Simulator sickness

Abstract: An important and troublesome problem with current virtual environment (VE) technology is the tendency for some users to exhibit symptoms that parallel symptoms of classical motion sickness both during and after the VE experience. This type of sickness, cybersickness, is distinct from motion sickness in that the user is often stationary but has a compelling sense of self motion through moving visual imagery. Unfortunately, there are many factors that can cause cybersickness and there is no foolproof method for eliminating the problem. In this paper, I discuss a number of the primary factors that contribute to the cause of cybersickness, describe three conflicting cybersickness theories that have been postulated, and discuss some possible methods for reducing cybersickness in VEs.

Abstract: In this article we present a new theory of motion sickness. In the sensory conflict theory, changes in stimulation of perceptual systems are believed to be responsible for motion sickness. We discuss the fact that these changes in stimulation are not independent of the animal-environment interaction, but are determined by corresponding changes in the constraints operating on the control of action. Thus, provocative situations may be characterized by novel demands on the control of action as well as by novel patterns of stimulation. Our hypothesis is that animals become sick in situations in which they do not possess (or have not yet learned) strategies that are effective for the maintenance of postural stability. We identify a broad range of situations over which the occurrence of motion sickness is related to factors that should influence postural stability. This allows us to establish a logical link between motion sickness and postural stability. Our analysis implies that an understanding of stability s...

Abstract: There are many different techniques for allowing users to specify locomotion in human-scale, immersive virtual environments. These include flying with a hand-controller, using a treadmill, walking-in-place, and others. Real walking, where the user actually and physically walks in the lab, and virtually moves the same distance and in the same direction in the virtual scene, is better than flying. It is more input-natural, does not require learning a new interface, results in a greater sense of presence, and theoretically results in less simulator sickness. One serious problem with real walking, however, is that the size of the virtual scene is limited by the size of tracked area. For example, for an architect to really walk in a virtual prototype of a house, the tracked area must be as large as the house. This requirement makes real walking infeasible for many facilities and virtual scenes. To address this limitation, I have developed Redirected Walking, which by interactively and imperceptibly rotating the virtual scene around her, makes the user turn herself. Under the right conditions, Redirected Walking would cause the user to unknowingly walk in circles in the lab, while thinking she is walking in a straight and infinitely long path in the virtual scene. In this dissertation I develop Redirection, discuss its theoretical and physiological underpinnings, and presents results to show that it can be used: (1) to make the user turn themselves, (2) without causing the user to be aware of Redirection, (3) without unacceptably increasing the user's level of simulator sickness and, most importantly, (4) to useful effect: (A) In head-mounted display systems, the user can experience a virtual scene larger than the lab while also having the benefits of real walking. (B) In an open-backed, three-walled CAVE, users can have the increased presence and input-naturalness normally associated with a fully enclosed CAVE. I also present guidelines for VE practitioners wishing to use Redirection, based on the theory and observations reported in this dissertation.