than the shape of a rock. Does variability in perceptual similarity among sets of small, inanimate objects correlate with behavioral ratings on any of these dimensions? We chose four sets (categories) of stimuli: manipulable artifacts (e.g., pens), non-manipulable artifacts (e.g., lamps), natural objects (e.g. pinecones), and fruits/vegetables. These categories did not differ on ratings of typicality, familiarity, internal details, and visual complexity, or in area, aspect ratio, contour variance, extent, spatial frequency, contrast, or luminance. Participants searched for a target image among distractors from the same or different category; they pressed a space bar when they found the target, and reported its location by clicking X's that replaced the original images. For each category pairing, the difference in search speeds between same- and different-category trials was taken as an index of perceptual dissimilarity, and correlated with distances in each dimension for each subject (representational similarity analysis). Neither manipulability nor edibility explained the pattern of perceptual dissimilarity among categories (all r< .1, t< 1,p>.3). Although naturalness explained some variance (r=.16, t=2.13, p=.048), shape arbitrariness explained more (r=.40, t=4.05, p< .0001). Visual features correlated with shape arbitrariness include shape symmetry and regularity, according to ratings(r=.74, p< .001). These results suggest that, among inanimate objects, the visual system may be particularly sensitive to the perceptual features correlated with the arbitrariness of their shapes. Meeting abstract presented at VSS 2015. PMID:26326853

  2. The Serial Process in Visual Search

    ERIC Educational Resources Information Center

    Gilden, David L.; Thornton, Thomas L.; Marusich, Laura R.

    2010-01-01

    The conditions for serial search are described. A multiple target search methodology (Thornton & Gilden, 2007) is used to home in on the simplest target/distractor contrast that effectively mandates a serial scheduling of attentional resources. It is found that serial search is required when (a) targets and distractors are mirror twins, and (b)…

  3. Visual Search in a Multi-Element Asynchronous Dynamic (MAD) World

    ERIC Educational Resources Information Center

    Kunar, Melina A.; Watson, Derrick G.

    2011-01-01

    In visual search tasks participants search for a target among distractors in strictly controlled displays. We show that visual search principles observed in these tasks do not necessarily apply in more ecologically valid search conditions, using dynamic and complex displays. A multi-element asynchronous dynamic (MAD) visual search was developed in…

  4. Eye-Mouse Coordination Patterns on Web Search Results Pages

    E-print Network

    Cortes, Corinna

    Eye-Mouse Coordination Patterns on Web Search Results Pages Abstract We analyzed the patterns of coordination between users' eye movements and mouse movements when scanning a web search results page, using data gathered from a study with 32 participants. We discovered 3 patterns of active mouse usage

  5. Modeling the Visual Search of Displays

    E-print Network

    Byrne, Mike

    -Tracking Data Michael D. Fleetwood and Michael D. Byrne Rice University Abstract Because of the visual natureD candidate in the psychology department at Rice University. Michael Byrne is an applied cognitive scientist professor in the psychology department at Rice University. #12;CONTENTS 1. INTRODUCTION 1.1. Relevant Visual

  6. Visual Object Pattern Separation Varies in Older Adults

    ERIC Educational Resources Information Center

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

    2013-01-01

    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…

  7. Rapid and implicit effects of color category on visual search

    NASA Astrophysics Data System (ADS)

    Yokoi, Kenji; Watanabe, Katsumi; Saida, Shinya

    2012-07-01

    Many studies suggest that the color category influences visual perception. It is also well known that oculomotor control and visual attention are closely linked. In order to clarify temporal characteristics of color categorization, we investigated eye movements during color visual search. Eight color disks were presented briefly for 20-320 ms, and the subject was instructed to gaze at a target shown prior to the trial. We found that the color category of the target modulated eye movements significantly when the stimulus was displayed for more than 40 ms and the categorization could be completed within 80 ms. With the 20 ms presentation, the search performance was at a chance level, however, the first saccadic latency suggested that the color category had an effect on visual attention. These results suggest that color categorization affects the guidance of visual attention rapidly and implicitly.

  8. Coloured Overlays, Visual Discomfort, Visual Search and Classroom Reading.

    ERIC Educational Resources Information Center

    Tyrrell, Ruth; And Others

    1995-01-01

    States that 46 children aged 12-16 were shown a page of meaningless text covered with plastic overlays, including 7 that were various colors and 1 that was clear. Explains that each child selected the overlay that made reading easiest. Notes that children who read with a colored overlay complained of visual discomfort when they read without the…

  9. Design and Implementation of Cancellation Tasks for Visual Search Strategies and Visual Attention in School Children

    ERIC Educational Resources Information Center

    Wang, Tsui-Ying; Huang, Ho-Chuan; Huang, Hsiu-Shuang

    2006-01-01

    We propose a computer-assisted cancellation test system (CACTS) to understand the visual attention performance and visual search strategies in school children. The main aim of this paper is to present our design and development of the CACTS and demonstrate some ways in which computer techniques can allow the educator not only to obtain more…

  10. Prior knowledge of objects improves efficiency during hybrid visual search.

    PubMed

    Johnson, Aaron; Brand, John; Esses, Yvette; Grohmann, Bianca; Bodur, H Onur

    2015-09-01

    In our daily lives, visual search often involves looking for items that we have in memory, such as in the search for products to purchase in a supermarket. Previous work has shown that this type of search (termed Hybrid Visual Search) becomes less efficient - as assessed by increases in reaction time - as a function of set size of objects in the search array, and set size of the objects that are memorized. This previous work involved the memorization of random objects. But what would happen if participants already had prior knowledge of the object? For example, searching for a popular brand of cola among other products on a grocery shelf may be faster, as the participant already knows that the target object is red and white. This prior knowledge may therefore improve the efficiency of hybrid search. To test this hypothesis, we ran a hybrid visual search task on 100 participants for known North American brands, versus unknown European brands. Known and unknown brands were matched in terms of product category (i.e. each group of objects contained the same type of products). Brand knowledge (or lack thereof) was confirmed post-experiment via a questionnaire. We manipulated set size (4, 8, 16) for both items memorized, and for number of objects on the screen. All distractors were random objects. Similar to previous studies, we found set size effects for both items memorized, as well as the number of items on the screen for both known and unknown brands. Furthermore, we observed a statistically significant (p< .01) increase in reaction times across all set sizes for the unknown (versus known) objects. In addition, search slopes are steeper for unknown versus known objects. We therefore conclude that prior knowledge of items helps to make hybrid visual search more efficient. Meeting abstract presented at VSS 2015. PMID:26327050

  11. The impact of expert visual guidance on trainee visual search strategy, visual attention and motor skills

    PubMed Central

    Leff, Daniel R.; James, David R. C.; Orihuela-Espina, Felipe; Kwok, Ka-Wai; Sun, Loi Wah; Mylonas, George; Athanasiou, Thanos; Darzi, Ara W.; Yang, Guang-Zhong

    2015-01-01

    Minimally invasive and robotic surgery changes the capacity for surgical mentors to guide their trainees with the control customary to open surgery. This neuroergonomic study aims to assess a “Collaborative Gaze Channel” (CGC); which detects trainer gaze-behavior and displays the point of regard to the trainee. A randomized crossover study was conducted in which twenty subjects performed a simulated robotic surgical task necessitating collaboration either with verbal (control condition) or visual guidance with CGC (study condition). Trainee occipito-parietal (O-P) cortical function was assessed with optical topography (OT) and gaze-behavior was evaluated using video-oculography. Performance during gaze-assistance was significantly superior [biopsy number: (mean ± SD): control = 5.6 ± 1.8 vs. CGC = 6.6 ± 2.0; p < 0.05] and was associated with significantly lower O-P cortical activity [?HbO2 mMol × cm [median (IQR)] control = 2.5 (12.0) vs. CGC 0.63 (11.2), p < 0.001]. A random effect model (REM) confirmed the association between guidance mode and O-P excitation. Network cost and global efficiency were not significantly influenced by guidance mode. A gaze channel enhances performance, modulates visual search, and alleviates the burden in brain centers subserving visual attention and does not induce changes in the trainee’s O-P functional network observable with the current OT technique. The results imply that through visual guidance, attentional resources may be liberated, potentially improving the capability of trainees to attend to other safety critical events during the procedure. PMID:26528160

  12. MotionFlow: Visual Abstraction and Aggregation of Sequential Patterns in Human Motion Tracking Data.

    PubMed

    Jang, Sujin; Elmqvist, Niklas; Ramani, Karthik

    2016-01-01

    Pattern analysis of human motions, which is useful in many research areas, requires understanding and comparison of different styles of motion patterns. However, working with human motion tracking data to support such analysis poses great challenges. In this paper, we propose MotionFlow, a visual analytics system that provides an effective overview of various motion patterns based on an interactive flow visualization. This visualization formulates a motion sequence as transitions between static poses, and aggregates these sequences into a tree diagram to construct a set of motion patterns. The system also allows the users to directly reflect the context of data and their perception of pose similarities in generating representative pose states. We provide local and global controls over the partition-based clustering process. To support the users in organizing unstructured motion data into pattern groups, we designed a set of interactions that enables searching for similar motion sequences from the data, detailed exploration of data subsets, and creating and modifying the group of motion patterns. To evaluate the usability of MotionFlow, we conducted a user study with six researchers with expertise in gesture-based interaction design. They used MotionFlow to explore and organize unstructured motion tracking data. Results show that the researchers were able to easily learn how to use MotionFlow, and the system effectively supported their pattern analysis activities, including leveraging their perception and domain knowledge. PMID:26529685

  13. Image pattern recognition supporting interactive analysis and graphical visualization

    NASA Technical Reports Server (NTRS)

    Coggins, James M.

    1992-01-01

    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.

  14. Visual search and attention to faces in early infancy

    PubMed Central

    Frank, Michael C.; Amso, Dima; Johnson, Scott P.

    2013-01-01

    Newborn babies look preferentially at faces and face-like displays; yet over the course of their first year, much changes about both the way infants process visual stimuli and how they allocate their attention to the social world. Despite this initial preference for faces in restricted contexts, the amount that infants look at faces increases considerably in the first year. Is this development related to changes in attentional orienting abilities? We explored this possibility by showing 3-, 6-, and 9-month-olds engaging animated and live-action videos of social stimuli and additionally measuring their visual search performance with both moving and static search displays. Replicating previous findings, looking at faces increased with age; in addition, the amount of looking at faces was strongly related to the youngest infants’ performance in visual search. These results suggest that infants’ attentional abilities may be an important factor facilitating their social attention early in development. PMID:24211654

  15. A Neural Decomposition of Visual Search Using Voxel-based Morphometry.

    PubMed

    Humphreys, Glyn W; Chechlacz, Magdalena

    2015-09-01

    The ability to search efficiently for visual targets among distractors can break down after a variety of brain lesions, but the specific processes affected by the lesions are unclear. We examined search over space (conjunction search) and over time plus space (preview search) in a consecutive series of patients with acquired brain lesions. We also assessed performance on standard neuropsychological measures of visuospatial short-term memory (Corsi Block), sustained attention and memory updating (the contrast between forward and backward digit span), and visual neglect. Voxel-based morphometry analyses revealed regions in the occipital (middle occipital gyrus), posterior parietal (angular gyrus), and temporal cortices (superior and middle temporal gyri extending to the insula), along with underlying white matter pathways, associated with poor search. Going beyond standard voxel-based morphometry analyses, we then report correlation measures of structural damage in these regions and the independent neuropsychological measures of other cognitive functions. We find distinct patterns of correlation in areas linked to poor search, suggesting that the areas play functionally different roles in search. We conclude that neuropsychological disorders of search can be linked to necessary and distinct cognitive functions, according to the site of lesion. PMID:26058605

  16. Sequential pattern data mining and visualization

    DOEpatents

    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

    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).

  17. Sequential pattern data mining and visualization

    DOEpatents

    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

    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).

  18. Learned face-voice pairings facilitate visual search.

    PubMed

    Zweig, L Jacob; Suzuki, Satoru; Grabowecky, Marcia

    2015-04-01

    Voices provide a rich source of information that is important for identifying individuals and for social interaction. During search for a face in a crowd, voices often accompany visual information, and they facilitate localization of the sought-after individual. However, it is unclear whether this facilitation occurs primarily because the voice cues the location of the face or because it also increases the salience of the associated face. Here we demonstrate that a voice that provides no location information nonetheless facilitates visual search for an associated face. We trained novel face-voice associations and verified learning using a two-alternative forced choice task in which participants had to correctly match a presented voice to the associated face. Following training, participants searched for a previously learned target face among other faces while hearing one of the following sounds (localized at the center of the display): a congruent learned voice, an incongruent but familiar voice, an unlearned and unfamiliar voice, or a time-reversed voice. Only the congruent learned voice speeded visual search for the associated face. This result suggests that voices facilitate the visual detection of associated faces, potentially by increasing their visual salience, and that the underlying crossmodal associations can be established through brief training. PMID:25023955

  19. Parallel and Serial Processes in Visual Search

    ERIC Educational Resources Information Center

    Thornton, Thomas L.; Gilden, David L.

    2007-01-01

    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…

  20. Visual Exploratory Search of Relationship Graphs on Smartphones

    PubMed Central

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

    2013-01-01

    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

  1. Visual search is influenced by 3D spatial layout.

    PubMed

    Finlayson, Nonie J; Grove, Philip M

    2015-10-01

    Many activities necessitate the deployment of attention to specific distances and directions in our three-dimensional (3D) environment. However, most research on how attention is deployed is conducted with two dimensional (2D) computer displays, leaving a large gap in our understanding about the deployment of attention in 3D space. We report how each of four parameters of 3D visual space influence visual search: 3D display volume, distance in depth, number of depth planes, and relative target position in depth. Using a search task, we find that visual search performance depends on 3D volume, relative target position in depth, and number of depth planes. Our results demonstrate an asymmetrical preference for targets in the front of a display unique to 3D search and show that arranging items into more depth planes reduces search efficiency. Consistent with research using 2D displays, we found slower response times to find targets in displays with larger 3D volumes compared with smaller 3D volumes. Finally, in contrast to the importance of target depth relative to other distractors, target depth relative to the fixation point did not affect response times or search efficiency. PMID:25971812

  2. Distributed Visual Working Memory Stores Revealed by Multivariate Pattern Analyses.

    PubMed

    Christophel, Thomas B

    2015-09-01

    Distributed Visual Working Memory Stores Revealed by Multivariate Pattern Analyses Thomas B. Christophel, Chang Yan, Carsten Allefeld & John-Dylan Haynes The storage buffers retaining visual working memory contents were originally postulated to reside in prefrontal cortex. Recently, a dissenting view has evolved claiming that working memory content depends on distributed storage in sensory brain regions. We provide strong evidence for this claim in a series of fMRI experiments investigating the content-specificity of delay-period activity using multivariate pattern analyses. Representations of color and motion patterns as well as complex shapes were identified in early visual, and lateral occipital posterior parietal cortex, but also in the frontal eye fields. A meta-analysis of content-specificity within these brain areas revealed large inter-areal differences critically depending on whether the stimuli were smooth global patterns or shapes with clear edges and on whether stimuli varied across color, luminance or motion direction dimensions. In addition, we show that areas beyond early visual cortex retain information in an inherently view-independent format and that coding of a given stimulus in higher visual areas is not solely driven by the visual display originally shown. Instead, the representation changes when a subject mentally transforms what they are holding in mind (i.e. during mental rotation). Extending our findings on visual working memory, we show that verbal content (Chinese Characters memorized by native speakers of Chinese) is selectively stored in prefrontal areas, more specifically Broca's area and articulatory premotor cortex. Finally, while working memory storage seems to be represented in a distributed way, working memory control could be traced to dorsolateral prefrontal cortex regardless of what content was memorized. PMID:26327095

  3. History effects in visual search for monsters: search times, choice biases, and liking.

    PubMed

    Chetverikov, Andrey; Kristjansson, Árni

    2015-02-01

    Repeating targets and distractors on consecutive visual search trials facilitates search performance, whereas switching targets and distractors harms search. In addition, search repetition leads to biases in free choice tasks, in that previously attended targets are more likely to be chosen than distractors. Another line of research has shown that attended items receive high liking ratings, whereas ignored distractors are rated negatively. Potential relations between the three effects are unclear, however. Here we simultaneously measured repetition benefits and switching costs for search times, choice biases, and liking ratings in color singleton visual search for "monster" shapes. We showed that if expectations from search repetition are violated, targets are liked to be less attended than otherwise. Choice biases were, on the other hand, affected by distractor repetition, but not by target/distractor switches. Target repetition speeded search times but had little influence on choice or liking. Our findings suggest that choice biases reflect distractor inhibition, and liking reflects the conflict associated with attending to previously inhibited stimuli, while speeded search follows both target and distractor repetition. Our results support the newly proposed affective-feedback-of-hypothesis-testing account of cognition, and additionally, shed new light on the priming of visual search. PMID:25338539

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

    ERIC Educational Resources Information Center

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

    2010-01-01

    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.,…

  5. Phase Oscillatory Network and Visual Pattern Recognition.

    PubMed

    Follmann, Rosangela; Macau, Elbert E N; Rosa, Epaminondas; Piqueira, José R C

    2015-07-01

    We explore a properly interconnected set of Kuramoto type oscillators that results in a new associative-memory network configuration, which includes second- and third-order additional terms in the Fourier expansion of the network's coupling. Investigation of the response of the network to different external stimuli indicates an increase in the network capability for coding and information retrieval. Comparison of the network output with that of an equivalent experiment with subjects, for recognizing perturbed binary patterns, shows comparable results between the two approaches. We also discuss the enhanced storage capacity of the network. PMID:25137734

  6. Recognizing patterns of visual field loss using unsupervised machine learning

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  7. Enhancing Visual Search Abilities of People with Intellectual Disabilities

    ERIC Educational Resources Information Center

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

    2009-01-01

    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…

  8. Information Search: The Intersection of Visual and Semantic Space

    E-print Network

    Byrne, Mike

    and Michael D. Byrne Rice University Department of Psychology 6100 S. Main Street, MS-25, Houston, TX 77005 USA +1 713 348 4856 {tambo, byrne}@rice.edu Abstract In the context of an information search task with high information scent even if they are not visually salient? Pirolli and Card [9] have put forth

  9. 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 scenes with remarkable speed and accuracy. Recent studies found human response times to be as fast as 120

  10. Content-Based Visual Landmark Search via Multimodal Hypergraph Learning.

    PubMed

    Zhu, Lei; Shen, Jialie; Jin, Hai; Zheng, Ran; Xie, Liang

    2015-12-01

    While content-based landmark image search has recently received a lot of attention and became a very active domain, it still remains a challenging problem. Among the various reasons, high diverse visual content is the most significant one. It is common that for the same landmark, images with a wide range of visual appearances can be found from different sources and different landmarks may share very similar sets of images. As a consequence, it is very hard to accurately estimate the similarities between the landmarks purely based on single type of visual feature. Moreover, the relationships between landmark images can be very complex and how to develop an effective modeling scheme to characterize the associations still remains an open question. Motivated by these concerns, we propose multimodal hypergraph (MMHG) to characterize the complex associations between landmark images. In MMHG, images are modeled as independent vertices and hyperedges contain several vertices corresponding to particular views. Multiple hypergraphs are firstly constructed independently based on different visual modalities to describe the hidden high-order relations from different aspects. Then, they are integrated together to involve discriminative information from heterogeneous sources. We also propose a novel content-based visual landmark search system based on MMHG to facilitate effective search. Distinguished from the existing approaches, we design a unified computational module to support query-specific combination weight learning. An extensive experiment study on a large-scale test collection demonstrates the effectiveness of our scheme over state-of-the-art approaches. PMID:25576590

  11. Accurate expectancies diminish perceptual distraction during visual search

    PubMed Central

    Sy, Jocelyn L.; Guerin, Scott A.; Stegman, Anna; Giesbrecht, Barry

    2014-01-01

    The load theory of visual attention proposes that efficient selective perceptual processing of task-relevant information during search is determined automatically by the perceptual demands of the display. If the perceptual demands required to process task-relevant information are not enough to consume all available capacity, then the remaining capacity automatically and exhaustively “spills-over” to task-irrelevant information. The spill-over of perceptual processing capacity increases the likelihood that task-irrelevant information will impair performance. In two visual search experiments, we tested the automaticity of the allocation of perceptual processing resources by measuring the extent to which the processing of task-irrelevant distracting stimuli was modulated by both perceptual load and top-down expectations using behavior, functional magnetic resonance imaging, and electrophysiology. Expectations were generated using a trial-by-trial cue that provided information about the likely load of the upcoming visual search task. When the cues were valid, behavioral interference was eliminated and the influence of load on frontoparietal and visual cortical responses was attenuated relative to when the cues were invalid. In conditions in which task-irrelevant information interfered with performance and modulated visual activity, individual differences in mean blood oxygenation level dependent responses measured from the left intraparietal sulcus were negatively correlated with individual differences in the severity of distraction. These results are consistent with the interpretation that a top-down biasing mechanism interacts with perceptual load to support filtering of task-irrelevant information. PMID:24904374

  12. The role of memory for visual search in scenes.

    PubMed

    Le-Hoa Võ, Melissa; Wolfe, Jeremy M

    2015-03-01

    Many daily activities involve looking for something. The ease with which these searches are performed often allows one to forget that searching represents complex interactions between visual attention and memory. Although a clear understanding exists of how search efficiency will be influenced by visual features of targets and their surrounding distractors or by the number of items in the display, the role of memory in search is less well understood. Contextual cueing studies have shown that implicit memory for repeated item configurations can facilitate search in artificial displays. When searching more naturalistic environments, other forms of memory come into play. For instance, semantic memory provides useful information about which objects are typically found where within a scene, and episodic scene memory provides information about where a particular object was seen the last time a particular scene was viewed. In this paper, we will review work on these topics, with special emphasis on the role of memory in guiding search in organized, real-world scenes. PMID:25684693

  13. Visual search for arbitrary objects in real scenes

    PubMed Central

    Alvarez, George A.; Rosenholtz, Ruth; Kuzmova, Yoana I.; Sherman, Ashley M.

    2011-01-01

    How efficient is visual search in real scenes? In searches for targets among arrays of randomly placed distractors, efficiency is often indexed by the slope of the reaction time (RT) × Set Size function. However, it may be impossible to define set size for real scenes. As an approximation, we hand-labeled 100 indoor scenes and used the number of labeled regions as a surrogate for set size. In Experiment 1, observers searched for named objects (a chair, bowl, etc.). With set size defined as the number of labeled regions, search was very efficient (~5 ms/item). When we controlled for a possible guessing strategy in Experiment 2, slopes increased somewhat (~15 ms/item), but they were much shallower than search for a random object among other distinctive objects outside of a scene setting (Exp. 3: ~40 ms/item). In Experiments 4–6, observers searched repeatedly through the same scene for different objects. Increased familiarity with scenes had modest effects on RTs, while repetition of target items had large effects (>500 ms). We propose that visual search in scenes is efficient because scene-specific forms of attentional guidance can eliminate most regions from the “functional set size” of items that could possibly be the target. PMID:21671156

  14. Visual Object Pattern Separation Deficits in Nondemented Older Adults

    ERIC Educational Resources Information Center

    Toner, Chelsea K.; Pirogovsky, Eva; Kirwan, C. Brock; Gilbert, Paul E.

    2009-01-01

    Young and nondemented older adults were tested on a continuous recognition memory task requiring visual pattern separation. During the task, some objects were repeated across trials and some objects, referred to as lures, were presented that were similar to previously presented objects. The lures resulted in increased interference and an increased…

  15. Fractal Analysis of Radiologists Visual Scanning Pattern in Screening Mammography

    SciTech Connect

    Alamudun, Folami T; Yoon, Hong-Jun; Hudson, Kathy; Morin-Ducote, Garnetta; Tourassi, Georgia

    2015-01-01

    Several investigators have investigated radiologists visual scanning patterns with respect to features such as total time examining a case, time to initially hit true lesions, number of hits, etc. The purpose of this study was to examine the complexity of the radiologists visual scanning pattern when viewing 4-view mammographic cases, as they typically do in clinical practice. Gaze data were collected from 10 readers (3 breast imaging experts and 7 radiology residents) while reviewing 100 screening mammograms (24 normal, 26 benign, 50 malignant). The radiologists scanpaths across the 4 mammographic views were mapped to a single 2-D image plane. Then, fractal analysis was applied on the derived scanpaths using the box counting method. For each case, the complexity of each radiologist s scanpath was estimated using fractal dimension. The association between gaze complexity, case pathology, case density, and radiologist experience was evaluated using 3 factor fixed effects ANOVA. ANOVA showed that case pathology, breast density, and experience level are all independent predictors of the visual scanning pattern complexity. Visual scanning patterns are significantly different for benign and malignant cases than for normal cases as well as when breast parenchyma density changes.

  16. Searching for pulsars using image pattern recognition

    SciTech Connect

    Zhu, W. W.; Berndsen, A.; Madsen, E. C.; Tan, M.; Stairs, I. H.; Brazier, A.; Lazarus, P.; Lynch, R.; Scholz, P.; Stovall, K.; Cohen, S.; Dartez, L. P.; Lunsford, G.; Martinez, J. G.; Mata, A.; Ransom, S. M.; Banaszak, S.; Biwer, C. M.; Flanigan, J.; Rohr, M. E-mail: berndsen@phas.ubc.ca; and others

    2014-02-01

    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.

  17. Searching for Pulsars Using Image Pattern Recognition

    NASA Astrophysics Data System (ADS)

    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

    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.

  18. Comparing target detection errors in visual search and manually-assisted search.

    PubMed

    Solman, Grayden J F; Hickey, Kersondra; Smilek, Daniel

    2014-05-01

    Subjects searched for low- or high-prevalence targets among static nonoverlapping items or items piled in heaps that could be moved using a computer mouse. We replicated the classical prevalence effect both in visual search and when unpacking items from heaps, with more target misses under low prevalence. Moreover, we replicated our previous finding that while unpacking, people often move the target item without noticing (the unpacking error) and determined that these errors also increase under low prevalence. On the basis of a comparison of item movements during the manually-assisted search and eye movements during static visual search, we suggest that low prevalence leads to broadly reduced diligence during search but that the locus of this reduced diligence depends on the nature of the task. In particular, while misses during visual search often arise from a failure to inspect all of the items, misses during manually-assisted search more often result from a failure to adequately inspect individual items. Indeed, during manually-assisted search, over 90 % of target misses occurred despite subjects having moved the target item during search. PMID:24554230

  19. Eye movements selective for spatial frequency and orientation during active visual search

    E-print Network

    Tavassoli, Abtine

    images Eye movements 1/f noise a b s t r a c t Visual search can simply be defined as the task of looking Keywords: Visual search Orientation tuning Spatial frequency selectivity Reverse-correlation Classification

  20. Selectively Searching for Conjunctively-Defined Visual Targets Charles E. Wright, April M. Main

    E-print Network

    White, Douglas R.

    MBS 96-14 Selectively Searching for Conjunctively-Defined Visual Targets Charles E. Wright, April M undergraduates) can search selectively through visual displays for a target defined by the conjunction of two

  1. Attention during visual search: The benefit of bilingualism

    PubMed Central

    Friesen, Deanna C; Latman, Vered; Calvo, Alejandra; Bialystok, Ellen

    2015-01-01

    Aims and Objectives/Purpose/Research Questions Following reports showing bilingual advantages in executive control (EC) performance, the current study investigated the role of selective attention as a foundational skill that might underlie these advantages. Design/Methodology/Approach Bilingual and monolingual young adults performed a visual search task by determining whether a target shape was present amid distractor shapes. Task difficulty was manipulated by search type (feature or conjunction) and by the number and discriminability of the distractors. In feature searches, the target (e.g., green triangle) differed on a single dimension (e.g., color) from the distractors (e.g., yellow triangles); in conjunction searches, two types of distractors (e.g., pink circles and turquoise squares) each differed from the target (e.g., turquoise circle) on a single but different dimension (e.g., color or shape). Data and Analysis Reaction time and accuracy data from 109 young adults (53 monolinguals and 56 bilinguals) were analyzed using a repeated-measures analysis of variance. Group membership, search type, number and discriminability of distractors were the independent variables. Findings/Conclusions Participants identified the target more quickly in the feature searches, when the target was highly discriminable from the distractors and when there were fewer distractors. Importantly, although monolinguals and bilinguals performed equivalently on the feature searches, bilinguals were significantly faster than monolinguals in identifying the target in the more difficult conjunction search, providing evidence for better control of visual attention in bilinguals Originality Unlike previous studies on bilingual visual attention, the current study found a bilingual attention advantage in a paradigm that did not include a Stroop-like manipulation to set up false expectations. Significance/Implications Thus, our findings indicate that the need to resolve explicit conflict or overcome false expectations is unnecessary for observing a bilingual advantage in selective attention. Observing this advantage in a fundamental skill suggests that it may underlie higher order bilingual advantages in EC.

  2. Visual object pattern separation varies in older adults

    PubMed Central

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

    2013-01-01

    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 deficits, older adults were divided into impaired and unimpaired groups based on performance on a standardized serial list-learning task. Impaired older adults showed intact recognition memory, but were impaired relative to young and unimpaired older adults when identifying similar lure stimuli, demonstrating that object pattern separation varies in older adults. PMID:23774765

  3. Entrainment of Human Alpha Oscillations Selectively Enhances Visual Conjunction Search

    PubMed Central

    Müller, Notger G.; Vellage, Anne-Katrin; Heinze, Hans-Jochen; Zaehle, Tino

    2015-01-01

    The functional role of the alpha-rhythm which dominates the human electroencephalogram (EEG) is unclear. It has been related to visual processing, attentional selection and object coherence, respectively. Here we tested the interaction of alpha oscillations of the human brain with visual search tasks that differed in their attentional demands (pre-attentive vs. attentive) and also in the necessity to establish object coherence (conjunction vs. single feature). Between pre- and post-assessment elderly subjects received 20 min/d of repetitive transcranial alternating current stimulation (tACS) over the occipital cortex adjusted to their individual alpha frequency over five consecutive days. Compared to sham the entrained alpha oscillations led to a selective, set size independent improvement in the conjunction search task performance but not in the easy or in the hard feature search task. These findings suggest that cortical alpha oscillations play a specific role in establishing object coherence through suppression of distracting objects. PMID:26606255

  4. Behavior and neural basis of near-optimal visual search

    PubMed Central

    Ma, Wei Ji; Navalpakkam, Vidhya; Beck, Jeffrey M; van den Berg, Ronald; Pouget, Alexandre

    2013-01-01

    The ability to search efficiently for a target in a cluttered environment is one of the most remarkable functions of the nervous system. This task is difficult under natural circumstances, as the reliability of sensory information can vary greatly across space and time and is typically a priori unknown to the observer. In contrast, visual-search experiments commonly use stimuli of equal and known reliability. In a target detection task, we randomly assigned high or low reliability to each item on a trial-by-trial basis. An optimal observer would weight the observations by their trial-to-trial reliability and combine them using a specific nonlinear integration rule. We found that humans were near-optimal, regardless of whether distractors were homogeneous or heterogeneous and whether reliability was manipulated through contrast or shape. We present a neural-network implementation of near-optimal visual search based on probabilistic population coding. The network matched human performance. PMID:21552276

  5. Levy flight as a robotic search pattern

    E-print Network

    Saldivar, Orlando

    2012-01-01

    Levy flights have been recently found to approximate the trajectories of animal foragers in their search for resources and food. Levy flights have proved to be effective in searching tasks because of their characteristic ...

  6. The Efficiency of a Visual Skills Training Program on Visual Search Performance

    PubMed Central

    Krzepota, Justyna; Zwierko, Teresa; Puchalska-Niedba?, Lidia; Markiewicz, Miko?aj; Florkiewicz, Beata; Lubi?ski, Wojciech

    2015-01-01

    In this study, we conducted an experiment in which we analyzed the possibilities to develop visual skills by specifically targeted training of visual search. The aim of our study was to investigate whether, for how long and to what extent a training program for visual functions could improve visual search. The study involved 24 healthy students from the Szczecin University who were divided into two groups: experimental (12) and control (12). In addition to regular sports and recreational activities of the curriculum, the subjects of the experimental group also participated in 8-week long training with visual functions, 3 times a week for 45 min. The Signal Test of the Vienna Test System was performed four times: before entering the study, after first 4 weeks of the experiment, immediately after its completion and 4 weeks after the study terminated. The results of this experiment proved that an 8-week long perceptual training program significantly differentiated the plot of visual detecting time. For the visual detecting time changes, the first factor, Group, was significant as a main effect (F(1,22)=6.49, p<0.05) as well as the second factor, Training (F(3,66)=5.06, p<0.01). The interaction between the two factors (Group vs. Training) of perceptual training was F(3,66)=6.82 (p<0.001). Similarly, for the number of correct reactions, there was a main effect of a Group factor (F(1,22)=23.40, p<0.001), a main effect of a Training factor (F(3,66)=11.60, p<0.001) and a significant interaction between factors (Group vs. Training) (F(3,66)=10.33, p<0.001). Our study suggests that 8-week training of visual functions can improve visual search performance. PMID:26240666

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

    E-print Network

    Peli, Eli

    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 the performance effect for a JPEG based image enhancement technique using the visual search task. Methods: One

  8. The Great Potato Search: The Effects of Visual Context on Users' Feature Search and Recognition Abilities in an IVR Scene

    E-print Network

    Laidlaw, David

    performance in an immersive virtual reality (IVR) system. Contrary to previous research on 2D visual search. The current study aims to examine the role of visual context on a visual search task in an immersive virtual and that are projected coincident to the physical CAVE walls will facilitate user performance. Furthermore, we

  9. Human Visual Search Performance for Camouflaged Targets.

    PubMed

    Matthews, Olivia; Liggins, Eric; Volonakis, Tim; Scott-Samuel, Nick; Baddeley, Roland; Cuthill, Innes

    2015-09-01

    There is a paucity of published systematic research investigating object detection within the military context. Here, we establish baseline human detection performance for five standard military issued camouflage patterns. Stimuli were drawn from a database of 1242 calibrated images of a mixed deciduous woodland environment in Bristol, UK. Images within this database were taken during daylight hours, in summer and contained a PASGT helmet, systematically positioned within each scene. Subjects (20) discriminated between the two image types in a temporal 2AFC task (500ms presentation for each interval), with the detection scenario being the percentage of instances participants correctly detected the target. Cueing (cued/not-cued to target location), colour (colour/greyscale) and distance from the observer (3.5/5/7.5m) were manipulated, as was helmet camouflage pattern. A Generalized Linear Mixed Model revealed significant interactions between all variables on participant performance, with greater accuracy when stimuli were in colour, and the target location was cued. There was also a clear ranking of patterns in terms of effectiveness of camouflage. We also compare the results with a computational model based on low-level vision, and eye tracking data, with encouraging results. Our methodology provides a controlled means of assessing any camouflage in any environment, and the potential to implement a machine vision solution to assessment. In this instance, we show differences in the effectiveness of existing solutions to the problem of camouflage, concealment and deception (CCD) on the battlefield. Funded by QinetiQ as part of Materials and Structures Low Observable Materials Research Programme. Meeting abstract presented at VSS 2015. PMID:26326852

  10. Pattern-visual evoked potentials in thinner abusers.

    PubMed

    Poblano, A; Lope Huerta, M; Martínez, J M; Falcón, H D

    1996-01-01

    Organic solvents cause injury to lipids of neuronal and glial membranes. A well known characteristic of workers exposed to thinner is optic neuropathy. We decided to look for neurophysiologic signs of visual damage in patients identified as thinner abusers. Pattern reversal visual evoked potentials was performed on 34 thinner abuser patients and 30 controls. P-100 wave latency was found to be longer on abuser than control subjects. Results show the possibility of central alterations on thinner abusers despite absence of clinical symptoms. PMID:8987190

  11. Low-complexity image coding technique using visual patterns

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Kuo, C.-C. Jay

    1998-10-01

    A visual pattern-based image compression technique is presented, in which 4 X 4 image blocks are classified in perceptually significant `shade' and `edge' classes. The proposed technique attempts to make use of neighboring blocks to encode a shade or an edge block by exploiting the Human Visual System characteristics. To reduce correlation present in the shade regions of an image, the mean intensity of a shade block is predicted from the neighboring shade blocks, and the error mean is computed. The error mean of a block is then encoded by choosing an appropriate quantizer based on its predicted mean. The quantizer has been designed after a careful study of the distribution of the error mean of shade blocks in test images, based on Weber's law, to maximize the compression ratio without introducing any visible error. Higher dimension shade blocks (8 X 8 and 16 X 16) are also formed, by merging adjacent shade blocks which further reduces the inter-block correlation. An edge block is assumed to contain two uniform intensity regions (low and high intensity) separated by a transition region. Hence, an edge block can be encoded by coding its edge pattern, low or high intensity and gradient. In order to reduce the inter-block correlation, the edge pattern and mean intensity (low or high) are predicted. The mean intensity of error is encoded by using an appropriate quantizer. Therefore, this technique achieves higher compression ratios, as compared to other visual pattern- based techniques, at very low computational complexity.

  12. The nature of the visual environment induces implicit biases during language-mediated visual search.

    PubMed

    Huettig, Falk; McQueen, James M

    2011-08-01

    Four eyetracking experiments examined whether semantic and visual-shape representations are routinely retrieved from printed word displays and used during language-mediated visual search. Participants listened to sentences containing target words that were similar semantically or in shape to concepts invoked by concurrently displayed printed words. In Experiment 1, the displays contained semantic and shape competitors of the targets along with two unrelated words. There were significant shifts in eye gaze as targets were heard toward semantic but not toward shape competitors. In Experiments 2-4, semantic competitors were replaced with unrelated words, semantically richer sentences were presented to encourage visual imagery, or participants rated the shape similarity of the stimuli before doing the eyetracking task. In all cases, there were no immediate shifts in eye gaze to shape competitors, even though, in response to the Experiment 1 spoken materials, participants looked to these competitors when they were presented as pictures (Huettig & McQueen, 2007). There was a late shape-competitor bias (more than 2,500 ms after target onset) in all experiments. These data show that shape information is not used in online search of printed word displays (whereas it is used with picture displays). The nature of the visual environment appears to induce implicit biases toward particular modes of processing during language-mediated visual search. PMID:21461784

  13. The role of priming in conjunctive visual search A rni Kristjanssona,*, DeLiang Wangb

    E-print Network

    Nakayama, Ken

    The role of priming in conjunctive visual search A´ rni Kristja´nssona,*, DeLiang Wangb , Ken Abstract To assess the role of priming in conjunctive visual search tasks, we systematically varied in the standard conjunctive search paradigm where identities remained constant. Search was slowest when potential

  14. Patterns in the sky: Natural visualization of aircraft flow fields

    NASA Technical Reports Server (NTRS)

    Campbell, James F.; Chambers, Joseph R.

    1994-01-01

    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.

  15. Visual search for category sets: Tradeoffs between exploration and memory

    PubMed Central

    Kibbe, Melissa M.; Kowler, Eileen

    2012-01-01

    Limitations of working memory force a reliance on motor exploration to retrieve forgotten features of the visual array. A category search task was devised to study tradeoffs between exploration and memory in the face of significant cognitive and motor demands. The task required search through arrays of hidden, multi-featured objects to find three belonging to the same category. Location contents were revealed briefly by either a: (1) mouseclick, or (2) saccadic eye movement with or without delays between saccade offset and object appearance. As the complexity of the category rule increased, search favored exploration, with more visits and revisits needed to find the set. As motor costs increased (mouseclick search or oculomotor search with delays) search favored reliance on memory. Application of the model of J. Epelboim and P. Suppes (2001) to the revisits produced an estimate of immediate memory span (M) of about 4–6 objects. Variation in estimates of M across category rules suggested that search was also driven by strategies of transforming the category rule into concrete perceptual hypotheses. The results show that tradeoffs between memory and exploration in a cognitively demanding task are determined by continual and effective monitoring of perceptual load, cognitive demand, decision strategies and motor effort. PMID:21421747

  16. Pattern Visual Evoked Potentials Elicited by Organic Electroluminescence Screen

    PubMed Central

    Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Funada, Hideaki; Minoda, Haruka

    2014-01-01

    Purpose. To determine whether organic electroluminescence (OLED) screens can be used as visual stimulators to elicit pattern-reversal visual evoked potentials (p-VEPs). Method. Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA) screen and on an OLED (17 inches, 320 × 230?mm, PVM-1741, Sony, Tokyo, Japan) screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years). Results. The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0?msec on the cathode-ray tube (CRT) screen and 0.5?msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. Conclusion. The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account. PMID:25197652

  17. The influence of attention, learning, and motivation on visual search.

    PubMed

    Dodd, Michael D; Flowers, John H

    2012-01-01

    The 59th Annual Nebraska Symposium on Motivation (The Influence of Attention, Learning, and Motivation on Visual Search) took place April 7-8, 2011, on the University of Nebraska-Lincoln campus. The symposium brought together leading scholars who conduct research related to visual search at a variety levels for a series of talks, poster presentations, panel discussions, and numerous additional opportunities for intellectual exchange. The Symposium was also streamed online for the first time in the history of the event, allowing individuals from around the world to view the presentations and submit questions. The present volume is intended to both commemorate the event itself and to allow our speakers additional opportunity to address issues and current research that have since arisen. Each of the speakers (and, in some cases, their graduate students and post docs) has provided a chapter which both summarizes and expands on their original presentations. In this chapter, we sought to a) provide additional context as to how the Symposium came to be, b) discuss why we thought that this was an ideal time to organize a visual search symposium, and c) to briefly address recent trends and potential future directions in the field. We hope you find the volume both enjoyable and informative, and we thank the authors who have contributed a series of engaging chapters. PMID:23437627

  18. Intertrial priming of popout search on visual prior entry.

    PubMed

    Burnham, Bryan R

    2015-10-01

    When the features of a visual target and of nontargets are repeated between successive search displays, responding to a subsequent target is faster than when the features of the target and the nontargets switch between trials. This intertrial priming effect can influence perceptual processes, postperceptual processes (e.g., episodic retrieval), or both. Previous studies have shown that repeating irrelevant visual features that do not define the target or the response can influence postperceptual processes. The present study examined whether intertrial priming by irrelevant features also influences perceptual processes. Subjects completed a temporal order judgment task that appeared within a popout visual search display containing a color singleton among nonsingletons, all of which served as placeholders for two probes. Intertrial priming by the placeholder colors shifted the psychometric function. Specifically, the probes appearing at the color singleton in the switch condition needed to appear earlier than the probes at the color singleton in the repeat condition to be perceived simultaneous with the probes on a nonsingleton. This suggests there was an influence of intertrial priming by the irrelevant colors on visual prior entry; hence, repeating irrelevant features between trials can influence perpetual processes. PMID:26473317

  19. How visual edge features influence cuttlefish camouflage patterning.

    PubMed

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

    2013-05-01

    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

  20. Automatic guidance of attention during real-world visual search.

    PubMed

    Seidl-Rathkopf, Katharina N; Turk-Browne, Nicholas B; Kastner, Sabine

    2015-08-01

    Looking for objects in cluttered natural environments is a frequent task in everyday life. This process can be difficult, because the features, locations, and times of appearance of relevant objects often are not known in advance. Thus, a mechanism by which attention is automatically biased toward information that is potentially relevant may be helpful. We tested for such a mechanism across five experiments by engaging participants in real-world visual search and then assessing attentional capture for information that was related to the search set but was otherwise irrelevant. Isolated objects captured attention while preparing to search for objects from the same category embedded in a scene, as revealed by lower detection performance (Experiment 1A). This capture effect was driven by a central processing bottleneck rather than the withdrawal of spatial attention (Experiment 1B), occurred automatically even in a secondary task (Experiment 2A), and reflected enhancement of matching information rather than suppression of nonmatching information (Experiment 2B). Finally, attentional capture extended to objects that were semantically associated with the target category (Experiment 3). We conclude that attention is efficiently drawn towards a wide range of information that may be relevant for an upcoming real-world visual search. This mechanism may be adaptive, allowing us to find information useful for our behavioral goals in the face of uncertainty. PMID:25898897

  1. Vibrio coralliilyticus Search Patterns across an Oxygen Gradient

    PubMed Central

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

    2013-01-01

    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

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

    E-print Network

    Hornof, Anthony

    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

  3. CiteRivers: Visual Analytics of Citation Patterns.

    PubMed

    Heimerl, Florian; Han, Qi; Koch, Steffen; Ertl, Thomas

    2016-01-01

    The exploration and analysis of scientific literature collections is an important task for effective knowledge management. Past interest in such document sets has spurred the development of numerous visualization approaches for their interactive analysis. They either focus on the textual content of publications, or on document metadata including authors and citations. Previously presented approaches for citation analysis aim primarily at the visualization of the structure of citation networks and their exploration. We extend the state-of-the-art by presenting an approach for the interactive visual analysis of the contents of scientific documents, and combine it with a new and flexible technique to analyze their citations. This technique facilitates user-steered aggregation of citations which are linked to the content of the citing publications using a highly interactive visualization approach. Through enriching the approach with additional interactive views of other important aspects of the data, we support the exploration of the dataset over time and enable users to analyze citation patterns, spot trends, and track long-term developments. We demonstrate the strengths of our approach through a use case and discuss it based on expert user feedback. PMID:26529699

  4. "Hot" Facilitation of "Cool" Processing: Emotional Distraction Can Enhance Priming of Visual Search

    ERIC Educational Resources Information Center

    Kristjansson, Arni; Oladottir, Berglind; Most, Steven B.

    2013-01-01

    Emotional stimuli often capture attention and disrupt effortful cognitive processing. However, cognitive processes vary in the degree to which they require effort. We investigated the impact of emotional pictures on visual search and on automatic priming of search. Observers performed visual search after task-irrelevant neutral or emotionally…

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

    ERIC Educational Resources Information Center

    McDougall, Sine; Tyrer, Victoria; Folkard, Simon

    2006-01-01

    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

  6. Exploring the Effects of Group Size and Display Configuration on Visual Search

    E-print Network

    Toronto, University of

    is the subject of countless psychology studies in which people search for target items within a scene. The bulk. In real-life applications, however, visual search may be conducted by groups of people rather thanExploring the Effects of Group Size and Display Configuration on Visual Search Clifton Forlines1

  7. Visual tracking method based on cuckoo search algorithm

    NASA Astrophysics Data System (ADS)

    Gao, Ming-Liang; Yin, Li-Ju; Zou, Guo-Feng; Li, Hai-Tao; Liu, Wei

    2015-07-01

    Cuckoo search (CS) is a new meta-heuristic optimization algorithm that is based on the obligate brood parasitic behavior of some cuckoo species in combination with the Lévy flight behavior of some birds and fruit flies. It has been found to be efficient in solving global optimization problems. An application of CS is presented to solve the visual tracking problem. The relationship between optimization and visual tracking is comparatively studied and the parameters' sensitivity and adjustment of CS in the tracking system are experimentally studied. To demonstrate the tracking ability of a CS-based tracker, a comparative study of tracking accuracy and speed of the CS-based tracker with six "state-of-art" trackers, namely, particle filter, meanshift, PSO, ensemble tracker, fragments tracker, and compressive tracker are presented. Comparative results show that the CS-based tracker outperforms the other trackers.

  8. Audio-visual object search is changed by bilingual experience.

    PubMed

    Chabal, Sarah; Schroeder, Scott R; Marian, Viorica

    2015-11-01

    The current study examined the impact of language experience on the ability to efficiently search for objects in the face of distractions. Monolingual and bilingual participants completed an ecologically-valid, object-finding task that contained conflicting, consistent, or neutral auditory cues. Bilinguals were faster than monolinguals at locating the target item, and eye movements revealed that this speed advantage was driven by bilinguals' ability to overcome interference from visual distractors and focus their attention on the relevant object. Bilinguals fixated the target object more often than did their monolingual peers, who, in contrast, attended more to a distracting image. Moreover, bilinguals', but not monolinguals', object-finding ability was positively associated with their executive control ability. We conclude that bilinguals' executive control advantages extend to real-world visual processing and object finding within a multi-modal environment. PMID:26272368

  9. Visualizing Neuronal Network Connectivity with Connectivity Pattern Tables

    PubMed Central

    Nordlie, Eilen; Plesser, Hans Ekkehard

    2009-01-01

    Complex ideas are best conveyed through well-designed illustrations. Up to now, computational neuroscientists have mostly relied on box-and-arrow diagrams of even complex neuronal networks, often using ad hoc notations with conflicting use of symbols from paper to paper. This significantly impedes the communication of ideas in neuronal network modeling. We present here Connectivity Pattern Tables (CPTs) as a clutter-free visualization of connectivity in large neuronal networks containing two-dimensional populations of neurons. CPTs can be generated automatically from the same script code used to create the actual network in the NEST simulator. Through aggregation, CPTs can be viewed at different levels, providing either full detail or summary information. We also provide the open source ConnPlotter tool as a means to create connectivity pattern tables. PMID:20140265

  10. In situ visualization of telomere elongation patterns in human cells.

    PubMed

    Diolaiti, Morgan E; Cimini, Beth A; Kageyama, Robin; Charles, Florie A; Stohr, Bradley A

    2013-10-01

    The telomerase enzyme plays a critical role in human aging and cancer biology by maintaining telomere length and extending the proliferative lifespan of most stem cells and cancer cells. Despite the importance of this enzyme, our understanding of the mechanisms that regulate its activity and establish telomere length homeostasis in mammalian cells is incomplete, in part because the perfect repetitive nature of telomeric sequence hampers in situ detection of telomere elongation patterns. Here, we describe a novel assay using a mutant telomerase that adds a well-tolerated variant telomeric repeat sequence to telomere ends. By specifically detecting the addition of these variant repeats, we can directly visualize telomere elongation events in human cells. We validate this approach by in situ mapping of telomere elongation patterns within individual nuclei and across a population of cells. PMID:23963699

  11. Searching for pulsars using image pattern recognition

    E-print Network

    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

    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...

  12. Pattern Visual Evoked Potentials in Dyslexic versus Normal Children

    PubMed Central

    Heravian, Javad; Sobhani-Rad, Davood; Lari, Samaneh; Khoshsima, Mohamadjavad; Azimi, Abbas; Ostadimoghaddam, Hadi; Yekta, Abbasali; Hoseini-Yazdi, Seyed Hosein

    2015-01-01

    Purpose: Presence of neurophysiological abnormalities in dyslexia has been a conflicting issue. This study was performed to evaluate the role of sensory visual deficits in the pathogenesis of dyslexia. Methods: Pattern visual evoked potentials (PVEP) were recorded in 72 children including 36 children with dyslexia and 36 children without dyslexia (controls) who were matched for age, sex and intelligence. Two check sizes of 15 and 60 min of arc were used with temporal frequencies of 1.5 Hz for transient and 6 Hz for steady-state methods. Results: Mean latency and amplitude values for 15 min arc and 60 min arc check sizes using steady state and transient methods showed no significant difference between the two study groups (P values: 0.139/0.481/0.356/0.062). Furthermore, no significant difference was observed between two methods of PVEPs in dyslexic and normal children using 60 min arc with high contrast (P values: 0.116, 0.402, 0.343 and 0.106). Conclusion: The sensitivity of PVEP has high validity to detect visual deficits in children with dyslexic problem. However, no significant difference was found between dyslexia and normal children using high contrast stimuli.

  13. Animating streamlines with repeated asymmetric patterns for steady flow visualization

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    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.

  14. Coarse guidance by numerosity in visual search Ester Reijnen & Jeremy M. Wolfe &

    E-print Network

    . Keywords Attention . Visual search Introduction Consider the problem of choosing one out of many raspberry the raspberry example into the laboratory, searching for the most fruit- laden bush can be replaced

  15. Towards Low Bit Rate Mobile Visual Search with Multiple-Channel Coding

    E-print Network

    Rui, Yong

    (such as GPS tags for mobile visual search and 2D barcodes or RFID tags for mobile product search, the quality of the user experience heavily depends on how much information has to be transferred. This issue

  16. Enhanced Visual Search in Infancy Predicts Emerging Autism Symptoms.

    PubMed

    Gliga, Teodora; Bedford, Rachael; Charman, Tony; Johnson, Mark H

    2015-06-29

    In addition to core symptoms, i.e., social interaction and communication difficulties and restricted and repetitive behaviors, autism is also characterized by aspects of superior perception. One well-replicated finding is that of superior performance in visual search tasks, in which participants have to indicate the presence of an odd-one-out element among a number of foils. Whether these aspects of superior perception contribute to the emergence of core autism symptoms remains debated. Perceptual and social interaction atypicalities could reflect co-expressed but biologically independent pathologies, as suggested by a "fractionable" phenotype model of autism. A developmental test of this hypothesis is now made possible by longitudinal cohorts of infants at high risk, such as of younger siblings of children with autism spectrum disorder (ASD). Around 20% of younger siblings are diagnosed with autism themselves, and up to another 30% manifest elevated levels of autism symptoms. We used eye tracking to measure spontaneous orienting to letter targets (O, S, V, and +) presented among distractors (the letter X; Figure 1). At 9 and 15 months, emerging autism symptoms were assessed using the Autism Observation Scale for Infants (AOSI;), and at 2 years of age, they were assessed using the Autism Diagnostic Observation Schedule (ADOS;). Enhanced visual search performance at 9 months predicted a higher level of autism symptoms at 15 months and at 2 years. Infant perceptual atypicalities are thus intrinsically linked to the emerging autism phenotype. PMID:26073135

  17. Visualization of Orbits and Pattern Evocation for the Double Spherical Pendulum

    E-print Network

    Wendlandt, Jeff

    Visualization of Orbits and Pattern Evocation for the Double Spherical Pendulum Jerrold E. Marsden pattern evocation and the visualization of orbits of the double spherical pendulum. Pattern evocation or symmetry. Examples of this theory are demonstrated for the double spherical pendulum. A differential

  18. Visualization of Orbits and Pattern Evocation for the Double Spherical Pendulum

    E-print Network

    Marsden, Jerrold

    Visualization of Orbits and Pattern Evocation for the Double Spherical Pendulum Jerrold E. Marsden and the visualization of orbits of the double spherical pendulum. Pattern evocation is a phenomenon where patterns of this theory are demonstrated for the double spherical pendulum. A dierential-algebraic model is created

  19. Effect of verbal instructions and image size on visual search strategies in basketball free throw shooting.

    PubMed

    Al-Abood, Saleh A; Bennett, Simon J; Hernandez, Francisco Moreno; Ashford, Derek; Davids, Keith

    2002-03-01

    We assessed the effects on basketball free throw performance of two types of verbal directions with an external attentional focus. Novices (n = 16) were pre-tested on free throw performance and assigned to two groups of similar ability (n = 8 in each). Both groups received verbal instructions with an external focus on either movement dynamics (movement form) or movement effects (e.g. ball trajectory relative to basket). The participants also observed a skilled model performing the task on either a small or large screen monitor, to ascertain the effects of visual presentation mode on task performance. After observation of six videotaped trials, all participants were given a post-test. Visual search patterns were monitored during observation and cross-referenced with performance on the pre- and post-test. Group effects were noted for verbal instructions and image size on visual search strategies and free throw performance. The 'movement effects' group saw a significant improvement in outcome scores between the pre-test and post-test. These results supported evidence that this group spent more viewing time on information outside the body than the 'movement dynamics' group. Image size affected both groups equally with more fixations of shorter duration when viewing the small screen. The results support the benefits of instructions when observing a model with an external focus on movement effects, not dynamics. PMID:11999481

  20. Task Specificity and the Influence of Memory on Visual Search: Comment on Vo and Wolfe (2012)

    ERIC Educational Resources Information Center

    Hollingworth, Andrew

    2012-01-01

    Recent results from Vo and Wolfe (2012b) suggest that the application of memory to visual search may be task specific: Previous experience searching for an object facilitated later search for that object, but object information acquired during a different task did not appear to transfer to search. The latter inference depended on evidence that a…

  1. Data visualization and journalism

    E-print Network

    Knight, Keith

    visualization as a tool to find patterns in media behavior data visualization as a tool to tell a story #12;data Russian blogosphere Flashmobs in Brazil data visualization to find patterns in media behavior www.mediacloud.org #12;What is Media Cloud? DatabaseWeb crawler Search platform www.mediacloud.org #12;SOPA

  2. Effects of visual search vs. auditory tasks on postural control in children with autism spectrum disorder.

    PubMed

    Memari, Amir Hossein; Ghanouni, Parisa; Shayestehfar, Monir; Ziaee, Vahid; Moshayedi, Pouria

    2014-01-01

    Recent research in motor control shows the interactive role of cognitive factors in postural control. However, there is little understanding in how children with autism spectrum disorder (ASD) develop their postural behaviors. This study compares the interference of visual or auditory tasks on postural control in children with ASD. We examined 19 children with ASD (10-15 years old) and also 28 age-matched typically developing (TD) children. They were asked to perform two tasks during postural control: (1) a visual searching task (2) an auditory digit span task. Postural performances were measured with a force platform. Results showed that children with ASD indicated higher postural sway scores in visual task vs. auditory task; as root mean square (p=0.04), mean velocity (p=0.01) and sway area (p=0.02) but TD children scores remained unchanged. Children with ASD also showed significantly higher sway scores than TD children in all parameters. We conclude that in addition to primary differences in patterns of postural control of children with ASD compared to TD children, visual and auditory tasks may differently influence the postural control in this population. PMID:23931847

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

    ERIC Educational Resources Information Center

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

    2014-01-01

    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…

  4. Toddlers with Autism Spectrum Disorder Are More Successful at Visual Search than Typically Developing Toddlers

    ERIC Educational Resources Information Center

    Kaldy, Zsuzsa; Kraper, Catherine; Carter, Alice S.; Blaser, Erik

    2011-01-01

    Plaisted, O'Riordan and colleagues (Plaisted, O'Riordan & Baron-Cohen, 1998; O'Riordan, 2004) showed that school-age children and adults with Autism Spectrum Disorder (ASD) are faster at finding targets in certain types of visual search tasks than typical controls. Currently though, there is very little known about the visual search skills of very…

  5. The Effect of Animated Banner Advertisements on a Visual Search Task

    E-print Network

    Hornof, Anthony

    The Effect of Animated Banner Advertisements on a Visual Search Task Moira Burke and Anthony J } @ cs.uoregon.edu ABSTRACT Though animated banners are the predominant form of advertising on the Web are on the screen. A visual search experiment was designed to measure both subjective impression of workload

  6. UNCORRECTED 2 Target selection in visual search as revealed by movement trajectories

    E-print Network

    Nakayama, Ken

    UNCORRECTED PROOF 1 2 Target selection in visual search as revealed by movement trajectories 3 Joo movements in visual search, in which participants reached to an odd-col- 9 ored target presented with two between red and green, and the location of the target was varied. Therefore either color could

  7. Designing patterns and profiles for faster HMM search.

    PubMed

    Sun, Yanni; Buhler, Jeremy

    2009-01-01

    Profile HMMs are powerful tools for modeling conserved motifs in proteins. They are widely used by search tools to classify new protein sequences into families based on domain architecture. However, the proliferation of known motifs and new proteomic sequence data poses a computational challenge for search, requiring days of CPU time to annotate an organism's proteome. It is highly desirable to speed up HMM search in large databases. We design PROSITE-like patterns and short profiles that are used as filters to rapidly eliminate protein-motif pairs for which a full profile HMM comparison does not yield a significant match. The design of the pattern-based filters is formulated as a multichoice knapsack problem. Profile-based filters with high sensitivity are extracted from a profile HMM based on their theoretical sensitivity and false positive rate. Experiments show that our profile-based filters achieve high sensitivity (near 100 percent) while keeping around 20\\times speedup with respect to the unfiltered search program. Pattern-based filters typically retain at least 90 percent of the sensitivity of the source HMM with 30-40\\times speedup. The profile-based filters have sensitivity comparable to the multistage filtering strategy HMMERHEAD [15] and are faster in most of our experiments. PMID:19407348

  8. Pupil diameter reflects uncertainty in attentional selection during visual search

    PubMed Central

    Geng, Joy J.; Blumenfeld, Zachary; Tyson, Terence L.; Minzenberg, Michael J.

    2015-01-01

    Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones and Cohen, 2005; Yu and Dayan, 2005). In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time (RT) and performance accuracy (Experiments 1-2). Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes. PMID:26300759

  9. Enhanced Visual Search in Infancy Predicts Emerging Autism Symptoms

    PubMed Central

    Gliga, Teodora; Bedford, Rachael; Charman, Tony; Johnson, Mark H.; Baron-Cohen, Simon; Bolton, Patrick; Cheung, Celeste; Davies, Kim; Liew, Michelle; Fernandes, Janice; Gammer, Issy; Maris, Helen; Salomone, Erica; Pasco, Greg; Pickles, Andrew; Ribeiro, Helena; Tucker, Leslie

    2015-01-01

    Summary In addition to core symptoms, i.e., social interaction and communication difficulties and restricted and repetitive behaviors, autism is also characterized by aspects of superior perception [1]. One well-replicated finding is that of superior performance in visual search tasks, in which participants have to indicate the presence of an odd-one-out element among a number of foils [2–5]. Whether these aspects of superior perception contribute to the emergence of core autism symptoms remains debated [4, 6]. Perceptual and social interaction atypicalities could reflect co-expressed but biologically independent pathologies, as suggested by a “fractionable” phenotype model of autism [7]. A developmental test of this hypothesis is now made possible by longitudinal cohorts of infants at high risk, such as of younger siblings of children with autism spectrum disorder (ASD). Around 20% of younger siblings are diagnosed with autism themselves [8], and up to another 30% manifest elevated levels of autism symptoms [9]. We used eye tracking to measure spontaneous orienting to letter targets (O, S, V, and +) presented among distractors (the letter X; Figure 1). At 9 and 15 months, emerging autism symptoms were assessed using the Autism Observation Scale for Infants (AOSI; [10]), and at 2 years of age, they were assessed using the Autism Diagnostic Observation Schedule (ADOS; [11]). Enhanced visual search performance at 9 months predicted a higher level of autism symptoms at 15 months and at 2 years. Infant perceptual atypicalities are thus intrinsically linked to the emerging autism phenotype. PMID:26073135

  10. Searching for the right word: Hybrid visual and memory search for words.

    PubMed

    Boettcher, Sage E P; Wolfe, Jeremy M

    2015-05-01

    In "hybrid search" (Wolfe Psychological Science, 23(7), 698-703, 2012), observers search through visual space for any of multiple targets held in memory. With photorealistic objects as the stimuli, response times (RTs) increase linearly with the visual set size and logarithmically with the memory set size, even when over 100 items are committed to memory. It is well-established that pictures of objects are particularly easy to memorize (Brady, Konkle, Alvarez, & Oliva Proceedings of the National Academy of Sciences, 105, 14325-14329, 2008). Would hybrid-search performance be similar if the targets were words or phrases, in which word order can be important, so that the processes of memorization might be different? In Experiment 1, observers memorized 2, 4, 8, or 16 words in four different blocks. After passing a memory test, confirming their memorization of the list, the observers searched for these words in visual displays containing two to 16 words. Replicating Wolfe (Psychological Science, 23(7), 698-703, 2012), the RTs increased linearly with the visual set size and logarithmically with the length of the word list. The word lists of Experiment 1 were random. In Experiment 2, words were drawn from phrases that observers reported knowing by heart (e.g., "London Bridge is falling down"). Observers were asked to provide four phrases, ranging in length from two words to no less than 20 words (range 21-86). All words longer than two characters from the phrase, constituted the target list. Distractor words were matched for length and frequency. Even with these strongly ordered lists, the results again replicated the curvilinear function of memory set size seen in hybrid search. One might expect to find serial position effects, perhaps reducing the RTs for the first (primacy) and/or the last (recency) members of a list (Atkinson & Shiffrin, 1968; Murdock Journal of Experimental Psychology, 64, 482-488, 1962). Surprisingly, we showed no reliable effects of word order. Thus, in "London Bridge is falling down," "London" and "down" were found no faster than "falling." PMID:25788035

  11. Role of computer-assisted visual search in mammographic interpretation

    NASA Astrophysics Data System (ADS)

    Nodine, Calvin F.; Kundel, Harold L.; Mello-Thoms, Claudia; Weinstein, Susan P.

    2001-06-01

    We used eye-position data to develop Computer-Assisted Visual Search (CAVS) as an aid to mammographic interpretation. CAVS feeds back regions of interest that receive prolonged visual dwell (greater than or equal to 1000 ms) by highlighting them on the mammogram. These regions are then reevaluated for possible missed breast cancers. Six radiology residents and fellows interpreted a test set of 40 mammograms twice, once with CAVS feedback (FB), and once without CAVS FB in a crossover, repeated- measures design. Eye position was monitored. LROC performance (area) was compared with and without CAVS FB. Detection and localization of malignant lesions improved 12% with CAVS FB. This was not significant. The test set contained subtle malignant lesions. 65% (176/272) of true lesions were fixated. Of those fixated, 49% (87/176) received prolonged attention resulting in CAVS FB, and 54% (47/87) of FBs resulted in TPs. Test-set difficulty and the lack of reading experience of the readers may have contributed to the relatively low overall performance, and may have also limited the effectiveness of CAVS FB which could only play a role in localizing potential lesions if the reader fixated and dwelled on them.

  12. Expectations developed over multiple timescales facilitate visual search performance

    PubMed Central

    Gekas, Nikos; Seitz, Aaron R.; Seriès, Peggy

    2015-01-01

    Our perception of the world is strongly influenced by our expectations, and a question of key importance is how the visual system develops and updates its expectations through interaction with the environment. We used a visual search task to investigate how expectations of different timescales (from the last few trials to hours to long-term statistics of natural scenes) interact to alter perception. We presented human observers with low-contrast white dots at 12 possible locations equally spaced on a circle, and we asked them to simultaneously identify the presence and location of the dots while manipulating their expectations by presenting stimuli at some locations more frequently than others. Our findings suggest that there are strong acuity differences between absolute target locations (e.g., horizontal vs. vertical) and preexisting long-term biases influencing observers' detection and localization performance, respectively. On top of these, subjects quickly learned about the stimulus distribution, which improved their detection performance but caused increased false alarms at the most frequently presented stimulus locations. Recent exposure to a stimulus resulted in significantly improved detection performance and significantly more false alarms but only at locations at which it was more probable that a stimulus would be presented. Our results can be modeled and understood within a Bayesian framework in terms of a near-optimal integration of sensory evidence with rapidly learned statistical priors, which are skewed toward the very recent history of trials and may help understanding the time scale of developing expectations at the neural level. PMID:26200891

  13. Case role filling as a side effect of visual search

    SciTech Connect

    Marburger, H.; Wahlster, W.

    1983-01-01

    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.

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

    PubMed

    Kim, Gho; Lee, Jang-Han

    2011-05-01

    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

  15. Visual Search in Typically Developing Toddlers and Toddlers with Fragile X or Williams Syndrome

    ERIC Educational Resources Information Center

    Scerif, Gaia; Cornish, Kim; Wilding, John; Driver, Jon; Karmiloff-Smith, Annette

    2004-01-01

    Visual selective attention is the ability to attend to relevant visual information and ignore irrelevant stimuli. Little is known about its typical and atypical development in early childhood. Experiment 1 investigates typically developing toddlers' visual search for multiple targets on a touch-screen. Time to hit a target, distance between…

  16. The role of object categories in hybrid visual and memory search

    PubMed Central

    Cunningham, Corbin A.; Wolfe, Jeremy M.

    2014-01-01

    In hybrid search, observers (Os) search for any of several possible targets in a visual display containing distracting items and, perhaps, a target. Wolfe (2012) found that responses times (RT) in such tasks increased linearly with increases in the number of items in the display. However, RT increased linearly with the log of the number of items in the memory set. In earlier work, all items in the memory set were unique instances (e.g. this apple in this pose). Typical real world tasks involve more broadly defined sets of stimuli (e.g. any “apple” or, perhaps, “fruit”). The present experiments show how sets or categories of targets are handled in joint visual and memory search. In Experiment 1, searching for a digit among letters was not like searching for targets from a 10-item memory set, though searching for targets from an N-item memory set of arbitrary alphanumeric characters was like searching for targets from an N-item memory set of arbitrary objects. In Experiment 2, Os searched for any instance of N sets or categories held in memory. This hybrid search was harder than search for specific objects. However, memory search remained logarithmic. Experiment 3 illustrates the interaction of visual guidance and memory search when a subset of visual stimuli are drawn from a target category. Furthermore, we outline a conceptual model, supported by our results, defining the core components that would be necessary to support such categorical hybrid searches. PMID:24661054

  17. Efficient visual-search model observers for PET

    PubMed Central

    2014-01-01

    Objective: Scanning model observers have been efficiently applied as a research tool to predict human-observer performance in F-18 positron emission tomography (PET). We investigated whether a visual-search (VS) observer could provide more reliable predictions with comparable efficiency. Methods: Simulated two-dimensional images of a digital phantom featuring tumours in the liver, lungs and background soft tissue were prepared in coronal, sagittal and transverse display formats. A localization receiver operating characteristic (LROC) study quantified tumour detectability as a function of organ and format for two human observers, a channelized non-prewhitening (CNPW) scanning observer and two versions of a basic VS observer. The VS observers compared watershed (WS) and gradient-based search processes that identified focal uptake points for subsequent analysis with the CNPW observer. The model observers treated “background-known-exactly” (BKE) and “background-assumed-homogeneous” assumptions, either searching the entire organ of interest (Task A) or a reduced area that helped limit false positives (Task B). Performance was indicated by area under the LROC curve. Concordance in the localizations between observers was also analysed. Results: With the BKE assumption, both VS observers demonstrated consistent Pearson correlation with humans (Task A: 0.92 and Task B: 0.93) compared with the scanning observer (Task A: 0.77 and Task B: 0.92). The WS VS observer read 624 study test images in 2.0?min. The scanning observer required 0.7?min. Conclusion: Computationally efficient VS can enhance the stability of statistical model observers with regard to uncertainties in PET tumour detection tasks. Advances in knowledge: VS models improve concordance with human observers. PMID:24837105

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

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  19. Sensitivity to global form in glass patterns after early visual deprivation in humans

    E-print Network

    Maurer, Daphne M.

    ; Visual development; Global form perception; Glass patterns; Humans 1. Introduction Numerous studies haveSensitivity to global form in glass patterns after early visual deprivation in humans Terri L Dirks b , Henry P. Brent a,c a Department of Ophthalmology, The Hospital for Sick Children, Toronto

  20. Evolutionary pattern search algorithms for unconstrained and linearly constrained optimization

    SciTech Connect

    HART,WILLIAM E.

    2000-06-01

    The authors describe a convergence theory for evolutionary pattern search algorithms (EPSAs) on a broad class of unconstrained and linearly constrained problems. 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. The analysis significantly extends the previous convergence theory for EPSAs. The analysis applies to a broader class of EPSAs,and it applies to problems that are nonsmooth, have unbounded objective functions, and which are linearly constrained. Further, they describe a modest change to the algorithmic framework of EPSAs for which a non-probabilistic convergence theory applies. These analyses are also noteworthy because they are considerably simpler than previous analyses of EPSAs.

  1. Using Pattern Search Methods for Surface Structure Determinationof Nanomaterials

    SciTech Connect

    Zhao, Zhengji; Meza, Juan; Van Hove, Michel

    2006-06-09

    Atomic scale surface structure plays an important roleindescribing many properties of materials, especially in the case ofnanomaterials. One of the most effective techniques for surface structuredetermination is low-energy electron diffraction (LEED), which can beused in conjunction with optimization to fit simulated LEED intensitiesto experimental data. This optimization problem has a number ofcharacteristics that make it challenging: it has many local minima, theoptimization variables can be either continuous or categorical, theobjective function can be discontinuous, there are no exact analyticderivatives (and no derivatives at all for categorical variables), andfunction evaluations are expensive. In this study, we show how to apply aparticular class of optimization methods known as pattern search methodsto address these challenges. These methods donot explicitly usederivatives, and are particularly appropriate when categorical variablesare present, an important feature that has not been addressed in previousLEED studies. We have found that pattern search methods can produceexcellent results, compared to previously used methods, both in terms ofperformance and locating optimal results.

  2. Visual-auditory integration for visual search: a behavioral study in barn owls.

    PubMed

    Hazan, Yael; Kra, Yonatan; Yarin, Inna; Wagner, Hermann; Gutfreund, Yoram

    2015-01-01

    Barn owls are nocturnal predators that rely on both vision and hearing for survival. The optic tectum of barn owls, a midbrain structure involved in selective attention, has been used as a model for studying visual-auditory integration at the neuronal level. However, behavioral data on visual-auditory integration in barn owls are lacking. The goal of this study was to examine if the integration of visual and auditory signals contributes to the process of guiding attention toward salient stimuli. We attached miniature wireless video cameras on barn owls' heads (OwlCam) to track their target of gaze. We first provide evidence that the area centralis (a retinal area with a maximal density of photoreceptors) is used as a functional fovea in barn owls. Thus, by mapping the projection of the area centralis on the OwlCam's video frame, it is possible to extract the target of gaze. For the experiment, owls were positioned on a high perch and four food items were scattered in a large arena on the floor. In addition, a hidden loudspeaker was positioned in the arena. The positions of the food items and speaker were changed every session. Video sequences from the OwlCam were saved for offline analysis while the owls spontaneously scanned the room and the food items with abrupt gaze shifts (head saccades). From time to time during the experiment, a brief sound was emitted from the speaker. The fixation points immediately following the sounds were extracted and the distances between the gaze position and the nearest items and loudspeaker were measured. The head saccades were rarely toward the location of the sound source but to salient visual features in the room, such as the door knob or the food items. However, among the food items, the one closest to the loudspeaker had the highest probability of attracting a gaze shift. This result supports the notion that auditory signals are integrated with visual information for the selection of the next visual search target. PMID:25762905

  3. Visual-auditory integration for visual search: a behavioral study in barn owls

    PubMed Central

    Hazan, Yael; Kra, Yonatan; Yarin, Inna; Wagner, Hermann; Gutfreund, Yoram

    2015-01-01

    Barn owls are nocturnal predators that rely on both vision and hearing for survival. The optic tectum of barn owls, a midbrain structure involved in selective attention, has been used as a model for studying visual-auditory integration at the neuronal level. However, behavioral data on visual-auditory integration in barn owls are lacking. The goal of this study was to examine if the integration of visual and auditory signals contributes to the process of guiding attention toward salient stimuli. We attached miniature wireless video cameras on barn owls’ heads (OwlCam) to track their target of gaze. We first provide evidence that the area centralis (a retinal area with a maximal density of photoreceptors) is used as a functional fovea in barn owls. Thus, by mapping the projection of the area centralis on the OwlCam’s video frame, it is possible to extract the target of gaze. For the experiment, owls were positioned on a high perch and four food items were scattered in a large arena on the floor. In addition, a hidden loudspeaker was positioned in the arena. The positions of the food items and speaker were changed every session. Video sequences from the OwlCam were saved for offline analysis while the owls spontaneously scanned the room and the food items with abrupt gaze shifts (head saccades). From time to time during the experiment, a brief sound was emitted from the speaker. The fixation points immediately following the sounds were extracted and the distances between the gaze position and the nearest items and loudspeaker were measured. The head saccades were rarely toward the location of the sound source but to salient visual features in the room, such as the door knob or the food items. However, among the food items, the one closest to the loudspeaker had the highest probability of attracting a gaze shift. This result supports the notion that auditory signals are integrated with visual information for the selection of the next visual search target. PMID:25762905

  4. Density Guides Visual Search: Sparse Groups are First even when Slower

    E-print Network

    Brumby, Duncan

    on the implications for models that assume people rationally adapt their search strategy to maximize the gain of task display. A core question concerns how people control the visual search process to decide in what order extensively is investigating how people search web pages to locate content information (e.g., Brumby & Howes

  5. High or Low Target Prevalence Increases the Dual-Target Cost in Visual Search

    ERIC Educational Resources Information Center

    Menneer, Tamaryn; Donnelly, Nick; Godwin, Hayward J.; Cave, Kyle R.

    2010-01-01

    Previous studies have demonstrated a dual-target cost in visual search. In the current study, the relationship between search for one and search for two targets was investigated to examine the effects of target prevalence and practice. Color-shape conjunction stimuli were used with response time, accuracy and signal detection measures. Performance…

  6. Visual Search Is Postponed during the Attentional Blink until the System Is Suitably Reconfigured

    ERIC Educational Resources Information Center

    Ghorashi, S. M. Shahab; Smilek, Daniel; Di Lollo, Vincent

    2007-01-01

    J. S. Joseph, M. M. Chun, and K. Nakayama (1997) found that pop-out visual search was impaired as a function of intertarget lag in an attentional blink (AB) paradigm in which the 1st target was a letter and the 2nd target was a search display. In 4 experiments, the present authors tested the implication that search efficiency should be similarly…

  7. The Importance of Slow Consistent Movement when Searching for Hard-to-Find Targets in Real-World Visual Search.

    PubMed

    Riggs, Charlotte; Cornes, Katherine; Godwin, Hayward; Guest, Richard; Donnelly, Nick

    2015-09-01

    Various real-world tasks require careful and exhaustive visual search. For example, searching for forensic evidence or signs of hidden threats (what we call hard-to-find targets). Here, we examine how search accuracy for hard-to-find targets is influenced by search behaviour. Participants searched for coins set amongst a 5m x 15m (defined as x and y axes respectively) piece of grassland. The grassland contained natural distractors of leaves and flowers and was not manicured. Coins were visually detectable from standing height. There was no time limit to the task and participants were instructed to search until they were confident they had completed their search. On average, participants detected 45% (SD=23%) of the targets and took 7:23 (SD=4:44) minutes to complete their search. Participants' movement over space and time was recorded as a series of time-stamped x, y coordinates using a Total Station theodolite. To quantify their search behaviour, the x- and y-coordinates of participants' physical locations as they searched the grassland were converted into the frequency domain using a Fourier transform. Decreases in dominant frequencies, a measure of the time before turning during search, resulted in increased response accuracy as well as increased search times. Furthermore, decreases in the number of iterations, defined by the total search time divided by the dominant frequency, also resulted in increased accuracy and search times. Comparing distance between the two most dominant frequency peaks provided a measure of consistency of movement over time. This measure showed that more variable search was associated with slower search times but no improvement in accuracy. Throughout our analyses, these results were true for the y-axis but not the x-axis. At least with respect to the present task, accurate search for hard-to-find targets is dependent on conducting search at a slow consistent speed where changes in direction are minimised. Meeting abstract presented at VSS 2015. PMID:26327043

  8. Prediction of shot success for basketball free throws: visual search strategy.

    PubMed

    Uchida, Yusuke; Mizuguchi, Nobuaki; Honda, Masaaki; Kanosue, Kazuyuki

    2014-01-01

    In ball games, players have to pay close attention to visual information in order to predict the movements of both the opponents and the ball. Previous studies have indicated that players primarily utilise cues concerning the ball and opponents' body motion. The information acquired must be effective for observing players to select the subsequent action. The present study evaluated the effects of changes in the video replay speed on the spatial visual search strategy and ability to predict free throw success. We compared eye movements made while observing a basketball free throw by novices and experienced basketball players. Correct response rates were close to chance (50%) at all video speeds for the novices. The correct response rate of experienced players was significantly above chance (and significantly above that of the novices) at the normal speed, but was not different from chance at both slow and fast speeds. Experienced players gazed more on the lower part of the player's body when viewing a normal speed video than the novices. The players likely detected critical visual information to predict shot success by properly moving their gaze according to the shooter's movements. This pattern did not change when the video speed was decreased, but changed when it was increased. These findings suggest that temporal information is important for predicting action outcomes and that such outcomes are sensitive to video speed. PMID:24319995

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

    PubMed Central

    Morawetz, Linde; Chittka, Lars; Spaethe, Johannes

    2014-01-01

    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

  10. Visual height intolerance and acrophobia: clinical characteristics and comorbidity patterns.

    PubMed

    Kapfhammer, Hans-Peter; Huppert, Doreen; Grill, Eva; Fitz, Werner; Brandt, Thomas

    2015-08-01

    The purpose of this study was to estimate the general population lifetime and point prevalence of visual height intolerance and acrophobia, to define their clinical characteristics, and to determine their anxious and depressive comorbidities. A case-control study was conducted within a German population-based cross-sectional telephone survey. A representative sample of 2,012 individuals aged 14 and above was selected. Defined neurological conditions (migraine, Menière's disease, motion sickness), symptom pattern, age of first manifestation, precipitating height stimuli, course of illness, psychosocial impairment, and comorbidity patterns (anxiety conditions, depressive disorders according to DSM-IV-TR) for vHI and acrophobia were assessed. The lifetime prevalence of vHI was 28.5% (women 32.4%, men 24.5%). Initial attacks occurred predominantly (36%) in the second decade. A rapid generalization to other height stimuli and a chronic course of illness with at least moderate impairment were observed. A total of 22.5% of individuals with vHI experienced the intensity of panic attacks. The lifetime prevalence of acrophobia was 6.4% (women 8.6%, men 4.1%), and point prevalence was 2.0% (women 2.8%; men 1.1%). VHI and even more acrophobia were associated with high rates of comorbid anxious and depressive conditions. Migraine was both a significant predictor of later acrophobia and a significant consequence of previous acrophobia. VHI affects nearly a third of the general population; in more than 20% of these persons, vHI occasionally develops into panic attacks and in 6.4%, it escalates to acrophobia. Symptoms and degree of social impairment form a continuum of mild to seriously distressing conditions in susceptible subjects. PMID:25262317

  11. Computer vision enhances mobile eye-tracking to expose expert cognition in natural-scene visual-search tasks

    NASA Astrophysics Data System (ADS)

    Keane, Tommy P.; Cahill, Nathan D.; Tarduno, John A.; Jacobs, Robert A.; Pelz, Jeff B.

    2014-02-01

    Mobile eye-tracking provides the fairly unique opportunity to record and elucidate cognition in action. In our research, we are searching for patterns in, and distinctions between, the visual-search performance of experts and novices in the geo-sciences. Traveling to regions resultant from various geological processes as part of an introductory field studies course in geology, we record the prima facie gaze patterns of experts and novices when they are asked to determine the modes of geological activity that have formed the scene-view presented to them. Recording eye video and scene video in natural settings generates complex imagery that requires advanced applications of computer vision research to generate registrations and mappings between the views of separate observers. By developing such mappings, we could then place many observers into a single mathematical space where we can spatio-temporally analyze inter- and intra-subject fixations, saccades, and head motions. While working towards perfecting these mappings, we developed an updated experiment setup that allowed us to statistically analyze intra-subject eye-movement events without the need for a common domain. Through such analyses we are finding statistical differences between novices and experts in these visual-search tasks. In the course of this research we have developed a unified, open-source, software framework for processing, visualization, and interaction of mobile eye-tracking and high-resolution panoramic imagery.

  12. A pyramidal neural network for visual pattern recognition.

    PubMed

    Phung, Son Lam; Bouzerdoum, Abdesselam

    2007-03-01

    In this paper, we propose a new neural architecture for classification of visual patterns that is motivated by the two concepts of image pyramids and local receptive fields. The new architecture, called pyramidal neural network (PyraNet), has a hierarchical structure with two types of processing layers: Pyramidal layers and one-dimensional (1-D) layers. In the new network, nonlinear two-dimensional (2-D) neurons are trained to perform both image feature extraction and dimensionality reduction. We present and analyze five training methods for PyraNet [gradient descent (GD), gradient descent with momentum, resilient back-propagation (RPROP), Polak-Ribiere conjugate gradient (CG), and Levenberg-Marquadrt (LM)] and two choices of error functions [mean-square-error (mse) and cross-entropy (CE)]. In this paper, we apply PyraNet to determine gender from a facial image, and compare its performance on the standard facial recognition technology (FERET) database with three classifiers: The convolutional neural network (NN), the k-nearest neighbor (k-NN), and the support vector machine (SVM). PMID:17385623

  13. Dynamic modulation of local population activity by rhythm phase in human occipital cortex during a visual search task.

    PubMed

    Miller, Kai J; Hermes, Dora; Honey, Christopher J; Sharma, Mohit; Rao, Rajesh P N; den Nijs, Marcel; Fetz, Eberhard E; Sejnowski, Terrence J; Hebb, Adam O; Ojemann, Jeffrey G; Makeig, Scott; Leuthardt, Eric C

    2010-01-01

    Brain rhythms are more than just passive phenomena in visual cortex. For the first time, we show that the physiology underlying brain rhythms actively suppresses and releases cortical areas on a second-to-second basis during visual processing. Furthermore, their influence is specific at the scale of individual gyri. We quantified the interaction between broadband spectral change and brain rhythms on a second-to-second basis in electrocorticographic (ECoG) measurement of brain surface potentials in five human subjects during a visual search task. Comparison of visual search epochs with a blank screen baseline revealed changes in the raw potential, the amplitude of rhythmic activity, and in the decoupled broadband spectral amplitude. We present new methods to characterize the intensity and preferred phase of coupling between broadband power and band-limited rhythms, and to estimate the magnitude of rhythm-to-broadband modulation on a trial-by-trial basis. These tools revealed numerous coupling motifs between the phase of low-frequency (?, ?, ?, ?, and ? band) rhythms and the amplitude of broadband spectral change. In the ? and ? ranges, the coupling of phase to broadband change is dynamic during visual processing, decreasing in some occipital areas and increasing in others, in a gyrally specific pattern. Finally, we demonstrate that the rhythms interact with one another across frequency ranges, and across cortical sites. PMID:21119778

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

    NASA Astrophysics Data System (ADS)

    Trippen, Gerhard

    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.

  15. Investigating the role of visual and auditory search in reading and developmental dyslexia

    PubMed Central

    Lallier, Marie; Donnadieu, Sophie; Valdois, Sylviane

    2013-01-01

    It has been suggested that auditory and visual sequential processing deficits contribute to phonological disorders in developmental dyslexia. As an alternative explanation to a phonological deficit as the proximal cause for reading disorders, the visual attention span hypothesis (VA Span) suggests that difficulties in processing visual elements simultaneously lead to dyslexia, regardless of the presence of a phonological disorder. In this study, we assessed whether deficits in processing simultaneously displayed visual or auditory elements is linked to dyslexia associated with a VA Span impairment. Sixteen children with developmental dyslexia and 16 age-matched skilled readers were assessed on visual and auditory search tasks. Participants were asked to detect a target presented simultaneously with 3, 9, or 15 distracters. In the visual modality, target detection was slower in the dyslexic children than in the control group on a “serial” search condition only: the intercepts (but not the slopes) of the search functions were higher in the dyslexic group than in the control group. In the auditory modality, although no group difference was observed, search performance was influenced by the number of distracters in the control group only. Within the dyslexic group, not only poor visual search (high reaction times and intercepts) but also low auditory search performance (d?) strongly correlated with poor irregular word reading accuracy. Moreover, both visual and auditory search performance was associated with the VA Span abilities of dyslexic participants but not with their phonological skills. The present data suggests that some visual mechanisms engaged in “serial” search contribute to reading and orthographic knowledge via VA Span skills regardless of phonological skills. The present results further open the question of the role of auditory simultaneous processing in reading as well as its link with VA Span skills. PMID:24093014

  16. Threat modulation of visual search efficiency in PTSD: A comparison of distinct stimulus categories.

    PubMed

    Olatunji, Bunmi O; Armstrong, Thomas; Bilsky, Sarah A; Zhao, Mimi

    2015-10-30

    Although an attentional bias for threat has been implicated in posttraumatic stress disorder (PTSD), the cues that best facilitate this bias are unclear. Some studies utilize images and others utilize facial expressions that communicate threat. However, the comparability of these two types of stimuli in PTSD is unclear. The present study contrasted the effects of images and expressions with the same valence on visual search among veterans with PTSD and controls. Overall, PTSD patients had slower visual search speed than controls. Images caused greater disruption in visual search than expressions, and emotional content modulated this effect with larger differences between images and expressions arising for more negatively valenced stimuli. However, this effect was not observed with the maximum number of items in the search array. Differences in visual search speed by images and expressions significantly varied between PTSD patients and controls for only anger and at the moderate level of task difficulty. Specifically, visual search speed did not significantly differ between PTSD patients and controls when exposed to angry expressions. However, PTSD patients displayed significantly slower visual search than controls when exposed to anger images. The implications of these findings for better understanding emotion modulated attention in PTSD are discussed. PMID:26254798

  17. Visual Search and Line Bisection in Hemianopia: Computational Modelling of Cortical Compensatory Mechanisms and Comparison with Hemineglect

    PubMed Central

    Lanyon, Linda J.; Barton, Jason J. S.

    2013-01-01

    Hemianopia patients have lost vision from the contralateral hemifield, but make behavioural adjustments to compensate for this field loss. As a result, their visual performance and behaviour contrast with those of hemineglect patients who fail to attend to objects contralateral to their lesion. These conditions differ in their ocular fixations and perceptual judgments. During visual search, hemianopic patients make more fixations in contralesional space while hemineglect patients make fewer. During line bisection, hemianopic patients fixate the contralesional line segment more and make a small contralesional bisection error, while hemineglect patients make few contralesional fixations and a larger ipsilesional bisection error. Hence, there is an attentional failure for contralesional space in hemineglect but a compensatory adaptation to attend more to the blind side in hemianopia. A challenge for models of visual attentional processes is to show how compensation is achieved in hemianopia, and why such processes are hindered or inaccessible in hemineglect. We used a neurophysiology-derived computational model to examine possible cortical compensatory processes in simulated hemianopia from a V1 lesion and compared results with those obtained with the same processes under conditions of simulated hemineglect from a parietal lesion. A spatial compensatory bias to increase attention contralesionally replicated hemianopic scanning patterns during visual search but not during line bisection. To reproduce the latter required a second process, an extrastriate lateral connectivity facilitating form completion into the blind field: this allowed accurate placement of fixations on contralesional stimuli and reproduced fixation patterns and the contralesional bisection error of hemianopia. Neither of these two cortical compensatory processes was effective in ameliorating the ipsilesional bias in the hemineglect model. Our results replicate normal and pathological patterns of visual scanning, line bisection, and differences between hemianopia and hemineglect, and may explain why compensatory processes that counter the effects of hemianopia are ineffective in hemineglect. PMID:23390506

  18. Integrating Interactive Visualizations in the Search Process of Digital Libraries and IR Systems

    E-print Network

    Hienert, Daniel; Schaer, Philipp; Mayr, Philipp

    2012-01-01

    Interactive visualizations for exploring and retrieval have not yet become an integral part of digital libraries and information retrieval systems. We have integrated a set of interactive graphics in a real world social science digital library. These visualizations support the exploration of search queries, results and authors, can filter search results, show trends in the database and can support the creation of new search queries. The use of weighted brushing supports the identification of related metadata for search facets. We discuss some use cases of the combination of IR systems and interactive graphics. In a user study we verify that users can gain insights from statistical graphics intuitively and can adopt interaction techniques.

  19. Feature-Based Attention in the Frontal Eye Field and Area V4 during Visual Search

    E-print Network

    Zhou, Huihui

    When we search for a target in a crowded visual scene, we often use the distinguishing features of the target, such as color or shape, to guide our attention and eye movements. To investigate the neural mechanisms of ...

  20. Studying visual search using systems factorial methodology with targetdistractor similarity as the factor

    E-print Network

    Townsend, James T.

    Systems factorial technology (SFT) is a theory-driven set of methodologies oriented toward identification employing SFT in visual search with small display sizes have repeatedly shown decisive evidence for parallel

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

    E-print Network

    Hidalgo-Sotelo, Barbara

    2010-01-01

    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, ...

  2. Phonological Interference in Visual Search: Object Names are Automatically Activated in Non-Linguistic Tasks.

    PubMed

    Walenchok, Stephen; Hout, Michael; Goldinger, Stephen

    2015-09-01

    During visual search, it is well known that items sharing visual similarity with the target create interference (e.g., searching for a baseball among softballs vs. a baseball among bats). Although such a task is inherently visual, might linguistic similarity between target and background items' names also create interference? We conducted several experiments in which people searched for either one or three potential targets, among a background of distractors that either shared a phonological overlap with the target(s) (e.g., "beast" and "beanstalk") or had no overlap (e.g., "beast" and "glasses"). Experiment 1 involved standard oculomotor search, Experiment 2 presented a serial search task in which participants manually rejected distractors (or confirmed the target), and Experiment 3 again presented oculomotor search, while also tracking eye movements. We varied whether targets were initially specified by visual icons or verbally as names. We predicted that when searching for a single item, people could easily maintain a visual representation of the target in memory, resulting in minimal activation of linguistic information. When searching for multiple items, however, visual memory demands are high. In order to minimize these demands, people might use less taxing verbal codes as a memory aid during search (i.e., rehearsing target names). If so, these verbal codes may increase the potential for linguistic interference when target and distractor names share phonological overlap. All three experiments revealed effects of phonological interference, but only under high target load, and primarily when targets were specified verbally. In Experiment 4, we tested whether concurrent articulatory suppression during search might minimize verbal memory strategies and eliminate such effects of phonological interference. Phonological competition effects remained robust, however, indicating that distractor names are automatically activated under high cognitive demands and that verbal strategies are not the sole source of phonological interference in search. Meeting abstract presented at VSS 2015. PMID:26325753

  3. The effects of task difficulty on visual search strategy in virtual 3D displays.

    PubMed

    Pomplun, Marc; Garaas, Tyler W; Carrasco, Marisa

    2013-01-01

    Analyzing the factors that determine our choice of visual search strategy may shed light on visual behavior in everyday situations. Previous results suggest that increasing task difficulty leads to more systematic search paths. Here we analyze observers' eye movements in an "easy" conjunction search task and a "difficult" shape search task to study visual search strategies in stereoscopic search displays with virtual depth induced by binocular disparity. Standard eye-movement variables, such as fixation duration and initial saccade latency, as well as new measures proposed here, such as saccadic step size, relative saccadic selectivity, and x-y target distance, revealed systematic effects on search dynamics in the horizontal-vertical plane throughout the search process. We found that in the "easy" task, observers start with the processing of display items in the display center immediately after stimulus onset and subsequently move their gaze outwards, guided by extrafoveally perceived stimulus color. In contrast, the "difficult" task induced an initial gaze shift to the upper-left display corner, followed by a systematic left-right and top-down search process. The only consistent depth effect was a trend of initial saccades in the easy task with smallest displays to the items closest to the observer. The results demonstrate the utility of eye-movement analysis for understanding search strategies and provide a first step toward studying search strategies in actual 3D scenarios. PMID:23986539

  4. Multi-voxel pattern analysis of selective representation of visual working memory in ventral temporal and occipital regions

    E-print Network

    Samaras, Dimitris

    that these regions are also involved in supporting visual working memory ­ the short-term representation of visualMulti-voxel pattern analysis of selective representation of visual working memory in ventral of visual information, though their role in the representation of visual working memory remains unclear

  5. Scan pattern adaptation during repeated visual search Christopher Wayne Myers

    E-print Network

    Gray, Wayne

    _________________________________________ Michael J. Schoelles, Member _________________________________________ James Watt, Member Rensselaer Brett R. Fajen, Member Michael J. Schoelles, Member James Watt, Member Rensselaer Polytechnic Institute

  6. Markov Models of Search State Patterns in a Hypertext Information Retrieval System.

    ERIC Educational Resources Information Center

    Qiu, Liwen

    1993-01-01

    Describes research that was conducted to determine the search state patterns through which users retrieve information in hypertext systems. Use of the Markov model to describe users' search behavior is discussed, and search patterns of different user groups were studied by comparing transition probability matrices. (Contains 25 references.) (LRW)

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

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  8. Detection of Emotional Faces: Salient Physical Features Guide Effective Visual Search

    ERIC Educational Resources Information Center

    Calvo, Manuel G.; Nummenmaa, Lauri

    2008-01-01

    In this study, the authors investigated how salient visual features capture attention and facilitate detection of emotional facial expressions. In a visual search task, a target emotional face (happy, disgusted, fearful, angry, sad, or surprised) was presented in an array of neutral faces. Faster detection of happy and, to a lesser extent,…

  9. Hand Movement Deviations in a Visual Search Task with Cross Modal Cuing

    ERIC Educational Resources Information Center

    Aslan, Asli; Aslan, Hurol

    2007-01-01

    The purpose of this study is to demonstrate the cross-modal effects of an auditory organization on a visual search task and to investigate the influence of the level of detail in instructions describing or hinting at the associations between auditory stimuli and the possible locations of a visual target. In addition to measuring the participants'…

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

    E-print Network

    Wei, Eric

    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 ...

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

    E-print Network

    Heer, Jeffrey

    Software Design Patterns for Information Visualization Jeffrey Heer and Maneesh Agrawala Abstract approach for addressing such difficulties is to capture successful solutions in design patterns, abstract software, we present a series of design patterns for the domain of information visualization. We discuss

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

    E-print Network

    California at Irvine, University of

    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

  13. Eye-Tracking Study Using Cellular Automaton Patterns as Visual Stimuli: Implications for

    E-print Network

    Smith, Marc L.

    Eye-Tracking Study Using Cellular Automaton Patterns as Visual Stimuli: Implications for Current- motor strategy. Hence, future eye-tracking studies with CAs as stimuli could greatly improve our current and selecting information more evident than in the visual system. For example, the human eye is composed of only

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

    E-print Network

    Hidalgo-Sotelo, Barbara Irene

    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 ...

  15. Central and Peripheral Vision Loss Differentially Affects Contextual Cueing in Visual Search

    ERIC Educational Resources Information Center

    Geringswald, Franziska; Pollmann, Stefan

    2015-01-01

    Visual search for targets in repeated displays is more efficient than search for the same targets in random distractor layouts. Previous work has shown that this contextual cueing is severely impaired under central vision loss. Here, we investigated whether central vision loss, simulated with gaze-contingent displays, prevents the incidental…

  16. Visual constraints in foraging bumblebees: Flower size and color affect search time

    E-print Network

    Chittka, Lars

    (received for review October 27, 2000) In optimal foraging theory, search time is a key variable defining addressed. Possibly for this reason, predictions of optimal foraging theory are often incon- sistentVisual constraints in foraging bumblebees: Flower size and color affect search time and flight

  17. Brief Report: Eye Movements during Visual Search Tasks Indicate Enhanced Stimulus Discriminability in Subjects with PDD

    ERIC Educational Resources Information Center

    Kemner, Chantal; van Ewijk, Lizet; van Engeland, Herman; Hooge, Ignace

    2008-01-01

    Subjects with PDD excel on certain visuo-spatial tasks, amongst which visual search tasks, and this has been attributed to enhanced perceptual discrimination. However, an alternative explanation is that subjects with PDD show a different, more effective search strategy. The present study aimed to test both hypotheses, by measuring eye movements…

  18. Cortical Dynamics of Contextually Cued Attentive Visual Learning and Search: Spatial and Object Evidence Accumulation

    ERIC Educational Resources Information Center

    Huang, Tsung-Ren; Grossberg, Stephen

    2010-01-01

    How do humans use target-predictive contextual information to facilitate visual search? How are consistently paired scenic objects and positions learned and used to more efficiently guide search in familiar scenes? For example, humans can learn that a certain combination of objects may define a context for a kitchen and trigger a more efficient…

  19. Contextual Cueing in Multiconjunction Visual Search Is Dependent on Color- and Configuration-Based Intertrial Contingencies

    ERIC Educational Resources Information Center

    Geyer, Thomas; Shi, Zhuanghua; Muller, Hermann J.

    2010-01-01

    Three experiments examined memory-based guidance of visual search using a modified version of the contextual-cueing paradigm (Jiang & Chun, 2001). The target, if present, was a conjunction of color and orientation, with target (and distractor) features randomly varying across trials (multiconjunction search). Under these conditions, reaction times…

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

    E-print Network

    Jones, Mark W.

    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

  1. Performance in a Visual Search Task Uniquely Predicts Reading Abilities in Third-Grade Hong Kong Chinese Children

    ERIC Educational Resources Information Center

    Liu, Duo; Chen, Xi; Chung, Kevin K. H.

    2015-01-01

    This study examined the relation between the performance in a visual search task and reading ability in 92 third-grade Hong Kong Chinese children. The visual search task, which is considered a measure of visual-spatial attention, accounted for unique variance in Chinese character reading after controlling for age, nonverbal intelligence,…

  2. Disruptive coloration in cuttlefish: a visual perception mechanism that regulates ontogenetic adjustment of skin patterning.

    PubMed

    Barbosa, Alexandra; Mäthger, Lydia M; Chubb, Charles; Florio, Christopher; Chiao, Chuan-Chin; Hanlon, Roger T

    2007-04-01

    Among the changeable camouflage patterns of cuttlefish, disruptive patterning is shown in response to certain features of light objects in the visual background. However, whether animals show disruptive patterns is dependent not only on object size but also on their body size. Here, we tested whether cuttlefish (Sepia officinalis) are able to match their disruptive body patterning with increasing size of background objects as they grow from hatchling to adult size (0.7 to 19.6 cm mantle length; factor of 28). Specifically, do cuttlefish have a single ;visual sampling rule' that scales accurately during ontogeny? For each of seven size classes of cuttlefish, we created black and white checkerboards whose check sizes corresponded to 4, 12, 40, 120, 400 and 1200% of the area of the cuttlefish's White square, which is a neurophysiologically controlled component of the skin. Disruptive body patterns were evoked when, regardless of animal size, the check size measured either 40 or 120% of the area of the cuttlefish's White square, thus demonstrating a remarkable ontogenetic conformity to a single visual sampling rule. Cuttlefish have no known visual feedback loop with which to adjust their skin patterns. Since the area of a cuttlefish's White square skin component is a function of body size, our results indicate that cuttlefish are solving a visual scaling problem of camouflage presumably without visual confirmation of the size of their own skin component. PMID:17371913

  3. Decoding Visual Location From Neural Patterns in the Auditory Cortex of the Congenitally Deaf.

    PubMed

    Almeida, Jorge; He, Dongjun; Chen, Quanjing; Mahon, Bradford Z; Zhang, Fan; Gonçalves, Óscar F; Fang, Fang; Bi, Yanchao

    2015-11-01

    Sensory cortices of individuals who are congenitally deprived of a sense can exhibit considerable plasticity and be recruited to process information from the senses that remain intact. Here, we explored whether the auditory cortex of congenitally deaf individuals represents visual field location of a stimulus-a dimension that is represented in early visual areas. We used functional MRI to measure neural activity in auditory and visual cortices of congenitally deaf and hearing humans while they observed stimuli typically used for mapping visual field preferences in visual cortex. We found that the location of a visual stimulus can be successfully decoded from the patterns of neural activity in auditory cortex of congenitally deaf but not hearing individuals. This is particularly true for locations within the horizontal plane and within peripheral vision. These data show that the representations stored within neuroplastically changed auditory cortex can align with dimensions that are typically represented in visual cortex. PMID:26423461

  4. Faceted visualization of three dimensional neuroanatomy by combining ontology with faceted search.

    PubMed

    Veeraraghavan, Harini; Miller, James V

    2014-04-01

    In this work, we present a faceted-search based approach for visualization of anatomy by combining a three dimensional digital atlas with an anatomy ontology. Specifically, our approach provides a drill-down search interface that exposes the relevant pieces of information (obtained by searching the ontology) for a user query. Hence, the user can produce visualizations starting with minimally specified queries. Furthermore, by automatically translating the user queries into the controlled terminology our approach eliminates the need for the user to use controlled terminology. We demonstrate the scalability of our approach using an abdominal atlas and the same ontology. We implemented our visualization tool on the opensource 3D Slicer software. We present results of our visualization approach by combining a modified Foundational Model of Anatomy (FMA) ontology with the Surgical Planning Laboratory (SPL) Brain 3D digital atlas, and geometric models specific to patients computed using the SPL brain tumor dataset. PMID:24006207

  5. Faceted Visualization of Three Dimensional Neuroanatomy By Combining Ontology with Faceted Search

    PubMed Central

    Veeraraghavan, Harini; Miller, James V.

    2013-01-01

    In this work, we present a faceted-search based approach for visualization of anatomy by combining a three dimensional digital atlas with an anatomy ontology. Specifically, our approach provides a drill-down search interface that exposes the relevant pieces of information (obtained by searching the ontology) for a user query. Hence, the user can produce visualizations starting with minimally specified queries. Furthermore, by automatically translating the user queries into the controlled terminology our approach eliminates the need for the user to use controlled terminology. We demonstrate the scalability of our approach using an abdominal atlas and the same ontology. We implemented our visualization tool on the opensource 3D Slicer software. We present results of our visualization approach by combining a modified Foundational Model of Anatomy (FMA) ontology with the Surgical Planning Laboratory (SPL) Brain 3D digital atlas, and geometric models specific to patients computed using the SPL brain tumor dataset. PMID:24006207

  6. Mottle camouflage patterns in cuttlefish: quantitative characterization and visual background stimuli that evoke them.

    PubMed

    Chiao, Chuan-Chin; Chubb, Charles; Buresch, Kendra C; Barbosa, Alexandra; Allen, Justine J; Mäthger, Lydia M; Hanlon, Roger T

    2010-01-15

    Cuttlefish and other cephalopods achieve dynamic background matching with two general classes of body patterns: uniform (or uniformly stippled) patterns and mottle patterns. Both pattern types have been described chiefly by the size scale and contrast of their skin components. Mottle body patterns in cephalopods have been characterized previously as small-to-moderate-scale light and dark skin patches (i.e. mottles) distributed somewhat evenly across the body surface. Here we move beyond this commonly accepted qualitative description by quantitatively measuring the scale and contrast of mottled skin components and relating these statistics to specific visual background stimuli (psychophysics approach) that evoke this type of background-matching pattern. Cuttlefish were tested on artificial and natural substrates to experimentally determine some primary visual background cues that evoke mottle patterns. Randomly distributed small-scale light and dark objects (or with some repetition of small-scale shapes/sizes) on a lighter substrate with moderate contrast are essential visual cues to elicit mottle camouflage patterns in cuttlefish. Lowering the mean luminance of the substrate without changing its spatial properties can modulate the mottle pattern toward disruptive patterns, which are of larger scale, different shape and higher contrast. Backgrounds throughout nature consist of a continuous range of spatial scales; backgrounds with medium-sized light/dark patches of moderate contrast are those in which cuttlefish Mottle patterns appear to be the most frequently observed. PMID:20038652

  7. Effects of targets embedded within words in a visual search task

    PubMed Central

    Grabbe, Jeremy W.

    2014-01-01

    Visual search performance can be negatively affected when both targets and distracters share a dimension relevant to the task. This study examined if visual search performance would be influenced by distracters that affect a dimension irrelevant from the task. In Experiment 1 within the letter string of a letter search task, target letters were embedded within a word. Experiment 2 compared targets embedded in words to targets embedded in nonwords. Experiment 3 compared targets embedded in words to a condition in which a word was present in a letter string, but the target letter, although in the letter string, was not embedded within the word. The results showed that visual search performance was negatively affected when a target appeared within a high frequency word. These results suggest that the interaction and effectiveness of distracters is not merely dependent upon common features of the target and distracters, but can be affected by word frequency (a dimension not related to the task demands). PMID:24855497

  8. Eye fixation determined by the visual shape and semantic matches in language-mediated visual search 

    E-print Network

    Shi, Lei

    2007-08-24

    When participants are presented simultaneously a visual display with spoken input, eye fixation could be determined by a match between representations from spoken input and visual objects. Previous studies found that eye ...

  9. Dynamic Visual Attention: Searching for coding length increments

    E-print Network

    Zhang, Liqing

    , China 2 Department of Computation and Neural Systems, California Institute of Technology MC 136. In order to optimize energy consumption, the limit amount of energy of the system is re-distributed amongst Visual attention plays an important role in the human visual system. This voluntary mechanism allows us

  10. Learning From Data: Recognizing Glaucomatous Defect Patterns and Detecting Progression From Visual Field Measurements

    PubMed Central

    Yousefi, Siamak; Goldbaum, Michael H.; Balasubramanian, Madhusudhanan; Medeiros, Felipe A.; Zangwill, Linda M.; Liebmann, Jeffrey M.; Girkin, Christopher A.; Weinreb, Robert N.

    2014-01-01

    A hierarchical approach to learn from visual field data was adopted to identify glaucomatous visual field defect patterns and to detect glaucomatous progression. The analysis pipeline included three stages, namely, clustering, glaucoma boundary limit detection, and glaucoma progression detection testing. First, cross-sectional visual field tests collected from each subject were clustered using a mixture of Gaussians and model parameters were estimated using expectation maximization. The visual field clusters were further estimated to recognize glaucomatous visual field defect patterns by decomposing each cluster into several axes. The glaucoma visual field defect patterns along each axis then were identified. To derive a definition of progression, the longitudinal visual fields of stable glaucoma eyes on the abnormal cluster axes were projected and the slope was approximated using linear regression (LR) to determine the confidence limit of each axis. For glaucoma progression detection, the longitudinal visual fields of each eye on the abnormal cluster axes were projected and the slope was approximated by LR. Progression was assigned if the progression rate was greater than the boundary limit of the stable eyes; otherwise, stability was assumed. The proposed method was compared to a recently developed progression detection method and to clinically available glaucoma progression detection software. The clinical accuracy of the proposed pipeline was as good as or better than the currently available methods. PMID:24710816

  11. A modified mirror projection visual evoked potential stimulator for presenting patterns in different orientations.

    PubMed

    Taylor, P K; Wynn-Williams, G M

    1986-07-01

    Modifications to a standard mirror projection visual evoked potential stimulator are described to enable projection of patterns in varying orientations. The galvanometer-mirror assembly is mounted on an arm which can be rotated through 90 degrees. This enables patterns in any orientation to be deflected perpendicular to their axes. PMID:2424725

  12. Increased Vulnerability to Pattern-Related Visual Stress in Myalgic Encephalomyelitis.

    PubMed

    Wilson, Rachel L; Paterson, Kevin B; Hutchinson, Claire V

    2015-12-01

    The objective of this study was to determine vulnerability to pattern-related visual stress in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). A total of 20 ME/CFS patients and 20 matched (age, gender) controls were recruited to the study. Pattern-related visual stress was determined using the Pattern Glare Test. Participants viewed three patterns, the spatial frequencies (SF) of which were 0.3 (low-SF), 2.3 (mid-SF), and 9.4 (high-SF) cycles per degree (c/deg). They reported the number of distortions they experienced when viewing each pattern. ME/CFS patients exhibited significantly higher pattern glare scores than controls for the mid-SF pattern. Mid-high SF differences were also significantly higher in patients than controls. These findings provide evidence of altered visual perception in ME/CFS. Pattern-related visual stress may represent an identifiable clinical feature of ME/CFS that will prove useful in its diagnosis. However, further research is required to establish if these symptoms reflect ME/CFS-related changes in the functioning of sensory neural pathways. PMID:26562880

  13. Visual Search Performance in the Autism Spectrum II: The Radial Frequency Search Task with Additional Segmentation Cues

    ERIC Educational Resources Information Center

    Almeida, Renita A.; Dickinson, J. Edwin; Maybery, Murray T.; Badcock, Johanna C.; Badcock, David R.

    2010-01-01

    The Embedded Figures Test (EFT) requires detecting a shape within a complex background and individuals with autism or high Autism-spectrum Quotient (AQ) scores are faster and more accurate on this task than controls. This research aimed to uncover the visual processes producing this difference. Previously we developed a search task using radial…

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

    PubMed Central

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

    2012-01-01

    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

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

    PubMed

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

    2012-07-19

    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

  16. Time Curves: Folding Time to Visualize Patterns of Temporal Evolution in Data.

    PubMed

    Bach, Benjamin; Shi, Conglei; Heulot, Nicolas; Madhyastha, Tara; Grabowski, Tom; Dragicevic, Pierre

    2016-01-01

    We introduce time curves as a general approach for visualizing patterns of evolution in temporal data. Examples of such patterns include slow and regular progressions, large sudden changes, and reversals to previous states. These patterns can be of interest in a range of domains, such as collaborative document editing, dynamic network analysis, and video analysis. Time curves employ the metaphor of folding a timeline visualization into itself so as to bring similar time points close to each other. This metaphor can be applied to any dataset where a similarity metric between temporal snapshots can be defined, thus it is largely datatype-agnostic. We illustrate how time curves can visually reveal informative patterns in a range of different datasets. PMID:26529718

  17. Universality in visual cortical pattern formation F. Wolf *, T. Geisel

    E-print Network

    , the visual cortical circuitry is remodeled by activity-dependent mechanisms of synaptic plas- ticity. From's structure. In this picture, spontaneous symmetry breaking in the developmental dynamics of the cortical]). Subsequent research in nonlinear dynamics and statistical physics has uncov- ered that universal behavior

  18. Playing shooter and driving videogames improves top-down guidance in visual search.

    PubMed

    Wu, Sijing; Spence, Ian

    2013-05-01

    Playing action videogames is known to improve visual spatial attention and related skills. Here, we showed that playing action videogames also improves classic visual search, as well as the ability to locate targets in a dual search that mimics certain aspects of an action videogame. In Experiment 1A, first-person shooter (FPS) videogame players were faster than nonplayers in both feature search and conjunction search, and in Experiment 1B, they were faster and more accurate in a peripheral search and identification task while simultaneously performing a central search. In Experiment 2, we showed that 10 h of play could improve the performance of nonplayers on each of these tasks. Three different genres of videogames were used for training: two action games and a 3-D puzzle game. Participants who played an action game (either an FPS or a driving game) achieved greater gains on all search tasks than did those who trained using the puzzle game. Feature searches were faster after playing an action videogame, suggesting that players developed a better target template to guide search in a top-down manner. The results of the dual search suggest that, in addition to enhancing the ability to divide attention, playing an action game improves the top-down guidance of attention to possible target locations. The results have practical implications for the development of training tools to improve perceptual and cognitive skills. PMID:23460295

  19. Visual Search in Learning Disabled and Hyperactive Boys.

    ERIC Educational Resources Information Center

    McIntyre, Curtis W.; And Others

    Twelve learning disabled (LD), 12 learning disabled hyperactive (LDH) and 12 hyperactive (H) boys (6-11 years old) participated in an investigation of selective attention. Ss were asked to search for a target letter embedded within an array of noise letters. Two variations were included: one involving a simultaneous search for four possible target…

  20. INTRODUCTION Human visual search is an important aspect of

    E-print Network

    Duchowski, Andrew T.

    and search strategy. Methods: This model ultimately took the form of a discrete-time nonstationary Markov: The model also has the capability of supporting assessment. That is, it can be used to assess © 2006, Human Factors and Ergonomics Society. All rights reserved #12;SEMISYSTEMATIC SEARCH MODEL 541

  1. Aging and Top-Down Attentional Control in Visual Search

    E-print Network

    McShea, Daniel W.

    such as a knife must be discriminated from visually similar items (McCarley, Kramer, Wickens, Vidoni, & Boot, 2004, & Weinstein, 2007) and airport baggage screening (McCarley, Kramer, Wickens, Vidoni, & Boot, 2004

  2. Visual Search and Dual Tasks Reveal Two Distinct Attentional Resources

    E-print Network

    Poggio, Tomaso

    perception of the visual world relies on the parallel extraction of a limited set of preattentive features have acknowledged the need to redefine this dualistic terminology, but continue instead to refer

  3. Foveal vision loss interferes with visual search guidance by learned spatial contexts in contextual cueing.

    PubMed

    Pollmann, Stefan; Geringswald, Franziska

    2015-09-01

    Visual search is guided by past experience of regularities in our visual environment. In the contextual cueing paradigm, incidental learning of repeated distractor configurations improves search times and eye movement parameters. Both in patients with age-related macular degeneration who suffer from foveal vision loss and in young normal-sighted observers with gaze-contingent central scotoma simulation contextual cueing was severely reduced (Geringswald et al., Front Hum Neurosci 2012, J Vis 2014). Previous work has shown that not the learning of spatial contexts but rather the utilization of previously learned context for efficient search guidance depends on visuospatial working-memory (Manginelli et al., Att Percept Psychophys 2013; Vickery et al., J Exp Psychol Hum Perc Perform 2010). Therefore, increased working memory demands due to top-down controlled visual search in the presence of foveal vision loss could lead to reduced contextual cueing. To test this hypothesis, we let normal-sighted observers search with simulated foveal scotoma during a learning phase but without scotoma in a subsequent transfer phase. Contextual cueing was absent during learning, but reinstated in the transfer phase. This indicated that context learning occured in the presence of foveal vision loss, but learning could not be utilized for more efficient search while the scotoma was present. However, in a further experiment, after few hours of search training with central scotoma simulation, contextual cueing was reinstated during scotomatous search, indicating that contextual cueing can be regained when the exploration of the environment becomes more automatic. Thus, foveal vision loss leads to inefficient use of implicitly learned contextual cues for the guidance of visual search. Automatization of search with a simulated scotoma leads to reinstatement of contextual cueing in normal-sighted observers. This may show a promising way for training programs in patients with foveal vision loss. Meeting abstract presented at VSS 2015. PMID:26326797

  4. Gene prediction by pattern recognition and homology search

    SciTech Connect

    Xu, Y.; Uberbacher, E.C.

    1996-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    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.

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

    PubMed Central

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

    2012-01-01

    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

  7. Visual cluster analysis and pattern recognition template and methods

    SciTech Connect

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

    1993-12-31

    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.

  8. Visual cluster analysis and pattern recognition template and methods

    DOEpatents

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

    1999-01-01

    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.

  9. Visual cluster analysis and pattern recognition template and methods

    DOEpatents

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

    1999-05-04

    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.

  10. Explorative Visualization of Citation Patterns in Social Network Research

    E-print Network

    Brandes, Ulrik

    and Christian Pich Department of Computer & Information Science University of Konstanz Abstract We propose, Florida, USA, 22-27 January 2008. 1 #12;Brandes, Pich: Citation Patterns in Social Network Research Jo

  11. Hypothesis Support Mechanism for Mid-Level Visual Pattern Recognition

    NASA Technical Reports Server (NTRS)

    Amador, Jose J (Inventor)

    2007-01-01

    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.

  12. Parametric Modeling of Visual Search Efficiency in Real Scenes

    PubMed Central

    Zhang, Xing; Li, Qingquan; Zou, Qin; Fang, Zhixiang; Zhou, Baoding

    2015-01-01

    How should the efficiency of searching for real objects in real scenes be measured? Traditionally, when searching for artificial targets, e.g., letters or rectangles, among distractors, efficiency is measured by a reaction time (RT) × Set Size function. However, it is not clear whether the set size of real scenes is as effective a parameter for measuring search efficiency as the set size of artificial scenes. The present study investigated search efficiency in real scenes based on a combination of low-level features, e.g., visible size and target-flanker separation factors, and high-level features, e.g., category effect and target template. Visible size refers to the pixel number of visible parts of an object in a scene, whereas separation is defined as the sum of the flank distances from a target to the nearest distractors. During the experiment, observers searched for targets in various urban scenes, using pictures as the target templates. The results indicated that the effect of the set size in real scenes decreased according to the variances of other factors, e.g., visible size and separation. Increasing visible size and separation factors increased search efficiency. Based on these results, an RT × Visible Size × Separation function was proposed. These results suggest that the proposed function is a practicable predictor of search efficiency in real scenes. PMID:26030908

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

    PubMed Central

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

    2014-01-01

    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. PMID:25400559

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

    PubMed

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

    2014-02-01

    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

  15. Looking and listening: A comparison of intertrial repetition effects in visual and auditory search tasks.

    PubMed

    Klein, Michael D; Stolz, Jennifer A

    2015-08-01

    Previous research shows that performance on pop-out search tasks is facilitated when the target and distractors repeat across trials compared to when they switch. This phenomenon has been shown for many different types of visual stimuli. We tested whether the effect would extend beyond visual stimuli to the auditory modality. Using a temporal search task that has previously been shown to elicit priming of pop-out with visual stimuli (Yashar & Lamy, Psychological Science, 21(2), 243-251, 2010), we showed that priming of pop-out does occur with auditory stimuli and has characteristics similar to those of an analogous visual task. These results suggest that either the same or similar mechanisms might underlie priming of pop-out in both modalities. PMID:25944447

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

    E-print Network

    Lucas, Christopher G

    2004-01-01

    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 ...

  17. Sequential patterns mining and gene sequence visualization to discover novelty from microarray data.

    PubMed

    Sallaberry, A; Pecheur, N; Bringay, S; Roche, M; Teisseire, M

    2011-10-01

    Data mining allow users to discover novelty in huge amounts of data. Frequent pattern methods have proved to be efficient, but the extracted patterns are often too numerous and thus difficult to analyze by end users. In this paper, we focus on sequential pattern mining and propose a new visualization system to help end users analyze the extracted knowledge and to highlight novelty according to databases of referenced biological documents. Our system is based on three visualization techniques: clouds, solar systems, and treemaps. We show that these techniques are very helpful for identifying associations and hierarchical relationships between patterns among related documents. Sequential patterns extracted from gene data using our system were successfully evaluated by two biology laboratories working on Alzheimer's disease and cancer. PMID:21527357

  18. Placing a Lower Bound on Transsaccadic Memory Capacity Using Visual Search.

    PubMed

    Kleene, Nicholas; Michel, Melchi

    2015-09-01

    Making eye-movements provides us with visual samples of the world that must be integrated to produce a coherent percept of the visual world. Transsaccadic Memory (TSM) is necessary for storing samples from previous fixations so they can be integrated with the current one. Visual search tasks place greater demands on TSM than change-detection since visual search often requires integration of multiple samples. Our goal was to estimate TSM capacity and investigate its relationship to visual short-term memory (VSTM) using two visual search tasks. Prior to the main experiment, participants completed a forced-choice detection task designed to estimate their psychometric function at each potential target location. Participants then completed a simulated or real saccade search task, requiring the localization of a target signal (Gabor) embedded in a field of 1/f filtered noise. Participants were presented with one, two or four fixation intervals and the target was present in each interval (redundancy condition) or only one (uncertainty condition). Trials were blocked by the number of intervals and target presence condition. In the real saccade task participants made a 5° saccade following each stimulus sample; in the simulated saccade task they maintained fixation while we simulated the dynamic transient produced by saccades. Performance was measured as target localization accuracy. We developed an ideal observer model of transsaccadic integration that takes into account the critical role of TSM. Our ideal observer model allowed us to place a lower bound on TSM capacity for each subject, quantified in terms of bits, a task independent unit of information. We found median capacity estimates of 7 bits for the simulated saccade task and 9.5 bits for the real saccade task. These estimates are somewhat higher than those previously found for VSTM, but they indicate that TSM capacity may play a limiting role in multiple fixation visual search. Meeting abstract presented at VSS 2015. PMID:26326981

  19. The individual and relative contributions of different regions of the visual field to visual search 

    E-print Network

    Greenwood Mears, Ruth

    2012-06-27

    of window or scotoma (1.5°, 5° or 8.6°) was centred on the viewer’s gaze using a Gaze Contingent Multiresolutional Display. Windows and scotoma had smoothedged boundaries and visual information which was restricted from contributing to the visual task...

  20. Quantifying the performance limits of human saccadic targeting during visual search

    NASA Technical Reports Server (NTRS)

    Eckstein, M. P.; Beutter, B. R.; Stone, L. S.

    2001-01-01

    In previous studies of saccadic targeting, the issue how visually guided saccades to unambiguous targets are programmed and executed has been examined. These studies have found different degrees of guidance for saccades depending on the task and task difficulty. In this study, we use ideal-observer analysis to estimate the visual information used for the first saccade during a search for a target disk in noise. We quantitatively compare the performance of the first saccadic decision to that of the ideal observer (ie absolute efficiency of the first saccade) and to that of the associated final perceptual decision at the end of the search (ie relative efficiency of the first saccade). Our results show, first, that at all levels of salience tested, the first saccade is based on visual information from the stimulus display, and its highest absolute efficiency is approximately 20%. Second, the efficiency of the first saccade is lower than that of the final perceptual decision after active search (with eye movements) and has a minimum relative efficiency of 19% at the lowest level of saliency investigated. Third, we found that requiring observers to maintain central fixation (no saccades allowed) decreased the absolute efficiency of their perceptual decision by up to a factor of two, but that the magnitude of this effect depended on target salience. Our results demonstrate that ideal-observer analysis can be extended to measure the visual information mediating saccadic target-selection decisions during visual search, which enables direct comparison of saccadic and perceptual efficiencies.

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

    NASA Technical Reports Server (NTRS)

    Lewis, Robert Michael; Torczon, Virginia

    1998-01-01

    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.

  2. Eye movements, visual search and scene memory, in an immersive virtual environment.

    PubMed

    Kit, Dmitry; Katz, Leor; Sullivan, Brian; Snyder, Kat; Ballard, Dana; Hayhoe, Mary

    2014-01-01

    Visual memory has been demonstrated to play a role in both visual search and attentional prioritization in natural scenes. However, it has been studied predominantly in experimental paradigms using multiple two-dimensional images. Natural experience, however, entails prolonged immersion in a limited number of three-dimensional environments. The goal of the present experiment was to recreate circumstances comparable to natural visual experience in order to evaluate the role of scene memory in guiding eye movements in a natural environment. Subjects performed a continuous visual-search task within an immersive virtual-reality environment over three days. We found that, similar to two-dimensional contexts, viewers rapidly learn the location of objects in the environment over time, and use spatial memory to guide search. Incidental fixations did not provide obvious benefit to subsequent search, suggesting that semantic contextual cues may often be just as efficient, or that many incidentally fixated items are not held in memory in the absence of a specific task. On the third day of the experience in the environment, previous search items changed in color. These items were fixated upon with increased probability relative to control objects, suggesting that memory-guided prioritization (or Surprise) may be a robust mechanisms for attracting gaze to novel features of natural environments, in addition to task factors and simple spatial saliency. PMID:24759905

  3. 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 ...

  4. The NLP Swish Pattern: An Innovative Visualizing Technique.

    ERIC Educational Resources Information Center

    Masters, Betsy J.; And Others

    1991-01-01

    Describes swish pattern, one of many innovative therapeutic interventions that developers of neurolinguistic programing (NLP) have contributed to counseling profession. Presents brief overview of NLP followed by an explanation of the basic theory and expected outcomes of the swish. Presents description of the intervention process and case studies…

  5. Use of a twin dataset to identify AMD-related visual patterns controlled by genetic factors

    NASA Astrophysics Data System (ADS)

    Quellec, Gwénolé; Abràmoff, Michael D.; Russell, Stephen R.

    2010-03-01

    The mapping of genotype to the phenotype of age-related macular degeneration (AMD) is expected to improve the diagnosis and treatment of the disease in a near future. In this study, we focused on the first step to discover this mapping: we identified visual patterns related to AMD which seem to be controlled by genetic factors, without explicitly relating them to the genes. For this purpose, we used a dataset of eye fundus photographs from 74 twin pairs, either monozygotic twins, who have the same genotype, or dizygotic twins, whose genes responsible for AMD are less likely to be identical. If we are able to differentiate monozygotic twins from dizygotic twins, based on a given visual pattern, then this pattern is likely to be controlled by genetic factors. The main visible consequence of AMD is the apparition of drusen between the retinal pigment epithelium and Bruch's membrane. We developed two automated drusen detectors based on the wavelet transform: a shape-based detector for hard drusen, and a texture- and color- based detector for soft drusen. Forty visual features were evaluated at the location of the automatically detected drusen. These features characterize the texture, the shape, the color, the spatial distribution, or the amount of drusen. A distance measure between twin pairs was defined for each visual feature; a smaller distance should be measured between monozygotic twins for visual features controlled by genetic factors. The predictions of several visual features (75.7% accuracy) are comparable or better than the predictions of human experts.

  6. Examining perceptual and conceptual set biases in multiple-target visual search.

    PubMed

    Biggs, Adam T; Adamo, Stephen H; Dowd, Emma Wu; Mitroff, Stephen R

    2015-04-01

    Visual search is a common practice conducted countless times every day, and one important aspect of visual search is that multiple targets can appear in a single search array. For example, an X-ray image of airport luggage could contain both a water bottle and a gun. Searchers are more likely to miss additional targets after locating a first target in multiple-target searches, which presents a potential problem: If airport security officers were to find a water bottle, would they then be more likely to miss a gun? One hypothetical cause of multiple-target search errors is that searchers become biased to detect additional targets that are similar to a found target, and therefore become less likely to find additional targets that are dissimilar to the first target. This particular hypothesis has received theoretical, but little empirical, support. In the present study, we tested the bounds of this idea by utilizing "big data" obtained from the mobile application Airport Scanner. Multiple-target search errors were substantially reduced when the two targets were identical, suggesting that the first-found target did indeed create biases during subsequent search. Further analyses delineated the nature of the biases, revealing both a perceptual set bias (i.e., a bias to find additional targets with features similar to those of the first-found target) and a conceptual set bias (i.e., a bias to find additional targets with a conceptual relationship to the first-found target). These biases are discussed in terms of the implications for visual-search theories and applications for professional visual searchers. PMID:25678271

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

    PubMed

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

    2012-07-01

    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

  8. Epistemic Beliefs, Online Search Strategies, and Behavioral Patterns While Exploring Socioscientific Issues

    NASA Astrophysics Data System (ADS)

    Hsu, Chung-Yuan; Tsai, Meng-Jung; Hou, Huei-Tse; Tsai, Chin-Chung

    2014-06-01

    Online information searching tasks are usually implemented in a technology-enhanced science curriculum or merged in an inquiry-based science curriculum. The purpose of this study was to examine the role students' different levels of scientific epistemic beliefs (SEBs) play in their online information searching strategies and behaviors. Based on the measurement of an SEB survey, 42 undergraduate and graduate students in Taiwan were recruited from a pool of 240 students and were divided into sophisticated and naïve SEB groups. The students' self-perceived online searching strategies were evaluated by the Online Information Searching Strategies Inventory, and their search behaviors were recorded by screen-capture videos. A sequential analysis was further used to analyze the students' searching behavioral patterns. The results showed that those students with more sophisticated SEBs tended to employ more advanced online searching strategies and to demonstrate a more metacognitive searching pattern.

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

    PubMed Central

    Krasheninnikova, Anastasia

    2013-01-01

    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

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

    ERIC Educational Resources Information Center

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

    2010-01-01

    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…

  11. Visual illusions in predator-prey interactions: birds find moving patterned prey harder to catch.

    PubMed

    Hämäläinen, Liisa; Valkonen, Janne; Mappes, Johanna; Rojas, Bibiana

    2015-09-01

    Several antipredator strategies are related to prey colouration. Some colour patterns can create visual illusions during movement (such as motion dazzle), making it difficult for a predator to capture moving prey successfully. Experimental evidence about motion dazzle, however, is still very scarce and comes only from studies using human predators capturing moving prey items in computer games. We tested a motion dazzle effect using for the first time natural predators (wild great tits, Parus major). We used artificial prey items bearing three different colour patterns: uniform brown (control), black with elongated yellow pattern and black with interrupted yellow pattern. The last two resembled colour patterns of the aposematic, polymorphic dart-poison frog Dendrobates tinctorius. We specifically tested whether an elongated colour pattern could create visual illusions when combined with straight movement. Our results, however, do not support this hypothesis. We found no differences in the number of successful attacks towards prey items with different patterns (elongated/interrupted) moving linearly. Nevertheless, both prey types were significantly more difficult to catch compared to the uniform brown prey, indicating that both colour patterns could provide some benefit for a moving individual. Surprisingly, no effect of background (complex vs. plain) was found. This is the first experiment with moving prey showing that some colour patterns can affect avian predators' ability to capture moving prey, but the mechanisms lowering the capture rate are still poorly understood. PMID:25947086

  12. Mapping the Color Space of Saccadic Selectivity in Visual Search

    ERIC Educational Resources Information Center

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

    2007-01-01

    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…

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

    ERIC Educational Resources Information Center

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

    2000-01-01

    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,…

  14. Search Pattern Leakage in Searchable Encryption: Attacks and New Construction

    E-print Network

    International Association for Cryptologic Research (IACR)

    data and search query should leak 100081, China Abstract Searching on remote encrypted data (commonly known as searchable en- cryption) has become an important issue in secure data outsourcing, since it allows users to outsource encrypted data

  15. Visual Servoing: A technology in search of an application

    SciTech Connect

    Feddema, J.T.

    1994-05-01

    Considerable research has been performed on Robotic Visual Servoing (RVS) over the past decade. Using real-time visual feedback, researchers have demonstrated that robotic systems can pick up moving parts, insert bolts, apply sealant, and guide vehicles. With the rapid improvements being made in computing and image processing hardware, one would expect that every robot manufacturer would have a RVS option by the end of the 1990s. So why aren`t the Fanucs, ABBs, Adepts, and Motomans of the world investing heavily in RVS? I would suggest four seasons: cost, complexity, reliability, and lack of demand. Solutions to the first three are approaching the point where RVS could be commercially available; however, the lack of demand is keeping RVS from becoming a reality in the near future. A new set of applications is needed to focus near term RVS development. These must be applications which currently do not have solutions. Once developed and working in one application area, the technology is more likely to quickly spread to other areas. DOE has several applications that are looking for technological solutions, such as agile weapons production, weapons disassembly, decontamination and dismantlement of nuclear facilities, and hazardous waste remediation. This paper will examine a few of these areas and suggest directions for application-driven visual servoing research.

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

    NASA Astrophysics Data System (ADS)

    Atit, Kinnari

    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.

  17. Visual Search Asymmetries within Color-Coded and Intensity-Coded Displays

    ERIC Educational Resources Information Center

    Yamani, Yusuke; McCarley, Jason S.

    2010-01-01

    Color and intensity coding provide perceptual cues to segregate categories of objects within a visual display, allowing operators to search more efficiently for needed information. Even within a perceptually distinct subset of display elements, however, it may often be useful to prioritize items representing urgent or task-critical information.…

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

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  19. Orientation anisotropies in visual search revealed Department of Electrical and Computer Engineering, &

    E-print Network

    Tavassoli, Abtine

    effect, orientation tuning, reverse correlation, classification images, eye movements, 1/f noise Citation, such as 1/f noise or natural images filtered in orientation, instead of gratings, could instead yieldOrientation anisotropies in visual search revealed by noise Department of Electrical and Computer

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

    ERIC Educational Resources Information Center

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

    2007-01-01

    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…

  1. The interplay of attention and consciousness in visual search, attentional blink and working memory consolidation

    E-print Network

    The interplay of attention and consciousness in visual search, attentional blink and working memory the acknowledged relationship between consciousness and attention, theories of the two have mostly been developed to bridge the gap between, on the one hand, a theory of consciousness based on the notion of global

  2. Comparative Search Reveals the Tradeoff between Eye Movements and Working Memory Use in Visual Tasks

    E-print Network

    Pomplun, Marc

    Comparative Search Reveals the Tradeoff between Eye Movements and Working Memory Use in Visual whether the two halves of the screen are exactly identical or contain a difference. The eye movement data additional eye movements towards the model and back to the workspace or source to acquire information only

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

    ERIC Educational Resources Information Center

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

    2014-01-01

    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…

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

    E-print Network

    Eustice, Ryan

    -based perception approach eliminates the need for having to deploy additional navigation infrastructureToward Real-Time Visually Augmented Navigation for Autonomous Search and Inspection of Ship Hulls using autonomous underwater vehicles (AUVs). We describe an automated feature-based navigation (FBN

  5. Target Location Probability Effects in Visual Search: An Effect of Sequential Dependencies

    ERIC Educational Resources Information Center

    Walthew, Carol; Gilchrist, Iain D.

    2006-01-01

    Target location probability was manipulated in a visual search task. When the target was twice as likely to appear on 1 side of the display as the other, manual button-press response times were faster (Experiment 1A) and first saccades were more frequently directed (Experiment 1B) to the more probable locations. When the target appeared with equal…

  6. Can a short nap and bright light function as implicit learning and visual search enhancers?

    PubMed

    Kaida, Kosuke; Takeda, Yuji; Tsuzuki, Kazuyo

    2012-01-01

    The present study examined effects of a short nap (20 min) and/or bright light (2000 lux) on visual search and implicit learning in a contextual cueing task. Fifteen participants performed a contextual cueing task twice a day (1200-1330 h and 1430-1600 h) and scored subjective sleepiness before and after a short afternoon nap or a break period. Participants served a total of four experimental conditions (control, short nap, bright light and short nap with bright light). During the second task, bright light treatment (BLT) was applied in the two of the four conditions. Participants performed both tasks in a dimly lit environment except during the light treatment. Results showed that a short nap reduced subjective sleepiness and improved visual search time, but it did not affect implicit learning. Bright light reduced subjective sleepiness. A short nap in the afternoon could be a countermeasure against sleepiness and an enhancer for visual search. Practitioner Summary: The study examined effects of a short afternoon nap (20 min) and/or bright light (2000 lux) on visual search and implicit learning. A short nap is a powerful countermeasure against sleepiness compared to bright light exposure in the afternoon. PMID:22928470

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

    ERIC Educational Resources Information Center

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

    2007-01-01

    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…

  8. Modeling cognitive effects on visual search for targets in cluttered backgrounds

    NASA Astrophysics Data System (ADS)

    Snorrason, Magnus; Ruda, Harald; Hoffman, James

    1998-07-01

    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.

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

    ERIC Educational Resources Information Center

    Cole, Charles; Mandelblatt, Bertie; Stevenson, John

    2002-01-01

    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…

  10. VisualRank: applying PageRank to large-scale image search.

    PubMed

    Jing, Yushi; Baluja, Shumeet

    2008-11-01

    Because of the relative ease in understanding and processing text, commercial image-search systems often rely on techniques that are largely indistinguishable from text-search. Recently, academic studies have demonstrated the effectiveness of employing image-based features to provide alternative or additional signals. However, it remains uncertain whether such techniques will generalize to a large number of popular web queries, and whether the potential improvement to search quality warrants the additional computational cost. In this work, we cast the image-ranking problem into the task of identifying "authority" nodes on an inferred visual similarity graph and propose VisualRank to analyze the visual link structures among images. The images found to be "authorities" are chosen as those that answer the image-queries well. To understand the performance of such an approach in a real system, we conducted a series of large-scale experiments based on the task of retrieving images for 2000 of the most popular products queries. Our experimental results show significant improvement, in terms of user satisfaction and relevancy, in comparison to the most recent Google Image Search results. Maintaining modest computational cost is vital to ensuring that this procedure can be used in practice; we describe the techniques required to make this system practical for large scale deployment in commercial search engines. PMID:18787237

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

    ERIC Educational Resources Information Center

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

    2011-01-01

    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)…

  12. Patterns of Visual Attention to Faces and Objects in Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    McPartland, James C.; Webb, Sara Jane; Keehn, Brandon; Dawson, Geraldine

    2011-01-01

    This study used eye-tracking to examine visual attention to faces and objects in adolescents with autism spectrum disorder (ASD) and typical peers. Point of gaze was recorded during passive viewing of images of human faces, inverted human faces, monkey faces, three-dimensional curvilinear objects, and two-dimensional geometric patterns.…

  13. 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...

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

    E-print Network

    Zaiane, Osmar R.

    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

  15. Recognising Visual Patterns to Communicate Gas Turbine Time-Series Data

    E-print Network

    Reiter, Ehud

    Recognising Visual Patterns to Communicate Gas Turbine Time-Series Data Jin Yu, Jim Hunter, Ehud analogue channels are sampled once per second and archived by the Tiger system for monitoring gas turbines turbine domain [2]. In the knowledge engineering field, knowledge acquisition plays an important role

  16. Visualizing and Classifying the Pattern of User's Browsing Behavior for Website Design Recommendation

    E-print Network

    Kimble, Chris

    Visualizing and Classifying the Pattern of User's Browsing Behavior for Website Design, Heslington, York, Y010 5DD, UK {derrick, kimble, kudenko}@cs.york.ac.uk Abstract. E-commerce website design, the information provided by these tools cannot be directly translated into changes in the website design. Rather

  17. Visualization of Flow Patterns in the Bonneville 2nd Powerhouse Forebay

    SciTech Connect

    Serkowski, John A.; Rakowski, Cynthia L.; Ebner, Laurie L.

    2002-12-31

    Three-dimensional (3D) computational fluid dynamics (CFD) models are increasingly being used to study forebay and tailrace flow systems associated with hydroelectric projects. This paper describes the fundamentals of creating effective 3D data visualizations from CFD model results using a case study from the Bonneville Dam. These visualizations enhance the utility of CFD models by helping the researcher and end user better understand the model results. To develop visualizations for the Bonneville Dam forebay model, we used specialized, but commonly available software and a standard high-end microprocessor workstation. With these tools we were able to compare flow patterns among several operational scenarios by producing a variety of contour, vector, stream-trace, and vortex-core plots. The differences in flow patterns we observed could impact efforts to divert downstream-migrating fish around powerhouse turbines.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  19. Studying visual search using systems factorial methodology with target–distractor similarity as the factor

    PubMed Central

    Fifi?, Mario; Townsend, James T.; Eidels, Ami

    2008-01-01

    Systems factorial technology (SFT) is a theory-driven set of methodologies oriented toward identification of basic mechanisms, such as parallel versus serial processing, of perception and cognition. Studies employing SFT in visual search with small display sizes have repeatedly shown decisive evidence for parallel processing. The first strong evidence for serial processing was recently found in short-term memory search, using target–distractor (T–D) similarity as a key experimental variable (Townsend & Fifi?, 2004). One of the major goals of the present study was to employ T–D similarity in visual search to learn whether this mode of manipulating processing speed would affect the parallel versus serial issue in that domain. The result was a surprising and regular departure from ordinary parallel or serial processing. The most plausible account at present relies on the notion of positively interacting parallel channels. PMID:18556921

  20. Visual contrast modulates maturation of camouflage body patterning in cuttlefish (Sepia pharaonis).

    PubMed

    Lee, Yi-Hsin; Yan, Hong Young; Chiao, Chuan-Chin

    2010-08-01

    Camouflage is the primary defense behavior in cephalopods. It is known that cuttlefish immediately after hatching are capable of showing various body patterns for concealing themselves, however recent studies suggest that maturation of camouflage body patterns is faster for cuttlefish (Sepia officinalis) reared in enriched environments than those reared in impoverished environments. Since camouflage patterning in cephalopods is predominately visually driven, this study specifically investigates effects of the rearing background contrast on the maturation of body patterns in cuttlefish (Sepia pharaonis). Newly hatched animals were separated into two cohorts, one reared in a uniform-gray background (low-contrast, or L group) and the other raised in a black/white checkerboard background (high-contrast, or H group). At Weeks 2, 4, 6, 8, 10, and 12, cuttlefish were placed individually either on uniform or checkerboard substrates to examine their body patterns. Animals from both L and H groups appear to show moderate disruptive patterns on the checkerboard and less disruptive on the uniform background at Week 2. Throughout development, however, cuttlefish from the H group showed stronger disruptive patterns than that of the L group on the checkerboard background at Weeks 10 and 12. In interesting findings, cuttlefish from both L and H groups showed similar strength but different disruptive components on the uniform background in later postembryonic stages. These results suggest that the maturation of camouflage body patterns in S. pharaonis is at least in part affected by visual contrast of their rearing backgrounds, although environmental complexity or social interaction is also likely to be involved in this process. This also implies that early visual experience could exert its effect on the seemingly preprogrammed behaviors such as camouflage body patterning in cephalopods. PMID:20695657

  1. Visual Map Development Depends On The Temporal Pattern of Binocular Activity in Mice

    PubMed Central

    Zhang, Jiayi; Ackman, James; Xu, Hong-Ping; Crair, Michael C.

    2011-01-01

    Binocular competition is thought to drive eye-specific segregation in the developing visual system, potentially through Hebbian synaptic learning rules that are sensitive to correlations in afferent activity. Altering retinal activity can disrupt eye-specific segregation, but little is known about the temporal features of binocular activity that modulate visual map development. We used optogenetic techniques to directly manipulate retinal activity in vivo and identified a critical period before eye opening in mice when specific binocular features of retinal activity drive visual map development. Synchronous activation of both eyes disrupted segregation, whereas asynchronous stimulation enhanced segregation. The optogenetic stimulus applied was spatially homogenous, and accordingly retinotopy of ipsilateral projections was dramatically perturbed, but contralateral retinotopy was unaffected or even improved. These results provide direct evidence that the synchrony and precise temporal pattern of binocular retinal activity during a critical period in development regulates eye-specific segregation and retinotopy in the developing visual system. PMID:22179110

  2. Effects of Individual Health Topic Familiarity on Activity Patterns During Health Information Searches

    PubMed Central

    Moriyama, Koichi; Fukui, Ken–ichi; Numao, Masayuki

    2015-01-01

    Background Non-medical professionals (consumers) are increasingly using the Internet to support their health information needs. However, the cognitive effort required to perform health information searches is affected by the consumer’s familiarity with health topics. Consumers may have different levels of familiarity with individual health topics. This variation in familiarity may cause misunderstandings because the information presented by search engines may not be understood correctly by the consumers. Objective As a first step toward the improvement of the health information search process, we aimed to examine the effects of health topic familiarity on health information search behaviors by identifying the common search activity patterns exhibited by groups of consumers with different levels of familiarity. Methods Each participant completed a health terminology familiarity questionnaire and health information search tasks. The responses to the familiarity questionnaire were used to grade the familiarity of participants with predefined health topics. The search task data were transcribed into a sequence of search activities using a coding scheme. A computational model was constructed from the sequence data using a Markov chain model to identify the common search patterns in each familiarity group. Results Forty participants were classified into L1 (not familiar), L2 (somewhat familiar), and L3 (familiar) groups based on their questionnaire responses. They had different levels of familiarity with four health topics. The video data obtained from all of the participants were transcribed into 4595 search activities (mean 28.7, SD 23.27 per session). The most frequent search activities and transitions in all the familiarity groups were related to evaluations of the relevancy of selected web pages in the retrieval results. However, the next most frequent transitions differed in each group and a chi-squared test confirmed this finding (P<.001). Next, according to the results of a perplexity evaluation, the health information search patterns were best represented as a 5-gram sequence pattern. The most common patterns in group L1 were frequent query modifications, with relatively low search efficiency, and accessing and evaluating selected results from a health website. Group L2 performed frequent query modifications, but with better search efficiency, and accessed and evaluated selected results from a health website. Finally, the members of group L3 successfully discovered relevant results from the first query submission, performed verification by accessing several health websites after they discovered relevant results, and directly accessed consumer health information websites. Conclusions Familiarity with health topics affects health information search behaviors. Our analysis of state transitions in search activities detected unique behaviors and common search activity patterns in each familiarity group during health information searches. PMID:25783222

  3. Does focused endogenous attention prevent attentional capture in pop-out visual search?

    PubMed Central

    Seiss, Ellen; Kiss, Monika; Eimer, Martin

    2009-01-01

    To investigate whether salient visual singletons capture attention when they appear outside the current endogenous attentional focus, we measured the N2pc component as a marker of attentional capture in a visual search task where target or nontarget singletons were presented at locations previously cued as task-relevant, or in the uncued irrelevant hemifield. In two experiments, targets were either defined by colour, or by a combination of colour and shape. The N2pc was elicited both for attended singletons and for singletons on the uncued side, demonstrating that focused endogenous attention cannot prevent attentional capture by salient unattended visual events. However, N2pc amplitudes were larger for attended and unattended singletons that shared features with the current target, suggesting that top-down task sets modulate the capacity of visual singletons to capture attention both within and outside the current attentional focus. PMID:19473304

  4. Incidental Learning Speeds Visual Search by Lowering Response Thresholds, Not by Improving Efficiency: Evidence from Eye Movements

    ERIC Educational Resources Information Center

    Hout, Michael C.; Goldinger, Stephen D.

    2012-01-01

    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. Despite these findings, visual search has been successfully modeled using architectures that maintain no…

  5. Topographical patterns of ERP elicited by different visual information-processing tasks.

    PubMed

    Kotani, K; Freivalds, A; Horii, K

    1993-08-01

    Topographical patterns of event-related potentials were compared on a visual display terminal for a data-input task and a number-comparison task. Maximum negative peaks were found in the frontal and central regions for the former but at midline locations for the latter. Latencies were shorter in the occipital regions than in the frontal regions for the former and the opposite pattern was found for the latter. An analysis of variance indicated that hemispheric location significantly affected the amplitude of peaks. On the other hand, latencies were affected by the task, frontal and occipital regions, and their interaction. These results suggest that a pattern of the topographic display of event-related potentials can be used as an objective means for classifying visual tasks. PMID:8367255

  6. Saved by a log: how do humans perform hybrid visual and memory search?

    PubMed

    Wolfe, Jeremy M

    2012-07-01

    Could you find 1 of your 1,000 Facebook friends in a crowd of 100? Even at a rate of 25 ms per comparison, determining that no friends were in the crowd would take more than 40 min if memory and visual search interacted linearly. In the experiment reported here, observers memorized pictures of 1 to 100 targets and then searched for any of these targets in visual displays of 1 to 16 objects. Response times varied linearly with visual set size but logarithmically with memory set size. Data from memory set sizes of 1 through 16 accurately predicted response times for different observers holding 100 objects in memory. The results would be consistent with a binary coding of visual objects in memory and are relevant to applied searches in which experts look for any of many items of interest (e.g., a radiologist running through a mental checklist of what might be wrong in a car-crash victim or an airport screener looking for any of a list of prohibited items in a carry-on bag). PMID:22623508

  7. Prevalence learning and decision making in a visual search task: an equivalent ideal observer approach

    NASA Astrophysics Data System (ADS)

    He, Xin; Samuelson, Frank; Zeng, Rongping; Sahiner, Berkman

    2015-03-01

    Research studies have observed an influence of target prevalence on observer performance for visual search tasks. The goal of this work is to develop models for prevalence effects on visual search. In a recent study by Wolfe et. al, a large scale observer study was conducted to understand the effects of varying target prevalence on visual search. Particularly, a total of 12 observers were recruited to perform 1000 trials of simulated baggage search as target prevalence varied sinusoidally from high to low and back to high. We attempted to model observers' behavior in prevalence learning and decision making. We modeled the observer as an equivalent ideal observer (EIO) with a prior belief of the signal prevalence. The use of EIO allows the application of ideal observer mathematics to characterize real observers' performance reading real-life images. For every given new image, the observer updates the belief on prevalence and adjusts his/her decision threshold according to utility theory. The model results agree well with the experimental results from the Wolfe study. The proposed models allow theoretical insights into observer behavior in learning prevalence and adjusting their decision threshold.

  8. Neural structures involved in visual search guidance by reward-enhanced contextual cueing of the target location.

    PubMed

    Pollmann, Stefan; Ešto?inová, Jana; Sommer, Susanne; Chelazzi, Leonardo; Zinke, Wolf

    2016-01-01

    Spatial contextual cueing reflects an incidental form of learning that occurs when spatial distractor configurations are repeated in visual search displays. Recently, it was reported that the efficiency of contextual cueing can be modulated by reward. We replicated this behavioral finding and investigated its neural basis with fMRI. Reward value was associated with repeated displays in a learning session. The effect of reward value on context-guided visual search was assessed in a subsequent fMRI session without reward. Structures known to support explicit reward valuation, such as ventral frontomedial cortex and posterior cingulate cortex, were modulated by incidental reward learning. Contextual cueing, leading to more efficient search, went along with decreased activation in the visual search network. Retrosplenial cortex played a special role in that it showed both a main effect of reward and a reward×configuration interaction and may thereby be a central structure for the reward modulation of context-guided visual search. PMID:26427645

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

    NASA Astrophysics Data System (ADS)

    Habibi, Mohammad S.; Shirkhodaie, Amir

    2013-05-01

    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.

  10. Optimization of boiling water reactor control rod patterns using linear search

    SciTech Connect

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

    1984-10-01

    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.

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

    E-print Network

    Buldyrev, Sergey

    LETTERS Revisiting Le´vy flight search patterns of wandering albatrosses, bumblebees and deer importance1 , and exemplifies the wider scientific problem of optimizing search strategies2 . Le´vy flights,4 , such that clusters of short steps are con- nected by rare long steps. Le´vy flights display fractal properties, have

  12. Job Search Patterns of College Graduates: The Role of Social Capital

    ERIC Educational Resources Information Center

    Coonfield, Emily S.

    2012-01-01

    This dissertation addresses job search patterns of college graduates and the implications of social capital by race and class. The purpose of this study is to explore (1) how the job search transpires for recent college graduates, (2) how potential social networks in a higher educational context, like KU, may make a difference for students with…

  13. Case study of visualizing global user download patterns using Google Earth and NASA World Wind

    NASA Astrophysics Data System (ADS)

    Zong, Ziliang; Job, Joshua; Zhang, Xuesong; Nijim, Mais; Qin, Xiao

    2012-01-01

    Geo-visualization is significantly changing the way we view spatial data and discover information. On the one hand, a large number of spatial data are generated every day. On the other hand, these data are not well utilized due to the lack of free and easily used data-visualization tools. This becomes even worse when most of the spatial data remains in the form of plain text such as log files. This paper describes a way of visualizing massive plain-text spatial data at no cost by utilizing Google Earth and NASA World Wind. We illustrate our methods by visualizing over 170,000 global download requests for satellite images maintained by the Earth Resources Observation and Science (EROS) Center of U.S. Geological Survey (USGS). Our visualization results identify the most popular satellite images around the world and discover the global user download patterns. The benefits of this research are: 1. assisting in improving the satellite image downloading services provided by USGS, and 2. providing a proxy for analyzing the "hot spot" areas of research. Most importantly, our methods demonstrate an easy way to geo-visualize massive textual spatial data, which is highly applicable to mining spatially referenced data and information on a wide variety of research domains (e.g., hydrology, agriculture, atmospheric science, natural hazard, and global climate change).

  14. In visual search, guidance by surface type is different than classic guidance

    PubMed Central

    Wolfe, Jeremy M; Reijnen, Ester; Van Wert, Michael J.; Kuzmova, Yoana

    2009-01-01

    Visual search for targets among distractors is more efficient if attention can be guided to targets by attributes like color. In real-world search, we guide attention using information about surfaces. (e.g., paintings are on walls). We compare “classic” color guidance to surface guidance in “scenes” of cubes. When a target can lie on one of many surfaces, color guidance is effective but surface guidance is not (Exp. 1-3). Surface guidance works when cued surfaces are coplanar (Exp. 4) or few in number (Exp. 5). We speculate that surface guidance is slow and limited to very few surfaces at one time. PMID:19236891

  15. Self-Organization of Spatio-Temporal Hierarchy via Learning of Dynamic Visual Image Patterns on Action Sequences

    PubMed Central

    Jung, Minju; Hwang, Jungsik; Tani, Jun

    2015-01-01

    It is well known that the visual cortex efficiently processes high-dimensional spatial information by using a hierarchical structure. Recently, computational models that were inspired by the spatial hierarchy of the visual cortex have shown remarkable performance in image recognition. Up to now, however, most biological and computational modeling studies have mainly focused on the spatial domain and do not discuss temporal domain processing of the visual cortex. Several studies on the visual cortex and other brain areas associated with motor control support that the brain also uses its hierarchical structure as a processing mechanism for temporal information. Based on the success of previous computational models using spatial hierarchy and temporal hierarchy observed in the brain, the current report introduces a novel neural network model for the recognition of dynamic visual image patterns based solely on the learning of exemplars. This model is characterized by the application of both spatial and temporal constraints on local neural activities, resulting in the self-organization of a spatio-temporal hierarchy necessary for the recognition of complex dynamic visual image patterns. The evaluation with the Weizmann dataset in recognition of a set of prototypical human movement patterns showed that the proposed model is significantly robust in recognizing dynamically occluded visual patterns compared to other baseline models. Furthermore, an evaluation test for the recognition of concatenated sequences of those prototypical movement patterns indicated that the model is endowed with a remarkable capability for the contextual recognition of long-range dynamic visual image patterns. PMID:26147887

  16. The evaluation of display symbology - A chronometric study of visual search. [on cathode ray tubes

    NASA Technical Reports Server (NTRS)

    Remington, R.; Williams, D.

    1984-01-01

    Three single-target visual search tasks were used to evaluate a set of CRT symbols for a helicopter traffic display. The search tasks were representative of the kinds of information extraction required in practice, and reaction time was used to measure the efficiency with which symbols could be located and identified. The results show that familiar numeric symbols were responded to more quickly than graphic symbols. The addition of modifier symbols such as a nearby flashing dot or surrounding square had a greater disruptive effect on the graphic symbols than the alphanumeric characters. The results suggest that a symbol set is like a list that must be learned. Factors that affect the time to respond to items in a list, such as familiarity and visual discriminability, and the division of list items into categories, also affect the time to identify symbols.

  17. Analysis and modeling of fixation point selection for visual search in cluttered backgrounds

    NASA Astrophysics Data System (ADS)

    Snorrason, Magnus; Hoffman, James; Ruda, Harald

    2000-07-01

    Hard-to-see targets are generally only detected by human observers once they have been fixated. Hence, understanding how the human visual system allocates fixation locations is necessary for predicting target detectability. Visual search experiments were conducted where observers searched for military vehicles in cluttered terrain. Instantaneous eye position measurements were collected using an eye tracker. The resulting data was partitioned into fixations and saccades, and analyzed for correlation with various image properties. The fixation data was used to validate out model for predicting fixation locations. This model generates a saliency map from bottom-up image features, such as local contrast. To account for top-down scene understanding effects, a separate cognitive bias map is generated. The combination of these two maps provides a fixation probability map, from which sequences of fixation points were generated.

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

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    1983-03-01

    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.

  1. Improvement in Visual Search with Practice: Mapping Learning-Related Changes in Neurocognitive Stages of Processing

    PubMed Central

    Clark, Kait; Appelbaum, L. Gregory; van den Berg, Berry; Mitroff, Stephen R.

    2015-01-01

    Practice can improve performance on visual search tasks; the neural mechanisms underlying such improvements, however, are not clear. Response time typically shortens with practice, but which components of the stimulus–response processing chain facilitate this behavioral change? Improved search performance could result from enhancements in various cognitive processing stages, including (1) sensory processing, (2) attentional allocation, (3) target discrimination, (4) motor-response preparation, and/or (5) response execution. We measured event-related potentials (ERPs) as human participants completed a five-day visual-search protocol in which they reported the orientation of a color popout target within an array of ellipses. We assessed changes in behavioral performance and in ERP components associated with various stages of processing. After practice, response time decreased in all participants (while accuracy remained consistent), and electrophysiological measures revealed modulation of several ERP components. First, amplitudes of the early sensory-evoked N1 component at 150 ms increased bilaterally, indicating enhanced visual sensory processing of the array. Second, the negative-polarity posterior–contralateral component (N2pc, 170–250 ms) was earlier and larger, demonstrating enhanced attentional orienting. Third, the amplitude of the sustained posterior contralateral negativity component (SPCN, 300–400 ms) decreased, indicating facilitated target discrimination. Finally, faster motor-response preparation and execution were observed after practice, as indicated by latency changes in both the stimulus-locked and response-locked lateralized readiness potentials (LRPs). These electrophysiological results delineate the functional plasticity in key mechanisms underlying visual search with high temporal resolution and illustrate how practice influences various cognitive and neural processing stages leading to enhanced behavioral performance. PMID:25834059

  2. Sleep-effects on implicit and explicit memory in repeated visual search.

    PubMed

    Geyer, Thomas; Mueller, Hermann J; Assumpcao, Leonardo; Gais, Steffen

    2013-01-01

    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

  3. Visual Circuit Development Requires Patterned Activity Mediated by Retinal Acetylcholine Receptors

    PubMed Central

    Burbridge, Timothy J.; Xu, Hong-Ping; Ackman, James B.; Ge, Xinxin; Zhang, Yueyi; Ye, Mei-Jun; Zhou, Z. Jimmy; Xu, Jian; Contractor, Anis; Crair, Michael C.

    2014-01-01

    SUMMARY The elaboration of nascent synaptic connections into highly ordered neural circuits is an integral feature of the developing vertebrate nervous system. In sensory systems, patterned spontaneous activity before the onset of sensation is thought to influence this process, but this conclusion remains controversial largely due to the inherent difficulty recording neural activity in early development. Here, we describe novel genetic and pharmacological manipulations of spontaneous retinal activity, assayed in vivo, that demonstrate a causal link between retinal waves and visual circuit refinement. We also report a de-coupling of downstream activity in retinorecipient regions of the developing brain after retinal wave disruption. Significantly, we show that the spatiotemporal characteristics of retinal waves affect the development of specific visual circuits. These results conclusively establish retinal waves as necessary and instructive for circuit refinement in the developing nervous system and reveal how neural circuits adjust to altered patterns of activity prior to experience. PMID:25466916

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

    PubMed Central

    Gillespie, James A; Quinn, Casey

    2012-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  7. Expectation violations in sensorimotor sequences: shifting from LTM-based attentional selection to visual search.

    PubMed

    Foerster, Rebecca M; Schneider, Werner X

    2015-03-01

    Long-term memory (LTM) delivers important control signals for attentional selection. LTM expectations have an important role in guiding the task-driven sequence of covert attention and gaze shifts, especially in well-practiced multistep sensorimotor actions. What happens when LTM expectations are disconfirmed? Does a sensory-based visual-search mode of attentional selection replace the LTM-based mode? What happens when prior LTM expectations become valid again? We investigated these questions in a computerized version of the number-connection test. Participants clicked on spatially distributed numbered shapes in ascending order while gaze was recorded. Sixty trials were performed with a constant spatial arrangement. In 20 consecutive trials, either numbers, shapes, both, or no features switched position. In 20 reversion trials, participants worked on the original arrangement. Only the sequence-affecting number switches elicited slower clicking, visual search-like scanning, and lower eye-hand synchrony. The effects were neither limited to the exchanged numbers nor to the corresponding actions. Thus, expectation violations in a well-learned sensorimotor sequence cause a regression from LTM-based attentional selection to visual search beyond deviant-related actions and locations. Effects lasted for several trials and reappeared during reversion. PMID:25708482

  8. Influence of being videotaped on the prevalence effect during visual search

    PubMed Central

    Miyazaki, Yuki

    2015-01-01

    Video monitoring modifies the task performance of those who are being monitored. The current study aims to prevent rare target-detection failures during visual search through the use of video monitoring. Targets are sometimes missed when their prevalence during visual search is extremely low (e.g., in airport baggage screenings). Participants performed a visual search in which they were required to discern the presence of a tool in the midst of other objects. The participants were monitored via video cameras as they performed the task in one session (the videotaped condition), and they performed the same task in another session without being monitored (the non-videotaped condition). The results showed that fewer miss errors occurred in the videotaped condition, regardless of target prevalence. It appears that the decrease in misses in the video monitoring condition resulted from a shift in criterion location. Video monitoring is considered useful in inducing accurate scanning. It is possible that the potential for evaluation involved in being observed motivates the participants to perform well and is related to the shift in criterion. PMID:25999895

  9. Multi-voxel patterns of visual category representation during episodic encoding are predictive of subsequent memory

    PubMed Central

    Kuhl, Brice A.; Rissman, Jesse; Wagner, Anthony D.

    2012-01-01

    Successful encoding of episodic memories is thought to depend on contributions from prefrontal and temporal lobe structures. Neural processes that contribute to successful encoding have been extensively explored through univariate analyses of neuroimaging data that compare mean activity levels elicited during the encoding of events that are subsequently remembered vs. those subsequently forgotten. Here, we applied pattern classification to fMRI data to assess the degree to which distributed patterns of activity within prefrontal and temporal lobe structures elicited during the encoding of word-image pairs were diagnostic of the visual category (Face or Scene) of the encoded image. We then assessed whether representation of category information was predictive of subsequent memory. Classification analyses indicated that temporal lobe structures contained information robustly diagnostic of visual category. Information in prefrontal cortex was less diagnostic of visual category, but was nonetheless associated with highly reliable classifier-based evidence for category representation. Critically, trials associated with greater classifier-based estimates of category representation in temporal and prefrontal regions were associated with a higher probability of subsequent remembering. Finally, consideration of trial-by-trial variance in classifier-based measures of category representation revealed positive correlations between prefrontal and temporal lobe representations, with the strength of these correlations varying as a function of the category of image being encoded. Together, these results indicate that multi-voxel representations of encoded information can provide unique insights into how visual experiences are transformed into episodic memories. PMID:21925190

  10. The Development of Visual Search in Infants and Very Young Children.

    ERIC Educational Resources Information Center

    Gerhardstein, Peter; Rovee-Collier, Carolyn

    2002-01-01

    Trained 1- to 3-year-olds to touch a video screen displaying a unique target and appearing among varying numbers of distracters; correct responses triggered a sound and four animated objects on the screen. Found that children's reaction time patterns resembled those from adults in corresponding search tasks, suggesting that basic perceptual…

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

    E-print Network

    Buschman, Tim

    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 ...

  12. The Perceptual Interaction of Simple and Complex Point Symbol Shapes and Background Textures in Visual Search on Tourist Maps

    E-print Network

    Alhosani, Naeema M.

    2009-05-31

    This study investigated visual search for simple and complex geometric and pictorial point symbols displayed on light and dark smooth and textured map backgrounds. Group-administered tests asked subjects to count occurrences ...

  13. Irrelevant relations and the active search for pattern structure in rat serial pattern learning

    PubMed Central

    Kundey, Shannon M. A.; Fountain, Stephen B.

    2012-01-01

    Hersh (Mem Cogn 2:771–774, 1974) investigated the role of irrelevant relations in college students’ pattern learning and performance for letter series completion problems. He created irrelevant relations in sequences by inserting items to make pattern structure ambiguous such that it was open to multiple interpretations during initial pattern processing. He reported irrelevant relations impaired humans’ performance more when placed at the beginning of patterns than at the end. However, once pattern structure was induced, irrelevant relations were not impairing. Here, we examined the impact on rat serial pattern learning of irrelevant relations positioned at the beginning or end of a serial pattern. Rats pressed levers in a circular array according to the same structured serial pattern, 123 234 345 456 567, where digits indicated the clockwise position of the correct lever. This structured serial pattern was interleaved with repeating responses on lever 2 to produce irrelevant relations at the beginning of the pattern (Beginning: 122232 223242 324252 425262 526272), on lever 6 to produce irrelevant relations at the end of the pattern (End: 162636 263646 364656 465666 566676), or on lever 8 to produce no irrelevant relations (No Irrelevant Relations: 182838 283848 384858 485868 586878. Irrelevant relations significantly retarded learning regardless of their placement within the pattern. However, irrelevant relations retarded learning significantly more when placed at the pattern beginning versus end. The results indicate that rats, like humans, process patterns from beginning to end. PMID:21246231

  14. Visual search in natural scenes: a double-dissociation paradigm for comparing observer models.

    PubMed

    Abrams, Jared; Geisler, Wilson

    2015-09-01

    Search is a fundamental and ubiquitous visual behavior. Here, we aim to model fixation search under naturalistic conditions and develop a strong test for comparing observer models. Previous work has identified the entropy limit minimization (ELM) observer as an optimal fixation selection model.1 The ELM observer selects fixations that maximally reduce uncertainty about the location of the target. However, this rule is optimal only if the detectability of the target falls off in the same way for every possible fixation (e.g., as in a uniform noise field). Most natural scenes do not satisfy this assumption; they are highly non-stationary. By combining empirical measurements of target detectability with a simple mathematical analysis, we arrive at a generalized ELM rule (nELM) that is optimal for non-stationary backgrounds. Then, we used the nELM rule to generate search time predictions for Gaussian blob targets embedded in hundreds of natural images. We also simulated a maximum a posteriori (MAP) observer, which is a common model in the search literature. To examine which model is more similar to human performance, we developed a double-dissociation search paradigm, selecting pairs of target locations where the nELM and the MAP observer made opposite predictions regarding search speed. By comparing the difference in human search times for each pair with the different model predictions, we can determine which model predictions are more similar to human behavior. Preliminary data from two observers show that human observers behave more like the nELM than the MAP. We conclude that the nELM observer is a useful normative model of fixation search and appears to be a good model of human search in natural scenes. Additionally, the proposed double-dissociation paradigm provides as a strong test for comparing competing models. 1Najemnik, J. & Geisler W.S. (2009) Vis. Res., 49, 1286-1294. Meeting abstract presented at VSS 2015. PMID:26326443

  15. Case study of visualizing global user download patterns using Google Earth and NASA World Wind

    SciTech Connect

    Zong, Ziliang; Job, Joshua; Zhang, Xuesong; Nijim, Mais; Qin, Xiao

    2012-10-09

    Geo-visualization is significantly changing the way we view spatial data and discover information. On the one hand, a large number of spatial data are generated every day. On the other hand, these data are not well utilized due to the lack of free and easily used data-visualization tools. This becomes even worse when most of the spatial data remains in the form of plain text such as log files. This paper describes a way of visualizing massive plain-text spatial data at no cost by utilizing Google Earth and NASAWorld Wind. We illustrate our methods by visualizing over 170,000 global download requests for satellite images maintained by the Earth Resources Observation and Science (EROS) Center of U.S. Geological Survey (USGS). Our visualization results identify the most popular satellite images around the world and discover the global user download patterns. The benefits of this research are: 1. assisting in improving the satellite image downloading services provided by USGS, and 2. providing a proxy for analyzing the hot spot areas of research. Most importantly, our methods demonstrate an easy way to geovisualize massive textual spatial data, which is highly applicable to mining spatially referenced data and information on a wide variety of research domains (e.g., hydrology, agriculture, atmospheric science, natural hazard, and global climate change).

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

    PubMed

    Huurneman, Bianca; Boonstra, F Nienke

    2014-01-01

    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

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

    PubMed Central

    Huurneman, Bianca; Boonstra, F. Nienke

    2014-01-01

    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

  18. Evidence for negative feature guidance in visual search is explained by spatial recoding.

    PubMed

    Beck, Valerie M; Hollingworth, Andrew

    2015-10-01

    Theories of attention and visual search explain how attention is guided toward objects with known target features. But can attention be directed away from objects with a feature known to be associated only with distractors? Most studies have found that the demand to maintain the to-be-avoided feature in visual working memory biases attention toward matching objects rather than away from them. In contrast, Arita, Carlisle, and Woodman (2012) claimed that attention can be configured to selectively avoid objects that match a cued distractor color, and they reported evidence that this type of negative cue generates search benefits. However, the colors of the search array items in Arita et al. (2012) were segregated by hemifield (e.g., blue items on the left, red on the right), which allowed for a strategy of translating the feature-cue information into a simple spatial template (e.g., avoid right, or attend left). In the present study, we replicated the negative cue benefit using the Arita et al. (2012), method (albeit within a subset of participants who reliably used the color cues to guide attention). Then, we eliminated the benefit by using search arrays that could not be grouped by hemifield. Our results suggest that feature-guided avoidance is implemented only indirectly, in this case by translating feature-cue information into a spatial template. (PsycINFO Database Record PMID:26191616

  19. Visually-evoked pattern and photomyoclonic responses in video game and television epilepsy: case reports.

    PubMed

    Anyanwu, E; Watson, N A

    1996-01-01

    This research paper reports a case study of two male photosensitive epileptic patients, aged 14 and 16 years old respectively, whose epileptic seizures were often triggered by the flickers from television and video games respectively. The 14-year old patient had no family history of epilepsy, while the 16 year old had a family history of epilepsy. A comprehensive electroencephalogram (EEG), including hyperventilation, intermittent photic stimulation (IPS) and pattern stimulation were carried out on them and EEG abnormalities including photoparoxysmal responses (PPR) and generalized myoclonic responses were evoked. A thorough analysis of the EEG morphology of the myclonic responses and the clinical manifestations showed evidence of two separate entitles of seizures namely: visually evoked pattern-myoclonic responses (PTMR) and visually evoked photomyoclonic responses (PMR). PTMR was independent of flash rate and occurred before a PPR and at the same time as the flash rate, while PMR occurred after the PPR and was dependent on flash rate. These findings suggest that "Video Game" epilepsy is probably a pattern sensitive epilepsy, electronic screen being the source of the triggering patterns; hence, the morphology and the family histories and the myoclonic phenomena differ from those of pure photosensitive epilepsy. PMID:9201318

  20. Noun representation in AAC grid displays: visual attention patterns of people with traumatic brain injury.

    PubMed

    Brown, Jessica; Thiessen, Amber; Beukelman, David; Hux, Karen

    2015-03-01

    Clinicians supporting the communication of people with traumatic brain injury (TBI) must determine an efficient message representation method for augmentative and alternative communication (AAC) systems. Due to the frequency with which visual deficits occur following brain injury, some adults with TBI may have difficulty locating items on AAC displays. The purpose of this study was to identify aspects of graphic supports that increase efficiency of target-specific visual searches. Nine adults with severe TBI and nine individuals without neurological conditions located targets on static grids displaying one of three message representation methods. Data collected through eye tracking technology revealed significantly more efficient target location for icon-only grids than for text-only or icon-plus-text grids for both participant groups; no significant differences emerged between participant groups. PMID:25685881

  1. Voice response system of color and pattern on clothes for visually handicapped person.

    PubMed

    Miyake, Masao; Manabe, Yoshitsugu; Uranishi, Yuki; Imura, Masataka; Oshiro, Osamu

    2013-01-01

    For visually handicapped people, a mental support is important in their independent daily life and participation in a society. It is expected to develop a system which can recognize colors and patterns on clothes so that they can go out with less concerns. We have worked on a basic study into such a system, and developed a prototype system which can stably recognize colors and patterns and immediately provide these information in voice, when a user faces it to clothes. In the results of evaluation experiments it is shown that the prototype system is superior to the system in the basic study at the accuracy rate for the recognition of color and pattern. PMID:24110782

  2. Beam angle optimization for intensity-modulated radiation therapy using a guided pattern search method

    NASA Astrophysics Data System (ADS)

    Rocha, Humberto; Dias, Joana M.; Ferreira, Brígida C.; Lopes, Maria C.

    2013-05-01

    Generally, the inverse planning of radiation therapy consists mainly of the fluence optimization. The beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) consists of selecting appropriate radiation incidence directions and may influence the quality of the IMRT plans, both to enhance better organ sparing and to improve tumor coverage. However, in clinical practice, most of the time, beam directions continue to be manually selected by the treatment planner without objective and rigorous criteria. The goal of this paper is to introduce a novel approach that uses beam’s-eye-view dose ray tracing metrics within a pattern search method framework in the optimization of the highly non-convex BAO problem. Pattern search methods are derivative-free optimization methods that require a few function evaluations to progress and converge and have the ability to better avoid local entrapment. The pattern search method framework is composed of a search step and a poll step at each iteration. The poll step performs a local search in a mesh neighborhood and ensures the convergence to a local minimizer or stationary point. The search step provides the flexibility for a global search since it allows searches away from the neighborhood of the current iterate. Beam’s-eye-view dose metrics assign a score to each radiation beam direction and can be used within the pattern search framework furnishing a priori knowledge of the problem so that directions with larger dosimetric scores are tested first. A set of clinical cases of head-and-neck tumors treated at the Portuguese Institute of Oncology of Coimbra is used to discuss the potential of this approach in the optimization of the BAO problem.

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

    NASA Astrophysics Data System (ADS)

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

    2011-03-01

    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.

  4. Segmentation of objects from backgrounds in visual search tasks Jeremy M. Wolfe a,b,*, Aude Oliva a,b

    E-print Network

    and WomenÕs Hospital, USA b Department of Ophthalmology, Harvard Medical School, USA c Department, we examine the ability of the visual system to separate search items from a background. The results the lab to the world. This paper concentrates on one dif- ference. In laboratory search tasks, items

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

    E-print Network

    Koutstaal, Wilma

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

  6. The pattern of ocular dominance columns in cat primary visual cortex: intra-and interindividual variability of column

    E-print Network

    The pattern of ocular dominance columns in cat primary visual cortex: intra- and interindividual variability of column spacing and its dependence on genetic background Matthias Kaschube,1,2 Fred Wolf,1, genetic determination, ocular dominance columns, visual cortex Abstract We present a comprehensive

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

    ERIC Educational Resources Information Center

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

    2009-01-01

    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…

  8. Why Do We Move Our Eyes while Trying to Remember? The Relationship between Non-Visual Gaze Patterns and Memory

    ERIC Educational Resources Information Center

    Micic, Dragana; Ehrlichman, Howard; Chen, Rebecca

    2010-01-01

    Non-visual gaze patterns (NVGPs) involve saccades and fixations that spontaneously occur in cognitive activities that are not ostensibly visual. While reasons for their appearance remain obscure, convergent empirical evidence suggests that NVGPs change according to processing requirements of tasks. We examined NVGPs in tasks with long-term memory…

  9. iRaster: a novel information visualization tool to explore spatiotemporal patterns in multiple spike trains.

    PubMed

    Somerville, J; Stuart, L; Sernagor, E; Borisyuk, R

    2010-12-15

    Over the last few years, simultaneous recordings of multiple spike trains have become widely used by neuroscientists. Therefore, it is important to develop new tools for analysing multiple spike trains in order to gain new insight into the function of neural systems. This paper describes how techniques from the field of visual analytics can be used to reveal specific patterns of neural activity. An interactive raster plot called iRaster has been developed. This software incorporates a selection of statistical procedures for visualization and flexible manipulations with multiple spike trains. For example, there are several procedures for the re-ordering of spike trains which can be used to unmask activity propagation, spiking synchronization, and many other important features of multiple spike train activity. Additionally, iRaster includes a rate representation of neural activity, a combined representation of rate and spikes, spike train removal and time interval removal. Furthermore, it provides multiple coordinated views, time and spike train zooming windows, a fisheye lens distortion, and dissemination facilities. iRaster is a user friendly, interactive, flexible tool which supports a broad range of visual representations. This tool has been successfully used to analyse both synthetic and experimentally recorded datasets. In this paper, the main features of iRaster are described and its performance and effectiveness are demonstrated using various types of data including experimental multi-electrode array recordings from the ganglion cell layer in mouse retina. iRaster is part of an ongoing research project called VISA (Visualization of Inter-Spike Associations) at the Visualization Lab in the University of Plymouth. The overall aim of the VISA project is to provide neuroscientists with the ability to freely explore and analyse their data. The software is freely available from the Visualization Lab website (see www.plymouth.ac.uk/infovis). PMID:20875457

  10. A glimpse of fear: Fast detection of threatening targets in visual search with brief stimulus durations.

    PubMed

    Soares, Sandra C; Esteves, Francisco

    2013-04-01

    Reliable detection of a threat based on temporally restricted information allows organisms to activate their defensive mechanisms. In the present study we investigated attentional efficiency for prototypical evolutionarily relevant stimuli, snakes (compared with spiders and mushrooms), during visual search conditions in which displays were presented for brief durations and under conditions of high perceptual load. Participants were exposed to a visual search paradigm in which the duration of the display varied between 150 and 300?ms. Perceptual load was manipulated using small, medium, and larger displays (4, 6, and 8 items, respectively). The results showed that fear stimuli, compared with neutral stimuli, were more accurately and quickly detected under both visually degraded conditions. The results also showed differences between the two categories of fear-relevant stimuli (snakes and spiders) in their dependency on perceptual load manipulations. Snake targets were overall detected more accurately than spiders, with this snake advantage effect being more clear-cut with many distracters (high load) than with few (low load). The results were interpreted in light of an evolutionary-based theory (the snake detection theory), which posits that snakes are the prototypical predators of primates. PMID:26272860

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

    PubMed Central

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

    2011-01-01

    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

  12. Patterns of corticocortical, corticotectal, and commissural connections in the opossum visual cortex.

    PubMed

    Martinich, S; Pontes, M N; Rocha-Miranda, C E

    2000-01-10

    Patterns of connections of the visual cortex of the South American opossum, Didelphis aurita, were revealed by using neuronal tracers to identify and characterize visual specializations of the peristriate cortex (PS). The visuotopy of corticotectal connections of the anterolateral portion of PS (PSal) is symmetrical to that of the striate cortex (ST or primary visual area [V1]). Three consecutive bands of commissural connections coincide, respectively, with the ST-PS border, the limit between the caudal and rostral PSal halves (PSc and PSr), and the border of PS with the parietal and temporal cortices. PSc and PSr contain regular commissural rings similar to those present in the peristriate cortex of eutherian mammals. ST projections define in PSc two strings of periodical foci consecutively concentric to V1 and a single focus in PSr. Although they were organized topographically, ascending, descending, and commissural connections between ST and PSal showed a high degree of convergence and divergence. These results conform to the model of a single area homologous to the second visual area (V2) bordering V1. Moreover, they suggest the possibility that PSal includes either one or two additional belt-like areas successively anterior to V2. Along with the finding of alternating bands of high and low cytochrome oxidase activity in PSal, the data further suggest that this region contains modular specializations similar to those of the peristriate cortex of primates and other eutherian mammals. The posterolateral peristriate cortex (PSpl) constitutes another visual area, since it consists of a distinct focus of reciprocal corticocortical and interhemispheric connections and a separate source of corticotectal projections. Finally, a visuomotor function for the orbital cortex is proposed based on its direct projections to optical tectal layers. The close cladistic relationship of opossums to mammalian ancestral forms suggests that the PSal parcelation into belt-like areas that contain modules reflects the primitive organization of the visual cortex. Moreover, a highly diffuse pattern of corticocortical connections may represent a requirement for a brain with few visual areas to perform global processing. PMID:10581468

  13. A Convergence Analysis of Unconstrained and Bound Constrained Evolutionary Pattern Search

    SciTech Connect

    Hart, W.E.

    1999-04-22

    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.

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

    USGS Publications Warehouse

    Drew, L.J.

    1979-01-01

    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 should be used when the orientations of the targets are unknown. The way in which the optimum hole spacing varies as a function of (1) the cost of drilling, (2) the value of the targets, (3) the shape of the targets, (4) the target occurrence probabilities was determined for several examples. Bayes' rule was used to show how target occurrence probabilities can be revised within a multistage pattern drilling scheme. ?? 1979 Plenum Publishing Corporation.

  15. A reference web architecture and patterns for real-time visual analytics on large streaming data

    NASA Astrophysics Data System (ADS)

    Kandogan, Eser; Soroker, Danny; Rohall, Steven; Bak, Peter; van Ham, Frank; Lu, Jie; Ship, Harold-Jeffrey; Wang, Chun-Fu; Lai, Jennifer

    2013-12-01

    Monitoring and analysis of streaming data, such as social media, sensors, and news feeds, has become increasingly important for business and government. The volume and velocity of incoming data are key challenges. To effectively support monitoring and analysis, statistical and visual analytics techniques need to be seamlessly integrated; analytic techniques for a variety of data types (e.g., text, numerical) and scope (e.g., incremental, rolling-window, global) must be properly accommodated; interaction, collaboration, and coordination among several visualizations must be supported in an efficient manner; and the system should support the use of different analytics techniques in a pluggable manner. Especially in web-based environments, these requirements pose restrictions on the basic visual analytics architecture for streaming data. In this paper we report on our experience of building a reference web architecture for real-time visual analytics of streaming data, identify and discuss architectural patterns that address these challenges, and report on applying the reference architecture for real-time Twitter monitoring and analysis.

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

    NASA Astrophysics Data System (ADS)

    Raja, Yogesh; Gong, Shaogang; Xiang, Tao

    2011-11-01

    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.

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

    PubMed

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

    2014-06-01

    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

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

    NASA Astrophysics Data System (ADS)

    Saripalli, K. R.

    1983-12-01

    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.

  19. Model-based analysis of pattern motion processing in mouse primary visual cortex

    PubMed Central

    Muir, Dylan R.; Roth, Morgane M.; Helmchen, Fritjof; Kampa, Björn M.

    2015-01-01

    Neurons in sensory areas of neocortex exhibit responses tuned to specific features of the environment. In visual cortex, information about features such as edges or textures with particular orientations must be integrated to recognize a visual scene or object. Connectivity studies in rodent cortex have revealed that neurons make specific connections within sub-networks sharing common input tuning. In principle, this sub-network architecture enables local cortical circuits to integrate sensory information. However, whether feature integration indeed occurs locally in rodent primary sensory areas has not been examined directly. We studied local integration of sensory features in primary visual cortex (V1) of the mouse by presenting drifting grating and plaid stimuli, while recording the activity of neuronal populations with two-photon calcium imaging. Using a Bayesian model-based analysis framework, we classified single-cell responses as being selective for either individual grating components or for moving plaid patterns. Rather than relying on trial-averaged responses, our model-based framework takes into account single-trial responses and can easily be extended to consider any number of arbitrary predictive models. Our analysis method was able to successfully classify significantly more responses than traditional partial correlation (PC) analysis, and provides a rigorous statistical framework to rank any number of models and reject poorly performing models. We also found a large proportion of cells that respond strongly to only one stimulus class. In addition, a quarter of selectively responding neurons had more complex responses that could not be explained by any simple integration model. Our results show that a broad range of pattern integration processes already take place at the level of V1. This diversity of integration is consistent with processing of visual inputs by local sub-networks within V1 that are tuned to combinations of sensory features. PMID:26300738

  20. Spatial Heterogeneity and Imperfect Mixing in Chemical Reactions: Visualization of Density-Driven Pattern Formation

    DOE PAGESBeta

    Sobel, Sabrina G.; Hastings, Harold M.; Testa, Matthew

    2009-01-01

    Imperfect mixing is a concern in industrial processes, everyday processes (mixing paint, bread machines), and in understanding salt water-fresh water mixing in ecosystems. The effects of imperfect mixing become evident in the unstirred ferroin-catalyzed Belousov-Zhabotinsky reaction, the prototype for chemical pattern formation. Over time, waves of oxidation (high ferriin concentration, blue) propagate into a background of low ferriin concentration (red); their structure reflects in part the history of mixing in the reaction vessel. However, it may be difficult to separate mixing effects from reaction effects. We describe a simpler model system for visualizing density-driven pattern formation in an essentiallymore »unmixed chemical system: the reaction of pale yellow Fe 3 + with colorless SCN ? to form the blood-red Fe ( SCN ) 2 + complex ion in aqueous solution. Careful addition of one drop of Fe ( NO 3 ) 3 to KSCN yields striped patterns after several minutes. The patterns appear reminiscent of Rayleigh-Taylor instabilities and convection rolls, arguing that pattern formation is caused by density-driven mixing. « less

  1. A wire length minimization approach to ocular dominance patterns in mammalian visual cortex

    NASA Astrophysics Data System (ADS)

    Chklovskii, Dmitri B.; Koulakov, Alexei A.

    2000-09-01

    The primary visual area (V1) of the mammalian brain is a thin sheet of neurons. Because each neuron is dominated by either right or left eye one can treat V1 as a binary mixture of neurons. The spatial arrangement of neurons dominated by different eyes is known as the ocular dominance (OD) pattern. We propose a theory for OD patterns based on the premise that they are evolutionary adaptations to minimize the length of intra-cortical connections. Thus, the existing OD patterns are obtained by solving a wire length minimization problem. We divide all the neurons into two classes: right- and left-eye dominated. We find that if the number of connections of each neuron with the neurons of the same class differs from that with the other class, the segregation of neurons into monocular regions indeed reduces the wire length. The shape of the regions depends on the relative number of neurons in the two classes. If both classes are equally represented we find that the optimal OD pattern consists of alternating stripes. If one class is less numerous than the other, the optimal OD pattern consists of patches of the underrepresented (ipsilateral) eye dominated neurons surrounded by the neurons of the other class. We predict the transition from stripes to patches when the fraction of neurons dominated by the ipsilateral eye is about 40%. This prediction agrees with the data in macaque and Cebus monkeys. Our theory can be applied to other binary cortical systems.

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

    PubMed

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

    2012-07-15

    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

  3. Examining wide-arc digital breast tomosynthesis: optimization using a visual-search model observer

    NASA Astrophysics Data System (ADS)

    Das, Mini; Liang, Zhihua; Gifford, Howard C.

    2015-03-01

    Mathematical model observers are expected to assist in preclinical optimization of image acquisition and reconstruction parameters. A clinically realistic and robust model observer platform could help in multiparameter optimizations without requiring frequent human-observer validations. We are developing search-capable visual-search (VS) model observers with this potential. In this work, we present initial results on optimization of DBT scan angle and the number of projection views for low-contrast mass detection. Comparison with human-observer results shows very good agreement. These results point towards the benefits of using relatively wider arcs and low projection angles per arc degree for improved mass detection. These results are particularly interesting considering that the FDA-approved DBT systems like Hologic Selenia Dimensions uses a narrow (15-degree) acquisition arc and one projection per arc degree.

  4. Strain distribution in InP grown on patterned Si: Direct visualization by cathodoluminescence wavelength imaging

    NASA Astrophysics Data System (ADS)

    Grundmann, M.; Christen, J.; Heinrichsdorff, F.; Krost, A.; Bimberg, D.

    1994-02-01

    InP has been grown on patterned Si substrates using a low temperature metalorganic chemical vapor deposition process which insures compatibility with integrated circuit technology. Two different patterns are investigated: wet chemically etched V-grooves and SiO2-masked dry etched grooves. Reduction of feature size leads to drastic defect reduction and quantum efficiencies up to those of homoepitaxially grown InP. Strain relaxation and quantum efficiency are directly visualized by cathololuminescence wavelength imaging. On (001)-and {111}-facets of V-grooves distinct relaxation of the tensile thermally induced strain are found. Surprisingly, in the bottom of V-grooves, close to or even at the InP/Si interface, a high quantum efficiency is found with a recombination time constant typical for thick InP layers of high crystallographic quality.

  5. Bilinear common spatial pattern for single-trial ERP-based rapid serial visual presentation triage

    NASA Astrophysics Data System (ADS)

    Yu, K.; Shen, K.; Shao, S.; Ng, W. C.; Li, X.

    2012-08-01

    Common spatial pattern (CSP) analysis is a useful tool for the feature extraction of event-related potentials (ERP). However, CSP is essentially time invariant, and thus unable to exploit the temporal information of ERP. This paper proposes a variant of CSP, namely bilinear common spatial pattern (BCSP), which is capable of accommodating both spatial and temporal information. BCSP generalizes CSP through iteratively optimizing bilinear filters. These bilinear filters constitute a spatio-temporal subspace in which the separation between two conditions is maximized. The method is unique in the sense that it is mathematically intuitive and simple, as all the bilinear filters are obtained by maximizing the power ratio as CSP does. The proposed method was evaluated on 20 subjects’ ERP data collected in rapid serial visual presentation triage experiments. The results show that BCSP achieved significantly higher average test accuracy (12.3% higher, p < 0.001).

  6. Selective pattern enhancement processing for digital mammography, algorithms, and the visual evaluation

    NASA Astrophysics Data System (ADS)

    Yamada, Masahiko; Shimura, Kazuo; Nagata, Takefumi

    2003-05-01

    In order to enhance the micro calcifications selectively without enhancing noises, PEM (Pattern Enhancement Processing for Mammography) has been developed by utilizing not only the frequency information but also the structural information of the specified objects. PEM processing uses two structural characteristics i.e. steep edge structure and low-density isolated-point structure. The visual evaluation of PEM processing was done using two different resolution CR mammography images. The enhanced image by PEM processing was compared with the image without enhancement, and the conventional usharp-mask processed image. In the PEM processed image, an increase of noises due to enhancement was suppressed as compared with that in the conventional unsharp-mask processed image. The evaluation using CDMAM phantom showed that PEM processing improved the detection performance of a minute circular pattern. By combining PEM processing with the low and medium frequency enhancement processing, both mammary glands and micro calcifications are clearly enhanced.

  7. Case of acute zonal occult outer retinopathy with abnormal pattern visual evoked potentials

    PubMed Central

    Chai, Yuzhu; Yamazaki, Hiroko; Fujinami, Kaoru; Tsunoda, Kazushige; Yamamoto, Shuichi

    2011-01-01

    Electrophysiological and morphological findings were studied in a case of acute zonal occult outer retinopathy (AZOOR) showing abnormal pattern visual evoked potentials (VEPs) at the onset and significant functional recovery in the natural course. A 21-year-old woman presented with acute onset of photopsia and a large scotoma in the right eye of 2 weeks duration. Her visual acuity was 20/20 in both eyes with no ophthalmoscopic and fluorescein angiographic abnormalities. However, a relative afferent pupillary defect and an enlarged blind spot were found in the right eye. The pattern VEPs were severely reduced when the right eye was stimulated. The amplitudes of both rod and cone full-field electroretinographics (ERGs) were reduced in the right eye. The amplitudes of the multifocal ERGs were reduced in the area of the enlarged blind spot. Irregularities in the inner segment/outer segment (IS/OS) line of the photoreceptors were observed over the nasal fovea by optical coherence tomography (OCT). The patient was followed without treatment. The enlarged blind spot disappeared in 3 months after the onset. At 5 months, reappearance of the IS/OS line was detected by OCT. At 6 months, the P100 recovered to normal values. At 1 year, the reduced full-field ERGs were almost normal size and the multifocal ERGs in the area corresponding to the enlarged blind spot were also improved. ERG findings are crucial for differentiating AZOOR from retrobulbar neuritis, especially in patients with abnormal pattern VEPs. The pattern VEPs, full-field ERGs, multifocal ERGs, and OCT images can be abnormal in the early phase of AZOOR, but they can all improve during the natural course. PMID:21966193

  8. Modeling peripheral visual acuity enables discovery of gaze strategies at multiple time scales during natural scene search

    PubMed Central

    Ramkumar, Pavan; Fernandes, Hugo; Kording, Konrad; Segraves, Mark

    2015-01-01

    Like humans, monkeys make saccades nearly three times a second. To understand the factors guiding this frequent decision, computational models of vision attempt to predict fixation locations using bottom-up visual features and top-down goals. How do the relative influences of these factors evolve over multiple time scales? Here we analyzed visual features at fixations using a retinal transform that provides realistic visual acuity by suitably degrading visual information in the periphery. In a task in which monkeys searched for a Gabor target in natural scenes, we characterized the relative importance of bottom-up and task-relevant influences by decoding fixated from nonfixated image patches based on visual features. At fast time scales, we found that search strategies can vary over the course of a single trial, with locations of higher saliency, target-similarity, edge–energy, and orientedness looked at later on in the trial. At slow time scales, we found that search strategies can be refined over several weeks of practice, and the influence of target orientation was significant only in the latter of two search tasks. Critically, these results were not observed without applying the retinal transform. Our results suggest that saccade-guidance strategies become apparent only when models take into account degraded visual representation in the periphery. PMID:25814545

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  10. Low-level properties of natural images predict topographic patterns of neural response in the ventral visual pathway

    PubMed Central

    Andrews, Timothy J.; Watson, David M.; Rice, Grace E.; Hartley, Tom

    2015-01-01

    Neuroimaging research over the past 20 years has begun to reveal a picture of how the human visual system is organized. A key distinction that has arisen from these studies is the difference in the organization of low-level and high-level visual regions. Low-level regions contain topographic maps that are tightly linked to properties of the image. In contrast, high-level visual areas are thought to be arranged in modules that are tightly linked to categorical or semantic information in the image. To date, an unresolved question has been how the strong functional selectivity for object categories in high-level visual regions might arise from the image-based representations found in low-level visual regions. Here, we review recent evidence suggesting that patterns of response in high-level visual areas may be better explained by response to image properties that are characteristic of different object categories. PMID:26024512

  11. Static Magnetic Field Stimulation over the Visual Cortex Increases Alpha Oscillations and Slows Visual Search in Humans.

    PubMed

    Gonzalez-Rosa, Javier J; Soto-Leon, Vanesa; Real, Pablo; Carrasco-Lopez, Carmen; Foffani, Guglielmo; Strange, Bryan A; Oliviero, Antonio

    2015-06-17

    Transcranial static magnetic field stimulation (tSMS) was recently introduced as a promising tool to modulate human cerebral excitability in a noninvasive and portable way. However, a demonstration that static magnetic fields can influence human brain activity and behavior is currently lacking, despite evidence that static magnetic fields interfere with neuronal function in animals. Here we show that transcranial application of a static magnetic field (120-200 mT at 2-3 cm from the magnet surface) over the human occiput produces a focal increase in the power of alpha oscillations in underlying cortex. Critically, this neurophysiological effect of tSMS is paralleled by slowed performance in a visual search task, selectively for the most difficult target detection trials. The typical relationship between prestimulus alpha power over posterior cortical areas and reaction time (RT) to targets during tSMS is altered such that tSMS-dependent increases in alpha power are associated with longer RTs for difficult, but not easy, target detection trials. Our results directly demonstrate that a powerful magnet placed on the scalp modulates normal brain activity and induces behavioral changes in humans. PMID:26085640

  12. For better or worse: Prior trial accuracy affects current trial accuracy in visual search.

    PubMed

    Winkle, Jonathan; Biggs, Adam; Ericson, Justin; Mitroff, Stephen

    2015-09-01

    Life is not a series of independent events, but rather, each event is influenced by what just happened and what might happen next. However, many research studies treat any given trial as an independent and isolated event. Some research fields explicitly test trial-to-trial influences (e.g., repetition priming, task switching), but many, including visual search, largely ignore potential inter-trial effects. While trial-order effects could wash out with random presentation orders, this does not diminish their potential impact (e.g., would you want your radiologist to be negatively affected by his/her prior success in screening for cancer?). To examine biases related to prior trial performance, data were analyzed from airport security officers and Duke University participants who had completed a visual search task. Participants searched for a target "T" amongst "pseudo-L" distractors with 50% of trials containing a target. Four set sizes were used (8,16,24,32), and participants completed the search task without feedback. Inter-trial analyses revealed that accuracy for the current trial was related to the outcome of the previous trial, with trials following successful searches being approximately 10% more accurate than trials following failed searches. Pairs of target-absent or target-present trials predominantly drove this effect; specifically, accuracy on target-present trials was contingent on a previous hit or miss (i.e., other target-present trials), while accuracy on target-absent trials was contingent on a previous correct rejection or false alarm (i.e., other target-absent trials). Inter-trial effects arose in both population samples and were not driven by individual differences, as assessed by mixed-effects linear modeling. These results have both theoretical and practical implications. Theoretically, it is worth considering how to control for inter-trial variance in statistical models of behavior. Practically, characterizing the conditions that modulate inter-trial effects might help professionals searchers perform more accurately, which can have life-saving consequences. Meeting abstract presented at VSS 2015. PMID:26327059

  13. Pattern-induced expectation bias in visual anticipation of action outcomes.

    PubMed

    Loffing, Florian; Stern, Ricarda; Hagemann, Norbert

    2015-10-01

    When anticipating an opponent's action intention, athletes may rely on both kinematic and contextual cues. Here we show that patterns of previous action outcomes (i.e., a contextual cue) bias visual anticipation of action outcome in subsequent trials. In two video-based experiments, skilled players and novices were presented with volleyball attacks stopping 360ms (Exp. 1) or 280ms (Exp. 2) before an attacker's hand-ball-contact and they were asked to predict the type of attack (smash or lob). Attacks were presented block-wise with six attacks per block. The fifth trial served as target trial where we presented identical attacks to control kinematic cues. We varied the outcomes of the preceding four attacks under three conditions: lobs only, smashes only or an alternating pattern of attack outcomes. In Exp. 1, skilled players but not novices were less accurate and responded later in target trials that were incongruent vs. congruent with preceding patterns. In Exp. 2, where the task was easier, another group of novices demonstrated a similar congruence effect for accuracy but not response time. Collectively, findings indicate that participants tended to preferentially expect the continuation of an attack pattern, while possibly attaching less importance to kinematic cues. Thus, overreliance on pattern continuation may be detrimental to anticipation in situations an action's outcome does not correspond to the pattern. From a methodological viewpoint, comparison of novices' performance in Exp. 1 and 2 suggests that task difficulty may be critical as to whether contextual cue effects can be identified in novices. PMID:26310873

  14. Interactive Visual Discovering of Movement Patterns from Sparsely Sampled Geo-tagged Social Media Data.

    PubMed

    Chen, Siming; Yuan, Xiaoru; Wang, Zhenhuang; Guo, Cong; Liang, Jie; Wang, Zuchao; Zhang, Xiaolong Luke; Zhang, Jiawan

    2016-01-01

    Social media data with geotags can be used to track people's movements in their daily lives. By providing both rich text and movement information, visual analysis on social media data can be both interesting and challenging. In contrast to traditional movement data, the sparseness and irregularity of social media data increase the difficulty of extracting movement patterns. To facilitate the understanding of people's movements, we present an interactive visual analytics system to support the exploration of sparsely sampled trajectory data from social media. We propose a heuristic model to reduce the uncertainty caused by the nature of social media data. In the proposed system, users can filter and select reliable data from each derived movement category, based on the guidance of uncertainty model and interactive selection tools. By iteratively analyzing filtered movements, users can explore the semantics of movements, including the transportation methods, frequent visiting sequences and keyword descriptions. We provide two cases to demonstrate how our system can help users to explore the movement patterns. PMID:26340781

  15. Structural Connectivity Patterns of the Visual Word Form Area and Children’s Reading Ability

    PubMed Central

    Fan, Qiuyun; Anderson, Adam W.; Davis, Nicole; Cutting, Laurie E.

    2014-01-01

    With the advent of neuroimaging techniques, especially functional MRI (fMRI), studies have mapped brain regions that are associated with good and poor reading, most centrally a region within the left occipito-temporal/fusiform region (L-OT/F) often referred to as the visual word form area (VWFA). Despite an abundance of fMRI studies of the VWFA, research about its structural connectivity has just started. Provided that the VWFA may be connected to distributed regions in the brain, it remains unclear how this network is engaged in constituting a well-tuned reading circuitry in the brain. Here we used diffusion MRI to study the structural connectivity patterns of the putative VWFA and surrounding areas within the L-OT/F in children with typically developing (TD) reading ability and with word recognition deficits (WRD; sometimes referred to as dyslexia). We found that L-OT/F connectivity varied along a posterior- anterior gradient, with specific structural connectivity patterns related to reading ability in the ROIs centered upon the putative VWFA. Findings suggest that the architecture of the VWFA connectivity is fundamentally different between TD and WRD, with TD showing greater connectivity to linguistic regions than WRD, and WRD showing greater connectivity to visual and parahippocampal regions than TD. Findings thus reveal clear structural abnormalities underlying the functional abnormalities in the VWFA in WRD. PMID:25152466

  16. Timing of saccadic eye movements during visual search for multiple targets

    PubMed Central

    Wu, Chia-Chien; Kowler, Eileen

    2013-01-01

    Visual search requires sequences of saccades. Many studies have focused on spatial aspects of saccadic decisions, while relatively few (e.g., Hooge & Erkelens, 1999) consider timing. We studied saccadic timing during search for targets (thin circles containing tilted lines) located among nontargets (thicker circles). Tasks required either (a) estimating the mean tilt of the lines, or (b) looking at targets without a concurrent psychophysical task. The visual similarity of targets and nontargets affected both the probability of hitting a target and the saccade rate in both tasks. Saccadic timing also depended on immediate conditions, specifically, (a) the type of currently fixated location (dwell time was longer on targets than nontargets), (b) the type of goal (dwell time was shorter prior to saccades that hit targets), and (c) the ordinal position of the saccade in the sequence. The results show that timing decisions take into account the difficulty of finding targets, as well as the cost of delays. Timing strategies may be a compromise between the attempt to find and locate targets, or other suitable landing locations, using eccentric vision (at the cost of increased dwell times) versus a strategy of exploring less selectively at a rapid rate. PMID:24049045

  17. Search of Possible Triggered Seismicity Patterns of Northern Tien Shan

    NASA Astrophysics Data System (ADS)

    Novikov, V.; Vorontsova, E.

    2007-12-01

    Statistical analysis of the Northern Tien Shan seismicity was performed considering the possible triggering impacts of natural and man-made mechanical and electromagnetic factors on seismic activity. Strong distant earthquakes, lunar-solar tides, and magnetic storms are considered as natural triggering factors. The man-made factors include underground nuclear explosions (UNE) and electromagnetic impacts provided by high-power magnetohydrodynamic pulsed (MHD) generators. The representative local earthquake catalog of the region under study (41°-46° N, 74°-82° E) includes 15577 events of M>1.67 from 1975 to 2000. Within this time period 330 UNE and 109 firing runs of MHD generators, which are considered as the possible man-made earthquake triggering factors, have been performed within or adjacent to the analyzed region. Various statistical methods (cross-correlation, spectral analysis, RTL-analysis, etc.) were employed. For the used statement of problem and applied initial data the statistically significant patterns of triggered seismicity of the Northern Tien-Shan due to impacts of UNE and MHD generators were not found. Large common periods of seismicity variation for time series of distant strong earthquakes and local seismic events were selected. There is significant number of common periods (7, 9, 14, 28, 186, and 16384 days) for variation of z-component of the earth tide and release of seismic energy that may point to an influence of the earth tides on the local seismicity.

  18. Autism spectrum disorder, but not amygdala lesions, impairs social attention in visual search

    PubMed Central

    Wang, Shuo; Xu, Juan; Jiang, Ming; Zhao, Qi; Hurlemann, Rene; Adolphs, Ralph

    2015-01-01

    People with autism spectrum disorders (ASD) have pervasive impairments in social interactions, a diagnostic component that may have its roots in atypical social motivation and attention. One of the brain structures implicated in the social abnormalities seen in ASD is the amygdala. To further characterize the impairment of people with ASD in social attention, and to explore the possible role of the amygdala, we employed a series of visual search tasks with both social (faces and people with different postures, emotions, ages, and genders) and non-social stimuli (e.g., electronics, food, and utensils). We first conducted trial-wise analyses of fixation properties and elucidated visual search mechanisms. We found that an attentional mechanism of initial orientation could explain the detection advantage of non-social targets. We then zoomed into fixation-wise analyses. We defined target-relevant effects as the difference in the percentage of fixations that fell on target-congruent vs. target-incongruent items in the array. In Experiment 1, we tested 8 high-functioning adults with ASD, 3 adults with focal bilateral amygdala lesions, and 19 controls. Controls rapidly oriented to target-congruent items and showed a strong and sustained preference for fixating them. Strikingly, people with ASD oriented significantly less and more slowly to target-congruent items, an attentional deficit especially with social targets. By contrast, patients with amygdala lesions performed indistinguishably from controls. In Experiment 2, we recruited a different sample of 13 people with ASD and 8 healthy controls, and tested them on the same search arrays but with all array items equalized for low-level saliency. The results replicated those of Experiment 1. In Experiment 3, we recruited 13 people with ASD, 8 healthy controls, 3 amygdala lesion patients and another group of 11 controls and tested them on a simpler array. Here our group effect for ASD strongly diminished and all four subject groups showed similar target-relevant effects. These findings argue for an attentional deficit in ASD that is disproportionate for social stimuli, cannot be explained by low-level visual properties of the stimuli, and is more severe with high-load top-down task demands. Furthermore, this deficit appears to be independent of the amygdala, and not evident from general social bias independent of the target-directed search. PMID:25218953

  19. Complete pattern of ocular dominance columns in human primary visual cortex.

    PubMed

    Adams, Daniel L; Sincich, Lawrence C; Horton, Jonathan C

    2007-09-26

    The occipital lobes were obtained after death from six adult subjects with monocular visual loss. Flat-mounts were processed for cytochrome oxidase (CO) to reveal metabolic activity in the primary (V1) and secondary (V2) visual cortices. Mean V1 surface area was 2643 mm2 (range, 1986-3477 mm2). Ocular dominance columns were present in all cases, having a mean width of 863 microm. There were 78-126 column pairs along the V1 perimeter. Human column patterns were highly variable, but in at least one person they resembled a scaled-up version of macaque columns. CO patches in the upper layers were centered on ocular dominance columns in layer 4C, with one exception. In this individual, the columns in a local area resembled those present in the squirrel monkey, and no evidence was found for column/patch alignment. In every subject, the blind spot of the contralateral eye was conspicuous as an oval region without ocular dominance columns. It provided a precise landmark for delineating the central 15 degrees of the visual field. A mean of 53.1% of striate cortex was devoted to the representation of the central 15 degrees. This fraction was less than the proportion of striate cortex allocated to the representation of the central 15 degrees in the macaque. Within the central 15 degrees, each eye occupied an equal territory. Beyond this eccentricity, the contralateral eye predominated, occupying 63% of the cortex. In one subject, monocular visual loss began at age 4 months, causing shrinkage of ocular dominance columns. In V2, which had a larger surface area than V1, CO stripes were present but could not be classified as thick or thin. PMID:17898211

  20. Visual Search Strategies of Soccer Players Executing a Power vs. Placement Penalty Kick

    PubMed Central

    Timmis, Matthew A.; Turner, Kieran; van Paridon, Kjell N.

    2014-01-01

    Introduction When taking a soccer penalty kick, there are two distinct kicking techniques that can be adopted; a ‘power’ penalty or a ‘placement’ penalty. The current study investigated how the type of penalty kick being taken affected the kicker’s visual search strategy and where the ball hit the goal (end ball location). Method Wearing a portable eye tracker, 12 university footballers executed 2 power and placement penalty kicks, indoors, both with and without the presence of a goalkeeper. Video cameras were used to determine initial ball velocity and end ball location. Results When taking the power penalty, the football was kicked significantly harder and more centrally in the goal compared to the placement penalty. During the power penalty, players fixated on the football for longer and more often at the goalkeeper (and by implication the middle of the goal), whereas in the placement penalty, fixated longer at the goal, specifically the edges. Findings remained consistent irrespective of goalkeeper presence. Discussion/conclusion Findings indicate differences in visual search strategy and end ball location as a function of type of penalty kick. When taking the placement penalty, players fixated and kicked the football to the edges of the goal in an attempt to direct the ball to an area that the goalkeeper would have difficulty reaching and saving. Fixating significantly longer on the football when taking the power compared to placement penalty indicates a greater importance of obtaining visual information from the football. This can be attributed to ensuring accurate foot-to-ball contact and subsequent generation of ball velocity. Aligning gaze and kicking the football centrally in the goal when executing the power compared to placement penalty may have been a strategy to reduce the risk of kicking wide of the goal altogether. PMID:25517405

  1. The Decline of Subject Searching: Long-Term Trends and Patterns of Index Use in an Online Catalog.

    ERIC Educational Resources Information Center

    Larson, Ray R.

    1991-01-01

    Describes a study that used transaction log analysis to investigate the use of subject searching in the University of California's Online Union Catalog, MELVYL. Mathematical models of trends and patterns in the data are presented, problems with subject searching are explained, and remedies to subject searching problems are suggested. (62…

  2. Spatial memory relative to the 3D environment guides body orientation in visual search.

    PubMed

    Aivar, M Pilar; Li, Chia-Ling; Kit, Dmitry; Tong, Matthew; Hayhoe, Mary

    2015-09-01

    Measurement of eye movements has revealed rapid development of memory for object locations in 3D immersive environments. To examine the nature of that representation, and to see if memory is coded with respect to the 3D coordinates of the room, head position was recorded while participants performed a visual search task in an immersive virtual reality apartment. The apartment had two rooms, connected by a corridor. Participants searched the apartment for a series of geometric target objects. Some target objects were always placed at the same location (stable objects), while others appeared at a new location in each trial (random objects). We analyzed whether body movements showed changes that reflected memory for target location. In each trial we calculated how far the participant's trajectory deviated from a straight path to the target object. Changes in head orientation from the moment the room was entered to the moment the target was reached were also computed. We found that the average deviation from the straight path was larger and more variable for random target objects (.47 vs .31 meters). Also the point of maximum deviation from the straight path occurred earlier for random objects than for stable objects (at 42% vs 52% of the total trajectory). On room entry lateral head deviation from the room center was already bigger for stable objects than for random objects (18º vs. 10º). Thus for random objects participants move to the center of the room until the target is located, while for stable objects subjects are more likely to follow a straight trajectory from first entry. We conclude that memory for target location is coded with respect to room coordinates and is revealed by body orientation at first entry. The visually guided component of search seems to be relatively unimportant or occurs very quickly upon entry. Meeting abstract presented at VSS 2015. PMID:26326635

  3. Progression of Patterns (POP): A Machine Classifier Algorithm to Identify Glaucoma Progression in Visual Fields

    PubMed Central

    Goldbaum, Michael H.; Lee, Intae; Jang, Giljin; Balasubramanian, Madhusudhanan; Sample, Pamela A.; Weinreb, Robert N.; Liebmann, Jeffrey M.; Girkin, Christopher A.; Anderson, Douglas R.; Zangwill, Linda M.; Fredette, Marie-Josee; Jung, Tzyy-Ping; Medeiros, Felipe A.; Bowd, Christopher

    2012-01-01

    Purpose. We evaluated Progression of Patterns (POP) for its ability to identify progression of glaucomatous visual field (VF) defects. Methods. POP uses variational Bayesian independent component mixture model (VIM), a machine learning classifier (MLC) developed previously. VIM separated Swedish Interactive Thresholding Algorithm (SITA) VFs from a set of 2,085 normal and glaucomatous eyes into nine axes (VF patterns): seven glaucomatous. Stable glaucoma was simulated in a second set of 55 patient eyes with five VFs each, collected within four weeks. A third set of 628 eyes with 4,186 VFs (mean ± SD of 6.7 ± 1.7 VFs over 4.0 ± 1.4 years) was tested for progression. Tested eyes were placed into suspect and glaucoma categories at baseline, based on VFs and disk stereoscopic photographs; a subset of eyes had stereophotographic evidence of progressive glaucomatous optic neuropathy (PGON). Each sequence of fields was projected along seven VIM glaucoma axes. Linear regression (LR) slopes generated from projections onto each axis yielded a degree of confidence (DOC) that there was progression. At 95% specificity, progression cutoffs were established for POP, visual field index (VFI), and mean deviation (MD). Guided progression analysis (GPA) was also compared. Results. POP identified a statistically similar number of eyes (P > 0.05) as progressing compared with VFI, MD, and GPA in suspects (3.8%, 2.7%, 5.6%, and 2.9%, respectively), and more eyes than GPA (P = 0.01) in glaucoma (16.0%, 15.3%, 12.0%, and 7.3%, respectively), and more eyes than GPA (P = 0.05) in PGON eyes (26.3%, 23.7%, 27.6%, and 14.5%, respectively). Conclusions. POP, with its display of DOC of progression and its identification of progressing VF defect pattern, adds to the information available to the clinician for detecting VF progression. PMID:22786913

  4. Pattern recognition-assisted infrared library searching of automotive clear coats.

    PubMed

    Fasasi, Ayuba; Mirjankar, Nikhil; Stoian, Razvan-Ionut; White, Collin; Allen, Matthew; Sandercock, Mark P; Lavine, Barry K

    2015-01-01

    Pattern recognition techniques have been developed to search the infrared (IR) spectral libraries of the paint data query (PDQ) database to differentiate between similar but nonidentical IR clear coat paint spectra. The library search system consists of two separate but interrelated components: search prefilters to reduce the size of the IR library to a specific assembly plant or plants corresponding to the unknown paint sample and a cross-correlation searching algorithm to identify IR spectra most similar to the unknown in the subset of spectra identified by the prefilters. To develop search prefilters with the necessary degree of accuracy, IR spectra from the PDQ database were preprocessed using wavelets to enhance subtle but significant features in the data. Wavelet coefficients characteristic of the assembly plant of the vehicle were identified using a genetic algorithm for pattern recognition and feature selection. A search algorithm was then used to cross-correlate the unknown with each IR spectrum in the subset of library spectra identified by the search prefilters. Each cross-correlated IR spectrum was simultaneously compared to an autocorrelated IR spectrum of the unknown using several spectral windows that span different regions of the cross-correlated and autocorrelated data from the midpoint. The top five hits identified in each search window are compiled, and a histogram is computed that summarizes the frequency of occurrence for each selected library sample. The five library samples with the highest frequency of occurrence are selected as potential hits. Even in challenging trials where the clear coat paint samples evaluated were all the same make (e.g., General Motors) within a limited production year range, the model of the automobile from which the unknown paint sample was obtained could be identified from its IR spectrum. PMID:25506887

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

    PubMed Central

    Miller, Mark P.; Haig, Susan M.

    2010-01-01

    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

  6. Sleep and rest facilitate implicit memory in a visual search task.

    PubMed

    Mednick, S C; Makovski, T; Cai, D J; Jiang, Y V

    2009-10-01

    Several forms of learning have been demonstrated to show improvements with sleep. Based on rodent models, it has been suggested that replay of waking events in the hippocampus during sleep may underlie memory consolidation in humans. However, behavioral data for the role of sleep in human hippocampal-related memory have been inconsistent. To further investigate the role of sleep in hippocampal-mediated learning, we tested subjects in two sessions of a contextual cueing paradigm, a form of hippocampus-dependent implicit learning, separated by intervals of sleep, active wake, or carefully controlled quiet rest. Participants completed a visual search task, and unbeknownst to them, some search displays were occasionally repeated in the experiment. Contextual cueing was revealed by faster search speed on repeated trials (Old) than unrepeated ones (New), even though subjects were unaware of the trial repetition. Notably, performance in a second testing session was equivalent for participants who underwent quiet resting, daytime sleep, or nocturnal sleep between the two sessions. These four groups showed equivalent transfer of learning from Session 1. Notably, learning of New configurations in Session 2 was absent in the active wake group, but was equally strong among the other three groups. These results indicate that this form of hippocampal learning is independent of sleep, and vulnerable to proactive interference during active wake. They prompt a reevaluation of the hippocampal replay hypothesis as a general model of sleep-dependent learning. PMID:19379769

  7. SVM-based visual-search model observers for PET tumor detection

    NASA Astrophysics Data System (ADS)

    Gifford, Howard C.; Sen, Anando; Azencott, Robert

    2015-03-01

    Many search-capable model observers follow task paradigms that specify clinically unrealistic prior knowledge about the anatomical backgrounds in study images. Visual-search (VS) observers, which implement distinct, feature-based candidate search and analysis stages, may provide a means of avoiding such paradigms. However, VS observers that conduct single-feature analysis have not been reliable in the absence of any background information. We investigated whether a VS observer based on multifeature analysis can overcome this background dependence. The testbed was a localization ROC (LROC) study with simulated whole-body PET images. Four target-dependent morphological features were defined in terms of 2D cross-correlations involving a known tumor profile and the test image. The feature values at the candidate locations in a set of training images were fed to a support-vector machine (SVM) to compute a linear discriminant that classified locations as tumor-present or tumor-absent. The LROC performance of this SVM-based VS observer was compared against the performances of human observers and a pair of existing model observers.

  8. Flexible Feature-Based Inhibition in Visual Search Mediates Magnified Impairments of Selection: Evidence from Carry-Over Effects under Dynamic Preview-Search Conditions

    ERIC Educational Resources Information Center

    Andrews, Lucy S.; Watson, Derrick G.; Humphreys, Glyn W.; Braithwaite, Jason J.

    2011-01-01

    Evidence for inhibitory processes in visual search comes from studies using preview conditions, where responses to new targets are delayed if they carry a featural attribute belonging to the old distractor items that are currently being ignored--the negative carry-over effect (Braithwaite, Humphreys, & Hodsoll, 2003). We examined whether…

  9. Zif268 mRNA Expression Patterns Reveal a Distinct Impact of Early Pattern Vision Deprivation on the Development of Primary Visual Cortical Areas in the Cat.

    PubMed

    Laskowska-Macios, Karolina; Zapasnik, Monika; Hu, Tjing-Tjing; Kossut, Malgorzata; Arckens, Lutgarde; Burnat, Kalina

    2015-10-01

    Pattern vision deprivation (BD) can induce permanent deficits in global motion perception. The impact of timing and duration of BD on the maturation of the central and peripheral visual field representations in cat primary visual areas 17 and 18 remains unknown. We compared early BD, from eye opening for 2, 4, or 6 months, with late onset BD, after 2 months of normal vision, using the expression pattern of the visually driven activity reporter gene zif268 as readout. Decreasing zif268 mRNA levels between months 2 and 4 characterized the normal maturation of the (supra)granular layers of the central and peripheral visual field representations in areas 17 and 18. In general, all BD conditions had higher than normal zif268 levels. In area 17, early BD induced a delayed decrease, beginning later in peripheral than in central area 17. In contrast, the decrease occurred between months 2 and 4 throughout area 18. Lack of pattern vision stimulation during the first 4 months of life therefore has a different impact on the development of areas 17 and 18. A high zif268 expression level at a time when normal vision is restored seems to predict the capacity of a visual area to compensate for BD. PMID:25205660

  10. Classification of Lower Extremity Movement Patterns Based on Visual Assessment: Reliability and Correlation With 2-Dimensional Video Analysis

    PubMed Central

    Harris-Hayes, Marcie; Steger-May, Karen; Koh, Christine; Royer, Nat K.; Graci, Valentina; Salsich, Gretchen B.

    2014-01-01

    Context: Abnormal movement patterns have been implicated in lower extremity injury. Reliable, valid, and easily implemented assessment methods are needed to examine existing musculoskeletal disorders and investigate predictive factors for lower extremity injury. Objective: To determine the reliability of experienced and novice testers in making visual assessments of lower extremity movement patterns and to characterize the construct validity of the visual assessments. Design: Cross-sectional study. Setting: University athletic department and research laboratory. Patients or Other Participants: Convenience sample of 30 undergraduate and graduate students who regularly participate in athletics (age = 19.3 ± 4.5 years). Testers were 2 experienced physical therapists and 1 novice postdoctoral fellow (nonclinician). Main Outcome Measure(s): We took videos of 30 athletes performing the single-legged squat. Three testers observed the videos on 2 occasions and classified the lower extremity movement as dynamic valgus, no change, or dynamic varus. The classification was based on the estimated change in frontal-plane projection angle (FPPA) of the knee from single-legged stance to maximum single-legged squat depth. The actual FPPA change was measured quantitatively. We used percentage agreement and weighted ? to examine tester reliability and to determine construct validity of the visual assessment. Results: The ? values for intratester and intertester reliability ranged from 0.75 to 0.90, indicating substantial to excellent reliability. Percentage agreement between the visual assessment and the quantitative FPPA change category was 90%, with a ? value of 0.85. Conclusions: Visual assessments were made reliably by experienced and novice testers. Additionally, movement-pattern categories based on visual assessments were in excellent agreement with objective methods to measure FPPA change. Therefore, visual assessments can be used in the clinic to assess movement patterns associated with musculoskeletal disorders and in large epidemiologic studies to assess the association between lower extremity movement patterns and musculoskeletal injury. PMID:24955621

  11. A probabilistic model for analysing the effect of performance levels on visual behaviour patterns of young sailors in simulated navigation.

    PubMed

    Manzanares, Aarón; Menayo, Ruperto; Segado, Francisco; Salmerón, Diego; Cano, Juan Antonio

    2015-01-01

    The visual behaviour is a determining factor in sailing due to the influence of the environmental conditions. The aim of this research was to determine the visual behaviour pattern in sailors with different practice time in one star race, applying a probabilistic model based on Markov chains. The sample of this study consisted of 20 sailors, distributed in two groups, top ranking (n = 10) and bottom ranking (n = 10), all of them competed in the Optimist Class. An automated system of measurement, which integrates the VSail-Trainer sail simulator and the Eye Tracking System(TM) was used. The variables under consideration were the sequence of fixations and the fixation recurrence time performed on each location by the sailors. The event consisted of one of simulated regatta start, with stable conditions of wind, competitor and sea. Results show that top ranking sailors perform a low recurrence time on relevant locations and higher on irrelevant locations while bottom ranking sailors make a low recurrence time in most of the locations. The visual pattern performed by bottom ranking sailors is focused around two visual pivots, which does not happen in the top ranking sailor's pattern. In conclusion, the Markov chains analysis has allowed knowing the visual behaviour pattern of the top and bottom ranking sailors and its comparison. PMID:25296294

  12. Systematic search for successful lepton mixing patterns with nonzero theta_13

    E-print Network

    Werner Rodejohann; He Zhang; Shun Zhou

    2011-10-28

    We perform a systematic search for simple but viable lepton mixing patterns. Our main criterion is that the mixing matrix can be parameterized by three rotation angles, which are simple fractions of pi. These simple rotation angles possess exact expressions for their sines and cosines, and often arise in the flavor symmetry models. All possible parameterizations of the mixing matrix are taken into account. In total, twenty successful mixing patterns are found to be consistent with the latest neutrino oscillation data (including the recent T2K results) in the CP conserving case, whereas fifteen mixing patterns are allowed in the maximal CP violating case. Potential radiative corrections to the constant mixing patterns are also calculated by solving the renormalization group equations.

  13. Discovering anatomical patterns with pathological meaning by clustering of visual primitives in structural brain MRI

    NASA Astrophysics Data System (ADS)

    Leon, Juan; Pulido, Andrea; Romero, Eduardo

    2015-01-01

    Computational anatomy is a subdiscipline of the anatomy that studies macroscopic details of the human body structure using a set of automatic techniques. Different reference systems have been developed for brain mapping and morphometry in functional and structural studies. Several models integrate particular anatomical regions to highlight pathological patterns in structural brain MRI, a really challenging task due to the complexity, variability, and nonlinearity of the human brain anatomy. In this paper, we present a strategy that aims to find anatomical regions with pathological meaning by using a probabilistic analysis. Our method starts by extracting visual primitives from brain MRI that are partitioned into small patches and which are then softly clustered, forming different regions not necessarily connected. Each of these regions is described by a co- occurrence histogram of visual features, upon which a probabilistic semantic analysis is used to find the underlying structure of the information, i.e., separated regions by their low level similarity. The proposed approach was tested with the OASIS data set which includes 69 Alzheimer's disease (AD) patients and 65 healthy subjects (NC).

  14. Visual Search Strategies of Tag Clouds - Results from an Eyetracking Study

    NASA Astrophysics Data System (ADS)

    Schrammel, Johann; Deutsch, Stephanie; Tscheligi, Manfred

    Tag clouds have become a frequently used interaction technique in the web in the past couple of years. Research has shown the influence of variables such as tag size and location on the perception of tag clouds. However, several questions remain unclear. First, little is know on how tag clouds are perceived visually and which search strategies users apply when looking for tags in a tag cloud. Second, there are variables, especially tag location, were prior work comes to conflicting results. Third, several approaches to present tag clouds with the tags semantically clustered have been proposed recently. However, it remains unclear which effects these new approaches have on the perception of tag clouds. In this paper we report the results of an extensive study on the perception of tag clouds using eye tracking technology that allows answering these questions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  16. Correlated variations in EEG pattern and visual responsiveness of cat lateral geniculate relay cells

    PubMed Central

    Li, Bing; Funke, Klaus; Wörgötter, Florentin; Eysel, Ulf T

    1999-01-01

    Simultaneous recordings of the EEG and the visual activity of cat dorsal lateral geniculate nucleus (dLGN) relay cells were analysed for covariance. Sliding time-window analyses were performed in parallel for the EEG power spectrum and single unit visual activity. The EEG power ratio (EEG-PR) of low (1-8 Hz) to high (20-40 Hz) frequencies was chosen to achieve a quantitative measure of the EEG which could be compared with the spike rate of a dLGN unit at any time. A high EEG-PR value indicates a synchronized EEG dominated by low frequencies (? waves and sleep spindles), a low value indicates a less synchronized EEG. In the anaesthetized animal, two different underlying patterns of activity in the EEG-PR were found: slow gradual changes (slow gradations) and oscillatory changes. In many cases both were accompanied by correlated variations in dLGN spike rate, either for overall activity or for burst firing. The slow gradations appear for long time periods of up to 200 s and, in most cases (76·3%), show a negative correlation between EEG-PR and overall spike rate, but predominantly a positive correlation for burst firing (85·1%). The oscillatory changes, which have not previously been reported, appear as temporally well-coupled variations in EEG-PR and spike rate with a stable cycle length within the range 4-10 s. In about 77% of correlated changes the temporal delay between the change in EEG-PR and that of the spike rate was less than ± 1·0 s. During simultaneous recordings from two dLGN cells the variations in spike rate tend to show the same sign of correlation with respect to the EEG pattern. This relationship is more pronounced with the slow gradations than with the oscillatory changes. Slow gradations in the spectral composition of the EEG may indicate global transitions between different stages within the sleep-wake cycle, reflecting the well-known influences of the brainstem arousal system. The oscillations in the spectral composition of the EEG are accompanied by gradual variations in thalamic transmission mode and are more likely to be due to involvement of a local feedback system via the thalamo-cortico-thalamic loop. The difference between the effects on overall and burst firing activity supports the notion that phasic (burst firing) and tonic visual responses may play distinctive roles in information processing, which are functionally related to the animal's behavioural state. PMID:9882756

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

    ERIC Educational Resources Information Center

    Zhaoping, Li; Frith, Uta

    2011-01-01

    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…

  18. Visual search for singleton targets redundantly defined in two feature dimensions: Coactive processing of color-motion targets?

    PubMed

    Krummenacher, Joseph; Müller, Hermann J

    2014-10-01

    In 2 visual search experiments, the role of feature contrast/saliency signals in generating detection responses to singleton feature targets in visual search was investigated using the redundant-target paradigm. Experiment 1 showed that coactive integration of dimensional signals is not restricted to targets defined on the color and orientation dimensions; rather, targets involving any of the combinations of color, orientation, and motion, are integrated coactively, as evidenced by violations of Miller's (1982) race model inequality. Experiment 2 replicated the findings of Experiment 1 for color-motion targets, with the target items' luminance adjusted, individually for each observer, to that of the distractors. The evidence for coactive processing of motion (saliency) with color and, respectively, orientation (saliency) signals suggests that, at variance with a recent suggestion by Li (2002; Koene & Zhaoping, 2007), signal integration in feature search tasks occurs at a stage following initial feature coding in primary visual cortex (V1), even though feature contrast computations in V1 may well contribute to saliency coding. In sum, the results suggest that detection responses were based on an integrated, overall-saliency representation indicating the presence of an odd-one-out item in the display, consistent with the dimension-weighting account of visual search (Müller et al., 1995, 2003). PMID:25089576

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

    ERIC Educational Resources Information Center

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

    2011-01-01

    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…

  20. Tracking fear in snake and spider fearful participants during visual search: A multi-response domain study

    E-print Network

    Caldara, Roberto

    Tracking fear in snake and spider fearful participants during visual search: A multi snake or spider fearful participants showed shorter reaction times (RTs) to respond to their feared, to investigate the nature of the responses to the feared animal, a nonfeared (but fear-relevant) animal, and fear

  1. Effects of Mora Deletion, Nonword Repetition, Rapid Naming, and Visual Search Performance on Beginning Reading in Japanese

    ERIC Educational Resources Information Center

    Kobayashi, Maya Shiho; Haynes, Charles W.; Macaruso, Paul; Hook, Pamela E.; Kato, Junko

    2005-01-01

    This study examined the extent to which mora deletion (phonological analysis), nonword repetition (phonological memory), rapid automatized naming (RAN), and visual search abilities predict reading in Japanese kindergartners and first graders. Analogous abilities have been identified as important predictors of reading skills in alphabetic languages…

  2. Practice Makes Improvement: How Adults with Autism Out-Perform Others in a Naturalistic Visual Search Task

    ERIC Educational Resources Information Center

    Gonzalez, Cleotilde; Martin, Jolie M.; Minshew, Nancy J.; Behrmann, Marlene

    2013-01-01

    People with autism spectrum disorder (ASD) often exhibit superior performance in visual search compared to others. However, most studies demonstrating this advantage have employed simple, uncluttered images with fully visible targets. We compare the performance of high-functioning adults with ASD and matched controls on a naturalistic luggage…

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

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  4. Effects of social stimuli on covert attentional orienting and saccaddic eye-movements during visual search.

    PubMed

    Morrisey, Marcus; Rutherford, M D

    2015-09-01

    Although visual attention and saccadic eye movements are tightly linked, our attention can move to objects in visual space without a saccade to the object, a phenomenon called covert attentional orienting. Socially significant targets like faces and human bodies attract attention. Using a visual search task we examined reaction to social targets by comparing the relationship between performance measures such as reaction time and error rate and saccadic eye movement measures. Participants briefly viewed a word representing 1 of 6 categories. One image from each category then appeared in a circular array on the screen. Participants identified the image in a target frame (the green frame) as either matching or not matching the presented word. On half of the trials, a distracter frame (the red frame) was also present. Consistent with previous results, participants responded faster when seeking a social target (face or body) compared to non-social targets and this effect was not diminished by inversion. They were slower and more error prone on trials containing a distracter frame. Participants saccadeed first and more often to social targets than to non-social targets but spent less time focused on social targets. When images were inverted, participants did not saccade more often to social stimuli than non-social distracters. Participants varied widely on the proportion of trials in which they saccaded to any object, between 2% and 97%,suggesting that some participants are capable of performing this task peripherally. Indeed, a lower proportion of trials with saccades to targets was associated with faster RT. The evidence supported an attentional effect of social stimuli that is independent of saccadic eye movement in addition to modulation of looking behavior. Meeting abstract presented at VSS 2015. PMID:26326954

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

    PubMed Central

    2010-01-01

    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

  6. A Game of Hide and Seek: Expectations of Clumpy Resources Influence Hiding and Searching Patterns

    PubMed Central

    Wilke, Andreas; Minich, Steven; Panis, Megane; Langen, Tom A.; Skufca, Joseph D.; Todd, Peter M.

    2015-01-01

    Resources are often distributed in clumps or patches in space, unless an agent is trying to protect them from discovery and theft using a dispersed distribution. We uncover human expectations of such spatial resource patterns in collaborative and competitive settings via a sequential multi-person game in which participants hid resources for the next participant to seek. When collaborating, resources were mostly hidden in clumpy distributions, but when competing, resources were hidden in more dispersed (random or hyperdispersed) patterns to increase the searching difficulty for the other player. More dispersed resource distributions came at the cost of higher overall hiding (as well as searching) times, decreased payoffs, and an increased difficulty when the hider had to recall earlier hiding locations at the end of the experiment. Participants’ search strategies were also affected by their underlying expectations, using a win-stay lose-shift strategy appropriate for clumpy resources when searching for collaboratively-hidden items, but moving equally far after finding or not finding an item in competitive settings, as appropriate for dispersed resources. Thus participants showed expectations for clumpy versus dispersed spatial resources that matched the distributions commonly found in collaborative versus competitive foraging settings. PMID:26154661

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

    PubMed Central

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

    2012-01-01

    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

  8. Visualization on flow patterns during condensation of R410A in a vertical rectangular channel

    NASA Astrophysics Data System (ADS)

    Xu, Wenyun; Jia, Li

    2014-06-01

    The visualization experiments on HFC R410A condensation in a vertical rectangular channel (14.34mm hydraulic diameter, 160mm length) were investigated. The flow patterns and heat transfer coefficients of condensation in the inlet region were presented in this paper. Better heat transfer performance can be obtained in the inlet region, and flow regime transition in other regions of the channel was also observed. Condensation experiments were carried out at different mass fluxes ( from 1.6 kg/h to 5.2 kg/h) and at saturation temperature 28°C. It was found that the flow patterns were mainly dominated by gravity at low mass fluxes. The effects of interfacial shear stress on condensate fluctuation are significant for the film condensation at higher mass flux in vertical flow, and consequently, the condensation heat transfer coefficient increases with the mass flux in the experimental conditions. The drop formation and growth process of condensation were also observed at considerably low refrigerant vapor flow rate.

  9. Target templates: the precision of mental representations affects attentional guidance and decision-making in visual search

    PubMed Central

    Hout, Michael C.; Goldinger, Stephen D.

    2014-01-01

    When people look for things in the environment, they use target templates—mental representations of the objects they are attempting to locate—to guide attention and to assess incoming visual input as potential targets. However, unlike laboratory participants, searchers in the real world rarely have perfect knowledge regarding the potential appearance of targets. In seven experiments, we examined how the precision of target templates affects the ability to conduct visual search. Specifically, we degraded template precision in two ways: 1) by contaminating searchers’ templates with inaccurate features, and 2) by introducing extraneous features to the template that were unhelpful. We recorded eye movements to allow inferences regarding the relative extents to which attentional guidance and decision-making are hindered by template imprecision. Our findings support a dual-function theory of the target template and highlight the importance of examining template precision in visual search. PMID:25214306

  10. Visual search, movement behaviour and boat control during the windward mark rounding in sailing.

    PubMed

    Pluijms, Joost P; Cañal-Bruland, Rouwen; Hoozemans, Marco J M; Savelsbergh, Geert J P

    2015-01-01

    In search of key-performance predictors in sailing, we examined to what degree visual search, movement behaviour and boat control contribute to skilled performance while rounding the windward mark. To this end, we analysed 62 windward mark roundings sailed without opponents and 40 windward mark roundings sailed with opponents while competing in small regattas. Across conditions, results revealed that better performances were related to gazing more to the tangent point during the actual rounding. More specifically, in the condition without opponents, skilled performance was associated with gazing more outside the dinghy during the actual rounding, while in the condition with opponents, superior performance was related to gazing less outside the dinghy. With respect to movement behaviour, superior performance was associated with the release of the trimming lines close to rounding the mark. In addition, better performances were related to approaching the mark with little heel, yet heeling the boat more to the windward side when being close to the mark. Potential implications for practice are suggested for each phase of the windward mark rounding. PMID:25105956

  11. Positional priming of visual pop-out search is supported by multiple spatial reference frames

    PubMed Central

    Gokce, Ahu; Müller, Hermann J.; Geyer, Thomas

    2015-01-01

    The present study investigates the representations(s) underlying positional priming of visual ‘pop-out’ search (Maljkovic and Nakayama, 1996). Three search items (one target and two distractors) were presented at different locations, in invariant (Experiment 1) or random (Experiment 2) cross-trial sequences. By these manipulations it was possible to disentangle retinotopic, spatiotopic, and object-centered priming representations. Two forms of priming were tested: target location facilitation (i.e., faster reaction times – RTs– when the trial n target is presented at a trial n-1 target relative to n-1 blank location) and distractor location inhibition (i.e., slower RTs for n targets presented at n-1 distractor compared to n-1 blank locations). It was found that target locations were coded in positional short-term memory with reference to both spatiotopic and object-centered representations (Experiment 1 vs. 2). In contrast, distractor locations were maintained in an object-centered reference frame (Experiments 1 and 2). We put forward the idea that the uncertainty induced by the experiment manipulation (predictable versus random cross-trial item displacements) modulates the transition from object- to space-based representations in cross-trial memory for target positions. PMID:26136718

  12. Hide and seek: the theory of mind of visual concealment and search.

    PubMed

    Anderson, Giles M; Foulsham, Tom; Nasiopoulos, Eleni; Chapman, Craig S; Kingstone, Alan

    2014-05-01

    Researchers have investigated visual search behavior for almost a century. During that time, few studies have examined the cognitive processes involved in hiding items rather than finding them. To investigate this, we developed a paradigm that allowed participants to indicate where they would hide (or find) an item that was to be found (or hidden) by a friend or a foe. We found that (i) for friends more than foes, participants selected the pop-out item in the display, and (ii) when the display was homogeneous, they selected nearby and corner items. These behaviors held for both hiding and finding, although hide and find behaviors were not identical. For pop-out displays, decision times were unusually long when hiding an item from a foe. These data converge on the conclusion that the principles of search and concealment are similar, but not the same. They also suggest that this paradigm will provide researchers a powerful method for investigating theory of mind in adults. PMID:24722955

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

    PubMed Central

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

    2013-01-01

    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

  14. Low-Level Image Properties of Visual Objects Predict Patterns of Neural Response across Category-Selective Regions of the Ventral Visual Pathway

    PubMed Central

    Rice, Grace E.; Watson, David M.; Hartley, Tom

    2014-01-01

    Neuroimaging studies have revealed strong selectivity for object categories in high-level regions of the human visual system. However, it is unknown whether this selectivity is truly based on object category, or whether it reflects tuning for low-level features that are common to images from a particular category. To address this issue, we measured the neural response to different object categories across the ventral visual pathway. Each object category elicited a distinct neural pattern of response. Next, we compared the patterns of neural response between object categories. We found a strong positive correlation between the neural patterns and the underlying low-level image properties. Importantly, this correlation was still evident when the within-category correlations were removed from the analysis. Next, we asked whether basic image properties could also explain variation in the pattern of response to different exemplars from one object category (faces). A significant correlation was also evident between the similarity of neural patterns of response and the low-level properties of different faces, particularly in regions associated with face processing. These results suggest that the appearance of category-selective regions at this coarse scale of representation may be explained by the systematic convergence of responses to low-level features that are characteristic of each category. PMID:24966383

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

    PubMed Central

    Gilchrist, Amanda L.; Cowan, Nelson

    2014-01-01

    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

  16. Effects of chronic iTBS-rTMS and enriched environment on visual cortex early critical period and visual pattern discrimination in dark-reared rats.

    PubMed

    Castillo-Padilla, Diana V; Funke, Klaus

    2016-01-01

    Early cortical critical period resembles a state of enhanced neuronal plasticity enabling the establishment of specific neuronal connections during first sensory experience. Visual performance with regard to pattern discrimination is impaired if the cortex is deprived from visual input during the critical period. We wondered how unspecific activation of the visual cortex before closure of the critical period using repetitive transcranial magnetic stimulation (rTMS) could affect the critical period and the visual performance of the experimental animals. Would it cause premature closure of the plastic state and thus worsen experience-dependent visual performance, or would it be able to preserve plasticity? Effects of intermittent theta-burst stimulation (iTBS) were compared with those of an enriched environment (EE) during dark-rearing (DR) from birth. Rats dark-reared in a standard cage showed poor improvement in a visual pattern discrimination task, while rats housed in EE or treated with iTBS showed a performance indistinguishable from rats reared in normal light/dark cycle. The behavioral effects were accompanied by correlated changes in the expression of brain-derived neurotrophic factor (BDNF) and atypical PKC (PKC?/PKM?), two factors controlling stabilization of synaptic potentiation. It appears that not only nonvisual sensory activity and exercise but also cortical activation induced by rTMS has the potential to alleviate the effects of DR on cortical development, most likely due to stimulation of BDNF synthesis and release. As we showed previously, iTBS reduced the expression of parvalbumin in inhibitory cortical interneurons, indicating that modulation of the activity of fast-spiking interneurons contributes to the observed effects of iTBS. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 19-33, 2016. PMID:25892203

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

    PubMed

    Nuthmann, Antje

    2014-02-01

    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

  18. Social and Non-Social Visual Attention Patterns and Associative Learning in Infants at Risk for Autism

    ERIC Educational Resources Information Center

    Bhat, A. N.; Galloway, J. C.; Landa, R. J.

    2010-01-01

    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…

  19. Icon flickering, flicker rate, and color combinations of an icon's symbol/background in visual search performance.

    PubMed

    Huang, Kuo-Chen; Chiang, Shu-Ying; Chen, Chen-Fu

    2008-02-01

    The effects of color combinations of an icon's symbol/background and components of flicker and flicker rate on visual search performance on a liquid crystal display screen were investigated with 39 subjects who searched for a target icon in a circular stimulus array (diameter = 20 cm) including one target and 19 distractors. Analysis showed that the icon's symbol/background color significantly affected search time. The search times for icons with black/red and white/blue were significantly shorter than for white/yellow, black/yellow, and black/blue. Flickering of different components of the icon significantly affected the search time. Search time for an icon's border flickering was shorter than for an icon symbol flickering; search for flicker rates of 3 and 5 Hz was shorter than that for 1 Hz. For icon's symbol/background color combinations, search error rate for black/blue was greater than for black/red and white/blue combinations, and the error rate for an icon's border flickering was lower than for an icon's symbol flickering. Interactions affected search time and error rate. Results are applicable to design of graphic user interfaces. PMID:18459362

  20. Separability of abstract-category and specific-exemplar visual object subsystems: evidence from fMRI pattern analysis.

    PubMed

    McMenamin, Brenton W; Deason, Rebecca G; Steele, Vaughn R; Koutstaal, Wilma; Marsolek, Chad J

    2015-02-01

    Previous research indicates that dissociable neural subsystems underlie abstract-category (AC) recognition and priming of objects (e.g., cat, piano) and specific-exemplar (SE) recognition and priming of objects (e.g., a calico cat, a different calico cat, a grand piano, etc.). However, the degree of separability between these subsystems is not known, despite the importance of this issue for assessing relevant theories. Visual object representations are widely distributed in visual cortex, thus a multivariate pattern analysis (MVPA) approach to analyzing functional magnetic resonance imaging (fMRI) data may be critical for assessing the separability of different kinds of visual object processing. Here we examined the neural representations of visual object categories and visual object exemplars using multi-voxel pattern analyses of brain activity elicited in visual object processing areas during a repetition-priming task. In the encoding phase, participants viewed visual objects and the printed names of other objects. In the subsequent test phase, participants identified objects that were either same-exemplar primed, different-exemplar primed, word-primed, or unprimed. In visual object processing areas, classifiers were trained to distinguish same-exemplar primed objects from word-primed objects. Then, the abilities of these classifiers to discriminate different-exemplar primed objects and word-primed objects (reflecting AC priming) and to discriminate same-exemplar primed objects and different-exemplar primed objects (reflecting SE priming) was assessed. Results indicated that (a) repetition priming in occipital-temporal regions is organized asymmetrically, such that AC priming is more prevalent in the left hemisphere and SE priming is more prevalent in the right hemisphere, and (b) AC and SE subsystems are weakly modular, not strongly modular or unified. PMID:25528436

  1. 3D PATTERN OF BRAIN ABNORMALITIES IN WILLIAMS SYNDROME VISUALIZED USING TENSOR-BASED MORPHOMETRY

    PubMed Central

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

    2009-01-01

    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 brain images. Methods 3D T1-weighted brain MRIs of 41 WS subjects (age: 29.2±9.2SD years; 23F/18M) and 39 age-matched healthy controls (age: 27.5±7.4 years; 23F/16M) were fluidly registered to a minimum deformation target. Fine-scale volumetric differences were mapped between diagnostic groups. Local regions were identified where regional structure volumes were associated with diagnosis, and with intelligence quotient (IQ) scores. Brain asymmetry was also mapped and compared between diagnostic groups. Results WS subjects exhibited widely distributed brain volume reductions (~10–15% reduction; P < 0.0002, permutation test). After adjusting for total brain volume, the frontal lobes, anterior cingulate, superior temporal gyrus, amygdala, fusiform gyrus and cerebellum were found to be relatively preserved in WS, but parietal and occipital lobes, thalamus and basal ganglia, and midbrain were disproportionally decreased in volume (P < 0.0002). These regional volumes also correlated positively with performance IQ in adult WS subjects (age ? 30 years, P = 0.038). Conclusion TBM facilitates 3D visualization of brain volume reductions in WS. Reduced parietal/occipital volumes may be associated with visuospatial deficits in WS. By contrast, frontal lobes, amygdala, and cingulate gyrus are relatively preserved or even enlarged, consistent with unusual affect regulation and language production in WS. PMID:17512756

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

    PubMed

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

    2014-05-01

    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

  3. Visual acuity trade-offs and microhabitat-driven adaptation of searching behaviour in psyllids (Hemiptera: Psylloidea: Aphalaridae).

    PubMed

    Farnier, Kevin; Dyer, Adrian G; Taylor, Gary S; Peters, Richard A; Steinbauer, Martin J

    2015-05-15

    Insects have evolved morphological and physiological adaptations in response to selection pressures inherent to their ecology. Consequently, visual performance and acuity often significantly vary between different insect species. Whilst psychophysics has allowed for the accurate determination of visual acuity for some Lepidoptera and Hymenoptera, very little is known about other insect taxa that cannot be trained to positively respond to a given stimulus. In this study, we demonstrate that prior knowledge of insect colour preferences can be used to facilitate acuity testing. We focused on four psyllid species (Hemiptera: Psylloidea: Aphalaridae), namely Ctenarytaina eucalypti, Ctenarytaina bipartita, Anoeconeossa bundoorensis and Glycaspis brimblecombei, that differ in their colour preferences and utilization of different host-plant modules (e.g. apical buds, stems, leaf lamellae) and tested their visual acuity in a modified Y-maze adapted to suit psyllid searching behaviour. Our study revealed that psyllids have visual acuity ranging from 6.3 to 8.7 deg. Morphological measurements for different species showed a close match between inter-ommatidial angles and behaviourally determined visual angles (between 5.5 and 6.6 deg) suggesting detection of colour stimuli at the single ommatidium level. Whilst our data support isometric scaling of psyllids' eyes for C. eucalypti, C. bipartita and G. brimblecombei, a morphological trade-off between light sensitivity and spatial resolution was found in A. bundoorensis. Overall, species whose microhabitat preferences require more movement between modules appear to possess superior visual acuity. The psyllid searching behaviours that we describe with the help of tracking software depict species-specific strategies that presumably evolved to optimize searching for food and oviposition sites. PMID:25827835

  4. Effect of sevoflurane concentration on visual evoked potentials with pattern stimulation in dogs

    PubMed Central

    ITO, Yosuke; MAEHARA, Seiya; ITOH, Yoshiki; HAYASHI, Miri; KUBO, Akira; ITAMI, Takaharu; ISHIZUKA, Tomohito; TAMURA, Jun; YAMASHITA, Kazuto

    2014-01-01

    The purpose of this study was to investigate the effects of sevoflurane concentration on canine visual evoked potentials with pattern stimulation (P-VEPs). Six clinically normal laboratory-beagle dogs were used. The minimum alveolar concentration (MAC) of sevoflurane was detected from all subjects by tail clamp method. The refractive power of the right eyes of all subjects was corrected to ?2 diopters after skiascopy. For P-VEP recording, the recording and reference electrode were positioned at inion and nasion, respectively, and the earth electrode was positioned on the inner surface. To grasp the state of CNS suppression objectively, the bispectral index (BIS) value was used. The stimulus pattern size and distance for VEP recording were constant, 50.3 arc-min and 50 cm, respectively. P-VEPs and BIS values were recorded under sevoflurane in oxygen inhalational anesthesia at 0.5, 1.0, 1.5, 2.0, 2.5 and 2.75 sevoflurane MAC. For analysis of P-VEP, the P100 implicit time and N75-P100 amplitude were estimated. P-VEPs were detected at 0.5 to 1.5 MAC in all dogs, and disappeared at 2.0 MAC in four dogs and at 2.5 and 2.75 MAC in one dog each. The BIS value decreased with increasing sevoflurane MAC, and burst suppression began to appear from 1.5 MAC. There was no significant change in P100 implicit time and N75-P100 amplitude with any concentration of sevoflurane. At concentrations around 1.5 MAC, which are used routinely to immobilize dogs, sevoflurane showed no effect on P-VEP. PMID:25373729

  5. Visual exploration patterns of human figures in action: an eye tracker study with art paintings

    PubMed Central

    Villani, Daniela; Morganti, Francesca; Cipresso, Pietro; Ruggi, Simona; Riva, Giuseppe; Gilli, Gabriella

    2015-01-01

    Art exploration is a complex process conditioned by factors at different levels and includes both basic visual principles and complex cognitive factors. The human figure is considered a critical factor attracting the attention in art painting. Using an eye-tracking methodology, the goal of this study was to explore different elements of the human figure performing an action (face and body parts in action) in complex social scenes characterized by different levels of social interaction between agents depicted in scenes (individual vs. social). The sample included 44 laypersons, and the stimuli consisted of 10 fine art paintings representing the figurative style of classical art. The results revealed different scanning patterns of the human figure elements related to the level of social interaction of agents depicted in the scene. The agents’ face attracted eye movements in social interaction scenes while the agents’ body parts attracted eye movements only when the agents were involved in individual actions. These processes were confirmed specifically in participants with high empathic abilities who became immediately fixated on faces to develop a mimetic engagement with other agents. Future studies integrating other measures would help confirm the results obtained and strengthen their implication for embodiment processes. PMID:26579021

  6. Understanding Patterns of User Visits to Web Sites: Interactive Starfield Visualizations of WWW Log Data.

    ERIC Educational Resources Information Center

    Hochheiser, Harry; Shneiderman, Ben

    1999-01-01

    Describes the use of Spotfire, a starfield visualization tool, to generate interactive visualizations of log data, ranging from aggregate views of all Web site hits in a time interval to close-ups that approximate the path of a user through a site. Highlights current efforts and provides examples of the visualizations created in Spotfire.…

  7. The Effects of Task- and Switch-Predictability on Oculomotor Inhibition of Return During Visual Search.

    PubMed

    Bahle, Brett; Mills, Mark; Dalmaijer, Edwin; Van der Stigchel, Stefan; Dodd, Michael

    2015-09-01

    Task-switching methods have long been used to study cognitive control processes but only recently have attempts been made to extend these methods to the study of oculomotor control processes. Nonetheless, preliminary examinations have demonstrated that oculomotor control processes are quite sensitive to changing task contexts, thus establishing the basic utility of task-switching methods for investigating oculomotor control processes. A recent study, for example, reported a general effect of task-switching on the expression of oculomotor inhibition-of-return (O-IOR) such that O-IOR was observed on task-repetition trials whereas facilitation-of-return (FOR) was observed on task-switch trials (Mills et al., VSS, 2014 ). From the perspective that O-IOR beneficially services search processes by biasing the eyes away from recently inspected locations and toward novel locations (Klein, 1998), the observation of FOR on task-switch trials represents a considerable cost to visual behavior for switching tasks. It would be instructive, therefore, to determine how the oculomotor system mitigates this cost. Behavioral studies of task-switching indicate that switch-costs can be markedly reduced and even eliminated if the schedule of a switch is predictable (Koch, 2005). The main goal of the present study, therefore, was to investigate effects of predictability on O-IOR switch-costs. Participants viewed scenes while either searching for a target 'N' or 'Z', memorizing the scene in preparation for a memory test, or evaluating scene pleasantness. The critical manipulations were Switch-Predictability (whether or not participants knew when a switch would occur) and Task-Predictability (whether or not participants knew on trial n which task to switch to on trial n+1). When participants were prepared for a task switch to search, their initial fixations were more efficient (e.g. less refixations and a greater degree of O-IOR) compared to when the switch-predictability and task-predictability was random. Meeting abstract presented at VSS 2015. PMID:26326465

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

    PubMed

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

    2014-10-01

    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

  9. A Performance Analysis of Evolutionary Pattern Search with Generalized Mutation Steps

    SciTech Connect

    Hart, W.; Hunter, K.

    1999-02-10

    Evolutionary pattern search algorithms (EPSAs) are a class of evolutionary algorithms (EAs) that have convergence guarantees on a broad class of nonconvex continuous problems. In previous work we have analyzed the empirical performance of EPSAs. This paper revisits that analysis and extends it to a more general model of mutation. We experimentally evaluate how the choice of the set of mutation offsets affects optimization performance for EPSAs. Additionally, we compare EPSAs to self-adaptive EAs with respect to robustness and rate of optimization. All experiments employ a suite of test functions representing a range of modality and number of multiple minima.

  10. A fully automatic peak-search program for the evaluation of Gauss-shaped diffraction patterns

    NASA Astrophysics Data System (ADS)

    Lauterjung, J.; Will, G.; Hinze, E.

    1985-09-01

    Diffraction patterns (X-rays or neutrons) often contain regions of overlapping, unresolved peaks. When using energy-dispersive techniques with solid state detectors the degree of overlap is especially high because of the poor resolution of such detectors. Profile analysis then offers the possibility to overcome, or at least reduce this drawback. In this paper a peak-search program is represented for fully automatic separation of the individual peaks. Only the instrumental parameter fwhm (full width at half-maximum) and the recorded spectrum are required as input for the program. Results are given for orthorhombic MnSO 4.

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

    PubMed Central

    Wilkinson, Krista M.; McIlvane, William J.

    2013-01-01

    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

  12. BDNF Val66Met and 5-HTTLPR Genotype are Each Associated with Visual Scanning Patterns of Faces in Young Children

    PubMed Central

    Christou, Antonios I.; Wallis, Yvonne; Bair, Hayley; Crawford, Hayley; Frisson, Steven; Zeegers, Maurice P.; McCleery, Joseph P.

    2015-01-01

    Previous studies have documented both neuroplasticity-related BDNF Val66Met and emotion regulation-related 5-HTTLPR polymorphisms as genetic variants that contribute to the processing of emotions from faces. More specifically, research has shown the BDNF Met allele and the 5-HTTLPR Short allele to be associated with mechanisms of negative affectivity that relate to susceptibility for psychopathology. We examined visual scanning pathways in response to angry, happy, and neutral faces in relation to BDNF Val66Met and 5-HTTLPR genotyping in 49 children aged 4–7?years. Analyses revealed that variations in the visual processing of facial expressions of anger interacted with BDNF Val66Met genotype, such that children who carried at least one low neuroplasticity Met allele exhibited a vigilance–avoidance pattern of visual scanning compared to homozygotes for the high neuroplasticity Val allele. In a separate investigation of eye gaze towards the eye versus mouth regions of neutral faces, we observed that short allele 5-HTTLPR carriers exhibited reduced looking at the eye region compared with those with the higher serotonin uptake Long allele. Together, these findings suggest that genetic mechanisms early in life may influence the establishment of patterns of visual scanning of environmental stressors, which in conjunction with other factors such as negative life events, may lead to psychological difficulties and disorders in the later adolescent and adult years. PMID:26217202

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

    E-print Network

    Makous, Walter

    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

  14. Cube search, revisited.

    PubMed

    Zhang, Xuetao; Huang, Jie; Yigit-Elliott, Serap; Rosenholtz, Ruth

    2015-01-01

    Observers can quickly search among shaded cubes for one lit from a unique direction. However, replace the cubes with similar 2-D patterns that do not appear to have a 3-D shape, and search difficulty increases. These results have challenged models of visual search and attention. We demonstrate that cube search displays differ from those with "equivalent" 2-D search items in terms of the informativeness of fairly low-level image statistics. This informativeness predicts peripheral discriminability of target-present from target-absent patches, which in turn predicts visual search performance, across a wide range of conditions. Comparing model performance on a number of classic search tasks, cube search does not appear unexpectedly easy. Easy cube search, per se, does not provide evidence for preattentive computation of 3-D scene properties. However, search asymmetries derived from rotating and/or flipping the cube search displays cannot be explained by the information in our current set of image statistics. This may merely suggest a need to modify the model's set of 2-D image statistics. Alternatively, it may be difficult cube search that provides evidence for preattentive computation of 3-D scene properties. By attributing 2-D luminance variations to a shaded 3-D shape, 3-D scene understanding may slow search for 2-D features of the target. PMID:25780063

  15. Cube search, revisited

    PubMed Central

    Zhang, Xuetao; Huang, Jie; Yigit-Elliott, Serap; Rosenholtz, Ruth

    2015-01-01

    Observers can quickly search among shaded cubes for one lit from a unique direction. However, replace the cubes with similar 2-D patterns that do not appear to have a 3-D shape, and search difficulty increases. These results have challenged models of visual search and attention. We demonstrate that cube search displays differ from those with “equivalent” 2-D search items in terms of the informativeness of fairly low-level image statistics. This informativeness predicts peripheral discriminability of target-present from target-absent patches, which in turn predicts visual search performance, across a wide range of conditions. Comparing model performance on a number of classic search tasks, cube search does not appear unexpectedly easy. Easy cube search, per se, does not provide evidence for preattentive computation of 3-D scene properties. However, search asymmetries derived from rotating and/or flipping the cube search displays cannot be explained by the information in our current set of image statistics. This may merely suggest a need to modify the model's set of 2-D image statistics. Alternatively, it may be difficult cube search that provides evidence for preattentive computation of 3-D scene properties. By attributing 2-D luminance variations to a shaded 3-D shape, 3-D scene understanding may slow search for 2-D features of the target. PMID:25780063

  16. Development of a Web GIS Application for Visualizing and Analyzing Community Out of Hospital Cardiac Arrest Patterns

    PubMed Central

    Semple, Hugh; Qin, Han; Sasson, Comilla

    2013-01-01

    Improving survival rates at the neighborhood level is increasingly seen as a priority for reducing overall rates of out-of-hospital cardiac arrest (OHCA) in the United States. Since wide disparities exist in OHCA rates at the neighborhood level, it is important for public health officials and residents to be able to quickly locate neighborhoods where people are at elevated risk for cardiac arrest and to target these areas for educational outreach and other mitigation strategies. This paper describes an OHCA web mapping application that was developed to provide users with interactive maps and data for them to quickly visualize and analyze the geographic pattern of cardiac arrest rates, bystander CPR rates, and survival rates at the neighborhood level in different U.S. cities. The data comes from the CARES Registry and is provided over a period spanning several years so users can visualize trends in neighborhood out-of-hospital cardiac arrest patterns. Users can also visualize areas that are statistical hot and cold spots for cardiac arrest and compare OHCA and bystander CPR rates in the hot and cold spots. Although not designed as a public participation GIS (PPGIS), this application seeks to provide a forum around which data and maps about local patterns of OHCA can be shared, analyzed and discussed with a view of empowering local communities to take action to address the high rates of OHCA in their vicinity. PMID:23923097

  17. Statistical-mechanical analysis of self-organization and pattern formation during the development of visual maps

    NASA Astrophysics Data System (ADS)

    Obermayer, K.; Blasdel, G. G.; Schulten, K.

    1992-05-01

    We report a detailed analytical and numerical model study of pattern formation during the development of visual maps, namely, the formation of topographic maps and orientation and ocular dominance columns in the striate cortex. Pattern formation is described by a stimulus-driven Markovian process, the self-organizing feature map. This algorithm generates topologically correct maps between a space of (visual) input signals and an array of formal ``neurons,'' which in our model represents the cortex. We define order parameters that are a function of the set of visual stimuli an animal perceives, and we demonstrate that the formation of orientation and ocular dominance columns is the result of a global instability of the retinoptic projection above a critical value of these order parameters. We characterize the spatial structure of the emerging patterns by power spectra, correlation functions, and Gabor transforms, and we compare model predictions with experimental data obtained from the striate cortex of the macaque monkey with optical imaging. Above the critical value of the order parameters the model predicts a lateral segregation of the striate cortex into (i) binocular regions with linear changes in orientation preference, where iso-orientation slabs run perpendicular to the ocular dominance bands, and (ii) monocular regions with low orientation specificity, which contain the singularities of the orientation map. Some of these predictions have already been verified by experiments.

  18. A signal detection model predicts the effects of set size on visual search accuracy for feature, conjunction, triple conjunction, and disjunction displays

    NASA Technical Reports Server (NTRS)

    Eckstein, M. P.; Thomas, J. P.; Palmer, J.; Shimozaki, S. S.

    2000-01-01

    Recently, quantitative models based on signal detection theory have been successfully applied to the prediction of human accuracy in visual search for a target that differs from distractors along a single attribute (feature search). The present paper extends these models for visual search accuracy to multidimensional search displays in which the target differs from the distractors along more than one feature dimension (conjunction, disjunction, and triple conjunction displays). The model assumes that each element in the display elicits a noisy representation for each of the relevant feature dimensions. The observer combines the representations across feature dimensions to obtain a single decision variable, and the stimulus with the maximum value determines the response. The model accurately predicts human experimental data on visual search accuracy in conjunctions and disjunctions of contrast and orientation. The model accounts for performance degradation without resorting to a limited-capacity spatially localized and temporally serial mechanism by which to bind information across feature dimensions.

  19. Neurofilament protein defines regional patterns of cortical organization in the macaque monkey visual system: a quantitative immunohistochemical analysis

    NASA Technical Reports Server (NTRS)

    Hof, P. R.; Morrison, J. H.; Bloom, F. E. (Principal Investigator)

    1995-01-01

    Visual function in monkeys is subserved at the cortical level by a large number of areas defined by their specific physiological properties and connectivity patterns. For most of these cortical fields, a precise index of their degree of anatomical specialization has not yet been defined, although many regional patterns have been described using Nissl or myelin stains. In the present study, an attempt has been made to elucidate the regional characteristics, and to varying degrees boundaries, of several visual cortical areas in the macaque monkey using an antibody to neurofilament protein (SMI32). This antibody labels a subset of pyramidal neurons with highly specific regional and laminar distribution patterns in the cerebral cortex. Based on the staining patterns and regional quantitative analysis, as many as 28 cortical fields were reliably identified. Each field had a homogeneous distribution of labeled neurons, except area V1, where increases in layer IVB cell and in Meynert cell counts paralleled the increase in the degree of eccentricity in the visual field representation. Within the occipitotemporal pathway, areas V3 and V4 and fields in the inferior temporal cortex were characterized by a distinct population of neurofilament-rich neurons in layers II-IIIa, whereas areas located in the parietal cortex and part of the occipitoparietal pathway had a consistent population of large labeled neurons in layer Va. The mediotemporal areas MT and MST displayed a distinct population of densely labeled neurons in layer VI. Quantitative analysis of the laminar distribution of the labeled neurons demonstrated that the visual cortical areas could be grouped in four hierarchical levels based on the ratio of neuron counts between infragranular and supragranular layers, with the first (areas V1, V2, V3, and V3A) and third (temporal and parietal regions) levels characterized by low ratios and the second (areas MT, MST, and V4) and fourth (frontal regions) levels characterized by high to very high ratios. Such density trends may correspond to differential representation of corticocortically (and corticosubcortically) projecting neurons at several functional steps in the integration of the visual stimuli. In this context, it is possible that neurofilament protein is crucial for the unique capacity of certain subsets of neurons to perform the highly precise mapping functions of the monkey visual system.

  20. Intrinsic motivation and attentional capture from gamelike features in a visual search task.

    PubMed

    Miranda, Andrew T; Palmer, Evan M

    2014-03-01

    In psychology research studies, the goals of the experimenter and the goals of the participants often do not align. Researchers are interested in having participants who take the experimental task seriously, whereas participants are interested in earning their incentive (e.g., money or course credit) as quickly as possible. Creating experimental methods that are pleasant for participants and that reward them for effortful and accurate data generation, while not compromising the scientific integrity of the experiment, would benefit both experimenters and participants alike. Here, we explored a gamelike system of points and sound effects that rewarded participants for fast and accurate responses. We measured participant engagement at both cognitive and perceptual levels and found that the point system (which invoked subtle, anonymous social competition between participants) led to positive intrinsic motivation, while the sound effects (which were pleasant and arousing) led to attentional capture for rewarded colors. In a visual search task, points were awarded after each trial for fast and accurate responses, accompanied by short, pleasant sound effects. We adapted a paradigm from Anderson, Laurent, and Yantis (Proceedings of the National Academy of Sciences 108(25):10367-10371, 2011b), in which participants completed a training phase during which red and green targets were probabilistically associated with reward (a point bonus multiplier). During a test phase, no points or sounds were delivered, color was irrelevant to the task, and previously rewarded targets were sometimes presented as distractors. Significantly longer response times on trials in which previously rewarded colors were present demonstrated attentional capture, and positive responses to a five-question intrinsic-motivation scale demonstrated participant engagement. PMID:23835649

  1. Identification and functional characterization of two patterning genes, Zic4 and Ten_m3, in topographic map formation of the visual pathway

    E-print Network

    Horng, Sam H

    2010-01-01

    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 ...

  2. Internet Search Patterns of Human Immunodeficiency Virus and the Digital Divide in the Russian Federation: Infoveillance Study

    PubMed Central

    Quinn, Casey; Hercz, Daniel; Gillespie, James A

    2013-01-01

    Background Human immunodeficiency virus (HIV) is a serious health problem in the Russian Federation. However, the true scale of HIV in Russia has long been the subject of considerable debate. Using digital surveillance to monitor diseases has become increasingly popular in high income countries. But Internet users may not be representative of overall populations, and the characteristics of the Internet-using population cannot be directly ascertained from search pattern data. This exploratory infoveillance study examined if Internet search patterns can be used for disease surveillance in a large middle-income country with a dispersed population. Objective This study had two main objectives: (1) to validate Internet search patterns against national HIV prevalence data, and (2) to investigate the relationship between search patterns and the determinants of Internet access. Methods We first assessed whether online surveillance is a valid and reliable method for monitoring HIV in the Russian Federation. Yandex and Google both provided tools to study search patterns in the Russian Federation. We evaluated the relationship between both Yandex and Google aggregated search patterns and HIV prevalence in 2011 at national and regional tiers. Second, we analyzed the determinants of Internet access to determine the extent to which they explained regional variations in searches for the Russian terms for “HIV” and “AIDS”. We sought to extend understanding of the characteristics of Internet searching populations by data matching the determinants of Internet access (age, education, income, broadband access price, and urbanization ratios) and searches for the term “HIV” using principal component analysis (PCA). Results We found generally strong correlations between HIV prevalence and searches for the terms “HIV” and “AIDS”. National correlations for Yandex searches for “HIV” were very strongly correlated with HIV prevalence (Spearman rank-order coefficient [rs]=.881, P?.001) and strongly correlated for “AIDS” (rs=.714, P?.001). The strength of correlations varied across Russian regions. National correlations in Google for the term “HIV” (rs=.672, P=.004) and “AIDS” (rs=.584, P?.001) were weaker than for Yandex. Second, we examined the relationship between the determinants of Internet access and search patterns for the term “HIV” across Russia using PCA. At the national level, we found Principal Component 1 loadings, including age (-0.56), HIV search (-0.533), and education (-0.479) contributed 32% of the variance. Principal Component 2 contributed 22% of national variance (income, -0.652 and broadband price, -0.460). Conclusions This study contributes to the methodological literature on search patterns in public health. Based on our preliminary research, we suggest that PCA may be used to evaluate the relationship between the determinants of Internet access and searches for health problems beyond high-income countries. We believe it is in middle-income countries that search methods can make the greatest contribution to public health. PMID:24220250

  3. Lévy flight and Brownian search patterns of a free-ranging predator reflect different prey field characteristics.

    PubMed

    Sims, David W; Humphries, Nicolas E; Bradford, Russell W; Bruce, Barry D

    2012-03-01

    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

  4. Comparing Evolutionary Programs and Evolutionary Pattern Search Algorithms: A Drug Docking Application

    SciTech Connect

    Hart, W.E.

    1999-02-10

    Evolutionary programs (EPs) and evolutionary pattern search algorithms (EPSAS) are two general classes of evolutionary methods for optimizing on continuous domains. The relative performance of these methods has been evaluated on standard global optimization test functions, and these results suggest that EPSAs more robustly converge to near-optimal solutions than EPs. In this paper we evaluate the relative performance of EPSAs and EPs on a real-world application: flexible ligand binding in the Autodock docking software. We compare the performance of these methods on a suite of docking test problems. Our results confirm that EPSAs and EPs have comparable performance, and they suggest that EPSAs may be more robust on larger, more complex problems.

  5. Does guidance take time to develop during a visual search trial? 1 Kristin O. Michod, 1,2 Jeremy M. Wolfe, 1,2 Todd S. Horowitz, 1,2 Evan M. Palmer

    E-print Network

    = MeanRT In conjunction search, people can use color and orientation to guide attention. But if guidanceDoes guidance take time to develop during a visual search trial? 1 Kristin O. Michod, 1,2 Jeremy M processing in vision? Perception, 18, 191-200. V E R I TAS Conclusions 1. In visual search, reaction time

  6. New Indicators for Visualizing Pattern Formation in Uncatalyzed Bromate Oscillatory Systems

    E-print Network

    Epstein, Irving R.

    -catalyst),1 in some uncatalyzed bromate-substrate (UBO) systems,2 in the bromate-cyclohex- anedione (CHD absorption between the oxidized and reduced forms of the catalyst can be observed either visually (for

  7. 3D pattern of brain atrophy in HIV/AIDS visualized using tensor-based morphometry

    E-print Network

    Thompson, Paul

    (TBM) to visualize brain deficits and clinical/anatomical correlations in HIV/AIDS. To perform TBM, we, correlated with cognitive impairment (P=0.033) and CD4+ T-lymphocyte depletion (P=0.005). Conclusion: TBM

  8. Patterns of visual sensory and sensorimotor abnormalities in autism vary in relation to history of early language delay

    PubMed Central

    Takarae, Yukari; Luna, Beatriz; Minshew, Nancy J.; Sweeney, John A.

    2010-01-01

    Visual motion perception and pursuit eye movement deficits have been reported in autism. However, it is unclear whether these impairments are related to each other or toclinical symptoms of the disorder. High-functioning individuals with autism (41 with and 36 without delayed language acquisition) and 46 control subjects participated in the present study. All three subject groups were matched on chronological age and Full-Scale IQ. The autism group with delayed language acquisition had bilateral impairments on visual motion discrimination tasks, while the autism group without delay showed marginal impairments only in the left hemifield. Both autism groups showed difficulty tracking visual targets, but only the autism group without delayed language acquisition showed increased pursuit latencies and a failure to show the typical rightward directional advantage in pursuit. We observed correlations between performance on the visual perception and pursuit tasks in both autism groups. However, pursuit performance was correlated with manual motor skills only in the autism group with delayed language, suggesting that general sensorimotor or motor disturbances are a significant additional factor related to pursuit deficits in this subgroup. These findings suggest that there may be distinct neurocognitive phenotypes in autism associated with patterns of early language development. PMID:18954478

  9. Frames of Reference for the Light-from-Above Prior in Visual Search and Shape Judgements

    ERIC Educational Resources Information Center

    Adams, Wendy J.

    2008-01-01

    Faced with highly complex and ambiguous visual input, human observers must rely on prior knowledge and assumptions to efficiently determine the structure of their surroundings. One of these assumptions is the "light-from-above" prior. In the absence of explicit light-source information, the visual system assumes that the light-source is roughly…

  10. Searching for Contracting Patterns over Time: Do Prime Contractor and Subcontractor Relations Follow Similar Patterns for Professional Services Provision?

    ERIC Educational Resources Information Center

    Ponomariov, Branco; Kingsley, Gordon; Boardman, Craig

    2011-01-01

    This paper compares over a 12-year period (1) patterns of contracting between a state transportation agency and its prime contractors providing engineering design services with (2) patterns between these prime contractors and their subcontractors. We find evidence of different contracting patterns at each level that emerge over time and coexist in…

  11. When is it time to move to the next raspberry bush? Foraging rules in human visual search

    PubMed Central

    Wolfe, Jeremy M.

    2013-01-01

    Animals, including humans, engage in many forms of foraging behavior in which resources are collected from the world. This paper examines human foraging in a visual search context. A real-world analog would be berry picking. The selection of individual berries is not the most interesting problem in such a task. Of more interest is when does a forager leave one patch or berry bush for the next one? Marginal Value Theorem (MVT; Charnov, 1976) predicts that observers will leave a patch when the instantaneous yield from that patch drops below the average yield from the entire “field.” Experiments 1, 2, 3, and 4 show that MVT gives a good description of human behavior for roughly uniform collections of patches. Experiments 5 and 6 show strong departures from MVT when patch quality varies and when visual information is degraded. PMID:23641077

  12. Towards grasping the underlying neuronal processes in ADHD using a visual search task: a computational modelling approach.

    PubMed

    Mavritsaki, Eirini; Cook, Amy; Humphreys, Glyn

    2015-09-01

    Attention is essential for our everyday life. The role of attention is to identify the most relevant information in our environment to be processed. Deficits in attention processes have been linked to attention deficit hyperactivity disorder (ADHD). ADHD is a disorder with an onset in childhood and is characterised by inattentiveness, hyperactivity and impulsivity. In the present study we investigate the link between ADHD and visual attention. ADHD is linked with a reduction in arousal levels, which is related to norepinephrine and dopamine function. It is difficult to investigate the role of these two neurotransmitters in ADHD without using interventions. An attractive approach is to use computational modelling, as there is no need for interventions, if the appropriate model is used. In the present study, we extended a neural-level model, the spiking Search over Time and Space (sSoTS) model which was developed to simulate visual search [1]. The important characteristics of sSoTS that qualifies it as an appropriate tool is the incorporated top-down processes and the neuronal details of the system. We will present the outcomes of the first step of our study; using neurotransmitter changes to simulate ADHD behavioural results in a visual search experiment. Importantly the combination of simulated dopamine and norepinephrine function in the model allowed us to be able to stimulate the ADHD behavioural results. The next step in this work is to identify the mechanism(s) responsible for the deficit of attentional function in children with ADHD. REFERENCES [1] Mavritsaki, et al. (2011) Psychological Review, 118(1): p.3-41. Meeting abstract presented at VSS 2015. PMID:26326946

  13. Open angle glaucoma effects on preattentive visual search efficiency for flicker, motion displacement and orientation pop?out tasks

    PubMed Central

    Loughman, James; Davison, Peter; Flitcroft, Ian

    2007-01-01

    Background/aim Preattentive visual search (PAVS) describes rapid and efficient retinal and neural processing capable of immediate target detection in the visual field. Damage to the nerve fibre layer or visual pathway might reduce the efficiency with which the visual system performs such analysis. The purpose of this study was to test the hypothesis that patients with glaucoma are impaired on parallel search tasks, and that this would serve to distinguish glaucoma in early cases. Methods Three groups of observers (glaucoma patients, suspect and normal individuals) were examined, using computer?generated flicker, orientation, and vertical motion displacement targets to assess PAVS efficiency. The task required rapid and accurate localisation of a singularity embedded in a field of 119 homogeneous distractors on either the left or right?hand side of a computer monitor. All subjects also completed a choice reaction time (CRT) task. Results Independent sample T tests revealed PAVS efficiency to be significantly impaired in the glaucoma group compared with both normal and suspect individuals. Performance was impaired in all types of glaucoma tested. Analysis between normal and suspect individuals revealed a significant difference only for motion displacement response times. Similar analysis using a PAVS/CRT index confirmed the glaucoma findings but also showed statistically significant differences between suspect and normal individuals across all target types. Conclusions A test of PAVS efficiency appears capable of differentiating early glaucoma from both normal and suspect cases. Analysis incorporating a PAVS/CRT index enhances the diagnostic capacity to differentiate normal from suspect cases. PMID:17702804

  14. Lexical decisions in adults with low and high susceptibility to pattern-related visual stress: a preliminary investigation.

    PubMed

    Gilchrist, James M; Allen, Peter M

    2015-01-01

    Pattern-related visual stress (PRVS) is a form of sensory hypersensitivity that some people experience when viewing high contrast repeating patterns, notably alternating dark and light stripes. Those susceptible to PRVS typically have a strong aversion to such stimuli, and this is often accompanied by experiences of visual discomfort and disturbance. The patterns most likely to elicit symptoms of PRVS have a square-wave grating configuration of spatial frequency ~3 cycles/degree. Such stimuli are characteristic of printed text in which lines of words and the spaces between them present a high contrast grating-like stimulus. Consequently, much printed reading material has the potential to elicit PRVS that may impair reading performance, and this problem appears to be common in individuals with reading difficulties including dyslexia. However, the manner in which PRVS affects reading ability is unknown. One possibility is that the early sensory visual stress may interfere with the later cognitive word recognition stage of the reading process, resulting in reading performance that is slower and/or less accurate. To explore the association of PRVS with word recognition ability, lexical decision performance (speed and accuracy) to words and pronounceable non-words was measured in two groups of adults, having low and high susceptibility to PRVS. Results showed that lexical decisions were generally faster but less accurate in high-PRVS, and also that high-PRVS participants made decisions significantly faster for words than for non-words, revealing a strong lexicality effect that was not present in low-PRVS. These findings are novel and, as yet, unconfirmed by other studies. PMID:25926810

  15. Lexical decisions in adults with low and high susceptibility to pattern-related visual stress: a preliminary investigation

    PubMed Central

    Gilchrist, James M.; Allen, Peter M.

    2015-01-01

    Pattern-related visual stress (PRVS) is a form of sensory hypersensitivity that some people experience when viewing high contrast repeating patterns, notably alternating dark and light stripes. Those susceptible to PRVS typically have a strong aversion to such stimuli, and this is often accompanied by experiences of visual discomfort and disturbance. The patterns most likely to elicit symptoms of PRVS have a square-wave grating configuration of spatial frequency ~3 cycles/degree. Such stimuli are characteristic of printed text in which lines of words and the spaces between them present a high contrast grating-like stimulus. Consequently, much printed reading material has the potential to elicit PRVS that may impair reading performance, and this problem appears to be common in individuals with reading difficulties including dyslexia. However, the manner in which PRVS affects reading ability is unknown. One possibility is that the early sensory visual stress may interfere with the later cognitive word recognition stage of the reading process, resulting in reading performance that is slower and/or less accurate. To explore the association of PRVS with word recognition ability, lexical decision performance (speed and accuracy) to words and pronounceable non-words was measured in two groups of adults, having low and high susceptibility to PRVS. Results showed that lexical decisions were generally faster but less accurate in high-PRVS, and also that high-PRVS participants made decisions significantly faster for words than for non-words, revealing a strong lexicality effect that was not present in low-PRVS. These findings are novel and, as yet, unconfirmed by other studies. PMID:25926810

  16. Elementary visual hallucinations and their relationships to neural pattern-forming mechanisms.

    PubMed

    Billock, Vincent A; Tsou, Brian H

    2012-07-01

    An extraordinary variety of experimental (e.g., flicker, magnetic fields) and clinical (epilepsy, migraine) conditions give rise to a surprisingly common set of elementary hallucinations, including spots, geometric patterns, and jagged lines, some of which also have color, depth, motion, and texture. Many of these simple hallucinations fall into a small number of perceptual geometries-the Klüver forms-that (via a nonlinear mapping from retina to cortex) correspond to even simpler sets of oriented stripes of cortical activity (and their superpositions). Other simple hallucinations (phosphenes and fortification auras) are linked to the Klüver forms and to pattern-forming cortical mechanisms by their spatial and temporal scales. The Klüver cortical activity patterns are examples of self-organized pattern formation that arise from nonlinear dynamic interactions between excitatory and inhibitory cortical neurons; with reasonable modifications, this model accounts for a wide range of hallucinated patterns. The Klüver cortical activity patterns are a subset of autonomous spatiotemporal cortical patterns, some of which have been studied with functional imaging techniques. Understanding the interaction of these intrinsic patterns with stimulus-driven cortical activity is an important problem in neuroscience. In line with this, hallucinatory pattern formation interacts with physical stimuli, and many conditions that induce hallucinations show interesting interactions with one another. Both types of interactions are predictable from neural and psychophysical principles such as localized processing, excitatory-inhibitory neural circuits, lateral inhibition, simultaneous and sequential contrast, saccadic suppression, and perceptual opponency. Elementary hallucinations arise from familiar mechanisms stimulated in unusual ways. PMID:22448914

  17. Patterns of cytochrome oxidase activity in the visual cortex of a South American opossum (Didelphis marsupialis aurita).

    PubMed

    Martinich, S; Rosa, M G; Rocha-Miranda, C E

    1990-01-01

    The normal pattern of cytochrome oxidase (CO) activity in the posterior cortical areas of the South American opossum (Didelphis marsupialis aurita) was assessed both in horizontal sections of flattened cortices and in transversal cortical sections. The tangential distribution of CO activity was uniformly high in the striate cortex. In the peristriate region alternating bands of dense and weak staining occupied all the cortical layers with the exception of layer I. This observation suggests the existence of a functional segregation of visual processing in the peristriate cortex of the opossum similar to that present in phylogenetically more recent groups. PMID:1966241

  18. Avoidance of conspecific odour trails results in scale-free movement patterns and the execution of an optimal searching strategy

    NASA Astrophysics Data System (ADS)

    Reynolds, A. M.

    2007-08-01

    It is shown how optimal Lévy flight searching patterns for the location of sparsely and randomly distributed targets can emerge from conspecific avoidance (i.e. behaviour designed to avoid locations previously traversed by individuals of the same species). The findings may account for the scale-free foraging movements of jackals and ground-foraging beetles.

  19. Google vs. the Library (Part II): Student Search Patterns and Behaviors When Using Google and a Federated Search Tool

    ERIC Educational Resources Information Center

    Georgas, Helen

    2014-01-01

    This study examines the information-seeking behavior of undergraduate students within a research context. Student searches were recorded while the participants used Google and a library (federated) search tool to find sources (one book, two articles, and one other source of their choosing) for a selected topic. The undergraduates in this study…

  20. Memory in visual search is task-dependent in both 2D and 3D environments.

    PubMed

    Li, Chia-Ling; Aivar, M Pilar; Tong, Matthew; Hayhoe, Mary

    2015-09-01

    Previous studies have indicated the effect of memory for both context and targets on search in 2D images of naturalistic scenes. However, recent results in 3D immersive environments failed to show much effect of context (Li et al., JOV, 2014). To examine whether this reflects differences between 2D vs. 3D environments, we ran a 2D experiment designed to parallel our previous 3D virtual reality environment. Subjects viewed 2D snapshots taken from the two rooms in the 3D immersive environment and then searched those images for a series of targets. The number of fixations required to locate the targets improved rapidly and was similar in both 2D and 3D environments. Interestingly, most of the improvement reflects learning to choose the correct room to look for a given target. Once in the correct room, search is very rapid and objects were located within 3-5 fixations in either environment. Previous exposure (one minute) to the context did not facilitate subsequent search. This was true for both 2D and 3D. In addition, there was little or no effect of experience with the environment on subsequent search for contextual objects in the scene. Even after 24 search trials, the number of fixations required to locate contextual objects in the room was close to values found with no experience. Incidental fixations made during previous trials also do not seem to benefit search much (though a small effect is detectable). Thus, search in both 2D and 3D environments is very comparable, and the primary effect of experience on search depends on task relevance (i.e., previously searched objects are easily remembered but not otherwise). We speculate that the effects of context either require much more extensive experience, or else a pre-exposure that immediately precedes the search episode. Meeting abstract presented at VSS 2015. PMID:26325744

  1. Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

    NASA Astrophysics Data System (ADS)

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Castillo, J. Alvarez; Alvarez-Muñiz, J.; Batista, R. Alves; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Aranda, V. M.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Awal, N.; Badescu, A. M.; Barber, K. B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blaess, S.; Blanco, M.; Bleve, C.; Blümer, H.; Bohá?ová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Bridgeman, A.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Cordier, A.; Coutu, S.; Covault, C. E.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; Almeida, R. M. de; Domenico, M. De; Jong, S. J. de; Neto, J. R. T. de Mello; Mitri, I. De; Oliveira, J. de; Souza, V. de; Peral, L. del; Deligny, O.; Dembinski, H.; Dhital, N.; Giulio, C. Di; Matteo, A. Di; Diaz, J. C.; Castro, M. L. Díaz; Diogo, F.; Dobrigkeit, C.; Docters, W.; D'Olivo, J. C.; Dorofeev, A.; Hasankiadeh, Q. Dorosti; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Luis, P. Facal San; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Fick, B.; Figueira, J. M.; Filevich, A.; Filip?i?, A.; Fox, B. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Fujii, T.; Gaior, R.; García, B.; Roca, S. T. Garcia; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Bravo, A. Gascon; Gate, F.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glaser, C.; Glass, H.; Berisso, M. Gómez; Vitale, P. F. Gómez; Gonçalves, P.; Gonzalez, J. G.; González, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Hartmann, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Coz, S. Le; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Oliveira, M. A. Leigui de; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Agüera, A. Lopez; Louedec, K.; Bahilo, J. Lozano; Lu, L.; Lucero, A.; Ludwig, M.; Malacari, M.; Maldera, S.; Mallamaci, M.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mari?, I. C.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Bravo, O. Martínez; Martraire, D.; Meza, J. J. Masías; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Meissner, R.; Melissas, M.; Melo, D.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mi?anovi?, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Ragaigne, D. Monnier; Montanet, F.; Morello, C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Müller, S.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nguyen, P.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Ochilo, L.; Olinto, A.; Oliveira, M.; Pacheco, N.; Selmi-Dei, D. Pakk; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; P?kala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petermann, E.; Peters, C.; Petrera, S.; Petrov, Y.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.

    2015-06-01

    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 eV by analyzing cosmic rays with energies above eV arriving within an angular separation of approximately 15. 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.

  2. Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

    SciTech Connect

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; Castillo, J. Alvarez; Alvarez-Muñiz, J.; Batista, R. Alves; Ambrosio, M.; Aminaei, A.; Anchordoqui, L.; Andringa, S.; Aramo, C.; Aranda, V. M.; Arqueros, F.; Asorey, H.; Assis, P.; Aublin, J.; Ave, M.; Avenier, M.; Avila, G.; Awal, N.; Badescu, A. M.; Barber, K. B.; Bäuml, J.; Baus, C.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Blaess, S.; Blanco, M.; Bleve, C.; Blümer, H.; Bohá?ová, M.; Boncioli, D.; Bonifazi, C.; Bonino, R.; Borodai, N.; Brack, J.; Brancus, I.; Bridgeman, A.; Brogueira, P.; Brown, W. C.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, B.; Caccianiga, L.; Candusso, M.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Cester, R.; Chavez, A. G.; Chiavassa, A.; Chinellato, J. A.; Chudoba, J.; Cilmo, M.; Clay, R. W.; Cocciolo, G.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Cordier, A.; Coutu, S.; Covault, C. E.; Cronin, J.; Curutiu, A.; Dallier, R.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; Almeida, R. M. de; Domenico, M. De; Jong, S. J. de; Neto, J. R. T. de Mello; Mitri, I. De; Oliveira, J. de; Souza, V. de; Peral, L. del; Deligny, O.; Dembinski, H.; Dhital, N.; Giulio, C. Di; Matteo, A. Di; Diaz, J. C.; Castro, M. L. Díaz; Diogo, F.; Dobrigkeit, C.; Docters, W.; D’Olivo, J. C.; Dorofeev, A.; Hasankiadeh, Q. Dorosti; Dova, M. T.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Luis, P. Facal San; Falcke, H.; Fang, K.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Ferguson, A. P.; Fernandes, M.; Fick, B.; Figueira, J. M.; Filevich, A.; Filip?i?, A.; Fox, B. D.; Fratu, O.; Fröhlich, U.; Fuchs, B.; Fujii, T.; Gaior, R.; García, B.; Roca, S. T. Garcia; Garcia-Gamez, D.; Garcia-Pinto, D.; Garilli, G.; Bravo, A. Gascon; Gate, F.; Gemmeke, H.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Glaser, C.; Glass, H.; Berisso, M. Gómez; Vitale, P. F. Gómez; Gonçalves, P.; Gonzalez, J. G.; González, N.; Gookin, B.; Gordon, J.; Gorgi, A.; Gorham, P.; Gouffon, P.; Grebe, S.; Griffith, N.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Hartmann, S.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Hollon, N.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huber, D.; Huege, T.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Jarne, C.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Kasper, P.; Katkov, I.; Kégl, B.; Keilhauer, B.; Keivani, A.; Kemp, E.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Krömer, O.; Kruppke-Hansen, D.; Kuempel, D.; Kunka, N.; LaHurd, D.; Latronico, L.; Lauer, R.; Lauscher, M.; Lautridou, P.; Coz, S. Le; Leão, M. S. A. B.; Lebrun, D.; Lebrun, P.; Oliveira, M. A. Leigui de; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; López, R.; Agüera, A. Lopez; Louedec, K.; Bahilo, J. Lozano; Lu, L.; Lucero, A.; Ludwig, M.; Malacari, M.; Maldera, S.; Mallamaci, M.; Maller, J.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Marin, V.; Mari?, I. C.; Marsella, G.; Martello, D.; Martin, L.; Martinez, H.; Bravo, O. Martínez; Martraire, D.; Meza, J. J. Masías; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Maurel, D.; Maurizio, D.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Meissner, R.; Melissas, M.; Melo, D.; Menshikov, A.; Messina, S.; Meyhandan, R.; Mi?anovi?, S.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Molina-Bueno, L.; Mollerach, S.; Monasor, M.; Ragaigne, D. Monnier; Montanet, F.; Morello, C.; Mostafá, M.; Moura, C. A.; Muller, M. A.; Müller, G.; Müller, S.; Münchmeyer, M.; Mussa, R.; Navarra, G.; Navas, S.; Necesal, P.; Nellen, L.; Nelles, A.; Neuser, J.; Nguyen, P.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, L.; Ochilo, L.; Olinto, A.; Oliveira, M.; Pacheco, N.; Selmi-Dei, D. Pakk; Palatka, M.; Pallotta, J.; Palmieri, N.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; P?kala, J.; Pelayo, R.; Pepe, I. M.; Perrone, L.; Petermann, E.; Peters, C.; Petrera, S.; Petrov, Y.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porcelli, A.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Purrello, V.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Rautenberg, J.; Ravel, O.; Ravignani, D.; Revenu, B.

    2015-06-20

    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 $E \\ge 6 \\times 10^{19}$ eV by analyzing cosmic rays with energies above $E \\ge 5 \\times 10^{18}$ eV arriving within an angular separation of approximately 15$^{\\circ }$ . 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. As a result, 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.

  3. Search for patterns by combining cosmic-ray energy and arrival directions at the Pierre Auger Observatory

    DOE PAGESBeta

    Aab, A.; Abreu, P.; Aglietta, M.; Ahn, E. J.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Allen, J.; Allison, P.; Almela, A.; et al

    2015-06-20

    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 $E \\ge 6 \\times 10^{19}$ eV by analyzing cosmic rays with energies above $E \\ge 5 \\times 10^{18}$ eV arriving within an angular separation of approximately 15$^{\\circ }$ . 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 aremore »found with this analysis. As a result, 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.« less

  4. Neural Activity Associated with Visual Search for Line Drawings on AAC Displays: An Exploration of the Use of fMRI.

    PubMed

    Wilkinson, Krista M; Dennis, Nancy A; Webb, Christina E; Therrien, Mari; Stradtman, Megan; Farmer, Jacquelyn; Leach, Raevynn; Warrenfeltz, Megan; Zeuner, Courtney

    2015-12-01

    Visual aided augmentative and alternative communication (AAC) consists of books or technologies that contain visual symbols to supplement spoken language. A common observation concerning some forms of aided AAC is that message preparation can be frustratingly slow. We explored the uses of fMRI to examine the neural correlates of visual search for line drawings on AAC displays in 18 college students under two experimental conditions. Under one condition, the location of the icons remained stable and participants were able to learn the spatial layout of the display. Under the other condition, constant shuffling of the locations of the icons prevented participants from learning the layout, impeding rapid search. Brain activation was contrasted under these conditions. Rapid search in the stable display was associated with greater activation of cortical and subcortical regions associated with memory, motor learning, and dorsal visual pathways compared to the search in the unpredictable display. Rapid search for line drawings on stable AAC displays involves not just the conceptual knowledge of the symbol meaning but also the integration of motor, memory, and visual-spatial knowledge about the display layout. Further research must study individuals who use AAC, as well as the functional effect of interventions that promote knowledge about array layout. PMID:26517757

  5. Visual search in depth: The neural correlates of segmenting a display into relevant and irrelevant three-dimensional regions.

    PubMed

    Roberts, Katherine L; Allen, Harriet A; Dent, Kevin; Humphreys, Glyn W

    2015-11-15

    Visual perception is facilitated by the ability to selectively attend to relevant parts of the world and to ignore irrelevant regions or features. In visual search tasks, viewers are able to segment displays into relevant and irrelevant items based on a number of factors including the colour, motion, and temporal onset of the target and distractors. Understanding the process by which viewers prioritise relevant parts of a display can provide insights into the effect of top-down control on visual perception. Here, we investigate the behavioural and neural correlates of segmenting a display according to the expected three-dimensional (3D) location of a target. We ask whether this segmentation is based on low-level visual features (e.g. common depth or common surface) or on higher-order representations of 3D regions. Similar response-time benefits and neural activity were obtained when items fell on common surfaces or within depth-defined volumes, and when displays were vertical (such that items shared a common depth/disparity) or were tilted in depth. These similarities indicate that segmenting items according to their 3D location is based on attending to a 3D region, rather than a specific depth or surface. Segmenting the items in depth was mainly associated with increased activation in depth-sensitive parietal regions rather than in depth-sensitive visual regions. We conclude that segmenting items in depth is primarily achieved via higher-order, cue invariant representations rather than through filtering in lower-level perceptual regions. PMID:26220748

  6. Visual search in depth: The neural correlates of segmenting a display into relevant and irrelevant three-dimensional regions

    PubMed Central

    Roberts, Katherine L.; Allen, Harriet A.; Dent, Kevin; Humphreys, Glyn W.

    2015-01-01

    Visual perception is facilitated by the ability to selectively attend to relevant parts of the world and to ignore irrelevant regions or features. In visual search tasks, viewers are able to segment displays into relevant and irrelevant items based on a number of factors including the colour, motion, and temporal onset of the target and distractors. Understanding the process by which viewers prioritise relevant parts of a display can provide insights into the effect of top-down control on visual perception. Here, we investigate the behavioural and neural correlates of segmenting a display according to the expected three-dimensional (3D) location of a target. We ask whether this segmentation is based on low-level visual features (e.g. common depth or common surface) or on higher-order representations of 3D regions. Similar response-time benefits and neural activity were obtained when items fell on common surfaces or within depth-defined volumes, and when displays were vertical (such that items shared a common depth/disparity) or were tilted in depth. These similarities indicate that segmenting items according to their 3D location is based on attending to a 3D region, rather than a specific depth or surface. Segmenting the items in depth was mainly associated with increased activation in depth-sensitive parietal regions rather than in depth-sensitive visual regions. We conclude that segmenting items in depth is primarily achieved via higher-order, cue invariant representations rather than through filtering in lower-level perceptual regions. PMID:26220748

  7. More than Just Finding Color: Strategy in Global Visual Search Is Shaped by Learned Target Probabilities

    ERIC Educational Resources Information Center

    Williams, Carrick C.; Pollatsek, Alexander; Cave, Kyle R.; Stroud, Michael J.

    2009-01-01

    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…

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

    E-print Network

    Jiang, Yuhong

    searched for a T among Ls. In the training phase, the spatial layout on trial N 1 was predictive an intertrial temporal contextual cuing effect: Search speed became progressively shorter in the training phase that provide consistent contextual information. Such stability affords us ample opportu- nities to learn from

  9. Visual search for a target changing in synchrony with an auditory signal

    E-print Network

    Johnston, Alan

    , a flash and a pip, or a bouncing ball and a collision sound). It is unclear how we find synchronous audio several dynamic visual stimuli were simultaneously presented in a display. The changes imposed on each

  10. Visualizing Interaction Patterns in Online Discussions and Indices of Cognitive Presence

    ERIC Educational Resources Information Center

    Gibbs, William J.

    2006-01-01

    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…

  11. Finding the Critical Facts: Children's Visual Scan Patterns When Solving Story Problems That Contain Irrelevant Information

    ERIC Educational Resources Information Center

    Cook, Joan Littlefield; Rieser, John J.

    2005-01-01

    Two experiments were conducted to understand the processes through which 5th graders discriminate relevant from irrelevant information when solving mathematical story problems. Visual scanning was recorded and coded as directed toward relevant information, irrelevant information, the question, workspace, and elsewhere. Experiment 1 focused on the…

  12. Patterns and Trajectories in Williams Syndrome: The Case of Visual Orientation Discrimination

    ERIC Educational Resources Information Center

    Palomares, Melanie; Englund, Julia A.; Ahlers, Stephanie

    2011-01-01

    Williams Syndrome (WS) is a developmental disorder typified by deficits in visuospatial cognition. To understand the nature of this deficit, we characterized how people with WS perceive visual orientation, a fundamental ability related to object identification. We compared WS participants to typically developing children (3-6 years of age) and…

  13. Age-Dependant Behavioral Strategies in a Visual Search Task in Baboons (Papio papio) and Their Relation to Inhibitory Control

    PubMed Central

    Fagot, Joël; Bonté, Elodie; Hopkins, William D.

    2014-01-01

    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

  14. Age-dependent behavioral strategies in a visual search task in baboons (Papio papio) and their relation to inhibitory control.

    PubMed

    Fagot, Joël; Bonté, Elodie; Hopkins, William D

    2013-05-01

    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

  15. Laparoscopic surgical skills training: an investigation of the potential of using surgeons' visual search behaviour as a performance indicator

    NASA Astrophysics Data System (ADS)

    Chen, Yan; Dong, Leng; Gale, Alastair G.; Rees, Benjamin; Maxwell-Armstrong, Charles

    2014-03-01

    Laparoscopic surgery is a difficult perceptual-motor task and effective and efficient training in the technique is important. Viewing previously recorded laparoscopic operations is a possible available training technique for surgeons to increase their knowledge of such minimal access surgery (MAS). It is not well known whether this is a useful technique, how effective it is or what effect it has on the surgeon watching the recorded video. As part of an on-going series of studies into laparoscopic surgery, an experiment was conducted to examine whether surgical skill level has an effect on the visual search behaviour of individuals of different surgical experience when they examine such imagery. Medically naive observers, medical students, junior surgeons and experienced surgeons viewed a laparoscopic recording of a recent operation. Initial examination of the recorded eye movement data indicated commonalities between all observers, largely irrespective of surgical experience. This, it is argued, is due to visual search in this situation largely being driven by the dynamic nature of the images. The data were then examined in terms of surgical steps and also in terms of interventions when differences were found related to surgical experience. Consequently, it is argued that monitoring the eye movements of trainee surgeons whilst they watch pre-recorded operations is a potential useful adjunct to existing training regimes.

  16. Modifying the Conventional Visual Field Test Pattern to Improve the Detection of Early Glaucomatous Defects in the Central 10°

    PubMed Central

    Ehrlich, Alyssa C.; Raza, Ali S.; Ritch, Robert; Hood, Donald C.

    2014-01-01

    Purpose To simulate modified versions of the 24-2 (6° grid) visual field (VF) test pattern by adding points from the 10-2 (2° grid) test pattern, and to assess their ability to detect early glaucomatous defects in the central 10°. Methods One hundred forty-four eyes of 144 glaucoma patients and suspects with 24-2 mean deviations better than ?6 dB were tested with 10-2 and 24-2 VFs. Based upon both 10-2 VF and optical coherence tomography probability plots, 63 hemifields were defined as abnormal, while 121 hemifields were defined as normal. Three modified 24-2 VF test patterns, called 24-2 +4, 24-2 +16 (Even), and 24-2 +16 (Empirical), were simulated by adding 4 or 16 test points from the 10-2 VF. Results Based upon the number of abnormal points (P ? 5%), the area under the ROC curves (AROC scores) of the three modified 24-2 VFs were significantly greater than that of the 24-2 VF for both the upper and lower VF. For a specificity of 85%, the number of true positives was 25 (24-2), 30 (24-2 +4), 31 (24-2 +16, even), and 32 (24-2 +16, empirical) of 34 total true positives for the upper VF and 23, 26, 27, and 28 of 29 for the lower VF. Conclusions Adding points from the 10-2 test pattern to the 24-2 test pattern significantly improved its ability to detect macular defects without employing more test points than a single 10-2 test. Translational Relevance Additional central points should be added to the 24-2 pattern to improve the detection of macular damage. PMID:25653884

  17. Introducing a New Interface for the Online MagIC Database by Integrating Data Uploading, Searching, and Visualization

    NASA Astrophysics Data System (ADS)

    Jarboe, N.; Minnett, R.; Constable, C.; Koppers, A. A.; Tauxe, L.

    2013-12-01

    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.

  18. Visual Pattern Memory Requires "Foraging" Function in the Central Complex of "Drosophila"

    ERIC Educational Resources Information Center

    Wang, Zhipeng; Pan, Yufeng; Li, Weizhe; Jiang, Huoqing; Chatzimanolis, Lazaros; Chang, Jianhong; Gong, Zhefeng; Liu, Li

    2008-01-01

    The role of the "foraging" ("for)" gene, which encodes a cyclic guanosine-3',5'-monophosphate (cGMP)-dependent protein kinase (PKG), in food-search behavior in "Drosophila" has been intensively studied. However, its functions in other complex behaviors have not been well-characterized. Here, we show experimentally in "Drosophila" that the "for"…

  19. A System for Automated Extraction of Metadata from Scanned Documents using Layout Recognition and String Pattern Search Models

    PubMed Central

    Misra, Dharitri; Chen, Siyuan; Thoma, George R.

    2010-01-01

    One of the most expensive aspects of archiving digital documents is the manual acquisition of context-sensitive metadata useful for the subsequent discovery of, and access to, the archived items. For certain types of textual documents, such as journal articles, pamphlets, official government records, etc., where the metadata is contained within the body of the documents, a cost effective method is to identify and extract the metadata in an automated way, applying machine learning and string pattern search techniques. At the U. S. National Library of Medicine (NLM) we have developed an automated metadata extraction (AME) system that employs layout classification and recognition models with a metadata pattern search model for a text corpus with structured or semi-structured information. A combination of Support Vector Machine and Hidden Markov Model is used to create the layout recognition models from a training set of the corpus, following which a rule-based metadata search model is used to extract the embedded metadata by analyzing the string patterns within and surrounding each field in the recognized layouts. In this paper, we describe the design of our AME system, with focus on the metadata search model. We present the extraction results for a historic collection from the Food and Drug Administration, and outline how the system may be adapted for similar collections. Finally, we discuss some ongoing enhancements to our AME system. PMID:21179386

  20. Brain activation patterns during visual episodic memory processing among first-degree relatives of schizophrenia subjects

    PubMed Central

    Stolz, Erin R.; Pancholi, Krishna; Goradia, Dhruman; Paul, Sarah; Keshavan, Matcheri S.; Nimgaonkar, Vishwajit; Prasad, Konasale

    2012-01-01

    Episodic memory deficits are proposed as a potential intermediate phenotype of schizophrenia. We examined deficits in visual episodic memory and associated brain activation differences among early course schizophrenia (n=22), first-degree relatives (n=16) and healthy controls without personal or family history of psychotic disorders (n=28). Study participants underwent functional magnetic resonance imaging on a 3T scanner while performing visual episodic memory encoding and retrieval task. We examined in-scanner behavioral performance evaluating response time and accuracy of performance. Whole-brain BOLD response differences were analyzed using SPM5 correcting for multiple comparisons. There was an incremental increase in response time among the study groups (Healthy Controlsvisual episodic memory retrieval but not for encoding in the prefrontal cortex and thalamus. PMID:22992490

  1. Noncoplanar beam angle optimization in IMRT treatment planning using pattern search methods

    NASA Astrophysics Data System (ADS)

    Rocha, Humberto; Dias, Joana M.; Ferreira, Brígida C.; Lopes, Maria C.

    2015-05-01

    Radiation therapy is used to treat localized cancers, aiming to deliver a dose of radiation to the tumor volume to sterilize all cancer cells while minimizing the collateral effects on the surrounding healthy organs and tissues. The planning of radiation therapy treatments requires decisions regarding the angles used for radiation incidence, the fluence intensities and, if multileaf collimators are used, the definition of the leaf sequencing. The beam angle optimization problem consists in finding the optimal number and incidence directions of the irradiation beams. The selection of appropriate radiation incidence directions is important for the quality of the treatment. However, the possibility of improving the quality of treatment plans by an optimized selection of the beam incidences is seldom done in the clinical practice. Adding the possibility for noncoplanar incidences is even more rarely used. Nevertheless, the advantage of noncoplanar beams is well known. The optimization of noncoplanar beam incidences may further allow the reduction of the number of beams needed to reach a clinically acceptable plan. In this paper we present the benefits of using pattern search methods for the optimization of the highly non-convex noncoplanar beam angle optimization problem.

  2. Fuzzy ruling between core porosity and petrophysical logs: Subtractive clustering vs. genetic algorithm-pattern search

    NASA Astrophysics Data System (ADS)

    Bagheripour, Parisa; Asoodeh, Mojtaba

    2013-12-01

    Porosity, the void portion of reservoir rocks, determines the volume of hydrocarbon accumulation and has a great control on assessment and development of hydrocarbon reservoirs. Accurate determination of porosity from core analysis is highly cost, time, and labor intensive. Therefore, the mission of finding an accurate, fast and cheap way of determining porosity is unavoidable. On the other hand, conventional well log data, available in almost all wells contain invaluable implicit information about the porosity. Therefore, an intelligent system can explicate this information. Fuzzy logic is a powerful tool for handling geosciences problem which is associated with uncertainty. However, determination of the best fuzzy formulation is still an issue. This study purposes an improved strategy, called hybrid genetic algorithm-pattern search (GA-PS) technique, against the widely held subtractive clustering (SC) method for setting up fuzzy rules between core porosity and petrophysical logs. Hybrid GA-PS technique is capable of extracting optimal parameters for fuzzy clusters (membership functions) which consequently results in the best fuzzy formulation. Results indicate that GA-PS technique manipulates both mean and variance of Gaussian membership functions contrary to SC that only has a control on mean of Gaussian membership functions. A comparison between hybrid GA-PS technique and SC method confirmed the superiority of GA-PS technique in setting up fuzzy rules. The proposed strategy was successfully applied to one of the Iranian carbonate reservoir rocks.

  3. Comparing the Precision of Information Retrieval of MeSH-Controlled Vocabulary Search Method and a Visual Method in the Medline Medical Database

    PubMed Central

    Hariri, Nadjla; Ravandi, Somayyeh Nadi

    2014-01-01

    Background: Medline is one of the most important databases in the biomedical field. One of the most important hosts for Medline is Elton B. Stephens CO. (EBSCO), which has presented different search methods that can be used based on the needs of the users. Visual search and MeSH-controlled search methods are among the most common methods. The goal of this research was to compare the precision of the retrieved sources in the EBSCO Medline base using MeSH-controlled and visual search methods. Methods: This research was a semi-empirical study. By holding training workshops, 70 students of higher education in different educational departments of Kashan University of Medical Sciences were taught MeSH-Controlled and visual search methods in 2012. Then, the precision of 300 searches made by these students was calculated based on Best Precision, Useful Precision, and Objective Precision formulas and analyzed in SPSS software using the independent sample T Test, and three precisions obtained with the three precision formulas were studied for the two search methods. Results: The mean precision of the visual method was greater than that of the MeSH-Controlled search for all three types of precision, i.e. Best Precision, Useful Precision, and Objective Precision, and their mean precisions were significantly different (P <0.001). Sixty-five percent of the researchers indicated that, although the visual method was better than the controlled method, the control of keywords in the controlled method resulted in finding more proper keywords for the searches. Fifty-three percent of the participants in the research also mentioned that the use of the combination of the two methods produced better results. Conclusion: For users, it is more appropriate to use a natural, language-based method, such as the visual method, in the EBSCO Medline host than to use the controlled method, which requires users to use special keywords. The potential reason for their preference was that the visual method allowed them more freedom of action. PMID:25763155

  4. Flexible Information Visualization of Multivariate Data from Biological Sequence Similarity Searches

    E-print Network

    Chi, Ed Huai-hsin

    --dimensional scenes, since data from different fields often require dramatically different visualization techniques in databases. Similarity anal­ ysis provides possible protein functions for the unknown input se­ quences has been using AV on a daily basis for the past 18 months. However, seeing the possibilities offered

  5. Flexible Information Visualization of Multivariate Data from Biological Sequence Similarity Searches

    E-print Network

    Chi, Ed Huai-hsin

    different fields often require dramatically different visualization techniques. Recently, we presented a new possible protein functions for the unknown input se- quences, reducing the need for painstaking lab work' ability to discover features in this in- formation space. Our group has been using AV on a daily basis

  6. The Tug of War between Phonological, Semantic and Shape Information in Language-Mediated Visual Search

    ERIC Educational Resources Information Center

    Huettig, Falk; McQueen, James M.

    2007-01-01

    Experiments 1 and 2 examined the time-course of retrieval of phonological, visual-shape and semantic knowledge as Dutch participants listened to sentences and looked at displays of four pictures. Given a sentence with "beker," "beaker," for example, the display contained phonological (a beaver, "bever"), shape (a bobbin, "klos"), and semantic (a…

  7. Diverse strategies engaged in establishing stereotypic wiring patterns among neurons sharing a common input at the visual system's first synapse

    PubMed Central

    Dunn, Felice A.; Wong, Rachel O.L.

    2012-01-01

    Sensory circuits use common strategies such as convergence and divergence, typically at different synapses, to pool or distribute inputs. Inputs from different presynaptic cell types converge onto a common postsynaptic cell, acting together to shape neuronal output (Klausberger and Somogyi, 2008). Also, individual presynaptic cells contact several postsynaptic cell types, generating divergence of signals. Attaining such complex wiring patterns relies on the orchestration of many events across development, including axonal and dendritic growth and synapse formation and elimination (reviewed by Waites et al., 2005; Sanes and Yamagata, 2009). Recent work has focused on how distinct presynaptic cell types form stereotypic connections with an individual postsynaptic cell (Williams et al., 2011; Morgan et al., 2011), but how a single presynaptic cell type diverges to form distinct wiring patterns with multiple postsynaptic cell types during development remains unexplored. Here we take advantage of the compactness of the visual system's first synapse to observe development of such a circuit in mouse retina. By imaging three types of postsynaptic bipolar cells and their common photoreceptor targets across development, we found that distinct bipolar cell types engage in disparate dendritic growth behaviors, exhibit targeted or exploratory approaches to contact photoreceptors, and adhere differently to the synaptotropic model of establishing synaptic territories. Furthermore each type establishes their final connectivity patterns with the same afferents on separate time-scales. We propose that such differences in strategy and timeline could facilitate the division of common inputs among multiple postsynaptic cell types to create parallel circuits with diverse function. PMID:22836264

  8. Seek and you shall remember: Scene semantics interact with visual search to build better memories

    PubMed Central

    Draschkow, Dejan; Wolfe, Jeremy M.; Võ, Melissa L.-H.

    2014-01-01

    Memorizing critical objects and their locations is an essential part of everyday life. In the present study, incidental encoding of objects in naturalistic scenes during search was compared to explicit memorization of those scenes. To investigate if prior knowledge of scene structure influences these two types of encoding differently, we used meaningless arrays of objects as well as objects in real-world, semantically meaningful images. Surprisingly, when participants were asked to recall scenes, their memory performance was markedly better for searched objects than for objects they had explicitly tried to memorize, even though participants in the search condition were not explicitly asked to memorize objects. This finding held true even when objects were observed for an equal amount of time in both conditions. Critically, the recall benefit for searched over memorized objects in scenes was eliminated when objects were presented on uniform, non-scene backgrounds rather than in a full scene context. Thus, scene semantics not only help us search for objects in naturalistic scenes, but appear to produce a representation that supports our memory for those objects beyond intentional memorization. PMID:25015385

  9. Visual ground pattern modulates flight speed of male Oriental fruit moths

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Male Grapholita molesta (Busck) were allowed to fly upwind along horizontal sex pheromone plumes in laboratory flight tunnels. Flying males experienced tunnel floor patterns (tunnel-width stripes perpendicular to the wind line) that were varied in width both longitudinally an laterally. Males' uptu...

  10. Adaptation of video game UVW mapping to 3D visualization of gene expression patterns

    E-print Network

    Vize, Peter D.

    RNA distribution patterns can be determined by annealing a complimentary nucleic acid probe containing expression data in different models can easily be compared to determine common regions of activity. pvize@ucalgary.ca; phone 403 220 8502; fax 403 289 9311 Invited Paper Multimedia Content Access

  11. How Bumblebees First Find Flowers: Habituation of Visual Pattern Preferences, Spontaneous Recovery, and Dishabituation

    ERIC Educational Resources Information Center

    Plowright, C. M. S.; Simonds, V. M.; Butler, M. A.

    2006-01-01

    Two experiments examined the exploratory behaviour of flower-naive bumblebees. Bees were tested four times in a 12-arm radial arm maze in which they never received reward. Patterned and unpatterned stimuli were presented at the end of each corridor and the choices of the bees were recorded. We examined the effects of two variables, time and the…

  12. Elementary Visual Hallucinations and Their Relationships to Neural Pattern-Forming Mechanisms

    ERIC Educational Resources Information Center

    Billock, Vincent A.; Tsou, Brian H.

    2012-01-01

    An extraordinary variety of experimental (e.g., flicker, magnetic fields) and clinical (epilepsy, migraine) conditions give rise to a surprisingly common set of elementary hallucinations, including spots, geometric patterns, and jagged lines, some of which also have color, depth, motion, and texture. Many of these simple hallucinations fall into a…

  13. Exploring Spatiotemporal Patterns By Integrating Visual Analytics With A Moving Objects Database

    E-print Network

    Güting, Ralf Hartmut

    . For example, it can be used to find the situations of Missed Approach in ATC data (Air Traffic Control sys, select an interesting subset for anal- ysis, tune parameters of the sophisticated queries in Secondo is preferable because of lower fuel consumption and lower pollution and noise. Studying such patterns in the ATC

  14. Pinwheel patterns give rise to the direction selectivity of complex cells in the primary visual cortex.

    PubMed

    Yao, Xingzhong; Jin, Lianghai; Hu, Hanping

    2007-09-19

    Understanding the relation between the 'pinwheel orientation map' and the 'direction map' in the cat primary visual cortex (V1) is a long-standing problem. Several relations between the direction and orientation maps have been previously noted; for example, one iso-orientation region is usually subdivided into two subregions preferring opposite directions. However, the reasons for these relations remain unknown. Here, we demonstrate that the organization of the cortical map for direction selectivity (DS) is intimately related to, and can be predicted from, the organization of the cortical orientation map. We have found that the magnitude of the direction preference of a complex cell is proportional to the change in the number of simple cells driven by a stimulus line moving across an iso-orientation region; the preferred direction of the complex cell points to the place where the number of simple cells driven by the visual stimulus is maximal. According to this rule, the direction map can be uniquely determined from the pinwheel orientation map, and the phenomena relating the two maps can be explained. PMID:17719018

  15. Gaze Patterns of Gross Anatomy Students Change with Classroom Learning

    ERIC Educational Resources Information Center

    Zumwalt, Ann C.; Iyer, Arjun; Ghebremichael, Abenet; Frustace, Bruno S.; Flannery, Sean

    2015-01-01

    Numerous studies have documented that experts exhibit more efficient gaze patterns than those of less experienced individuals. In visual search tasks, experts use fewer, longer fixations to fixate for relatively longer on salient regions of the visual field while less experienced observers spend more time examining nonsalient regions. This study…

  16. Feature Integration Theory Revisited: Dissociating Feature Detection and Attentional Guidance in Visual Search

    ERIC Educational Resources Information Center

    Chan, Louis K. H.; Hayward, William G.

    2009-01-01

    In feature integration theory (FIT; A. Treisman & S. Sato, 1990), feature detection is driven by independent dimensional modules, and other searches are driven by a master map of locations that integrates dimensional information into salience signals. Although recent theoretical models have largely abandoned this distinction, some observed results…

  17. Talent Search and Development in the Visual and Performing Arts. User's Guide.

    ERIC Educational Resources Information Center

    Niro, Lynne D.; Wolf, Mary Hunter

    A program to identify culturally-diverse adolescents with the potential of becoming gifted adults is described, and instructions for conducting theater activities are presented. "Talent Search and Development Model Project" of the New Haven Connecticut School System involves middle schools serving primarily Black and Hispanic (bilingual) students.…

  18. Interactive Visualization of Search Intent for Exploratory Information Antti Kangasraasio1

    E-print Network

    Kaski, Samuel

    abstract summarizes recent research on Intent Radar, an interactive search user interface that allows in an intuitive way with- out the need to type specific queries. In user experiments, Intent Radar improves task the disadvantages that they can trap the user to the initial query context and cause cognitive burden to the user

  19. Search Path Mapping: A Versatile Approach for Visualizing Problem-Solving Behavior.

    ERIC Educational Resources Information Center

    Stevens, Ronald H.

    1991-01-01

    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…

  20. Development of Search Behavior Through Visual Representation in Infancy. RIEEC Research Bulletin RRB-11.

    ERIC Educational Resources Information Center

    Shimada, Shoko; And Others

    The purpose of this study was to cross-sectionally and longitudinally examine the developmental process of search behavior in infancy. Subjects were 23 Japanese normal infants (11 males and 12 females) who were individually tested once a month from the age of six to 13 months in laboratory settings. Small toys and three white opaque cubic boxes…

  1. Two-Year-Olds' Search Strategies and Visual Tracking in a Hidden Displacement Task.

    ERIC Educational Resources Information Center

    Butler, Samantha C.; Berthier, Neil E.; Clifton, Rachel K.

    2002-01-01

    Provided 2- and 2.5-year-olds with partial visual information about a ball's path as it moved toward a hiding place. Found that both age groups were equally proficient at tracking the ball as it rolled behind a transparent screen with 4 opaque doors, but 2.5-year-olds were more likely to reach to the correct door when asked to find the ball.…

  2. The vision in "blind" justice: expert perception, judgment, and visual cognition in forensic pattern recognition.

    PubMed

    Dror, Itiel E; Cole, Simon A

    2010-04-01

    Many forensic disciplines require experts to judge whether two complex patterns are sufficiently similar to conclude that both originate from the same source. Studies in this area have revealed that there are a number of factors that affect perception and judgment and that decisions are subjective and susceptible to extraneous influences (such as emotional context, expectation, and motivation). Some studies have shown that the same expert examiner, examining the same prints but within different contexts, may reach different and contradictory decisions. However, such effects are not always present; some examiners seem more susceptible to such influences than do others--especially when the pattern matching is "hard to call" and when the forensic experts are not aware that they are being observed in an experimental study. Studying forensic examiners can contribute to our understanding of expertise and decision making, as well as have implications for forensic science and other areas of expertise. PMID:20382914

  3. Requirement of keratan sulfate proteoglycan phosphacan with a specific sulfation pattern for critical period plasticity in the visual cortex.

    PubMed

    Takeda-Uchimura, Yoshiko; Uchimura, Kenji; Sugimura, Taketoshi; Yanagawa, Yuchio; Kawasaki, Toshisuke; Komatsu, Yukio; Kadomatsu, Kenji

    2015-12-01

    Proteoglycans play important roles in regulating the development and functions of the brain. They consist of a core protein and glycosaminoglycans, which are long sugar chains of repeating disaccharide units with sulfation. A recent study demonstrated that the sulfation pattern of chondroitin sulfate on proteoglycans contributes to regulation of the critical period of experience-dependent plasticity in the mouse visual cortex. In the present study, we investigated the role of keratan sulfate (KS), another glycosaminoglycan, in critical period plasticity in the mouse visual cortex. Immunohistochemical analyses demonstrated the presence of KS containing disaccharide units of N-acetylglucosamine (GlcNAc)-6-sulfate and nonsulfated galactose during the critical period, although KS containing disaccharide units of GlcNAc-6-sulfate and galactose-6-sulfate was already known to disappear before that period. The KS chains were distributed diffusely in the extracellular space and densely around the soma of a large population of excitatory and inhibitory neurons. Electron microscopic analysis revealed that the KS was localized within the perisynaptic spaces and dendrites but not in presynaptic sites. KS was mainly located on phosphacan. In mice deficient in GlcNAc-6-O-sulfotransferase 1, which is one of the enzymes necessary for the synthesis of KS chains, the expression of KS was one half that in wild-type mice. In the knockout mice, monocular deprivation during the critical period resulted in a depression of deprived-eye responses but failed to produce potentiation of nondeprived-eye responses. In addition, T-type Ca(2+) channel-dependent long-term potentiation (LTP), which occurs only during the critical period, was not observed. These results suggest that regulation by KS-phosphacan with a specific sulfation pattern is necessary for the generation of LTP and hence the potentiation of nondeprived-eye responses after monocular deprivation. PMID:26277687

  4. Stimulus- and response-locked neuronal generator patterns of auditory and visual word recognition memory in schizophrenia

    PubMed Central

    Kayser, Jürgen; Tenke, Craig E.; Gil, Roberto B.; Bruder, Gerard E.

    2009-01-01

    Examining visual word recognition memory (WRM) with nose-referenced EEGs, we reported a preserved ERP ‘old-new effect’ (enhanced parietal positivity 300–800 ms to correctly-recognized repeated items) in schizophrenia (Kayser et al., 1999). However, patients showed reduced early negative potentials (N1, N2) and poorer WRM. Because group differences in neuronal generator patterns (i.e., sink-source orientation) may be masked by choice of EEG recording reference, the current study combined surface Laplacians and principal components analysis (PCA) to clarify ERP component topography and polarity and to disentangle stimulus- and response-related contributions. To investigate the impact of stimulus modality, 31-channel ERPs were recorded from 20 schizophrenic patients (15 male) and 20 age-, gender-, and handedness-matched healthy adults during parallel visual and auditory continuous WRM tasks. Stimulus- and response-locked reference-free current source densities (spherical splines) were submitted to unrestricted Varimax-PCA to identify and measure neuronal generator patterns underlying ERPs. Poorer (78.2±18.7% vs. 87.8±11.3% correct) and slower (958±226 vs. 773±206 ms) performance in patients was accompanied by reduced stimulus-related left parietal P3 sources (150 ms pre-response) and vertex N2 sinks (both overall and old/new effects) but modality-specific N1 sinks were not significantly reduced. A distinct mid-frontal sink 50-ms post-response was markedly attenuated in patients. Reductions were more robust for auditory stimuli. However, patients showed increased lateral-frontotemporal sinks (T7 maximum) concurrent with auditory P3 sources. Electrophysiologic correlates of WRM deficits in schizophrenia suggest functional impairments of posterior cortex (stimulus representation) and anterior cingulate (stimulus categorization, response monitoring), primarily affecting memory for spoken words. PMID:19275917

  5. SIMULATION AND VISUALIZATION OF FLOW PATTERN IN MICROARRAYS FOR LIQUID PHASE OLIGONUCLEOTIDE AND PEPTIDE SYNTHESIS

    PubMed Central

    O-Charoen, Sirimon; Srivannavit, Onnop; Gulari, Erdogan

    2008-01-01

    Microfluidic microarrays have been developed for economical and rapid parallel synthesis of oligonucleotide and peptide libraries. For a synthesis system to be reproducible and uniform, it is crucial to have a uniform reagent delivery throughout the system. Computational fluid dynamics (CFD) is used to model and simulate the microfluidic microarrays to study geometrical effects on flow patterns. By proper design geometry, flow uniformity could be obtained in every microreactor in the microarrays. PMID:17480053

  6. Visual Search for Basic Emotional Expressions in Autism; Impaired Processing of Anger, Fear and Sadness, but a Typical Happy Face Advantage

    ERIC Educational Resources Information Center

    Farran, Emily K.; Branson, Amanda; King, Ben J.

    2011-01-01

    Facial expression recognition was investigated in 20 males with high functioning autism (HFA) or Asperger syndrome (AS), compared to typically developing individuals matched for chronological age (TD CA group) and verbal and non-verbal ability (TD V/NV group). This was the first study to employ a visual search, "face in the crowd" paradigm with a…

  7. What Top-Down Task Sets Do for Us: An ERP Study on the Benefits of Advance Preparation in Visual Search

    ERIC Educational Resources Information Center

    Eimer, Martin; Kiss, Monika; Nicholas, Susan

    2011-01-01

    When target-defining features are specified in advance, attentional target selection in visual search is controlled by preparatory top-down task sets. We used ERP measures to study voluntary target selection in the absence of such feature-specific task sets, and to compare it to selection that is guided by advance knowledge about target features.…

  8. was presented as a digit ("zero") or as a A con~eptualcategory effect in visual search: letter (the V O W ~ I 16ss*)amidst field

    E-print Network

    Jonides, John

    by Brand (1971), whose Ss were generally faster when scanning down a long array of letters for a digit proposed by Posner (1970) and Brand (1971) among others. But it is not clear that the "category effect employed in these studies. There is good evidence that RT functions in visual search are flat when target

  9. Glimpses of a one-speed mind: focus-switching and search for verbal and visual, and easy and difficult items in working memory.

    PubMed

    Zhang, Yanmin; Verhaeghen, Paul

    2009-07-01

    We investigated focus-switching and search rates in an N-Back task for stimuli presumably encoded either in a phonological/semantic or an abstract-visual format. Experiment 1 used Chinese characters and tested Chinese speakers and non-Chinese speakers; character frequency and visual complexity were also manipulated. Experiment 2 presented Chinese characters and English words to non-Chinese English speakers. Effects of focus-switching on accuracy were larger for abstract-visual stimuli and for more difficult stimuli; effects on RT were larger for abstract-visual stimuli, but there was no effect of difficulty, with the exception of the most difficult stimulus set in Experiment 1. Search slopes outside the focus of attention did not covary with either type of code or item difficulty. The decline in accuracy over set-size was stronger for the items coded in abstract-visual format. This suggests that item availability is sensitive to robustness of the memory representations, but item accessibility is not. The data fit well with a model of STM in which a fixed number of 'slots' are searched at a constant rate, regardless of the slot's contents. PMID:19552896

  10. Saccadic and perceptual performance in visual search tasks. II. Letter discrimination

    NASA Astrophysics Data System (ADS)

    Murray, Richard F.; Beutter, Brent R.; Eckstein, Miguel P.; Stone, Leland S.

    2003-07-01

    Can the oculomotor system use shape cues to guide search saccades? Observers searched for target letters (D, U, or X) among distractors (the letter O in the discrimination task and blank locations in the detection task) in Gaussian white noise. We measured the accuracy of first saccadic responses on each trial and perceptual (i.e., button-press) responses in separate trials with the stimulus duration chosen so that the saccadic and perceptual processing times were matched. We calculated the relative efficiency of saccadic decisions compared with perceptual decisions, rel =(d sac /d per ) 2 . Relative efficiency was low but consistently greater than zero in discrimination tasks (156) and high in detection tasks (6010). We conclude that the saccadic targeting system can use shape cues, but less efficiently than the perceptual system can. 2003 Optical Society of America

  11. Effects of perceptual load in visual search in immersive virtual reality.

    PubMed

    Olk, Bettina; Zielinski, David; Kopper, Regis

    2015-09-01

    Research using computerized displays of simple stimuli has identified perceptual load as a critical factor for modulating distraction. Distraction is stronger when perceptual load is low than when it is high. Typically, participants determine which of two targets, e.g., letters, is present in a search array composed of other letters and perceptual load of the displays is varied. In the present experiment we made contact with the literature but increased ecological validity by assessing distraction in immersive Virtual Reality (VR), in which life-sized stimuli can be displayed in realistic settings, without losing the advantage of controlling conditions. Participants searched for a target (soda or yoghurt) among other daily objects on the countertop in a virtual kitchen. The search array was accompanied by a congruent or incongruent flanker. Perceptual load was manipulated. As expected, participants responded slower with incongruent flankers (flanker effect) and with high load (load effect), confirming that our materials and set up in the VR environment were suitable to elicit the basic effects. Contrary to our expectations based on the load theory of attention the flanker effect was not modulated by load. This finding may suggest that perceptual load may play a smaller role in attention and search in everyday situations than one would assume based on previous work. Obviously, virtual scenarios are more complex than the stimuli used and the conditions run in previous studies. Further, it is possible that daily, very familiar objects may be harder to ignore or be prioritized for processing also under high perceptual load. We discuss factors that may dilute or negate effects of perceptual load in a more ecologically valid situation and outline suggestions for further research. We suggest that VR offers an exciting interdisciplinary approach that may challenge our beliefs based on traditional laboratory research. Meeting abstract presented at VSS 2015. PMID:26326752

  12. Visual search through a 3D volume: Studying novices in order to help radiologists.

    PubMed

    Aizenman, Avigael; Thompson, Matthew; Ehinger, Krista; Wolfe, Jeremy

    2015-09-01

    Modern radiology often involves search for abnormalities in 3D volumes of imagery (e.g. chest CT, breast tomosynthesis). Drew et al., (2013) used eye tracking to identify two different search strategies: "drillers" scroll quickly through depth while keeping their eye position relatively constant, while "scanners" examine each XY plane before scrolling more slowly in depth. To determine if one method is inherently superior, we developed an analog to radiologic search that can be performed by non-experts. Target "T's" and distractor "L's" were inserted into a 3D block of 1/f noise. Naive participants were given driller or scanner instructions. Observers marked T's they found with mouse clicks. XY eye-position was recorded at 1000 Hz and co-registered with slice/depth plane as the observers scrolled through the 3D volume. Scan paths indicate that observers were scanning or drilling as instructed. Results from 8 participants reading 21 simulated cases suggest that miss error rates were lower for drillers than for scanners. Search durations, however, were ~2X longer for drillers (186sec vs 98sec). This raises the obvious possibility of a speed-accuracy tradeoff that might be countered by further instruction. Drilling, overall, was associated with somewhat shorter fixations (270 msec vs 229 msec) and shorter distances travelled per unit of time by the eyes, consistent with the differences between drilling and scanning. More extensive testing of non-radiologists is required before recommendations could be made regarding best practice by experts. Meeting abstract presented at VSS 2015. PMID:26326795

  13. Towards using eye-tracking data to develop visual-search observers for x-ray breast imaging

    NASA Astrophysics Data System (ADS)

    Jiang, Zhengqiang; Liang, Zhihua; Das, Mini; Gifford, Howard C.

    2015-03-01

    Visual-search (VS) model observers have the potential to provide reliable predictions of human-observer performance in detection-localization tasks. The purpose of this work was to examine some characteristics of human gaze on breast images with the goal of informing the design of our VS observers. Using a helmet-mounted eye- tracking system, we recording the movement of gaze from human observers as they searched for masses in sets of 2D digital breast tomosynthesis (DBT) images. The masses in this study were of a single profile. The DBT images were extracted from image volumes reconstructed with filtered back-projection and penalized maximum- likelihood methods. Fixation times associated with observer points of interest (POIs) were computed from the observer data. The fixation times were then compared to sets of morphological feature values extracted from the images. These features, extracted as cross-correlations involving the mass profile and the test image, included the matched filter (MF), gradient MF, and Laplacian MF. For this initial investigation, we computed correlation coefficients between the fixation times and the feature values.

  14. Effects of Symbol Brightness Cueing on Attention During a Visual Search of a Cockpit Display of Traffic Information

    NASA Technical Reports Server (NTRS)

    Johnson, Walter W.; Liao, Min-Ju; Granada, Stacie

    2003-01-01

    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.

  15. Visual search for singleton feature targets across dimensions: Stimulus- and expectancy-driven effects in dimensional weighting.

    PubMed

    Muller, Hermann J; Reimann, Brit; Krummenacher, Joseph

    2003-10-01

    Four pop-out search experiments investigated whether dimension-based visual attention is top-down modulable. Observers searched for singleton feature targets defined, variably across trials, by a color or an orientation difference to nontargets. Observers were precued to the most probable target-defining dimension (e.g., by the word color) or feature (red) on a given trial. Results revealed expedited reaction times (RTs) for valid-dimension targets relative to neutral-cue conditions, and slowed RTs for invalid-dimension targets. Cue information as to precise target feature yielded some extra effect only for color targets. The dimensional cuing significantly reduced, but did not abolish, the dimension-specific influence of the previous target on detection of the current target (same-dimension RT < different-dimension RT). These findings confirm that top-down dimensional set modulates stimulus-driven dimension processes in the detection of pop-out signals. ((c) 2003 APA, all rights reserved) PMID:14585020

  16. Flexible cue combination in the guidance of attention in visual search.

    PubMed

    Brand, John; Oriet, Chris; Johnson, Aaron P; Wolfe, Jeremy M

    2014-11-01

    Hodsoll and Humphreys (2001) have assessed the relative contributions of stimulus-driven and user-driven knowledge on linearly- and nonlinearly separable searches. However, the target feature used to determine linear separability in their task (i.e., target size) was required to locate the target. In the present work, we investigated the contributions of stimulus-driven and user-driven knowledge when a linearly- or a nonlinearly-separable feature is available but not required for target identification. We asked observers to complete a series of standard color×orientation conjunction searches in which target size was either linearly- or nonlinearly separable from the size of the distractors. When guidance by color×orientation and guidance by size information are both available, observers rely on whichever information results in the best search efficiency. This is the case irrespective of whether we provide target foreknowledge by blocking stimulus conditions, suggesting that feature information is used in both a stimulus-driven and a user-driven fashion. PMID:25463553

  17. Prisoner's Dilemma in One-Dimensional Cellular Automata:. Visualization of Evolutionary Patterns

    NASA Astrophysics Data System (ADS)

    Pereira, Marcelo Alves; Martinez, Alexandre Souto; Espíndola, Aquino Lauri

    The spatial Prisoner's Dilemma is a prototype model to show the emergence of cooperation in very competitive environments. It considers players, at sites of lattices, that can either cooperate or defect when playing the Prisoner's Dilemma with z other players. This model presents a rich phase diagram. Here we consider players in cells of one-dimensional cellular automata. Each player interacts with z other players. This geometry allows us to vary, in a simple manner, the number of neighbors ranging from one up to the lattice size, including self-interaction. This approach has multiple advantages. It is simple to implement numerically and we are able to retrieve all the results found in the previously considered lattices, with a faster convergence to stationary values. More remarkable, it permits us to keep track of the spatio-temporal evolution of each player of the automaton, giving rise to interesting patterns. These patterns allow the interpretation of cooperation/defection clusters as particles, which can be absorbed and collided among themselves. The presented approach represents a new paradigm to study the emergence and maintenance of cooperation in the spatial Prisoner's Dilemma.

  18. Visualization of placental hypocirculation with typical patterns using conventional magnetic resonance imaging: Two case reports.

    PubMed

    Himoto, Yuki; Kido, Aki; Minamiguchi, Sachiko; Mogami, Haruta; Konishi, Ikuo; Togashi, Kaori

    2015-05-01

    We report two cases of clinically suspected placental hypocirculation, as per evidenced by specific half-Fourier acquisition single-shot turbo spin-echo (HASTE) magnetic resonance findings of the whole placenta. Patient 1 was a case of fetal growth restriction caused by pregnancy-induced hypertension, while patient 2 experienced a discordant dichorionic diamniotic twin pregnancy with fetal growth restriction complication with a velamentous insertion of the umbilical cord in the smaller twin. In both cases, HASTE images showed noticeably decreased signal intensity with high-intensity signal spots present in the central region of the placenta. In the twin pregnancy case, the low-intensity signal area in the placenta of the smaller twin was much lower compared to that of the larger twin. Pathological findings failed to support or explain these observations. HASTE images might reflect compensatory alternation of the distribution of maternal blood and villus caused by hypocirculation. In conclusion, our results suggest that HASTE imaging might be a useful approach for the visualization of placental hypocirculation. PMID:25511628

  19. Epistemic Beliefs, Online Search Strategies, and Behavioral Patterns While Exploring Socioscientific Issues

    ERIC Educational Resources Information Center

    Hsu, Chung-Yuan; Tsai, Meng-Jung; Hou, Huei-Tse; Tsai, Chin-Chung

    2014-01-01

    Online information searching tasks are usually implemented in a technology-enhanced science curriculum or merged in an inquiry-based science curriculum. The purpose of this study was to examine the role students' different levels of scientific epistemic beliefs (SEBs) play in their online information searching strategies and behaviors. Based…

  20. Visual detection of spatial contrast patterns: evaluation of five simple models

    NASA Technical Reports Server (NTRS)

    Watson, A. B.

    2000-01-01

    The ModelFest Phase One dataset is a collection of luminance contrast thresholds for 43 two-dimensional monochromatic spatial patterns confined to an area of approximately two by two degrees. These data were collected by a collaboration among twelve laboratories, and were designed to provide a common database for calibration and testing of spatial vision models. Here I report fits of the ModelFest data with five models: Peak Contrast, Contrast Energy, Generalized Energy, a Gabor Channels model, and a Discrete Cosine Transform model. The Gabor Channels model provides the best fit, though the other, simpler models, with the exception of Peak Contrast, provide remarkably good fits as well. Though there are clear individual differences, regularities in the data suggest the possibility of constructing a standard observer for spatial vision. c2000 Optical Society of America.