The thesis describes a series of studies on the perception of speed of self-motion in realistically simulated environments. We carried out several experiments in order to explore from both the behavioral and the perceptual point of view how visual changes in the environment lead to a misperception of self-speed. More specifically, we investigated the issues of image contrast reduction, gaze direction and field-of-view and their influence on the perceived and produced speed of self-motion. Virtual environments technology was employed to display visual motion for both driving and walking speeds. Given the first results obtained from the implementation of a realistic contrast reduction in a driving simulation we formulate the hypothesis that changes in the perceived and produced speed are due to a non-optimal combination of the retinal angular velocities during self-motion. Indeed, the retinal projection of the environment during forward self-motion consists of expanding optic-flow patterns in which the angular velocities of the objects on the scene vary gradually according to their position and speed relatively to the moving observer. Objects very far away appear as moving slowly in the centre of the field-of-view, while the proximal regions appear as moving faster at the periphery of the visual field. The second part of the thesis is then dedicated to a systematic investigation on how the angular velocities from central and peripheral regions of the field-of-view contribute to the generation of the percept of a unique speed of forward translation. In Chapter 1 we present a brief overview of the principal aspects of visual motion processing. We report some psychophysical and physiological findings that have been produced in the last decades of research, together with some models that try to describe the functional aspects of motion and speed processing. Moreover, we introduce and explain the theme of the visual speed of self-motion. Finally, we describe the technical and methodological tools that have been adopted ...
The perception and production of speed during self-motion: evidence for non-optimal compensation mechanisms
2008-01-01
Hochschulschrift
Elektronische Ressource
Englisch
DDC: | 629 |
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