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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Respostas corticais hemodinâmicas a estímulos de movimento aparente em tarefas de percepção temporal

Giorjiani, Giuliana Martinatti January 2017 (has links)
Orientador: Dr. Marcelo Salvador Caetano / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Neurociência e Cognição, 2017. / A percepção de movimento pode alterar a percepção do tempo. Existem diferentes categorias de estímulos de movimento, entre eles: o movimento biológico (representação humana do movimento) e o movimento não biológico (qualquer outro tipo de representação do movimento não humano). Estudos de neuroimagem sugerem que algumas áreas corticais apresentam respostas mais evidentes para estímulos de movimento biológico (Sulco Temporal Superior ¿ STS) enquanto outras preferem o movimento não biológico (Giro Temporal Médio ¿ MTG, do inglês). Dado esses achados, o presente estudo se propôs primeiramente a investigar se categorias distintas de movimento (biológico e não biológico) poderiam modular a percepção de tempo de forma diferente. Além disso, o estudo também se propôs a examinar o padrão das respostas corticais hemodinâmicas das áreas STS e MTG durante a exposição aos estímulos de movimentos biológicos e não biológicos entre diferentes velocidades aparentes. O principal achado deste estudo refere-se à descrição de diferenças na distorção temporal entre estímulos com representação de movimento biológico e não biológico, em velocidades em que o movimento é julgado mais natural e plausível. Os resultados fisiológicos também sugerem uma diferença na atividade cortical hemodinâmica frente a estímulos com diferentes intensidades de movimento, além de mostrar correlações entre a percepção temporal e respostas fisiológicas. / The perception of motion can distort time perception. There are several categories of motion stimuli such as biological motion (human representation of motion) and non-biological motion (any other type of representation of non-human things). Neuroimaging studies suggest that some cortical areas in the brain are more responsive to stimuli of biological motion (Superior Temporal Sulcus), while others are more responsive to non-biological motion stimuli (Middle Temporal Gyrus). The present study has investigated if different categories of stimuli (biological and non-biological) can distort time perception in different manners. Furthermore, this study also investigated the patterns of hemodynamic responses in the STS and MTG areas while participants watched stimuli presented at different speeds. The main result was the difference in the temporal distortion caused by stimuli representing biological and non-biological motion in speeds in which the movement was judged to be natural and plausible. Physiological results suggest differences in hemodynamic responses during observation and performance in the time-reproduction task, and show correlations between temporal perception and cortical hemodynamic responses.
182

O efeito modulatório de ações motoras em latências perceptivas visuais. / The modulation of visual perceptual latencies by motor actions.

Hamilton Haddad Junior 10 November 2008 (has links)
Organismos são capazes de diferenciar estímulos sensoriais gerados independentemente pelo ambiente dos estímulos causados por sua própria ação no mundo. Esse processo depende de mecanismos neurais e cognitivos que unam suas ações às percepções por elas geradas. Objetivo desse trabalho foi investigar a interação da ação com a percepção visual no domínio temporal. Em cinco experimentos psicofísicos, foi estudado o efeito modulatório da ação no efeito flash-lag e em tarefas envolvendo estimativas de intervalos temporais. Nossos resultados mostraram que o planejamento e/ou execução de atos motores voluntários são capazes de reduzir em algumas dezenas de milissegundos as latências com que estímulos visuais são percebidos e também de reduzir as estimativas de intervalos temporais. A redução dessas latências é maior quando a conseqüência sensorial da ação é apresentada na fóvea, assim como quando existe um atraso entre a ação e o estímulo por ela causado. / Organisms are able to distinguish between sensory stimuli from the environment and sensory stimuli they cause. This process depends on neural and cognitive mechanisms that link actions to perceptions generated by these actions. This work aimed to investigate the interaction of action and perception in the temporal domain. In five psychophysical experiments, we have assessed the modulation of action in the flash-lag effect and in tasks involving temporal interval estimations. Our results showed that the planning and execution of a voluntary motor action are capable of reducing both visual perceptual latencies and temporal interval estimations. This reduction increases when the sensory consequences of motor actions are presented on the fovea and when a delay is injected between the action and the stimuli caused by it.
183

The Impact of Waiting Time Distributions on QoE of Task-Based Web Browsing Sessions / Påverkan av väntetiden distributioner på QoE av Task-Based Web webbläsning

Islam, Nazrul, Elepe, Vijaya John David January 2014 (has links)
There has been an enormous growth in the Internet usage in recent years, fueled by the increasing number of multimedia applications and widespread availability of World Wide Web (WWW). The end-user generally accesses these applications through web browsing activities. These time-critical services often suffer from the delays ranging from small chunks to long peaks which can have severe implications on the Quality of Experience (QoE). Hence, it is worthwhile to identify the impact of different variations of delay on the end-user QoE. This research focused on the end-user QoE for three different distributions of delays occurring during an e-commerce shopping experiment. By keeping the overall waiting time of every sessions same, the study shows that the end-user QoE is different for different variety of delays. And the research also concludes that, the users prefer small frequently occurring delays as compared to the long rarely occurring delays within a task-driven web browsing session.
184

Rosângela Rennó = fotografia, deslocamentos e desaparição na arte contemporânea brasileira = Rosângela Rennó: photography, displacements and disappearance in brazilian contemporary art / Rosângela Rennó : photography, displacements and disappearance in brazilian contemporary art

Mendes, Talita, 1985- 24 August 2018 (has links)
Orientador: Maria de Fátima Morethy Couto / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-24T11:13:41Z (GMT). No. of bitstreams: 1 Mendes_Talita_M.pdf: 6181643 bytes, checksum: 13de2f327820836fe396de02355bc780 (MD5) Previous issue date: 2014 / Resumo: Esta pesquisa tem por objeto a análise de três instalações realizadas pela artista brasileira Rosângela Rennó ¿ a saber: Imemorial (1994-1995), In Oblivionem (1994-1995) e Hipocampo (1995) ¿ com o propósito de compreender as investigações da artista em torno da imagem fotográfica e das implicações de seu uso no que concerne aos conceitos de memória, deslocamento e estética da desaparição na arte contemporânea. Além das citadas obras deve-se considerar, para efeito analítico, o work in progress da artista, seu Arquivo Universal (desde 1992), por se tratar de coleção pessoal de notícias de jornal que, frequentemente, é revisitada para a elaboração das obras. Fundamental para a pesquisa é a análise do posicionamento de Rennó enquanto colecionadora de ruínas (fotografias descartadas e outros resíduos culturais), de modo a problematizar a tensão existente entre duas formas de coleção que implicam maneiras diferentes de lidar com o tempo e a história: têm-se a dimensão singular e afetiva das coleções da artista como uma prática da memória ¿ fragmentária por excelência ¿ e a organização de suas instalações nos espaços destinados às exposições de arte (galerias e museus), em que prevalece o discurso pautado na linearidade histórica. O papel da artista, que é discutido na pesquisa, coincide, a meu ver, com o contratipo positivo do colecionador, definido por Walter Benjamin como aquele que descarta a função utilitária dos objetos ligando o ato de colecionar a uma percepção dialética do tempo, não linear. A este posicionamento da artista está associado o conceito de desaparição do teórico da cultura e urbanista Paul Virilio, importante para a análise das manipulações que Rosângela Rennó exerce nas imagens das quais se apropria / Abstract: In this research were analyzed three installations made by the Brazilian artist Rosângela Rennó ¿ Imemorial (1994-1995), In Oblivionem (1994-1995) and Hipocampo (1995) ¿ aiming to understand the artist's investigations about the photographic image and the implication of its uses when related to memory, displacement and aesthetics of disappearance concepts in contemporary art. Besides the mentioned works, the artist's work in progress Arquivo Universal (since 1992) is also considered in the analysis, once it consists in her personal collection of news articles which are usually consulted during the conception of her works. It¿s fundamental for this research the analysis of Rennó's position as a collector of ruins (wasted photos and other cultural remains) to problematize the tension between the two types of collection, which mean different ways to deal with time and history: there is the unique and affectionate dimension of the artist's collection as a memory practice ¿ fragmentary par excellence ¿ and the organization of her installations in spaces for art expositions (galleries and museums), where the historical linear discourse is predominant. The role of the artist, which is discussed during this research, coincides with the positive countertype of the collector, defined by Walter Benjamin as the one who discards the utility functions of the objects, connecting the action of collecting to a nonlinear dialectical perception of time. The artist's position is related to the disappearance concept thought by the cultural theorist and urbanist Paul Virilio, important for the analysis of the alterations Rosângela Rennó does in the images she appropriates / Mestrado / Artes Visuais / Mestra em Artes Visuais
185

Stratégie de navigation sûre dans un environnement industriel partiellement connu en présence d’activité humaine / Safe navigation strategy in a partially known industrial environment in the presence of human activity

Burtin, Gabriel Louis 26 June 2019 (has links)
Dans ces travaux, nous proposons un système sûr pour la localisation de robot mobile en milieu intérieur structuré. Le principe repose sur l’utilisation de deux capteurs (lidar et caméra monoculaire) combinés astucieusement pour assurer une rapidité de calcul et une robustesse d’utilisation. En choisissant des capteurs reposant sur des principes physiques différents, les chances qu'ils se retrouvent simultanément perturbés sont minimes. L’algorithme de localisation doit être rapide et efficient tout en conservant la possibilité de fournir un mode dégradé dans éventualité où l’un des capteurs serait endommagé. Pour atteindre cet objectif de localisation rapide, nous optimisons le traitement des données à divers niveaux tels que la quantité de données à traiter ou l’optimisation algorithmique. Nous opérons une approximation polygonale des données du lidar 2D ainsi qu’une détection des segments verticaux dans l’image couleur. Le croisement de ces deux informations, à l’aide d’un filtre de Kalman étendu, nous donne alors une localisation fiable. En cas de perte du lidar, le filtre de Kalman peut toujours fonctionner et, en cas de perte de la caméra, le robot peut faire un recalage laser avec le lidar. Les données des deux capteurs peuvent également servir à d’autres objectifs. Les données lidar permettent d’identifier les portes (points de collision potentiels avec des humains), les données caméra peuvent permettre la détection et le suivi des piétons. Les travaux ont été majoritairement menés et validés avec un simulateur robotique avancé (4DV-Sim) puis ont été confirmés par des expériences réelles. Cette méthodologie permet à la fois de développer nos travaux et de valider et améliorer le caractère fonctionnel de cet outil de robotique. / In this work, we propose a safe system for robot navigation in an indoor and structured environment. The main idea is the use of two combined sensors (lidar and monocular camera) to ensure fast computation and robustness. The choice of these sensors is based on the physic principles behind their measures. They are less likely to go blind with the same disturbance. The localization algorithm is fast and efficient while keeping in mind the possibility of a downgraded mode in case of the failure of one sensor. To reach this objective, we optimized the data processing at different levels. We applied a polygonal approximation to the 2D lidar data and a vertical contour detection to the colour image. The fusion of these data in an extended Kalman filter provides a reliable localization system. In case of a lidar failure, the Kalman filter still works, in case of a camera failure the robot can rely upon a lidar scan matching. Data provided by these sensors can also deserve other purposes. The lidar provides us the localization of doors, potential location for encounter with humans. The camera can help to detect and track humans. This work has been done and validated using an advanced robotic simulator (4DV-Sim), then confirmed with real experiments. This methodology allowed us to both develop our ideas and confirm the usefulness of this robotic tool.
186

Action, Prediction, or Attention: Does the “Egocentric Temporal Order Bias” Support a Constructive Model of Perception?

January 2020 (has links)
abstract: Temporal-order judgments can require integration of self-generated action-events and external sensory information. In a previous study, it was found that participants are biased to perceive one’s own action-events to occur prior to simultaneous external events. This phenomenon, named the “Egocentric Temporal Order Bias”, or ETO bias, was demonstrated as a 67% probability for participants to report self-generated events as occurring prior to simultaneous externally-determined events. These results were interpreted as supporting a feed-forward, constructive model of perception. However, the empirical data could support many potential mechanisms. The present study tests whether the ETO bias is driven by attentional differences, feed-forward predictability, or action. These findings support that participants exhibit a bias due to both feed-forward predictability and action, and a Bayesian analysis supports that these effects are quantitatively unique. Therefore, the results indicate that the ETO bias is largely driven by one’s own action, over and above feed-forward predictability. / Dissertation/Thesis / Masters Thesis Psychology 2020
187

Visualizing Time : Visualizing Time through Location Based Habits and Routines / Tidsvisualisering : Tidsvisualisering genom platsbaserade vanor och rutiner

Rönnmark, Marcus January 2016 (has links)
Mobile devices have become a massively prevalent part of everyday life, as their capabilities and functionality have expanded into new domains. One form factor that has attracted recent renewed interest is the smartwatch.  This paper looks at how devices can be used to track the time, and in particular how we can invent new visualisations for timekeeping. It draws on different psychological theories of time to sketch out six new time visualisations, drawing on both old and new timekeeping devices as inspiration. These visualisations address linear time visualisations and cyclical time visualisations. The designs are contrasted with each other, with a final design selected and prototyped on the Apple Watch. The prototype is briefly evaluated through a 48 hour user test with one user. The design is then reiterated upon based on the feedback from this user test. / Mobila enheter har blivit en allt större del av våra vardagliga liv i samma takt som deras kapacitet och funktionalitet har ökat och spridit sig till nya områden. Ett av dessa områden som nyligen fått ett nyfunnet intresse är smarta klockor. Den här uppsatsen tittar på hur mobila enheter och framför allt smarta klockor kan användas för att hålla reda på tiden. Den undersöker framför allt på hur vi kan ta fram nya sätt att visualisera tid. Arbetet bygger på olika psykologiska teorier om tid för att skissa sex stycken olika tidsvisualiseringar, de olika visualiseringarna använder också historiska tidmätningsinstrument som inspiration. Dessa visualiseringar bygger också på ett framtaget koncept om att tid kan ses som konstant eller cyklisk. Designförslagen jämförs sedan med varandra och en slutgiltig design väljs ut. En prototyp för Apple Watch skapas, baserat på den slutgiltiga designen. Prototypen utvärderas genom att en användare bär klockan under 48 timmar. Därefter förbättras och förändras designen baserat på återkopplingen från testet.
188

The perceived timing of events across different sensory modalities. A psychophysical investigation of multisensory time perception in humans.

Hanson, James Vincent Michael January 2009 (has links)
The experiments reported within this thesis use psychophysical techniques to examine the factors which determine perceived multisensory timing in humans. Chapters 1 and 2 describe anatomical and psychophysical features of temporal processing, respectively, whilst Chapter 3 introduces the reader to psychophysical methods. Chapter 4 examines the relationship between two measures of sensory latency, reaction time (RT) and crossmodal temporal order judgment (TOJ). Despite task and attentional manipulations the two measures do not correlate, suggesting that they measure some fundamentally different aspect(s) of temporal perception. Chapter 5 examines the effects of adaptation to asynchronous stimulus pairs on perceived audiovisual (AV), audiotactile (AT) and visuotactile (VT) temporal order. Significant temporal shifts are recorded in all three conditions. Evidence is also presented showing that crossmodal TOJs are intransitive. Chapter 6 shows that concurrent adaptation to two sets of asynchronous AV stimulus pairs causes perceived AV temporal order to recalibrate at two locations simultaneously, and that AV asynchrony adaptation effects are significantly affected by observers¿ attention during adaptation. Finally, Chapter 7 shows that when observers are accustomed to a physical delay between motor actions and sensory events, an event presented at a reduced delay appears to precede the causative motor action. The data are well-described by a simple model based on a strong prior assumption of physical synchrony between motor actions and their sensory consequences.
189

Examining the Description-Experienced Gap in Time Discounting and itsPossible Mechanisms

Xu, Ping 13 July 2018 (has links)
No description available.
190

Attention regulates the plasticity of multisensory timing

Heron, James, Roach, N.W., Whitaker, David J., Hanson, James Vincent Michael January 2010 (has links)
No / Evidence suggests than human time perception is likely to reflect an ensemble of recent temporal experience. For example, prolonged exposure to consistent temporal patterns can adaptively realign the perception of event order, both within and between sensory modalities (e.g. Fujisaki et al., 2004 Nat. Neurosci., 7, 773-778). In addition, the observation that 'a watched pot never boils' serves to illustrate the fact that dynamic shifts in our attentional state can also produce marked distortions in our temporal estimates. In the current study we provide evidence for a hitherto unknown link between adaptation, temporal perception and our attentional state. We show that our ability to use recent sensory history as a perceptual baseline for ongoing temporal judgments is subject to striking top-down modulation via shifts in the observer's selective attention. Specifically, attending to the temporal structure of asynchronous auditory and visual adapting stimuli generates a substantial increase in the temporal recalibration induced by these stimuli. We propose a conceptual framework accounting for our findings whereby attention modulates the perceived salience of temporal patterns. This heightened salience allows the formation of audiovisual perceptual 'objects', defined solely by their temporal structure. Repeated exposure to these objects induces high-level pattern adaptation effects, akin to those found in visual and auditory domains (e.g. Leopold & Bondar (2005) Fitting the Mind to the World: Adaptation and Aftereffects in High-Level Vision. Oxford University Press, Oxford, 189-211; Schweinberger et al. (2008) Curr. Biol., 18, 684-688).

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