The effectiveness of virtual environments (VEs) has often been linked to the sense of presence reported by users of those VEs. (Presence is defined as the subjective experience of being in one place or environment, even when one is physically situated in another.) We believe that presence is a normal awareness phenomenon that requires directed attention and is based in the interaction between sensory stimulation, environmental factors that encourage involvement and enable immersion, and internal tendencies to become involved. Factors believed to underlie presence were described in the premier issue of Presence: Teleoperators and Virtual Environments. We used these factors and others as the basis for a presence questionnaire (PQ) to measure presence in VEs. In addition we developed an immersive tendencies questionnaire (ITQ) to measure differences in the tendencies of individuals to experience presence. These questionnaires are being used to evaluate relationships among reported presence and other research variables. Combined results from four experiments lead to the following conclusions: 
the PQ and ITQ are internally consistent measures with high reliability;
there is a weak but consistent positive relation between presence and task performance in VEs;
individual tendencies as measured by the ITQ predict presence as measured by the PQ; and
individuals who report more simulator sickness symptoms in VE report less presence than those who report fewer symptoms.

/pdf/measuring-presence-in-virtual-environments-a-presence-40c26nz3zb.pdf

Measuring Presence in Virtual Environments: A Presence Questionnaire

A number of emerging technologies including virtual reality, simulation rides, video conferencing, home theater, and high definition television are designed to provide media users with an illusion that a mediated experience is not mediated, a perception defined here as presence. Traditional media such as the telephone, radio, television, film, and many others offer a lesser degree of presence as well. This article examines the key concept of presence. It begins by noting practical and theoretical reasons for studying this concept. Six conceptualizations of presence found in a diverse set of literatures are identified and a detailed explication of the concept that incorporates these conceptualizations is presented. Existing research and speculation about the factors that encourage or discourage a sense of presence in media users as well as the physiological and psychological effects of presence are then outlined. Finally, suggestions concerning future systematic research about presence are presented.

At the Heart of It All: The Concept of Presence

StudyW Academ Excellen Award Collab-U CMC Play E-Commerce Symposium Net Law InfoSpaces Usenet NetStudy VEs

The Cyborg's Dilemma: Progressive Embodiment in Virtual Environments

Understanding Virtual Reality arrives at a time when the technologies behind virtual reality have advanced to the point that it is possible to develop and deploy meaningful, productive virtual reality applications. The aim of this thorough, accessible exploration is to help you take advantage of this moment, equipping you with the understanding needed to identify and prepare for ways VR can be used in your field, whatever your field may be.


By approaching VR as a communications medium, the authors have created a resource that will remain relevant even as the underlying technologies evolve. You get a history of VR, along with a good look at systems currently in use. However, the focus remains squarely on the application of VR and the many issues that arise in the application design and implementation, including hardware requirements, system integration, interaction techniques, and usability. This book also counters both exaggerated claims for VR and the view that would reduce it to entertainment, citing dozens of real-world examples from many different fields and presenting (in a series of appendices) four in-depth application case studies.

* Substantive, illuminating coverage designed for technical and business readers and well-suited to the classroom.
* Examines VR's constituent technologies, drawn from visualization, representation, graphics, human-computer interaction, and other fields, and explains how they are being united in cohesive VR systems.
* Via a companion Web site, provides additional case studies, tutorials, instructional materials, and a link to an open-source VR programming system.

Table of Contents

Foreword 
Preface

Part I - What is Virtual Reality?
Chapter 1: Introduction to Virtual Reality - What it is and Where it Comes From
Chapter 2: VR the Medium

Part II - Virtual Reality Systems 
Chapter 3: Interface to the Virtual World -- Input 
Chapter 4: Interface to the Virtual World -- Output 
Chapter 5: Rendering a Virtual World 
Chapter 6: Interacting with a Virtual World 
Chapter 7: Virtual Reality Experience 
Chapter 8: Experience Design: Applying VR to a Problem
Chapter 9: What Dreams May Come: The Future of VR 

Appendices
A: NICE educational application (EVL) 
B: Crumbs visualization application (NCSA)
C: Aircraft wiring application (Boeing, Inc.) 
D: Placeholder artistic application (Interval Research)

Understanding Virtual Reality: Interface, Application, and Design

A study by Slater, et al., [1995] indicated that naive subjects in an immersive virtual environment experience a higher subjective sense of presence when they locomote by walking-in-place (virtual walking) than when they push-button-fly (along the floor plane). We replicated their study, adding real walking as a third condition. Our study confirmed their findings. We also found that real walking is significantly better than both virtual walking and flying in ease (simplicity, straightforwardness, naturalness) as a mode of locomotion. The greatest difference in subjective presence was between flyers and both kinds of walkers. In addition, subjective presence was higher for real walkers than virtual walkers, but the difference was statistically significant only in some models. Follow-on studies show virtual walking can be substantially improved by detecting footfalls with a head accelerometer. As in the Slater study, subjective presence significantly correlated with subjects' degree of association with their virtual bodies (avatars). This, our strongest statistical result, suggests that substantial potential presence gains can be had from tracking all limbs and customizing avatar appearance. An unexpected by-product was that real walking through our enhanced version of Slater's visual-cliff virtual environment (Figure 1) yielded a strikingly compelling virtual experience - The strongest we and most of our visitors have yet experienced. The most needed system improvement is the substitution of wireless technology for all links to the user. Copyright ACM 1999.

/pdf/walking-walking-in-place-flying-in-virtual-environments-5e18hc0psi.pdf

Walking > walking-in-place > flying, in virtual environments

Simulator sickness (SS) in high-fidelity visual simulators is a byproduct of modem simulation technology. Although it involves symptoms similar to those of motion-induced sickness (MS), SS tends to be less severe, to be of lower incidence, and to originate from elements of visual display and visuo-vestibular interaction atypical of conditions that induce MS. Most studies of SS to date index severity with some variant of the Pensacola Motion Sickness Questionnaire (MSQ). The MSQ has several deficiencies as an instrument for measuring SS. Some symptoms included in the scoring of MS are irrelevant for SS, and several are misleading. Also, the configural approach of the MSQ is not readily adaptable to computer administration and scoring. This article describes the development of a Simulator Sickness Questiomaire (SSQ), derived from the MSQ using a series of factor analyses, and illustrates its use in monitoring simulator performance with data from a computerized SSQ survey of 3,691 simulator hops. The databas...

Simulator Sickness Questionnaire: An enhanced method for quantifying simulator sickness.

Flight simulators are examples of virtual environment VE systems that often give rise to a form of discomfort resembling classical motion sickness. The major difference between simulator sickness and other forms of motion sickness is that the former exhibits more oculomotor-related symptoms and far less actual vomiting. VEs of the future are likely to include more compellingly realistic visual display systems, and these systems can also be expected to produce adverse symptoms. The implications of simulator sickness for future uses of VEs include adverse consequences for users' safety and health, user acceptance, training effectiveness, and overall system performance. Based on data from a factor analysis of over 1000 Navy and Marine Corps pilot simulation exposures, a new scoring procedure for simulator sickness has recently been developed Lane & Kennedy, 1988; Kennedy, Lane, Berbaum, & Lilienthal, 1992. The factor analytic scoring key provides subscales for oculomotor stress eyestrain, nausea, and disorientation. Simulators are being examined in terms of these factor profiles to identify causes of simulator sickness. This approach could also be used in evaluating motion sickness-like symptomatology that occurs in connection with the use of VEs. This paper describes the use of the multifactor scoring of the Simulator Sickness Questionnaire SSQ in diagnosing sources of simulator sickness in individual simulators. Reanalysis by this new methodology was employed to standardize existing simulator sickness survey data and to determine whether relationships existed that were missed by the more traditional scoring approaches.

Profile analysis of simulator sickness symptoms: application to virtual environment systems

Simulator Sickness Questionnaire

Improved assessment of operational performance is critical for studies of selection, training and human engineering as well as those examining the performance effects of environmental changes, chemicals or other stressors imposed by military duties. The present discussion focuses on what we consider to be the major problem with such enterprises – the lack of sensitivity of operational measures because of poor reliability. The well-documented impact of low field measure reliability includes the inability to demonstrate differences resulting from experimental treatments and the chronic underrepresentation of validity in predictive studies. This paper describes a general methodology for using specially-developed performance batteries as surrogates for real-world performances, in particular for determining whether such performance may be disrupted by environmental or chemical agents. The logical and metric rationale of surrogate measurement is presented, and the advantages and disadvantages are discussed and compared to alternative approaches (job samples, synthetic tasks, etc.).

http://pro.sagepub.com/content/30/14/1398.full.pdf

Overcoming Unreliability in Operational Measures: The Use of Surrogate Measure Systems

Surrogate measures are proposed as an alternative to direct assessment of operational performance for purposes of screening agents who may have to work under unusual stresses or in exotic environments. Such measures are particularly proposed when the surrogate can be empirically validated against the operational criterion. The focus is on cognitive (or throughput) performances in humans as opposed to sensory (input) or motor (output) measures, but the methods should be applicable for development of batteries which will tap input/output functions. A menu of performance tasks is under development for implementation on a battery-operated portable microcomputer, with 21 tests currently available. The tasks are reliable and become stable in minimum amounts of time; appear sensitive to some agents; comprise constructs related to actual job tasks; and are easily administered in most environments. Implications for human factors engineering studies in environmental stress are discussed.

Norman E. Lane

Papers

Simulator Sickness Questionnaire: An enhanced method for quantifying simulator sickness.

Profile analysis of simulator sickness symptoms: application to virtual environment systems

Simulator Sickness Questionnaire

Overcoming Unreliability in Operational Measures: The Use of Surrogate Measure Systems

Surrogate measures: A proposed alternative in human factors assessment of operational measures of performance