This dissertation sought to address key problems facing the human factors of virtual interfaces in a unified way. To this end, the RFC was introduced as a convenient summary of a considerable part of the literature on spatial perception. The RFC was applied to the problems of understanding, measuring, and manipulating presence, and to the alleviation of simulator sickness.
Presence correlates with high-level aspects of the quality of a virtual interface, including its intuitiveness and its ability to convey meaning. Therefore, a robust presence measure supports the systematic development of knowledge about how to construct virtual interfaces. This dissertation introduced a presence measure based on spatial perception, possibly at the brain-stem level. By evaluating presence at such a fundamental level the problems associated with self-report measures, such as range and anchor effects, may be reduced or eliminated.
Simulator sickness poses a critical problem for virtual interfaces. As virtual interfaces become more compelling, they become more able to cause unwanted side-effects. To address this problem, a link through the RFC between the spatial perception literature and the motion sickness literature was exploited. This link was used to suggest a technique for reducing simulator sickness through manipulations to the visual background.
This dissertation is, of course, no more than a beginning. It does not reach closure; it seeks to steer research in particular directions. It is based on the belief that fundamental problems should be approached from fundamental principles; in this case, fundamental principles of spatial perception.
There are many interesting ways in which this research could be further pursued. These have been summarized in the preceding two chapters. The most pressing are improvements to the presence measure; its use for the systematic study of the factors affecting presence in virtual environments; and the application of independent visual backgrounds to reducing simulator sickness in high-end virtual environments. Beyond this basic research lies the application of the more sophisticated virtual interfaces which it will engender. In many application domains, well-designed virtual interfaces provide a means to confront the complexity explosion by increasing the human-computer bandwidth. But these are stories which remain to be told.