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Conduire un véhicule dans le brouillard requiert d’intégrer de l’information visuelle bruitée avec des attentes sur la scène routière pour rechercher des indices visuels importants pour la navigation. Les tâches d’identification et de recherche visuelle peuvent être vues comme des processus de prise de décision où l’information est accumulée et où des attentes sur l’objet et son contexte sont intégrées. L’accumulation d’information est souvent modélisée comme un processus passif. Cette thèse vise à mettre en avant des mécanismes actifs, intégrant les attentes sur la cible (sur sa position, sur son identité) et de l’information sensorielle dégradée (e.g., brouillard). Nous avons employé le paradigme de mouse-tracking, permettant d’inférer des aspects dynamiques du processus de prise de décision via les mouvements de la souris d’ordinateur. L’Étude 1 évalue l’effet du contexte dans la catégorisation de cible et suggère un compromis entre rapidité et exactitude de l’accumulation d’évidence pouvant être vu comme influençant activement la décision. Mais elle n’évalue pas directement la collecte active d’évidence. Les Études 2 et 3 incluent la mesure de la détection et vérification de la cible via les mouvement des yeux lors de la recherche visuelle dans des scènes dégradée. Les attentes sur la localisation (Étude 2) et sur l’identité de la cible (Étude 3) sont manipulées. Ces études éclairent les contributions de la détection et de la vérification dans l’accumulation d’évidence pour la réponse cible absente et cible présente. Pour conclure, nous proposons une ébauche de modèle de prise de décision intégrant une dynamique entre accumulation d’évidence et système oculomoteur. / Driving a vehicle in the fog requires the integration of noisy visual information with expectations about the visual road scene, in order to search for visual clues important for navigating. The visual search and identification of relevant objects can be seen as decision-making processes where sensory information is accumulated and where the expectations about the target object and its context are integrated. The accumulation of information is often modelled as a passive process. This thesis focuses on the contribution of active mechanisms integrating expectations about the target (its identity, its location) with degraded sensory information (with fog or artificial noise). We used the mouse-tracking paradigm, allowing to infer dynamic aspects of the decision-making process through a computer mouse movements. Study 1 evaluates the effect of the context for categorizing a target and suggests a trade-off between the speed and accuracy of the evidence accumulation process which can be seen as actively influencing the decision. But this study cannot directly evaluate the active collection of evidence. In Studies 2 and 3, target detection and verification are directly measured through eye movements during visual search tasks in visually degraded scenes. We manipulated the expectations about the location (Study 2) and the target’s identity (Study 3). These studies emphasize the contributions of the detection and verification processes in the accumulation of evidence toward the target present and target absent responses. In conclusion, we propose the draft of a decision-making model which integrates the dynamics between the accumulation of evidence, and the oculomotor system.

根據恐懼管理理論（Terror Management Theory, 1986）人們會適時地管理死亡想法的威脅，故Pyszczynski、Greenberg及Solomon（1999）依據此理論提出了一套雙元歷程模式來解釋人們的防衛方式：近端防衛與遠端防衛。在遠端防衛中文化世界觀尤為重要，在過去的西方研究之中，發現人們常以對自身文化世界觀持正向或偏好的態度，來防衛死亡想法的威脅；然而這樣的現象卻在亞洲研究中難以得到驗證，因此本研究的目的即在於重新檢驗文化世界觀的防衛方式。本研究操弄參與者的死亡想法，並藉由分心作業的方式，使其死亡想法掉入意識邊陲之中，以探究遠端防衛的本質。本研究除了以偏好的評估作為依變項外，且從認知的注意力面向出發，探討文化世界觀與防衛死亡想法之間的關係。本研究設計兩個實驗：實驗一以視覺搜尋作業的派典進行研究，以對自身文化的偏好、正確率與反應時間當作依變項。結果發現當參與者進行遠端防衛時，會對於與自身文化有關的線索，表現出較高的正確率，但在對自身文化的偏好，與反應時間的變項上，未能發現有顯著差異。實驗二以眼動追蹤儀器當作研究工具，並以眼動指標中首次凝視位置的數量，以及凝視時間作為依變項。結果發現當參與者進行遠端防衛時，會對於與自身文化有關的線索，表現出較長的凝視時間，但在首次凝視位置的數量上，亦未能發現有顯著差異。因此，綜合以上兩個實驗，本研究並未能完全支持文化世界觀的遠端防衛效果。 / According to terror management theory (1986), people can manage the threat from death thought. Thus, Pyszczynski, Greenberg, & Solomon (1999) proposed a dual-process model to explain how people defend the death. There are two defense routes: the proximal defense and the distal defense. The culture-worldview is an important function in the distal defense. In the western research, it was found that people were more positive or preferred to self-culture-worldview. However, there are mixed findings in the eastern research. In order to investigate the distal defense mechanism, this study manipulated participants’ death thought, and let the thought drop into the unconscious level via a distracting task. Furthermore, this study examined the relationship between the culture-worldview and the death defense from attentional paradigms. We conducted two experiments. In the first experiment, we adopted the visual search paradigm, and the dependent variables were self-cultural preference, reaction time and the rate of accuracy. We found it was more accurate when participants were asked to search the self-related cultural cue after reminding one’s death comparing to those are not reminding about death. But they were no significant difference in the self-cultural preference and reaction time. In the second experiment, we adopted the eye-tracker as the instrument, and the dependent variables were the index of number of first fixation and the duration of fixations. We found the fixation duration was longer for the self-related cultural cues than for the non-self-related cultural cues when participants being reminded about one’s death. But it was no significant difference in the number of first fixation. So, through these two experiments we found an inconsistent result in the distal defense.

Made available in DSpace on 2016-12-12T20:22:52Z (GMT). No. of bitstreams: 1 Eduardo B Viecilli.pdf: 12003318 bytes, checksum: 049902e80d65ca85726715d69e30469a (MD5) Previous issue date: 2014-03-17 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Mobile robots should be able to seek (explore the environment and recognize the objects) autonomously and efficiently. This work developed a mobile robot capable of performing the search for a 3D object in an unknown environment, using only one depth camera (RGB + Depth) as sensor and executing a strategy of active vision. The Microsoft Kinect was adopted as sensor. Also a mobile robot (XKBO) was build using the Robot Operating System (ROS), and with its architecture adapted from the norm STANAG 4586. A new active exploration strategy was developed in which considers the effort of the robot to move to the frontier regions (occult areas), and the presence of traces of the object. The metrics used demonstrated that the use of depth cameras for visual search tasks have a potential for deployment because associates visual and depth information, allowing the robot to better understand the environment and the target object of the search. / Robôs móveis devem ter a capacidade de buscar (explorar o ambiente e reconhecer objetos) de forma autônoma e eficiente. Este trabalho desenvolveu um robô móvel capaz de executar a busca a um objeto (3D) em ambiente desconhecido, utilizando somente uma câmera de profundidade (RGB + distancia) como sensor e executando uma estratégia de visão ativa. A Microsoft Kinect foi a câmera adotada. Também construiu-se um robô móvel (XKBO) que utiliza o Sistema Operacional Robótico (ROS), e com a arquitetura adaptada da norma STANAG 4586. Foi possível usar algoritmos existentes para reconhecer objetos 3D usando o Kinect graças as ferramentas presentes no ROS. E o uso do Kinect facilitou a geração de mapas do ambiente. Desenvolveu-se uma nova estratégia de exploração ativa que considera o esforço de movimentação para as regiões de fronteiras (áreas ocultas), e a existência de indícios da presença do objeto. As métricas utilizadas demonstram que o uso de câmeras de profundidade para tarefas de busca tem potencial para evolução por associar informação visuais com as de profundidade, permitindo que o robô possa entender o ambiente e o objeto alvo da busca. Palavras-chave: Robô Móvel. Exploração. Busca Visual. Câmera RGB-D.

Our vision is as yet unsurpassed by machines because of the sophisticated representations of objects in our brains. This representation is vastly different from a pixel-based representation used in machine storages. It is this sophisticated representation that enables us to perceive two faces as very different, i.e, they are far apart in the “perceptual space”, even though they are close to each other in their pixel-based representations. Neuroscientists have proposed distances between responses of neurons to the images (as measured in macaque monkeys) as a quantification of the “perceptual distance” between the images. Let us call these neuronal dissimilarity indices of perceptual distances. They have also proposed behavioural experiments to quantify these perceptual distances. Human subjects are asked to identify, as quickly as possible, an oddball image embedded among multiple distractor images. The reciprocal of the search times for identifying the oddball is taken as a measure of perceptual distance between the oddball and the distractor. Let us call such estimates as behavioural dissimilarity indices. In this thesis, we describe a decision-theoretic model for visual search that suggests a connection between these two notions of perceptual distances. In the first part of the thesis, we model visual search as an active sequential hypothesis testing problem. Our analysis suggests an appropriate neuronal dissimilarity index which correlates strongly with the reciprocal of search times. We also consider a number of alternative possibilities such as relative entropy (Kullback-Leibler divergence), the Chernoff entropy and the L1-distance associated with the neuronal firing rate profiles. We then come up with a means to rank the various neuronal dissimilarity indices based on how well they explain the behavioural observations. Our proposed dissimilarity index does better than the other three, followed by relative entropy, then Chernoff entropy and then L1 distance. In the second part of the thesis, we consider a scenario where the subject has to find an oddball image, but without any prior knowledge of the oddball and distractor images. Equivalently, in the neuronal space, the task for the decision maker is to find the image that elicits firing rates different from the others. Here, the decision maker has to “learn” the underlying statistics and then make a decision on the oddball. We model this scenario as one of detecting an odd Poisson point process having a rate different from the common rate of the others. The revised model suggests a new neuronal dissimilarity index. The new dissimilarity index is also strongly correlated with the behavioural data. However, the new dissimilarity index performs worse than the dissimilarity index proposed in the first part on existing behavioural data. The degradation in performance may be attributed to the experimental setup used for the current behavioural tasks, where search tasks associated with a given image pair were sequenced one after another, thereby possibly cueing the subject about the upcoming image pair, and thus violating the assumption of this part on the lack of prior knowledge of the image pairs to the decision maker. In conclusion, the thesis provides a framework for connecting the perceptual distances in the neuronal and the behavioural spaces. Our framework can possibly be used to analyze the connection between the neuronal space and the behavioural space for various other behavioural tasks.

THIS THESIS IS IN THE EXAMINATION PROCESS The ability to locate symbols on a visual display forms an integral part of the effective use of AAC systems. Characteristics of display design and perceptual features of symbols have been shown to influence rate and accuracy of symbol location (Thistle&Wilkinson, 2009; Wilkinson, Carlin,&Jagaroo, 2006). The current study endeavoured to compare the use of two colour-coded organisational strategies (alphabetical order and subcategorisation) for their effectiveness in symbol location and to investigate if some bottom-up features influenced the performance of the participants in these tasks. 114 learners in Grade 1 to 3 in a mainstream school were randomly divided into two groups. Both of the groups were exposed to two visual search tests in alternating order. The tests involved searching for 36 visual targets amongst 81 coloured Picture Communication Symbols on a computer screen in one of two colour-coded organizational methods, namely alphabetical order or subcategorisation. The data from the research task was collected through computer logging of all mouse selections. Findings showed that locating symbols on a computer screen with a subcategorisation strategy was significantly faster and more accurate than with an alphabetical strategy for the Grade 1 to 3 participants. The differences between the rates and accuracy of target symbol location using the two strategies decreased significantly as grade increased. It was also found that although the tests in this study placed heavy top-down processing demands on the participants, there was still evidence of bottom-up factors influencing their performance. Implications for display design in AAC clinical practice were discussed. / Thesis (PhD)--University of Pretoria, 2012. / Centre for Augmentative and Alternative Communication (CAAC) / Unrestricted

Uma das tarefas básicas dos mecanismos atencionais é decidir qual a localização dentro do campo visual, em que devemos prestar atenção primeiro. Um objeto que contenha características distintas, tais como orientação, forma, cor, tamanho, brilho, textura, etc. diferentes, pode atrair a atenção de uma maneira \"bottom-up\". A informação \"top-down\" baseia-se no conhecimento prévio e tem uma grande influência nas localizações atendidas. Inspirado nos mecanismos da Atenção Visual Humana, embora sem a pretensão de simulá-la, este trabalho prevê o desenvolvimento de uma nova metodologia que integra os dois tipos de informações: \"bottom-up\" e \"top-down\". Características \"bottom-up\" são geradas a partir de Momentos e essas informações são utilizadas em mapas de saliência, enquanto que um conhecimento prévio é utilizado para gerar pistas \"top-down\". Neste trabalho, desenvolveu-se uma metodologia específica para a busca e o reconhecimento visual em cenas com múltiplos objetos, utilizando para isso uma rede \"fuzzy\" contendo três subsistemas \"fuzzy\". Dada uma imagem de entrada, o objetivo consiste em se detectar regiões que possam conter informações mais significativas, a fim de que se possa guiar e restringir processamentos mais complexos. A inclusão de mecanismos de atenção (seleção de uma região de interesse dentro da imagem) é de fundamental importância pois os resultados obtidos pelo método podem ser usados para controlar a aquisição da imagem de uma maneira dinâmica. O modelo proposto está estruturado em três estágios principais: O primeiro estágio consiste em se segmentar os objetos e extrair características globais dos mesmos baseadas principalmente na teoria dos momentos, tais como tamanho, orientação, formato e distância e também média de nível de cinza. Por intermédio da comparação de um objeto com os outros presentes na cena, características \"bottom-up\" de conspicuidade são usadas para guiar a atenção ao objeto mais diferente. Por intermédio do uso da lógica \"fuzzy\" é possível inferir com grande flexibilidade algumas regras de decisão baseadas nos princípios de percepção visual tais como as leis Gestalt. O segundo estágio consiste de um subsistema \"fuzzy top-down\" que combina diferentes características de acordo com a relevância das mesmas em diferentes tarefas. Finalmente, o terceiro estágio consiste de um subsistema \"fuzzy\" que integra as informações obtidas dos subsistemas anteriores e fornece um índice geral de saliência, e indica a provável localização do objeto a ser reconhecido. A nova abordagem foi testada com objetos geométricos levando-se em consideração as características que atraem a atenção dos serem humanos / One of the basic tasks assigned to the human attentional mechanisms is to decide which location in the visual field we must pay attention first. An object containing distinctive features (such as different orientation, shape, color, size, shine, texture, etc.) can attract attention in a bottom-up way. Top-down information is based on the previous knowledge and has a large influence on the attended locations. Inspired on human visual attention mechanisms, although it doesn\'t want simulate it, this work presents a new methodology to integrate two different kind of information: bottom-up and top-down. Bottom-up features are obtained from Moment Theory and this information is used in salience maps, while a previous knowledge is used to create top-down hints. In this work, an specific methodology to visual search and recognition was developed to be applied to scenes containing multiple objects by a fuzzy net with three fuzzy subsystems. The aim of this methodology is to detect regions that may contain the most significant information, in order to guide and to restrict most complex processing. The inclusion of attentional mechanisms (the selection of a region of interest in the image) is fundamental and can be used to control the image acquisition in a dynamic way. The proposed model is structured in three main stages. The first stage segments the objects and extracts global features of them, based on the Moment Theory such as size, orientation, shape and distance and gray level average. By comparing one object with the other ones present in the scene, bottom-up features of conspicuity are used to guide the attention to the most different object. The Fuzzy Logic allows us to infer with great flexibility some of decision rules based on the visual perception principles such as the Gestalt Laws. The second stage is a top-down fuzzy subsystem that combines different features according to the relevance of them in different tasks. Finally, the third stage is a fuzzy subsystem that integrates the information obtained from the previous sub-systems and gives us a general salience index. The new methodology was tested in geometrical objects considering the feature that attracts attention to human beings

本研究探討高齡者在視覺搜尋作業中，其由上而下（Top-down）與由下而上（Bottom-up）的注意力運作對於情緒刺激的反應，是否會因為注意力功能退化而與年輕成人的表現不同。過去研究指出，雖然高齡者注意力功能衰退，但是高齡者的由上而下注意力運作，仍可以幫助高齡者的表現。為了解由上而下注意力運作是否對於高齡者的反應有所幫助，本研究以兩個實驗分別探討內因與外因線索以及操弄訊息量所造成的影響。 實驗一包括80％有效的內因線索與25％有效的外因線索兩階段，外因線索階段為由下而上注意力運作，內因線索階段則為由上而下注意力運作，獨變項為年齡（高齡者、年輕成人）、情緒（生氣、快樂）以及線索有效情況（有效線索、中性線索、無效線索），記錄反應時間與正確率。實驗二的兩階段使用不同訊息量的外因線索（80％有效比例為高訊息量、25％有效比例為低訊息量），其餘操弄都與實驗一相同，低訊息量為單純的由下而上注意力運作，而高訊息量兼具由下而上與由上而下注意力運作。 研究結果發現，兩實驗高齡者與年輕成人都對於生氣情緒反應較快，符合威脅優勢。高齡者較年輕人更需要借助由上而下的注意力運作幫助反應，高訊息量的線索對於高齡者幫助也較年輕成人大。另外，實驗一增益效果的結果顯示，有效線索在高齡者搜尋生氣臉孔幫助較大，在年輕成人則搜尋快樂臉孔幫助較大，但是實驗二結果則顯示，有效線索在高齡者與年輕成人搜尋快樂臉孔的幫助都較生氣臉孔大，兩實驗的年齡與情緒的交互作用結果不同可能與高齡者異質性有關。由研究結果可知，由上而下注意力運作對於高齡者在情緒臉孔反應有幫助，在未來實務上，可以多運用由上而下注意力運作的線索幫助高齡者反應。 / This research is aim to understand attention in visual search of emotional faces in aging. Two types of attention process, that is top-down and bottom-up attention, were concerned in this study. In past researches, there are empirical evidences showing age-related declination in attention function, especially in bottom-up attention. But top-down attention is still playing an important role in doing task for the older adults. In order to understand the effect of top-down attention in aging, two experiments using endogenous or exogenous spatial cues were designed. Participants have to respond whether there is a different emotional face or not in a visual search task. The independent variables are age（aging and young）, emotional face（happy and angry）, and cue（valid, neutral, and invalid）. Dependent variables are reaction times and accuracy. In Experiment 1, there are two stages: 80％ valid endogenous cues and 25％ valid exogenous cues. The endogenous cues stage and exogenous cues stage were designed to probe top-down attention and bottom-up attention, respectively. In Experiment 2, there are two stages: 80％ valid exogenous cues（highly informative cues）and 25％ valid exogenous cues（non-informative cues）. Using highly informative exogenous cues involve both top-down and bottom-up attention. In contrast, non-informative exogenous cues only trigger bottom-up attention. The major results of this study support threat advantage hypothesis that both older and young adults respond to angry face target quicker than happy face. Benefit from top-down attention was larger in older adults than young adults. Highly informative cues help older adults more in searching emotional faces than young adults. The cuing effects in two emotional face conditions were different between Experiment 1 and 2. This inconsistent result maybe relates to aging heterogeneity. In conclusion, top-down attention can help older adults search for emotional faces.

Decision making for fast-moving consumer goods involves a choice between numerous similar alternatives. Under such demanding circumstances, a decision is made for one product. The decision is dependent on the interaction between the environment and the mind of the consumer, both of which are filled with information that can influence the outcome. The aim of this dissertation is to explore how the mind and the environment guides attention towards considered and chosen products in consumer decision making at the point-of-purchase. Consumers are equipped with several effort reduction strategies to simplify complex decision making. The selection of strategies can be conscious or automatic and driven by information in the environment or the mind of the decision maker. The selected decision strategy reduces the set of options to one alternative in an iterative process of comparisons that are fast and rely on perceptual cues to quickly exclude irrelevant products. This thesis uses eye-tracking to explore this rapid processing that lacks conscious access or control. The purpose is to explore how product packaging and placement (as in-store factors), and recognition, preferences, and choice task (as out-of-store factors) influence the decision-making process through visual attention. The results of the 10 experiments in the five papers that comprise this thesis shed new light on the role of visual attention in the interaction between the environment and the mind, and its influence on the consumer. It is said that consumers choose with their eyes, which means that unseen is unsold. The results of this thesis show that it is just as important to be comprehended as it is to be seen. In split-second decision making, the ability to recognize and comprehend a product can significantly impact preferences. Comprehension stretches beyond perception as consumers infer value from memory structures that influence attention. Hence, the eye truly sees what the mind is prepared to comprehend.

Uma das tarefas básicas dos mecanismos atencionais é decidir qual a localização dentro do campo visual, em que devemos prestar atenção primeiro. Um objeto que contenha características distintas, tais como orientação, forma, cor, tamanho, brilho, textura, etc. diferentes, pode atrair a atenção de uma maneira \"bottom-up\". A informação \"top-down\" baseia-se no conhecimento prévio e tem uma grande influência nas localizações atendidas. Inspirado nos mecanismos da Atenção Visual Humana, embora sem a pretensão de simulá-la, este trabalho prevê o desenvolvimento de uma nova metodologia que integra os dois tipos de informações: \"bottom-up\" e \"top-down\". Características \"bottom-up\" são geradas a partir de Momentos e essas informações são utilizadas em mapas de saliência, enquanto que um conhecimento prévio é utilizado para gerar pistas \"top-down\". Neste trabalho, desenvolveu-se uma metodologia específica para a busca e o reconhecimento visual em cenas com múltiplos objetos, utilizando para isso uma rede \"fuzzy\" contendo três subsistemas \"fuzzy\". Dada uma imagem de entrada, o objetivo consiste em se detectar regiões que possam conter informações mais significativas, a fim de que se possa guiar e restringir processamentos mais complexos. A inclusão de mecanismos de atenção (seleção de uma região de interesse dentro da imagem) é de fundamental importância pois os resultados obtidos pelo método podem ser usados para controlar a aquisição da imagem de uma maneira dinâmica. O modelo proposto está estruturado em três estágios principais: O primeiro estágio consiste em se segmentar os objetos e extrair características globais dos mesmos baseadas principalmente na teoria dos momentos, tais como tamanho, orientação, formato e distância e também média de nível de cinza. Por intermédio da comparação de um objeto com os outros presentes na cena, características \"bottom-up\" de conspicuidade são usadas para guiar a atenção ao objeto mais diferente. Por intermédio do uso da lógica \"fuzzy\" é possível inferir com grande flexibilidade algumas regras de decisão baseadas nos princípios de percepção visual tais como as leis Gestalt. O segundo estágio consiste de um subsistema \"fuzzy top-down\" que combina diferentes características de acordo com a relevância das mesmas em diferentes tarefas. Finalmente, o terceiro estágio consiste de um subsistema \"fuzzy\" que integra as informações obtidas dos subsistemas anteriores e fornece um índice geral de saliência, e indica a provável localização do objeto a ser reconhecido. A nova abordagem foi testada com objetos geométricos levando-se em consideração as características que atraem a atenção dos serem humanos / One of the basic tasks assigned to the human attentional mechanisms is to decide which location in the visual field we must pay attention first. An object containing distinctive features (such as different orientation, shape, color, size, shine, texture, etc.) can attract attention in a bottom-up way. Top-down information is based on the previous knowledge and has a large influence on the attended locations. Inspired on human visual attention mechanisms, although it doesn\'t want simulate it, this work presents a new methodology to integrate two different kind of information: bottom-up and top-down. Bottom-up features are obtained from Moment Theory and this information is used in salience maps, while a previous knowledge is used to create top-down hints. In this work, an specific methodology to visual search and recognition was developed to be applied to scenes containing multiple objects by a fuzzy net with three fuzzy subsystems. The aim of this methodology is to detect regions that may contain the most significant information, in order to guide and to restrict most complex processing. The inclusion of attentional mechanisms (the selection of a region of interest in the image) is fundamental and can be used to control the image acquisition in a dynamic way. The proposed model is structured in three main stages. The first stage segments the objects and extracts global features of them, based on the Moment Theory such as size, orientation, shape and distance and gray level average. By comparing one object with the other ones present in the scene, bottom-up features of conspicuity are used to guide the attention to the most different object. The Fuzzy Logic allows us to infer with great flexibility some of decision rules based on the visual perception principles such as the Gestalt Laws. The second stage is a top-down fuzzy subsystem that combines different features according to the relevance of them in different tasks. Finally, the third stage is a fuzzy subsystem that integrates the information obtained from the previous sub-systems and gives us a general salience index. The new methodology was tested in geometrical objects considering the feature that attracts attention to human beings