Overt visual attention under natural conditions

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Title: Overt visual attention under natural conditions
Authors: Frey, Hans-Peter
Thesis advisor: Prof. Dr. Peter K√∂nig
Thesis referee: PD Dr. Ulrich Ansorge
Prof. Dr. Markus Lappe
Abstract: In a natural environment, humans are not able to process all information available to the visual system simultaneously. As a consequence, we attend to different subparts of the input one after the other. Under natural viewing conditions, these shifts of attention are associated with changes in fixation. This so-called overt attention therefore provides an objective measure of attention shifts. In my thesis, I investigate the influence of color on overt visual attention. I present human subjects with different categories of color-calibrated images and record their eye-movements. In the first series of experiments, images of 7 different categories (Face, Flower, Forest, Fractal, Landscape, Man-Made object, and Rainforest) are presented either in natural color or grayscale. With regard to the influence of color on overt attention, I find two extreme categories: while in Rainforest images all color features examined are salient, none is salient in Fractal. In all other categories, color features are selectively salient. This shows that the influence of color on overt attention depends on the type of image. In the second series of experiments, I use only Rainforest images. These are presented to color-normal or deuteranope subjects with several modifications in the color domain. I find a causal influence of color-contrast on overt attention, processed in a way that it is not specific to either the red-green or blue-yellow color channel. In the case of color blindness, a slower high-level compensatory mechanism affects the selection of fixation points. These experiments show that there is no single color feature, which influences overt attention in all possible environments. I provide evidence that different levels of the visual hierarchy are involved in the computation of saliency.
URL: https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2009073116
Subject Keywords: Attention; Eye-movements; Color; Natural Scenes
Issue Date: 30-Jul-2009
Type of publication: Dissertation oder Habilitation [doctoralThesis]
Appears in Collections:FB08 - E-Dissertationen

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