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Results for “virtual environment”

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At least 415 records · Page 23Linked to original sources

PubMed2006

Virtual vestibular re-education. A new technology.

This paper will provide an introduction to the use of virtual environments for vestibular re-education. The author illustrates some of the ways in which researchers are using virtual reality to improve therapy for vertigo. Users of virtual reality must make adaptations to avoid mismatches between perception due to virtual reality and that due to vestibular and proprioceptive subsystems. Virtual reality may be an interesting new way of studying vestibular compensation in normal and pathological conditions.

Humans↗

PubMed1998

Assessing a VR-based learning environment for anatomy education.

The purpose of the research proposed herein is to develop an empirical, methodological tool for the assessment of visual depth perception in virtual environments (VEs). Our goal is to develop and employ a behaviorally-based method for assessing the impact of VE design features on the perception of visual depth as indexed by the performance of fundamental perceptual-motor activities. Specifically, in this experiment we will assess the affect of two dimensions of VE system design--(1) viewing condition or "level of immersion", and (2) layout/design of the VE--on the performance of an engaging, game-like task. The characteristics of the task to be employed are as follows--(1) it places no demands on cognition in the form of problem solving, retrieval of previously learned information, or other analytic activity in order to assure that (2) variations in task performance can be exclusively attributed to the extent to which the experimental factors influence visual depth perception. Subjects' performance will be assessed in terms of the speed and accuracy of task performance, as well as underlying dimensions of performance such as workload, fatigue, and physiological well being (i.e., cybersickness). The results of this experiment will provide important information on the effect of VE immersion and other VE design issues on human perception and performance. Further development, refinement, and validation of this behaviorally-based methodology will be pursued to provide user-centered design criteria for the design and use of VE systems.

Anatomy↗

PubMed2006

GiPSiNet: an open source/open architecture network middleware for surgical simulations.

In this paper, we present the design and techniques of GiPSiNet, an open source/open architecture network middleware being developed for surgical simulations. GiPSiNet extends GiPSi (General Interactive Physical Simulation Interface), our framework for developing organ level surgical simulations, to network environments. This network extension is non-trivial, since the network settings pose several serious problems for distributed surgical virtual environments such as band-width limit, delays, and packet losses. Our goal is to enhance the quality (fidelity and realism) of networked simulations in the absence of network QoS (Quality of Service) through the GiPSiNet middleware.

Computer Simulation↗

PubMed2004

Effect of virtual reality graded exposure on anxiety levels of performing musicians: a case study.

This study examined the effect of computer generated virtual reality graded exposure on the physiological and psychological responses of performing musicians. Three upper division undergraduate saxophonists, two female and one male, performed while immersed in four virtual environments each designed to gradually increase the expected anxiety level of the performer. Heart rates and subjective measurements were taken throughout the exposure period. Results of this study indicated that virtual reality graded exposure did elicit physiological and psychological indications of increased anxiety in musical performance environments designed for that purpose. Findings also corroborated previous research that found gender to be a predictor of heart rate during performance.

Adult↗

PubMed2003

The information for catching fly balls: judging and intercepting virtual balls in a CAVE.

Visually guided action implies the existence of information as well as a control law relating that information to movement. For ball catching, the Chapman Strategy--keeping constant the rate of change of the tangent of the elevation angle (d(tan(alpha))/dt)--leads a catcher to the right location at the right time to intercept a fly ball. Previous studies showed the ability to detect the information and the consistency of running patterns with the use of the strategy. However, only direct manipulation of information can show its use. Participants were asked to intercept virtual balls in a Cave Automated Virtual Environment (CAVE) or to judge whether balls would pass behind or in front of them. Catchers in the CAVE successfully intercepted virtual balls with their forehead. Furthermore, the timing of judgments was related to the patterns of changing d(tan(alpha))/dt. The advantages and disadvantages of a CAVE as a tool for studying interceptive action are discussed.

Adult↗

PubMed2002

Simultaneous virtual representation of both vascular and neural tissue within the subarachnoid space of the basal cistern--technical note.

BACKGROUND: The representation of different anatomical structures requires varying imaging modalities and protocols. By mental composition of single-slice images, a three-dimensional (3D) impression can be achieved. However, this presupposes an outstanding imagination and is subject to inaccuracies. The use of an interactive and multi-modal planning system which represents different data sets in one single virtual environment holds promise to facilitate and improve neurosurgical decision-making. The authors report the clinical application of a self-developed virtual planning system in a case of trigeminal neuralgia due to an ectatic basilar artery. MATERIAL/METHODS: We modified our virtual planning system (VIVENDI), to achieve a virtual representation of the basal cistern illustrating both vascular and neuronal information. After conducting several experiments to determine an appropriate scanning protocol, we matched the data achieved by magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). RESULTS: The system provides the vascular topography combined with information on the anatomical structure of the subarachnoid space. To illustrate the clinical usefulness of this planning approach, the authors present a case of trigeminal neuralgia caused by an ectatic basilar artery. Pre-operatively, the virtual representation returned accurate information on the anatomical configuration of the cerebellopontine angle and the course of the ectatic vessel. This information was confirmed during surgery. CONCLUSIONS: The presented case demonstrates the clinical applicability of VIVENDI within the subarachnoid space of the basal cistern. The virtual representation enables pre-operative planning and simulation based on the patient's individual anatomy.

Humans↗

PubMed2006

Walking from thought.

Online analysis and classification of single electroencephalogram (EEG) trials during motor imagery were used for navigation in the virtual environment (VE). The EEG was recorded bipolarly with electrode placement over the hand and foot representation areas. The aim of the study was to demonstrate for the first time that it is possible to move through a virtual street without muscular activity when the participant only imagines feet movements. This is achieved by exploiting a brain-computer interface (BCI) which transforms thought-modulated EEG signals into an output signal that controls events within the VE. The experiments were carried out in an immersive projection environment, commonly referred to as a "Cave" (Cruz-Neira, C., Sandin, D.J., DeFanti, T.A., Surround-screen projection-based virtual reality: the design and implementation of the CAVE. Proceedings of the 20th annual conference on Computer graphics and interactive techniques, ACM Press, 1993, pp. 135-142) where participants were able to move through a virtual street by foot imagery only. Prior to the final experiments in the Cave, the participants underwent an extensive BCI training.

Adult↗

PubMed2006

Extrahippocampal contributions to age differences in human spatial navigation.

The hippocampus (HC) and associated neural structures are hypothesized to contribute to individual differences in human spatial navigation. However, functional imaging studies and theoretical models underscore the importance of extrahippocampal regions as well. The purpose of the present study was to examine age differences in virtual environment navigation and to assess possible relationships between navigation and structural integrity of hippocampal and extrahippocampal brain regions. Healthy adult volunteers completed a virtual navigation task and underwent magnetic resonance imaging to assess volumes of the caudate nucleus (CN), cerebellum, HC, prefrontal, and primary visual cortices. Results demonstrated robust age-related differences in place learning. Moreover, individual differences in regional brain volumes as well as performance on the tests of memory and executive functions contributed to age differences in human place learning. High performance in a virtual navigation task was associated with larger volume of the CN and prefrontal gray and white matter. Larger hippocampal volume was associated with improved performance in the young but not old participants. We conclude that human navigation requires both hippocampal and extrahippocampal brain systems and draws on executive resources for successful performance.

Adult↗

PubMed1999

Simulation and virtual reality in surgical education: real or unreal?

Rapid change is under way on several fronts in medicine and surgery. Advances in computing power have enabled continued growth in virtual reality, visualization, and simulation technologies. The ideal learning opportunities afforded by simulated and virtual environments have prompted their exploration as learning modalities for surgical education and training. Ongoing improvements in this technology suggest an important future role for virtual reality and simulation in surgical education and training.

Computer Simulation↗

PubMed2004

Water-friendly virtual reality pain control during wound care.

Recent research suggests that entering an immersive virtual environment can serve as a powerful nonpharmacologic analgesic for severe burn pain. The present case study describes an attempt to use water-friendly virtual reality (VR) technology with a burn patient undergoing wound care in a hydrotherapy tub. The patient was a 40-year-old male with 19% total body surface area deep flame/flash burns to his legs, neck, back, and buttocks. The virtual reality treatment decreased the patient's sensory and affective pain ratings and decreased the amount of time spent thinking about his pain during wound care. We believe that VR analgesia works by drawing attention away from the wound care, leaving less attention available to process incoming pain signals. The water-friendly VR helmet dramatically increases the number of patients with severe burns that could potentially be treated with VR (see http://www.vrpain.com).

Adult↗

PubMed2001

What controls attention in natural environments?

The highly task-specific fixation patterns revealed in performance of natural tasks demonstrate the fundamentally active nature of vision, and suggest that in many situations, top-down processes may be a major factor in the acquisition of visual information. Understanding how a top-down visual system could function requires understanding the mechanisms that control the initiation of the different task-specific computations at the appropriate time. This is particularly difficult in dynamic environments, like driving, where many aspects of the visual input may be unpredictable. We therefore examined drivers' abilities to detect Stop signs in a virtual environment when the signs were visible for restricted periods of time. Detection performance is heavily modulated both by the instructions and the local visual context. This suggests that visibility of the signs requires active search, and that the frequency of this search is influenced by learnt knowledge of the probabilistic structure of the environment.

Attention↗

PubMed2005

Absolute travel distance from optic flow.

Optic flow fields provide rich information about the observer's self-motion. Besides estimation of the direction of self-motion human observers are also able to discriminate the travel distances of two self-motion simulations. Recent studies have shown that observers estimate the simulated ego velocity of the self-motion simulation and integrate it over time. Thus, observers use a 3-D percept of the ego motion through the environment. In the present work we ask if human observers are able to use this 3-D percept of the motion simulation to build up an internal representation of travel distance and indicate it in a static scene. We visually simulated self-motion in different virtual environments and asked subjects to indicate the perceived distances in terms of static virtual intervals on the ground. The results show that human observers possess a static distance gauge, but that they undershoot the travel distances for short motion simulations. In further experiments we changed the modality of the distance indication but the undershoot in distance estimation remained. This suggests that the undershoot is linked to the perception of the optic flow field.

Cues↗

PubMed2004

Lifestyles of virtual world residents: living in the on-line game "lineage".

This study was conducted to explore the lifestyles of online game players who have adopted the virtual world as part of their life. An online survey was conducted on players of an Internet-based game, Lineage. Lineage is the largest online game where people assume new identities and play various roles in a virtual environment, accommodating over 6 million users worldwide. A total of 4,786 game players participated in this survey, and their lifestyles were compared with their values and attitudes in the virtual world. Upon classification of their real-world lifestyles, their tendencies and desires were compared to lifestyles in the virtual world. This study showed that game players have developed their own distinctive lifestyles, and their lifestyles were a strong criterion for explaining behavior patterns and desires in the virtual world. Lifestyles were classified into three general categories: (1) single-oriented player, (2) community-oriented player, and (3) off-Real world player. Each group displayed distinct differences in their values and game activities, as well as in their anti-social behavior tendencies. The differences reflected not only their personality but also their socio-economic status within the virtual world, which is constructed through game activities. This study serves as a model to understand how players from different real-life backgrounds will behave in various game features and how they adopt the virtual world for their new social identities.

Choice Behavior↗

PubMed2005

Humans use continuous visual feedback from the hand to control both the direction and distance of pointing movements.

Vision of the hand during reaching provides dynamic feedback that can be used to control movement. We investigated the relative contributions of feedback about the direction and distance of the hand relative to a target. Subjects made pointing movements in a 3-D virtual environment, in which a small sphere provided dynamic visual feedback about the position of their unseen fingertip. On a subset of trials, the position of the virtual fingertip was smoothly shifted by 2 cm during movement, either (1) in the direction of movement, which would require adjustments to the distance moved, or (2) orthogonal to the direction of movement, which would require adjustments to the direction moved. Despite not noticing the perturbations, subjects adjusted their movements to compensate for both types of visual shifts. Corrective responses to direction perturbations were observed within 117 ms, and response latencies were invariant to movement speed and perturbation onset time. Initial corrections to distance perturbations were smaller and appeared after longer delays of 130-200 ms, and both the speed and magnitude of responses were reduced for early onset perturbations. Simulations of a feedback control model that optimally integrates visual information over time show that the results can be explained by differences in the sensory noise levels in the visual dimensions relevant for direction and distance control.

Adaptation, Physiological↗

PubMed2005

Do humans integrate routes into a cognitive map? Map- versus landmark-based navigation of novel shortcuts.

Do humans integrate experience on specific routes into metric survey knowledge of the environment, or do they depend on a simpler strategy of landmark navigation? The authors tested this question using a novel shortcut paradigm during walking in a virtual environment. The authors find that participants could not take successful shortcuts in a desert world but could do so with dispersed landmarks in a forest. On catch trials, participants were drawn toward the displaced landmarks whether the landmarks were clustered near the target location or along the shortcut route. However, when landmarks appeared unreliable, participants fell back on coarse survey knowledge. Like honeybees (F. C. Dyer, 1991), humans do not appear to derive accurate cognitive maps from path integration to guide navigation but, instead, depend on landmarks when they are available.

Adolescent↗

PubMed2006

Virtual action planning in Parkinson's disease: a control study.

Cognitive planning deficits affect patients with Parkinson's disease (PD) and traditional psychometric tests meet difficulties to evaluate their impact on daily life activities. Virtual reality (VR) may provide a new means of assessment. The objective of this study was firstly to develop a virtual environment (VE) useful to explore planning and secondly to examine the effectiveness of using VR in the assessment of cognitive planning for patients with PD. A virtual supermarket (VS) was designed in which participants carried out a task close to daily activities: a test of shopping list. There were two preliminary sessions to familiarize the participants with the software and the supermarket's layout. Then, during the assessment session, participants completed the task, without any time limitation. Global intellectual efficiency was assessed in order to exclude patients with dementia. Data related to the performance in the VS were recorded. Five patients with PD and five age-matched healthy volunteers, meeting inclusion criteria, constituted our convenience sample. The patients did not perform as well as the control group. In particular, the session's duration and the distance covered were longer. The patients' path is specific with numerous stops, turning around, and hesitancies. Finally, their motivation for further training sessions is aroused. The results underline the potential of using VR in the assessment of cognitive planning in PD. A larger analysis is currently being carried out to confirm and to explore all the outcome measures.

Aged↗

PubMed1999

Anatomic VisualizeR: realizing the vision of a VR-based learning environment.

The University of California, San Diego's Anatomic VisualizeR project has reached another milestone. As the period of DARPA-funded research and development comes to a close, UCSD's VR-based learning environment has matured to the point where curricular implementation is now underway. In this presentation, we will reflect on the process by which lessons in this virtual environment are realized, highlight the results of ongoing 3-D perception studies, and describe examples of how Anatomic VisualizeR is being used in medical school anatomy and high school biology classes. To conclude, we will outline the future of this project which will include full scale curricular implementation, learning outcomes assessment, and dissemination through industrial and academic partnerships.

Anatomy↗

PubMed2002

The VEPSY UPDATED project: technical and clinical rationale.

The emergence of new shared media, such as the Internet and virtual reality are changing the ways in which people relate, communicate, and live. Health care, and in particular clinical psychology, is one of the areas that could be most dramatically reshaped by these new technologies. To exploit and understand this potential is the overall goal of the "Telemedicine and Portable Virtual Environment in Clinical Psychology"--VEPSY UPDATED--an European Community funded research project (IST-2000-25323, http://www.vepsy.com) whose specific goal is the development of different PC based virtual reality modules to be used in clinical assessment and treatment. In particular the developed modules have been using to address the following pathologies: anxiety disorders; male impotence and premature ejaculation; obesity, bulimia and binge-eating disorders. The chapter details the general technical and clinical characteristics of the developed modules.

Diagnosis, Computer-Assisted↗