Bob G. Witmer

Bio: Bob G. Witmer is an academic researcher from United States Department of the Army. The author has contributed to research in topics: Augmented reality & Virtual machine. The author has an hindex of 14, co-authored 25 publications receiving 6174 citations. Previous affiliations of Bob G. Witmer include University of Central Florida.

Measuring Presence in Virtual Environments: A Presence Questionnaire

Abstract: 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.

The factor structure of the presence questionnaire

Abstract: Constructing a valid measure of presence and discovering the factors that contribute to presence have been much sought after goals of presence researchers and at times have generated controversy among them. This paper describes the results of principal-components analyses of Presence Questionnaire (PQ) data from 325 participants following exposure to immersive virtual environments. The analyses suggest that a 4-factor model provides the best fit to our data. The factors are Involvement, Adaptation/Immersion, Sensory Fidelity, and Interface Quality. Except for the Adaptation/Immersion factor, these factors corresponded to those identified in a cluster analysis of data from an earlier version of the questionnaire. The existence of an Adaptation/Immersion factor leads us to postulate that immersion is greater for those individuals who rapidly and easily adapt to the virtual environment. The magnitudes of the correlations among the factors indicate moderately strong relationships among the 4 factors. Within these relationships, Sensory Fidelity items seem to be more closely related to Involvement, whereas Interface Quality items appear to be more closely related to Adaptation/Immersion, even though there is a moderately strong relationship between the Involvement and Adaptation/Immersion factors.

Virtual spaces and real world places: transfer of route knowledge

Abstract: It has been widely suggested, but rarely demonstrated, that virtual environments (VEs) are effective training media. The purpose of this investigation was to evaluate how well a VE model of a complex office building trained individuals to navigate in the actual building. Sixty participants studied route directions and landmark photographs, then rehearsed the route using either the VE model, the actual building, or verbal directions and photographs. The VE model was presented in real time via a head-tracked display. Half of the participants in each rehearsal group also studied route maps. Everyone's route knowledge was then measured in the actual building. Building configuration knowledge was also measured. VE rehearsal produced more route knowledge than verbal rehearsal, but less than with rehearsal in the actual building. Type of rehearsal had no effect on configuration knowledge. Map study influenced neither route nor configuration knowledge. These results suggest that VEs that adequately represent real world complexity can be effective training media for learning complex routes in buildings, and should be considered whenever the real world site is unavailable for training.

Judging Perceived and Traversed Distance in Virtual Environments

Abstract: The ability to accurately estimate distance is an essential component of navigating large-scale spaces. Although the factors that influence distance estimation have been a topic of research in real-world environments for decades and are well known, research on distance estimation in virtual environments (VEs) has only just begun. Initial investigations of distance estimation in VEs suggest that observers are less accurate in estimating distance in VEs than in the real world (Lampton et al., 1995). Factors influencing distance estimates may be divided into those affecting perceived distance (visual cues only) and those affecting traversed distance to include visual, cognitive, and proprioceptive cues. To assess the contribution of the various distance cues in VEs, two experiments were conducted. The first required a static observer to estimate the distance to a cylinder placed at various points along a 130-foot hallway. This experiment examined the effects of floor texture, floor pattern, and object size on distance estimates in a VE. The second experiment required a moving observer to estimate route segment distances and total route distances along four routes, each totaling 1210 feet. This experiment assessed the effects of movement method, movement speed, compensatory cues, and wall texture density. Results indicate that observers underestimate distances both in VEs and in the real world, but the underestimates are more extreme in VEs. Texture did not reliably affect the distance estimates, providing no compensation for the gross underestimates of distance in VE. Traversing a distance improves the ability to estimate that distance, but more natural means of moving via a treadmill do not necessarily improve distance estimates over traditional methods of moving in VE (e.g., using a joystick). The addition of compensatory cues (tone every 10 feet traversed on alternate route segments) improves VE distance estimation to almost perfect performance.

Aftereffects and sense of presence in virtual environments: formulation of a research and development agenda.

Abstract: This report represents a committee summary of the current state of knowledge regarding aftereffects and sense of presence in virtual environments (VEs). The work presented in this article, and the proposed research agenda, are the result of a special session that was set up in the framework of the Seventh International Conference on Human Computer Interaction Recommendations were made by the committee regarding research needs in after effects and sense of presence, and, where possible, priorities were suggested. The research needs were structured in terms of the short medium, and long term and, if followed, should lead toward the effective use of VE technology. The 2 most critical research issues identified were (a) standardization and use of measurement approaches for aftereffects and (b) identification and prioritization of sensorimotor discordances that drive after effects. Identification of aftereffects countermeasures (i.e., techniques to assist users in readily transitioning between the real and vir...

Measuring Presence in Virtual Environments: A Presence Questionnaire

Abstract: 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.

Educating the Net Generation

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Measuring and defining the experience of immersion in games

Abstract: Despite the word's common usage by gamers and reviewers alike, it is still not clear what immersion means. This paper explores immersion further by investigating whether immersion can be defined quantitatively, describing three experiments in total. The first experiment investigated participants' abilities to switch from an immersive to a non-immersive task. The second experiment investigated whether there were changes in participants' eye movements during an immersive task. The third experiment investigated the effect of an externally imposed pace of interaction on immersion and affective measures (state anxiety, positive affect, negative affect). Overall the findings suggest that immersion can be measured subjectively (through questionnaires) as well as objectively (task completion time, eye movements). Furthermore, immersion is not only viewed as a positive experience: negative emotions and uneasiness (i.e. anxiety) also run high.

Toward a more robust theory and measure of social presence: review and suggested criteria

Abstract: 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.