Distributed systems technologies supporting 3D visualization and social collaboration will be increasing in frequency and type over time. An emerging type of head-mounted display referred to as the head-mounted projection display (HMPD) was recently developed that only requires ultralight optics (i.e., less than 8 g per eye) that enables immersive multiuser, mobile augmented reality 3D visualization, as well as remote 3D collaborations. In this paper a review of the development of lightweight HMPD technology is provided, together with insight into what makes this technology timely and so unique. Two novel emerging HMPD-based technologies are then described: a teleportal HMPD (T-HMPD) enabling face-to-face communication and visualization of shared 3D virtual objects, and a mobile HMPD (M-HMPD) designed for outdoor wearable visualization and communication. Finally, the use of HMPD in medical visualization and training, as well as in infospaces, two applications developed in the ODA and MIND labs respectively, are discussed.

We report on an experiment that examined the influence of anthropomorphism and perceived agency on presence, copresence, and social presence in a virtual environment. The experiment varied the level of anthropomorphism of the image of interactants: high anthropomorphism, low anthropomorphism, or no image. Perceived agency was manipulated by telling the participants that the image was either an avatar controlled by a human, or an agent controlled by a computer. The results support the prediction that people respond socially to both human and computer-controlled entities, and that the existence of a virtual image increases tele-presence. Participants interacting with the less-anthropomorphic image reported more copresence and social presence than those interacting with partners represented by either no image at all or by a highly anthropomorphic image of the other, indicating that the more anthropomorphic images set up higher expectations that lead to reduced presence when these expectations were not met.

At a time of increased social usage of net and collaborative applications, a robust and detailed theory of social presence could contribute to our understanding of social behavior in mediated environments, allow researchers to predict and measure differences among media interfaces, and guide the design of new social environments and interfaces. A broader theory of social presence can guide more valid and reliable measures. The article reviews, classifies, and critiques existing theories and measures of social presence. A set of criteria and scope conditions is proposed to help remedy limitations in past theories and measures and to provide a contribution to a more robust theory and measure of social presence.

This article considers the following question: What is the best foundation for a theory of presence? After establishing criteria for a philosophy of presence, the article applies these criteria to a set of articles on the philosophy of presence by Sheridan (1999), Mantovani and Riva (1999), and others. Although we share common goals, it is suggested that these articles advance a philosophy of presence that may be ill suited to support theory and research on presence. Several arguments are advanced to support this judgment. J. J. Gibson's work may be misinterpreted to accommodate relativistic models of physical reality. By directly referencing Gibson's writings, especially his concepts of ecological invariants, the article details how Gibson's work could not be used to support cultural, relativistic, or “engineering” arguments about “different realities”, perceptual or otherwise, without significant modification of Gibson's work and violation of his apparent intent. Another source of problems for a philosophy of presence is traced. There appears to be a terminological and theoretical confusion about the difference between epistemology and ontology. This article proposes that ontological debates about divine presence represented by these authors may be inappropriate or sterile for three reasons: (1) although perceptual presence (that is, phenomenal states of distal attribution) and “divine presence” (that is, immanence of God) share the term presence, they are fundamentally different philosophical problems; (2) the concept of divine presence and Sheridan's associated “estimation paradigm” is framed at such a level of generality to be incapable of supporting specific, actionable, and researchable theories about perceptual presence; and (3) any theory about “virtual reality”, a technology with a misleading oxymoronic term, provides no more ontological insight into reality than does theory and research on any other communication medium such as photography, film, or sound recording. Finally, the article proposes a remedy. The philosophy of presence might be most fruitfully approached via the philosophy of mind. Specifically, it is suggested that presence opens the door to related problems in the science of human consciousness, notably the mind-body problem. The article also suggests that the problem of presence bridges the philosophy of mind and the philosophy of technology on the issue of mediated embodiment, that is, the fuzzy boundary between the body and technological extensions of the body.

How do users generate an illusion of presence in a rich and consistent virtual environment from an impoverished, incomplete, and often inconsistent set of sensory cues? We conducted an experiment to explore how multimodal perceptual cues are integrated into a coherent experience of virtual objects and spaces. Specifically, we explored whether inter-modal integration contributes to generating the illusion of presence in virtual environments. To discover whether intermodal integration might play a role in presence, we looked for evidence of intermodal integration in the form of cross-modal interactions—perceptual illusions in which users use sensory cues in one modality to “fill in” the “missing” components of perceptual experience. One form of cross-modal interaction, a cross-modal transfer, is defined as a form of synesthesia, that is, a perceptual illusion in which stimulation to a sensory modality connected to the interface (such as the visual modality) is accompanied by perceived stimulation to an unconnected sensory modality that receives no apparent stimulation from the virtual environment (such as the haptic modality). Users of our experimental virtual environment who manipulated the visual analog of a physical force, a virtual spring, reported haptic sensations of “physical resistance”, even though the interface included no haptic displays. A path model of the data suggested that this cross-modal illusion was correlated with and dependent upon the sensation of spatial and sensory presence. We conclude that this is evidence that presence may derive from the process of multi-modal integration and, therefore, may be associated with other illusions, such as cross-modal transfers, that result from the process of creating a coherent mental model of the space. Finally, we suggest that this perceptual phenomenon might be used to improve user experiences with multimodal interfaces, specifically by supporting limited sensory displays (such as haptic displays) with appropriate synesthetic stimulation to other sensory modalities (such as visual and auditory analogs of haptic forces).

The widespread diffusion of immersive virtual environments (VE) is threatened by persistent reports that some users experience simulation sickness, a form of motion sickness that accompanies extended use of the medium. Experience with the problem of simulation sickness is most extensive in the military where the illness has accompanied the use of various simulators since the 1950s. This article considers the obstacles presented by simulation sickness to the diffusion of VE systems, its physiological and technological causes, and, finally, the remedies that have been suggested to fix the problems. This issue is also considered in light of previous reports of purported illnesses that accompanied the diffusion of other communication technologies.