Number Of Target Locations Research Articles

Developing a Screening Tool for Areas of Abnormal Central Vision Using Visual Stimuli With Natural Scene Statistics.

PurposePrevious studies show that some visual field (VF) defects are detectable from visual search behavior; for example, when watching video. Here, we developed and tested a VF testing approach that measures the number of fixations to find targets on a background with spatial frequency content similar to natural scenes.MethodsTwenty-one older controls and 20 people with glaucoma participated. Participants searched for a Gabor (6 c/°) that appeared in one of 25 possible locations within a 15° (visual angle) 1/f noise background (RMS contrast: 0.20). Procedure performance was assessed by calculating sensitivity and specificity for different combinations of control performance limits (p = 95%, 98%, 99%), number of target locations with fixations outside control performance limits (k = 0 to 25) and number of repeated target presentations (n = 1 to 20).ResultsControls made a median of two to three fixations (twenty-fifth to seventy-fifth percentile: two to four) to locate the target depending on location. A VF was flagged “abnormal” when the number of fixations was greater than the p = 99% for k = 3 or more locations with n = 2 repeated presentations, giving 85% sensitivity and 95.2% specificity. The median test time for controls was 85.71 (twenty-fifth to seventy-fifth percentile: 66.49–113.53) seconds.ConclusionOur prototype test demonstrated effective and efficient screening of abnormal areas in central vision.Translational RelevanceVisual search behavior can be used to detect central vision loss and may produce results that relate well to performance in natural visual environments.

Decreased working memory capacity among individuals with a mood disorder who have increased metabolic burden

BackgroundIndividuals with mood disorders experience a higher rate of obesity than the general population, putting them at risk for poorer outcomes. The relationship between obesity and a core feature of the mood disorders, neurocognition, is less understood. We examined the interaction of obesity as indexed by body mass index (BMI) and working memory performance in a large sample of individuals with bipolar disorder (BD), major depressive disorder (MDD), and healthy controls (HC). MethodsParticipants with BD (n = 133), MDD (n = 78), and HC (n = 113) (age range 18–40) completed a spatial working memory (SWM) task that included three-graded increases in the number of target locations. Participants were subdivided by BMI classification into six diagnostic-BMI (BMI groups: Normal Weight, Overweight/Obese) subgroups. Performance on the task was indexed by number of errors within each difficulty level. ResultsThe number of errors, across all groups, increased with task difficulty. There was an interaction between errors and diagnostic-BMI group. Post-hoc analyses indicated that while the Normal Weight-BD group did not differ in performance from the other groups, the Overweight/Obese-BD group performed significantly worse than HC groups. LimitationsMetabolic effects of psychotropic medications due to the naturalistic nature of the study, younger age of the MDD sample, and utilizing self-reported indicators of obesity may limit generalizability. ConclusionsIndividuals with BD with increased metabolic burden exhibit increased working memory errors than non-psychiatric controls who also have increased metabolic burden. Future work could address prevention and amelioration of such difficulties to reduce associated functional morbidity.

A Model-Based Design System for Terrestrial Laser Scanning Networks in Complex Sites

With the rapid increase of terrestrial laser scanner (TLS) applications, especially for the high-accuracy modelling of large-volume objects, a design system is needed to provide solutions for both scanner and target placement that can meet the project requirements in terms of completeness, precision, economy, and reliability. In this paper, a hierarchical strategy driven by an improved optimization method is developed to solve the TLS viewpoint planning problem. In addition, the placement of the targets is determined by optimizing the target arrangement criterion, and the number of target locations is minimized by accepting the close to optimal target arrangements. Finally, the quality of the design, including the sensitivity of the object coverage to viewpoint placement and the precision of the point cloud are provided. Two building complexes located on University of Calgary campus are used as the experimental datasets in this research. The designs for scanner placement are compared with the “brute force” strategy in terms of the optimality of the solutions and runtime. The results showed that the proposed strategy provided scanning networks with a compatible quality but with more than 80% time savings in design. The number of targets necessary for registration from our system is surprisingly small, considering the volume and complexity of the networks. Through the quality assessments, the sensitivity of the object coverage to the scanner placement indicates how careful the field crew should be when placing the scanner for data capture, and the point cloud precision indicates if the network design can meet the project requirements.

The role of the subthalamic nucleus in multi-alternative perceptual decision making revealed by 7T structural and functional MRI

Event Abstract Back to Event The role of the subthalamic nucleus in multi-alternative perceptual decision making revealed by 7T structural and functional MRI Max Keuken1*, Robert Turner2, Leendert Van Maanen1, Rafal Bogacz3, Andreas Schafer2, Jane Neumann2 and Birte U. Forstmann1 1 University of Amsterdam, Netherlands 2 Max-Planck Institute for Human Cognitive and Brain Sciences, Germany 3 University of Bristol, United Kingdom Recently, quantitative mathematical and neurocomputational models have been developed that make predictions about the latent psychological processes and brain structures involved in multiple alternative decision-making. In particular, the subthalamic nucleus (STN), a small structure in the basal ganglia (BG), is hypothesized to become more active with an increasing amount of choice alternatives. This increase of activity is thought to reflect a decrease in baseline activity causing a delayed response of the output nuclei of the BG so that more evidence can be accumulated in favor of the correct response. In the present study, first the behavioral data were fit with the linear ballistic accumulator (LBA) model to capture the latent psychological processes involved in multiple alternative perceptual decision-making. Secondly, ultra-high resolution 7T functional and structural MRI data were collected to test our STN hypotheses. The best fitting LBA model parameters indicate that the threshold increases and the drift rate decreases with the number of target locations. 7T functional data showed higher stimulus-related activation with an increase of choice alternatives only in the right STN. As predicted, the STN becomes more active when the number of choice alternatives increases. This increase in activity is thought to reflect a decrease in baseline activity causing a delayed response of the output nuclei of the BG so that more evidence can be accumulated in favor of the correct response. These results are also captured by the LBA model fits as the drift rate decreases and the threshold increases due to a prolonged decision process. In sum, the present study highlights the functional role of the STN in multiple alternative perceptual decision-making. Funding: Supported by the Research Priority Program Brain & Cognition at the University of Amsterdam. Keywords: decision-making, MRI Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Decision Making, Reward Processing & Response Selection Citation: Keuken M, Turner R, Van Maanen L, Bogacz R, Schafer A, Neumann J and Forstmann BU (2011). The role of the subthalamic nucleus in multi-alternative perceptual decision making revealed by 7T structural and functional MRI. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00388 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 24 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Dr. Max Keuken, University of Amsterdam, Amsterdam, Netherlands, mckeuken@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Max Keuken Robert Turner Leendert Van Maanen Rafal Bogacz Andreas Schafer Jane Neumann Birte U Forstmann Google Max Keuken Robert Turner Leendert Van Maanen Rafal Bogacz Andreas Schafer Jane Neumann Birte U Forstmann Google Scholar Max Keuken Robert Turner Leendert Van Maanen Rafal Bogacz Andreas Schafer Jane Neumann Birte U Forstmann PubMed Max Keuken Robert Turner Leendert Van Maanen Rafal Bogacz Andreas Schafer Jane Neumann Birte U Forstmann Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

가상 환경에서의 효과적인 네비게이션을 위한 도구 분석

This study examines different types of navigation aids when a navigator performs target search tasks in Virtual Environments. The factors manipulated in this study include target information (None/Landmark). navigational difficulty (Easy/Difficult). and map types (None/2D Map/3D Map). Navigation performance was measured by using task completion time and the number of target locations that was remembered by the navigator. In addition, user satisfaction on the navigation aids was also measured by using a 7-point Likert`s scale. The results showed that the user satisfaction on the landmark was high when the 3D Map was provided. The task completion time shortened when navigational difficulty was set at easy. The number of remembered target locations was large when there was no landmark. It was also large with an easy navigation task. or a map (20 or 3D) provided. Guidelines for selecting navigation aids were proposed based on the results.

The spatial relationship between cues and targets mediates inhibition of return.

Abstract Although inhibition of return (IOR) has been examined in a number of experimental circumstances, it is not known if the number of potential target locations affects the magnitude of the inhibition at a cued location. To investigate this issue, participants were randomly presented with displays of two, four, or six potential target locations in a typical IOR detection task. The findings indicated that number of target locations did not affect IOR and that RTs at uncued locations varied systematically as a function of the spatial relationship between the cued and uncued location. Resume Bien que l'inhibition du retour (IOR) ait ete etudiee dans differents contextes experimentaux, on ne sait pas si le nombre d'emplacements possibles des cibles a un effet sur l'importance de l'inhibition a un emplacement marque par un indice. Pour approfondir l'examen de la question, on a presente aux participants des series de 2, 4 ou 6 emplacements possibles de cibles dans le contexte d'une tache typique de detection IOR. Les resultats indiquent que le nombre d'emplacements des cibles n'influe pas sur l'inhibition du retour et que le temps de reponse, pour les emplacements sans indice, varie systematiquement en fonction de la relation spatiale entre les emplacements accompagnes et non accompagnes d'indices. A considerable amount of research has examined inhibition of return (IOR) since the discovery of the phenomenon by Posner and Cohen in 1984. Posner and Cohen found that targets were detected more slowly at locations that had previously been cued when the delay between the presentation of the cue and the target exceeded 300 ms. They coined the term IOR for the effect, referring to their original notion that attention was inhibited to return to previously attended locations. Presumably, this inhibition occurred to make visual or attentional searches more efficient by biasing attention toward novel locations and away from previously inspected locations. It is because of this implication that IOR has been a topic for researchers in visual attention for more than a decade. Despite the wealth of research that has been conducted on IOR, some basic questions regarding the inhibitory effect have remained unasked and, consequently, unanswered. One of these questions is: Does the number of potential target locations affect IOR? This is a pertinent question because studies that have examined IOR have used anywhere from two (e.g., Maylor, 1984) to eight (e.g., Wright & Richard, 1996) potential target locations. Without knowing whether the number of potential target locations does or does not affect IOR, it is difficult to examine and interpret the different inhibitory effects produced between various experimental conditions. In addition to the pragmatic reasons for examining the effect of various possible target locations on IOR, there are also theoretical reasons to suggest that the number of locations may, or may not, differently affect IOR. On the one hand, if IOR does reflect the output of an attentional mechanism that improves searches, one might expect that the number of locations where the target might potentially occur would have a negative influence on the magnitude of IOR. Assuming that some amount of attention is allocated to each target location placeholder in a display, larger number of placeholders should require a greater proportion of the available attentional resources. This leads to a situation in which the amount of inhibition might be expected to decrease with increasing numbers of potential target locations because it would become more difficult to keep track of novel and previously attended locations. On the other hand, it may be that previously attended locations are tagged with inhibitory tags that require relatively little cognitive overhead, making the number of potential target locations largely irrelevant. For example, Klein and Taylor (1994) suggested that IOR occurs when eye movements are planned, but not executed, toward a specific location. …