Henry B - Human Interface Technology Laboratory - University of ...

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non-optimal conditions (Stanney and Salvendy, 1998). Consider for example SS / VE sickness (or so-called cybersickness). Most users experience some level of SS the first time they use a VE system (Regan and Price, 1994). With repeated exposures, they adapt and SS symptoms decrease. Hettinger et al. (1987) suggested that SS may correlate with the ability of a VE to elicit illusory self-motion (vection). Hypothesized contributors to SS also include scene content, FOV, image resolution, motion trajectory, frequency characteristics of scene motion, etc. Postural disturbance has been proposed for evaluating VE systems (Stanney and Salvendy, 1998). Kennedy and Stanney (1996) evaluated postural stability measures for assessing aftereffects from VE exposure. Previous studies (Cobb and Nichols, 1998; Hamilton et al, 1989) indicate that balance disturbance correlates with simulator sickness. Also, balance disturbance has been suggested as a surrogate measure for SS intensity. Scene content, FOV, image resolution, motion trajectory, and frequency characteristics of scene motion affect vection as well as SS. Vection, presence and SS are related to postural disturbance. In this study, we examine effects of FOV, image resolution and scene content on postural disturbance. 1.1 Central/Peripheral vision Vection has been proposed as a contributor to presence in virtual environments (McGreevy, 1992) and to inducing SS (Kennedy, Hettinger, & Lilienthal, 1990). Because large FOVs stimulate peripheral
egions of the retina, they may more effectively produce self-motion perception (Hettinger et al., 1987). Questions about the region of the retina most responsible for the perception of self-motion has been asked by many researchers (see Wolpert, 1990). Initial reports indicated that stimulation of peripheral areas of the retina was more effective in eliciting perception of self-motion than simulation of more central areas (Dichgans & Brandt, 1978; Held, Dichgans, & Bauer, 1975). These experiments led scientists to theorize that human vision is mediated by two functionally different systems. Leibowitz and Post (1982) extended the notion of “two modes of processing spatially distributed information” which was proposed by Held (1970) and others. The two-modes model of spatial processing described two different kinds of visual functions associated with different parts of the brain. These are the focal mode and the ambient mode. The former was thought to be responsible for object recognition and identification and concerned with the ‘what’ question. The later was thought to be responsible for spatial orientation, locomotion and posture and concerned with the ‘where’ question. Several studies examined this theory. Brandt, Dichgans, and Koenig (1973) found that when the central retina was stimulated, self-motion was not experienced, but strong self-rotation was elicited when the peripheral retina was exposed to optical flow. Hulk and Rempt (1983) using sine-wave gratings of
Page 1: Effects of Characteristics of Image
Page 5 and 6: element in perceiving self-motion.
Page 7 and 8: contribute to SS. Higher picture re
Page 9 and 10: Laboratory subject pool. None repor
Page 11 and 12: 3. Results Because of large inter-
Page 13 and 14: 4. Discussion All the data showed t
Page 15 and 16: Scene content and resolution also a
Page 17 and 18: References 1. Alfano, P., & Michel,
Page 19 and 20: Simulation and Simulator sickness.
Page 21 and 22: Interaction, 10(2), 135-187 30. Sto
Page 23 and 24: Figure 2: Stimuli. High-resolution

Henry B - Human Interface Technology Laboratory - University of ...

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