Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 172-182).

No description available.

Thesis (Ph. D.)--University of Delaware, 2005. / Principal faculty advisor: Chandra Kambhamettu, Dept. of Computer & Information Sciences. Includes bibliographical references.

No description available.

Exquisite visually-guided movements underpin expertise in fast interceptive sports. The assumption that skilled performance relies on superior visual skills has been challenged by studies of sporting expertise which typically advocate vision to be a poor predictor of sporting success. This discordance is addressed in this thesis by examining whether visual degradation (in the form of blur) affects the performance of an interceptive action where successful execution demands precise spatial and temporal visual-motor control. The vision of skilled cricket batters was blurred using contact lenses (four increasing levels: plano, +1.00, +2.00, +3.00) in each of two experimental phases. In the first phase batters faced a bowling-machine and in-situ bowlers to examine the effect of blur on bat-ball interception. The highest level of blur (+3.00) was required to produce a significant decrease in batting performance when facing the bowling-machine at medium-paced ball-velocities (105-115 kph). A similar effect of blur was found when facing in-situ bowlers of comparable ball-velocity, however performance was found to be affected by a lower level of blur (+2.00) for faster-paced ball-velocities (120-130 kph). The +1.00 blur was concluded even at this higher ball-velocity to have no measurable effect on interceptive performance in a natural setting. The second phase sought to investigate the effect of blur on anticipation: a perceptual skill established to be an important component of expertise in many interceptive sports. It was established, using temporal occlusion of a bowling sequence, that optimal anticipation required an opportunity for bat-ball interception (facilitating close coupling between perception and action). Coupled anticipation demonstrated velocity-dependent resilience to blur; +3.00 and +2.00 were required for respective decreases in the anticipation of action-sequences for medium- and fast-paced ball-velocities. Remarkably, results suggest that blur may enhance uncoupled (verbal) anticipation according to the movement velocity of the bowler. Experimental results led to the conclusion that clear vision is not necessarily required for optimal interceptive performance, even when the demanding spatio-temporal task simulates the conditions experienced at the highest levels of competition. Results are interpreted based on the predictions of the dual-pathway theory of vision, including differences in the underlying visual information processed via these pathways.

Exquisite visually-guided movements underpin expertise in fast interceptive sports. The assumption that skilled performance relies on superior visual skills has been challenged by studies of sporting expertise which typically advocate vision to be a poor predictor of sporting success. This discordance is addressed in this thesis by examining whether visual degradation (in the form of blur) affects the performance of an interceptive action where successful execution demands precise spatial and temporal visual-motor control. The vision of skilled cricket batters was blurred using contact lenses (four increasing levels: plano, +1.00, +2.00, +3.00) in each of two experimental phases. In the first phase batters faced a bowling-machine and in-situ bowlers to examine the effect of blur on bat-ball interception. The highest level of blur (+3.00) was required to produce a significant decrease in batting performance when facing the bowling-machine at medium-paced ball-velocities (105-115 kph). A similar effect of blur was found when facing in-situ bowlers of comparable ball-velocity, however performance was found to be affected by a lower level of blur (+2.00) for faster-paced ball-velocities (120-130 kph). The +1.00 blur was concluded even at this higher ball-velocity to have no measurable effect on interceptive performance in a natural setting. The second phase sought to investigate the effect of blur on anticipation: a perceptual skill established to be an important component of expertise in many interceptive sports. It was established, using temporal occlusion of a bowling sequence, that optimal anticipation required an opportunity for bat-ball interception (facilitating close coupling between perception and action). Coupled anticipation demonstrated velocity-dependent resilience to blur; +3.00 and +2.00 were required for respective decreases in the anticipation of action-sequences for medium- and fast-paced ball-velocities. Remarkably, results suggest that blur may enhance uncoupled (verbal) anticipation according to the movement velocity of the bowler. Experimental results led to the conclusion that clear vision is not necessarily required for optimal interceptive performance, even when the demanding spatio-temporal task simulates the conditions experienced at the highest levels of competition. Results are interpreted based on the predictions of the dual-pathway theory of vision, including differences in the underlying visual information processed via these pathways.

La présente thèse a pour objet l’étude d’une partie du vocabulaire hobbesien, que nous définirons ici comme lexique de l’ "apparence". Par le terme d’apparence, que nous utilisons en tant que catégorie conceptuelle, nous nous référons à la problématique philosophique, typique des XVIe-XVIIe siècles, qui met en lumière une conscience nouvelle de la nature de la perception sensible. L’apparence montre, d’un côté, l’existence réelle et objective d’un monde en mesure de déterminer la sensibilité ; de l’autre, la conscience que nos représentations ne nous livrent pas un portrait fidèle du monde. La réflexion de Hobbes s’insère à l’intérieur de ce contexte: considérant la sensation comme le stade initial de la connaissance, dont dérive l’entière vie psychologique du sujet, le philosophe réduit nos représentations à des apparences qui n’ont aucune réalité en dehors de notre esprit. Cette conception détermine l’utilisation d’une terminologie particulière dont Hobbes se sert pour traiter le complexe thème de l’apparence des phénomènes. Notre travail se propose de reconstruire la réflexion hobbesienne sur une telle problématique en privilégiant une approche de type lexicographique, fondée sur la vérification des occurrences et concordances (publiées dans le vol. 2), mais aussi conceptuel, à travers les entrées répertoriées à cet effet. La méthodologie choisie est celle d’un examen des écrits de Hobbes mené dans un sens diachronique, en partant du principe qu’il s’agit là de la seule façon de vérifier la modulation des entrées dans leurs différents contextes (de la physiologie de la vision au rêve) tout en éclairant la pertinence par rapport à Hobbes du thème de phénoménisme. / This thesis aims at studying part of Hobbes’s vocabulary, that I define «lexicon of appearance». The word ‘appearance’, used as a conceptual category, refers to the philosophic problematic, greatly debated in the XVIth and XVIIth century, that highlights a new conscience of the nature of the sensitive perception. On one hand, the image appearance shows the real and objective existence of a world capable of defining sensitivity. On the other hand, it shows us that our representations do not always portray a faithful image of the world. Hobbes’s theory fits perfectly in this context: by considering sensitivity as the initial phase of our knowledge, by which our whole psychological life derives from, he reduces our representations into ‘appearances’ that only exist in our mind.This conception determines the use of a particular terminology that Hobbes uses to deal with the complex theme of the appearances of phenomena. This thesis aims at reconstructing Hobbes’s reflection by favouring a lexicographic approach, checking the material elements (occurrences and concordances, published in Vol. 2) aswell as the conceptual aspects of the entry words. The methodology chosen focuses on examining Hobbes’s lexicon in a diachronic fashion. I will assume that this is the only way to verify the words’ variations in the different contexts (from physiology of vision to dream) and highlight, at the same time, Hobbes’s relevance to ‘phenomenalism’.