No / Precortical vision is mediated by three opponent mechanisms that combine receptoral outputs to form a luminance channel (L + M) and two chromatic channels, red-green (L/M) and blue-yellow (S/L + M). Here we ask the extent to which these basic color opponent mechanisms interact in the phenomenon of crowding, where nearby targets interfere with the processing of a central test target. The task was to identify the orientation of a Gabor patch while an annular plaid surrounded the patch. The radius of the annulus was varied in order to produce different separations of the test and flanker. The chromatic content of the Gabor and the annulus could be varied independently along the (L + M), (L/M), and (S/L + M) cardinal axes. For all targets, when the target and flanker shared the same chromaticity, performance decreased with decreasing separation of the target and annulus, i.e., a typical crowding effect was seen. When the test and flanker isolated different chromatic mechanisms, very little crowding was observed, even at the minimum separation of test target and annulus. In addition to this, intermediate chromaticities were found to produce intermediate levels of crowding. Finally, crowding effects using "half-wave rectified" stimuli suggest a locus for crowding effects beyond the level of color opponent mechanisms.

Decision Support Systems (DSS) should increase the effectiveness of a decision and the efficiency of the decision making process. The success of DSSs has varied among individual users. One explanation for this variation is that individual’s spatial ability has a moderating effect on performance. Another factor found to impact decision performance is the structure of the task. The purpose of this study is to determine whether spatial ability factors have a moderating effect on decision making performance in a DSS environment under differing task structure. Three of the major factors of spatial ability (spatial scanning, spatial relations, and field independence) and two levels of task structure (moderately complex and complex) are considered in the study. Spatial scanning and field independence were assessed by the Kit Factor-Reference Cognitive Tests, Map Planning Test and Hidden Figures Test, respectively [Ekstrom et al., 1976]. Spatial relations was assessed by the Mental Rotations Test [Vanderberg & Kuse, 1978]. Model formulation and data analysis are two stages of decision making considered in the study. Decision making performance is assessed by time to complete the task, DSS features used, decision confidence, and decision accuracy. Computer experience is treated as a control variable. Fifty Master level students in the School of Business attended three experimental sessions which involved completing several spatial ability tests, participating in a ninety minute lecture on the software package, and completing four practice problems and two experimental cases. The software package employed in the experiment is IFPS, a DSS generator. The results of the study indicate that spatial relations has a moderating effect on decision confidence during the data analysis stage of decision making. Furthermore, there is a significant moderating interaction effect between spatial relations and task complexity when performance is assessed by decision confidence. Spatial relations is found to be more significantly related to performance in the complex case than in the moderately complex case. / Ph. D.

董群. / 呈交日期: "1999年11月" / 論文(博士)--香港中文大學, 2000. / 參考文獻 (p. 155-161) / 中英文摘要. / Cheng jiao ri qi: "1999 nian 11 yue" / Available also through the Internet via Dissertations & theses @ Chinese University of Hong Kong. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Dong Qun. / Lun wen (Bo shi)--Xianggang Zhong wen da xue, 2000. / Can kao wen xian (p. 155-161) / Zhong Ying wen zhai yao.

The hippocampal formation has been implicated in spatial formation for many decades. The hippocampus proper has received the most attention but other regions of the hippocampal formation contribute largely to spatial cognition. This thesis concentrated on one such region, the postsubiculum. The postsubiculum is considered important because it contains head direction cells and because it thought to be a major input to the hippocampus, via the entorhinal cortex. This thesis aims to test the functional role of the rat postsubiculum under two types of situation: one where the rat must rely on idiothetic cues for navigation, and another where the rat has visual cues present and can rely on these for orientation. The thesis also investigates hippocampal place cells and their stability over time after short exposures to novel environments. Chapter 3 of this thesis aimed to test whether the postsubiculum is necessary for path integration during a homing task. Rats were trained on a homing task on a circular platform maze. Once the task was acquired, rats were given lesions of the postsubiculum or sham lesions and then re-tested on the path integration task. The homing performance of rats with lesions of the postsubiculum was as good as that of the sham rats. A series of manipulations suggests that the rats were homing by path integration, confirmed by probe tests. The rats were then tested on a forced-choice delayed alternation T-maze task that revealed a significant impairment in alternation with delays of 5, 30, and 60 seconds. This suggests that the postsubiculum is not necessary for path integration in a homing task but is necessary for avoiding previously visited locations as is necessary in an alternation task. The experiments in Chapters 4 and 5 of this thesis aimed to investigate the effects of postsubiculum pharmacological inactivation on hippocampal CA1 place cells when rats were introduced to a novel environment with visual cues. A necessary first step was to assess place cells without any manipulation of the postsubiculum (Chapter 4) and then use information gained from this in the design of experiments in Chapter 5. Rats chronically implanted with recording electrodes in the CA1 region of the hippocampus were exposed to novel cue-rich environments whilst place fields were recorded. Following delays of 3, 6, or 24 hours, the same cells were recorded again in the same environment but with the cues rotated by 90°. Pixel-by-pixel correlations of the place fields show that stability of the place fields was significantly lower at 24 hours than at 3 hours. Stability after 6 hours was not significantly different from 3 hours. In the third set of experiments, rats were implanted with drug infusion cannulae in the postsubiculum and recording electrodes in CA1. Following infusions of either the AMPA receptor antagonist CXQX, the NMDA receptor antagonist D-AP5 or a control infusion of ACSF, place field stability was assessed as rats were exposed to a cylindrical environment with a single polarising cue card for 3 x 10 minute sessions and then again 6 hours later. There were no differences in place field correlations between the 3 drug conditions, although there was evidence of larger changes in spatial information content between cells in the CNQX and AP5 drug condition, but not the ACSF condition. The results suggest that, under the present testing conditions, place fields stability did not depend upon AMPA receptor-mediated transmission nor did it depend on NMDA receptor-mediated synaptic plasticity.

Space perceived and experienced through movement presents an interesting array of imagery which blends together to form a comprehensive whole. My thesis explores this dimension of spatial complexity through the public ritual of pilgrimage. This profound and deeply significant human activity connects the individual places to form an integrated sacred network. The practice of pilgrimage has developed over centuries across the globe and continues to grow and influence a huge cross section of society to come together and move en-masse towards religious centres and personal enlightenment. Public spaces demand a simultaneous co-existence of people, activities and their setting. The phenomenon of pilgrimage is central to the public realm. Its study involves an intricate layering of beliefs, customs, traditions and religion which collectively govern the people-space relationship. The transformation of a space to a place, from static to dynamic, from passive to active occurs during this activity, maintaining the traditional usage while simultaneously evolving as a product of interaction between people, rituals and spaces. In this thesis, I examine the experiential shaping of space which occurs through pilgrims' activities and their impacts on the given urban and architectural conditions. The research is based on my study of the Alandi-Pandharpur Pilgrimage in India. It is an outcome of my participation in the ritual as, both, an architect and a pilgrim. I focus on the existing public spaces and their spontaneous response to the unplanned activity of the Pilgrimage. The spatial experience transcends the criteria of aesthetics and functionality of a public space to a deeper exploration of human characteristics and convictions. From this perspective, the thesis considers the broader role of designed public spaces, the extent of inclusion of community rituals and their significance in the shaping of built environment.

The hippocampus is necessary for normal memory in rodents, birds, monkeys, and people. Damage to the hippocampus can result in the inability to learn new facts, defined by the relationship among stimuli. In rodents, spatial learning involves learning about the relationships among stimuli, and exemplifies the kind of learning the requires the hippocampus. Therefore, understanding the neural mechanisms underlying spatial learning may elucidate basic memory processes. Many hippocampal neurons fire when behaving rats, cats, or monkeys are in circumscribed regions (place fields) of an environment. The neurons, called place cells, fire in relation to distal stimuli, but can persist in signaling location when the stimuli are removed or lights are turned off (memory fields). In this thesis, computational models of spatial information processing simulated many of the defining properties of hippocampal place cells, including memory fields. Furthermore, the models suggested a neurally plausible mechanism of goal directed spatial navigation which involved the encoding of distances in the connections between place cells. To navigate using memory fields, the models required an excitatory, distributed, and plastic association system among place cells. Such properties are well characterized in area CA3 of the hippocampus. In this thesis, a new electrophysiological study provides evidence that a second system in the dentate gyrus has similar properties. Thus, two circuits in the hippocampus meet the requirements of the models. Some predictions of the models were then tested in a single-unit recording experiment in behaving rats. Place fields were more likely to occur in information rich areas of the environment, and removal of single cues altered place fields in a way consistent with the distance encoding mechanism suggested by the models. It was concluded that a distance encoding theory of rat spatial navigation has much descriptive and predictive utility, but most of its predic

Space perceived and experienced through movement presents an interesting array of imagery which blends together to form a comprehensive whole. My thesis explores this dimension of spatial complexity through the public ritual of pilgrimage. This profound and deeply significant human activity connects the individual places to form an integrated sacred network. The practice of pilgrimage has developed over centuries across the globe and continues to grow and influence a huge cross section of society to come together and move en-masse towards religious centres and personal enlightenment. Public spaces demand a simultaneous co-existence of people, activities and their setting. The phenomenon of pilgrimage is central to the public realm. Its study involves an intricate layering of beliefs, customs, traditions and religion which collectively govern the people-space relationship. The transformation of a space to a place, from static to dynamic, from passive to active occurs during this activity, maintaining the traditional usage while simultaneously evolving as a product of interaction between people, rituals and spaces. In this thesis, I examine the experiential shaping of space which occurs through pilgrims' activities and their impacts on the given urban and architectural conditions. The research is based on my study of the Alandi-Pandharpur Pilgrimage in India. It is an outcome of my participation in the ritual as, both, an architect and a pilgrim. I focus on the existing public spaces and their spontaneous response to the unplanned activity of the Pilgrimage. The spatial experience transcends the criteria of aesthetics and functionality of a public space to a deeper exploration of human characteristics and convictions. From this perspective, the thesis considers the broader role of designed public spaces, the extent of inclusion of community rituals and their significance in the shaping of built environment.

The starting point of my dissertation is the question: What would be needed of a device to culturally reconfigure the way that we see? The question has been addressed through a theoretical examination of spatial theories in modern times and a creative exploration of new spatialities in new media technologies, both visual and aural. Central to my thesis are three claims: 1. the paradigmatic mathematical theory of single-point perspective is fundamental to the imagining and construction of space in modern times; 2. perspective is a seductive space because its virtualisations seem more authentic than phenomenological experience; 3. the structure of perspective space prefigures the computer screen, hence any attempt to reconfigure the spatial imaginary through the devices of new media technologies must first confront the historical ubiquity of perspective. The specific focus of my written research is a comparative study of Filippo Brunelleschi's perspective device and the virtual reality work of Char Davies. This comparative study focuses on the ingredients of both devices as well as the similarities between the environments in which they were demonstrated. Brunelleschi's Peephole device, according to his biographer Manetti, first demonstrated perspective theory in the early fifteenth century. Brunelleschi's device, with its three main components, the mirror, the burnished silver and the painted panel, are examined in regards to the environment it was demonstrated in. The dissertation explores these elements as the essential conceptual ingredients for the reconfiguration of space in modern times. Aspects of Brunelleschi's device are also examined creatively in my practical work. Today emergent technologies are being used to explore the potential of a new spatial world order. However, these new technologies are generally based on an Old World order perspective. Even the cubist reconfiguration of space did not change, in any fundamental way, the dominant perspectival model of perception because it did not have the same ideological and psychological power as perspective, which seduced the viewer into believing that the gap (or loss) between the technology and reality had been compensated. Arguably, the same claims can be made for virtual reality devices. Hence, important to the dissertation is a comparative study of Brunelleschi's perspective device and the virtual reality work of Char Davies. The creative work investigates the effects and work of perspectival spatiality by examining (through digital video, photographically and sonically) residual spaces in the environment. To me these residual spaces provide potential resistances to the perspectival space from which they evolved, and thus show new ways of exploring the virtual reality of cyberspace that, while acknowledging the pervasive presence of perspective systems, also deconstruct or even map new post-perspective spatialities.

Thesis (Ph. D.)--University of Sydney, 2008. / Title from title screen (viewed Apr. 22, 2009) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Sydney College of the Arts. Includes bibliographical references. Also available in print form.

Made available in DSpace on 2015-07-22T20:50:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-24 / A Doença de Alzheimer é a causa mais frequente de demência. Os sintomas clínicos da doença se iniciam com um comprometimento da memória e da função executiva, gradativamente há um envolvimento de outras funções como a linguagem, conhecimento semântico, pensamento abstrato, atenção e habilidades visuoespaciais. A função visuoespacial consiste na identificação de um estímulo e sua localização, e pode estar comprometida no início do quadro clínico. A bateria “Visual Object and Space Perception” (VOSP) se propõe a avaliar as funções visuoespaciais minimizando a interferência de outras funções cognitivas. Objetivos: Avaliar as funções visuoespaciais na doença de Alzheimer de intensidade leve; Avaliar a sensibilidade desta bateria em uma amostra brasileira; Determinar escores de corte preliminares para diferenciar idosos saudáveis de pacientes com doença de Alzheimer. Métodos: 31 pacientes com Doença de Alzheimer leve e 44 idosos saudáveis foram avaliados com uma bateria de testes neuropsicológicos e com a VOSP. Resultados: Controles tiveram melhor desempenho em todos os testes neuropsicológicos. Na VOSP, os pacientes com Doença de Alzheimer mostraram pior desempenho em todos os testes de percepção de objeto, e em dois testes de percepção de espaço (Localização de Numero e Análise de Cubos). Conclusões: A função visuoespacial mostra-se comprometida em estágios iniciais da doença de Alzheimer. A bateria VOSP demonstrou ser sensível a déficits visuoespaciais. / TEDE / BV UNIFESP: Teses e dissertações