ABSTRACT
Virtual environments (VEs) are altered environments that provide novel patterns of intersensory stimulation. The novelty may be correct (i.e., if the VE corresponds accurately to a real environment that is new to the user), or incorrect (i.e., if the VE presents perceptual stimulation that is not faithful to the simulated environment; Moroney & Moroney, 1998; Riccio, 1995; Stoffregen, Bardy, Smart, & Pagulayan, in press; cf. Stappers, Overbeeke, & Gaver, in press). In either case, adaptation is the natural response to VE systems (Stanney, Kennedy, Drexler, & Harm, 1999; see chap. 31, this volume). The majority of research interest is focused on VE-related patterns of stimulation that are not faithful to the simulated environment. Due to technological limitations, such as slow system update rates, sluggish and imprecise positiontracking sensors, and imperfect models of environmental dynamics, the user is exposed to unusual patterns of intersensory stimulation (e.g., a disparity between seen and felt limb position). The change may not be apparent to the user until critical performance errors arise while actively interacting with the virtual environment. There is substantial evidence for the existence of adaptation and aftereffects in VEs; such effects indicate altered demands on various perceptual-motor systems, such as the visual system (Stanney et al., 1999; see chap. 37, this volume), proprioceptive (see chap. 38, this volume), and the visual-vestibular systems (Draper, 1998b). With VEs, adaptation and aftereffects can also include a wide variety of
subjective experiences, such as fatigue, malaise, nausea, headache, eyestrain, and drowsiness (see chap. 30, this volume). The vestibular system may be implicated in many of these experiences.
