Thesis (Ph. D.)--University of Wisconsin--Madison, 1938. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 104-111).

No description available.

Issued also as Thesis (Ph. D.)--Columbia University. / Bibliography: p. 86-88.

Research has shown the color used to represent threat information can influence perceived risk and how individuals respond to watches and warnings. However, there is no standardized color scheme for hazardous weather products across the weather enterprise. This study’s objective was to determine if color inconsistencies have an effect on a product’s intended risk perception utilizing two public surveys. Results suggest color inconsistencies when representing hazardous weather products have a detrimental effect on that product’s intended message. The first survey found people use color to help determine risk and rely on whether a filled or outlined polygon is displayed. The second survey found the term “warning” is perceived to have more risk than the term “watch” for all hazardous weather types tested. The results from both surveys suggest a national, uniform color scale based on risk should be implemented across all weather enterprise agencies.

Diss. Linköping : Univ., 2001.

Thesis (Ph.D.). / Written for the Dept. of Ophthalmology, Neurology and Neurosurgery. Title from title page of PDF (viewed 2008/03/12). Includes bibliographical references.

Two experiments investigated the effects of pre-receptoral absorption and levels of illumination on colour vision. Simulation filters approximating lens and macular pigment changes were constructed on the basis of previous investigations. Experiment I investigated the effects of these filters on young, normal subject performance. Shifts were found in the direction of ageing populations but not as great as is required. Experiment II investigated the additional effect of reductions in illumination. The two experimental manipulations together account for senile decreases in discrimination at slightly higher levels than previously reported / Arts, Faculty of / Psychology, Department of / Graduate

In the field of information sciences, attention has been focused on developing mature information retrieval systems that abstract information automatically from the contents of information resources, such as books, images and films. As a subset of information retrieval research, content-based image retrieval systems automatically abstract elementary information from images in terms of colors, shapes, and texture. Color is the most commonly used in similarity measurement for content-based image retrieval systems. Human-computer interface design and image retrieval methods benefit from studies based on the understanding of their potential users. Today's children are exposed to digital technology at a very young age, and they will be the major technology users in five to ten years. This study focuses on children's color perception and color association with a controlled set of digital images. The method of survey research was used to gather data for this exploratory study about children's color association from a children's population, third to sixth graders. An online questionnaire with fifteen images was used to collect quantitative data of children's color selections. Face-to-face interviews investigated the rationale and factors affecting the color choices and children's interpretation of the images. The findings in this study indicate that the color children associated with in the images was the one that took the most space or the biggest part of an image. Another powerful factor in color selection was the vividness or saturation of the color. Colors that stood out the most generally attracted the greatest attention. Preferences of color, character, or subject matter in an image also strongly affected children's color association with images. One of the most unexpected findings was that children would choose a color to replace a color in an image. In general, children saw more things than what were actually represented in the images. However, the children's interpretation of the images had little effect on their color selections.

L’effet de potentialisation motrice, initialement décrit par Tucker et Ellis (1998), correspond au bénéfice entrainé par l’action potentielle évoquée par la perception d’objets manipulables en lien avec le dispositif de réponse. Cet effet a été observé dans de nombreux contextes expérimentaux. Toutefois, il semble que cet effet ne s’observe pas lorsque la tâche des participants ne porte pas directement sur une caractéristique requise pour le contrôle de l’action (Tipper, Paul & Hayes, 2006) ou qui n’entraîne pas suffisamment d’attention sur l’objet (Ellis, Tucker, Symes & Vainio, 2007 ; Symes, Ellis & Tucker, 2005). Le cas particulier de l’identification de la couleur est un exemple dans lequel cet effet n’est généralement pas constaté (Symes et al. 2005 ; Tipper et al. 2006). En s’appuyant sur des travaux qui proposent une alternative aux théories dissociatives classiques du système visuel (Creem & Proffitt, 2001 ; Frey, 2007 ; Young, 2006 ; Derbyshire, Ellis & Tucker, 2006) et qui se basent essentiellement sur des processus de résonance motrice et de simulation comme condition nécessaire à l’identification et à la reconnaissance (Rizzolatti & Matelli, 2003 ; Bar, 2007 ; Berthoz & Petit, 2003), cette thèse a pour objet de spécifier les conditions d’observation du phénomène de potentialisation motrice en tâche d’identification chromatique. Pour ce faire, nous avons adapté le paradigme SRC modifié de Tucker et Ellis (1998) et le protocole d’amorçage développé par Phillips et Ward (2002) à l’étude de l’identification des couleurs d’objets manipulables. Les résultats que nous avons obtenus montrent une interaction entre l’identification de la couleur et les simulations motrices associées à la perception d’objets manipulables. Ces résultats sont discutés en faveur des modèles qui cherchent à réconcilier les approches écologiques et représentationnelles de la perception ainsi que de ceux qui insistent sur la nature profondément proactive et simulationniste du système perceptif. / Potentiation of action effect, originally described by Tucker and Ellis (1998), corresponds to the advantage led by action evoked by the perception of graspable objects related to the response device. These effects have been reported for many experimental conditions. However, this effect is not observed when the task is not directly about a characteristic required for action control (Tipper, Paul & Hayes, 2006) or when it does not allowed for enough attention on the object (Ellis, Tucker, Symes & Vainio, 2007; Symes, Ellis & Tucker, 2005). Color perception and identification is a particular case where these effects are generally not observed (Symes et al. 2005; Tipper et al. 2006). Relying on recent works that propose an alternative to theories of classic dissociation of the visual system (Creem & Proffitt, 2001; Frey, 2007; Young, 2006; Derbyshire, Ellis & Tucker, 2006) and that are essentially based on motor resonance and simulation processes as a condition to identification and recognition (Rizzolatti & Matelli, 2003; Bar, 2007; Berthoz & Petit, 2003), this thesis aims to specify the conditions of observation of a potentiation of action phenomenon in a chromatic identification task. To that end, we have adapted the SRC paradigm (stimulus response compatibility) modified by Tucker and Ellis (1998) and the priming paradigm developed by Phillips and Ward (2002) to study color identification of graspable objects. Results we obtain shows an interaction between the identification of color and the motor simulations associated with the perception of graspable objects. We discuss our results in the light of models which tend to reconcile ecological and representational approaches of perception as well as those which insist on the deeply proactive and simulationist nature of the perceptual system.

Nas últimas décadas uma série de experimentos realizados em vertebrados tem demonstrado a capacidade que alguns destes possuem de discriminar a luz ultravioleta, ao contrário do acreditado anteriormente. O peixe dourado (Carassius auratus), um bom modelo experimental para pesquisas sobre visão, apresentou em experimentos comportamentais altos níveis de discriminação de cor nas regiões espectrais do azul e do violeta, o que só seria possível com a existência de um receptor adicional para o ultravioleta (Neumeyer, 1985; Hawryshyn & Beauchamp, 1985; Neumeyer & Arnold, 1989; Neumeyer, 1992; Fratzer, Dörr & Neumeyer, 1994). Estes resultados foram confirmados pela determinação microespectrofotométrica (Bowmaker, Thorpe & Douglas, 1991) e eletrofisiológica (Palacios et al., 1998) da existência de cones com pigmentos específicos para luz ultravioleta, sem haver entretanto um estudo da codificação dessa entrada em neurônios de segunda ordem até o momento. Além disso, permanece ainda em discussão na literatura o papel das células horizontais retinianas no processamento cromático. O presente projeto teve por objetivo investigar qual a contribuição da entrada do receptor UV para os perfis de resposta eletrofisiológica das células horizontais e quais tipos celulares da retina externa do Carassius auratus são subjacentes à discriminação observada comportamentalmente. Para tanto, registros intracelulares de células horizontais e bipolares foram obtidos sob estimulaçãomonocromática de diferentes intensidades, ) diâmetros e comprimentos de onda, com o intuito de determinar suas respostas espectrais, bem como o campo receptivo e as possíveis interações entre estas e os cones. As células horizontais mono-, bi- e trifásica apenas hiperpolarizam na região do UV, não havendo oponência cromática entre as regiões do UV e do azul em nenhum destes tipos celulares; tampouco encontramos uma célula horizontal tetrafásica. Através de adaptações cromáticas, observamos serem as respostas eletrofisiológicas à luz das células horizontais mono- e bifásicas resultado de interações entre os sistemas de cones vermelho,verde e azul, não tendo sido identificada nenhuma entrada UV significativa nessas células. Por fim, encontramos uma célula bipolar oponente entre as regiões espectrais do UV e do azul, o que constitui uma base neural compatível com a discriminação comportamentalmente observada. Uma vez que canais oponentes são necessários para a discriminação de cor, e essa oponência não foi encontrada nas células horizontais, mais sim nas bipolares, acreditamos ser esse um indício de que as células horizontais não participam diretamente da codificação da informação UV na retina do Carassius auratus. Essa idéia está de acordo com dados recentes da literatura, que atribuem às células horizontais papel relacionado aos mecanismos de constância e contraste simultâneo de cor, deixando para as células bipolares a função de codificar cores para os neurôniossubseqüentes (Kamermans, Kraaij & Spekreijse, 1998) / In the last decades a number of experiments in vertebrates has demonstrated the ability of some of these animals to discriminate ultraviolet light. Among them, the goldfish (Carassius auratus), considered a good model in vision research, presented in behavioural experiments high discrimination rates in the violet and blue spectral regions, which could only be accomplished through an additional UV receptor (Neumeyer, 1985; Hawryshyn & Beauchamp, 1985; Neumeyer & Arnold, 1989; Neumeyer, 1992; Fratzer, Dörr & Neumeyer, 1994). These results were confirmed by microspectrophotometrical (Bowmaker, Thorpe & Douglas, 1991) and electrophysiological (Palacios et al., 1998) determinations of the existence of cones with specific photopigments with a maximum in the UV region of the light spectrum. However, to date there are no data concerning the spectral coding of this input in second order neurons. Furthermore, the role of the retinal horizontal cells in chromatic processing remains under debate. The present study aimed at investigating the contribution of the UV input to the electrophysiological response profiles of the cone-driven horizontal cells, as well as determining which neurons in the outer retina of the goldfish could subserve vision in the UV range, as observed behaviourally. For that purpose, intracellular recordings of horizontal and bipolar cells under monochromatic stimuli of different intensities, diameters and wavelengths were obtained in order to determinetheir action spectra, receptive field sizes and characteristics as well as the possible interactions between them and the different cone systems. Mono-, bi- and triphasic horizontal cells always hyperpolarised in the UV spectral range: there was no chromatic opponency between the UV and the blue zones in any of these cell types. We have also failed to find a tetraphasic horizontal cell. We observed through chromatic adaptation experiments that the electrophysiological responses recorded from mono- and biphasic horizontal cells are the result of interactions between the red, green and blue cone systems. No relevant UV input to these cells could be found. Finally, we found a bipolar cell type with spectral opponency between the UV and blue regions, which could be the neural basis of the discrimination observed behaviourally. Colour-opponent channels are thought to be necessary for colour discrimination, and the absence of a horizontal cell type with opponency between the UV and blue spectral regions provides further evidence that this cell type might not play a major role in the chromatic processing in the goldfish retina. Since this opponency pattern was found in a bipolar cell, we think that this cell type, and not the horizontal cells, might underlie the coding of the UV information in this animal. This idea is in good agreement with some recent literature data that ascribe the horizontal cells a role in colour constancy and simultaneous colour contrast phenomena,leaving the function of colour codification to the bipolar cells (Kamermans, Kraaij & Spekreijse, 1998)