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Results for “virtual environment”

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At least 163 records · Page 9Linked to original sources

PubMed1991

Auditory localization in teleoperator and virtual environment systems: ideas, issues, and problems.

The increasing availability and use of advanced high-tech human-machine interfaces raise many interesting questions about what information should be presented to each sensory modality and how the information should be coded for a given modality. In this paper, attention is confined to the auditory component of the interface and, more specifically, to auditory localization. Both teleoperator systems and virtual-environment systems are considered, and attention is focused upon the opportunities and difficulties associated with the use of unnatural perceptual cues in these systems. Of central interest in this discussion is the use of such cues to improve resolution and thereby obtain systems with superlocalization capabilities.

Computer Simulation↗

PubMed2003

A virtual environment for investigating schizophrenic patients' characteristics: assessment of cognitive and navigation ability.

Patients with schizophrenia have thinking disorders such as delusions or hallucinations because they have a deficit in the ability to systematize and integrate information. Therefore, they cannot integrate or systematize visual, auditory, and tactile stimuli. The multimodal integration model of the brain can provide a theoretical background from which one can approach multimodal stimulus integration. In this study, we suggest a virtual reality system for the multi-modal assessment of cognitive ability of schizophrenia patients. The virtual reality system can provide multimodal stimuli, such as visual and auditory stimuli, to the patient and can evaluate the patient's multimodal integration and working memory integration abilities by making the patient interpret and react to multimodal stimuli, which must be remembered for a given period of time. The clinical study showed that the virtual reality program developed is comparable to those of the Wisconsin Card Sorting Test (WCST) and the Standard Progressive Matrices (SPM), and it provides some information related to the schizophrenic patients' behavior in 3D virtual environment.

Adult↗

PubMed2005

A functional magnetic resonance imaging (FMRI) study of cue-induced smoking craving in virtual environments.

Smokers who are exposed to smoking-related cues show cardiovascular reactivity and smoking craving compared with their responses to neutral cues, and increased cue reactivity predicts decreased likelihood of successful cessation. Several brain imaging studies suggested four candidate brain regions that might differ in gray matter volumes and densities between smokers and nonsmokers. However, in these studies, smokers were only exposed to smoking-related objects. In our pilot study utilizing a virtual reality (VR) technique, virtual environments (VEs) were more immersive and evoked smoking craving more effectively than traditionally used methods. In this study, we sought to test whether smokers could experience cue-induced smoking craving inside the MRI scanner by using the VR system. The smoking cue reactivity scenario was based in part on our preliminary task and consisted of 2D and 3D (or VE) conditions. The group mean of participants had increased activity in the prefrontal cortex (PFC), left anterior cingulate gyrus (ACC), left supplementary motor area, left uncus, right inferior temporal gyrus, right lingual gyrus, and right precuneus in the 2D condition. Areas of differential activation in the 3D condition were as follows: left superior temporal gyrus, right superior frontal gyrus, and left inferior occipital gyrus in the 3D condition. This finding is consistent with those of previous studies of nicotine craving showing PFC and ACC activation. However, in the 3D condition, the PFC including the superior frontal gyrus as well as the superior temporal gyrus, inferior occipital gyrus, and cerebellum were activated. Therefore, in the 3D condition, participants seemed to have more attention, visual balance, and coordinating movement than in the 2D condition.

Adolescent↗

PubMed2004

Distributed interactive virtual environments for collaborative medical education and training: design and characterization.

Project TOUCH (Telehealth Outreach for Unified Community Health) is a collaborative effort between University of New Mexico and University of Hawaii. The purpose of the project is to demonstrate the feasibility of using advanced technologies to overcome geographical barriers to delivery of medical education and to enhance the learning process within a group setting. This has led to the design and implementation of a new system that addresses the critical requirements for collaborative virtual environments: consistency, networking, scalability, and system integration. The objective of this study is to evaluate the performance of the collaborative system based on use patterns during Project TOUCH sessions.

Cooperative Behavior↗

PubMed2002

Three dimensional spatial memory and learning in real and virtual environments.

Human orientation and spatial cognition partly depends on our ability to remember sets of visual landmarks and imagine their relationship to us from a different viewpoint. We normally make large body rotations only about a single axis which is aligned with gravity. However, astronauts who try to recognize environments rotated in 3 dimensions report that their terrestrial ability to imagine the relative orientation of remembered landmarks does not easily generalize. The ability of human subjects to learn to mentally rotate a simple array of six objects around them was studied in 1-G laboratory experiments. Subjects were tested in a cubic chamber (n = 73) and a equivalent virtual environment (n = 24), analogous to the interior of a space station node module. A picture of an object was presented at the center of each wall. Subjects had to memorize the spatial relationships among the six objects and learn to predict the direction to a specific object if their body were in a specified 3D orientation. Percent correct learning curves and response times were measured. Most subjects achieved high accuracy from a given viewpoint within 20 trials, regardless of roll orientation, and learned a second view direction with equal or greater ease. Performance of the subject group that used a head mounted display/head tracker was qualitatively similar to that of the second group tested in a physical node simulator. Body position with respect to gravity had a significant but minor effect on performance of each group, suggesting that results may also apply to weightless situations. A correlation was found between task performance measures and conventional paper-and-pencil tests of field independence and 2&3 dimensional figure rotation ability.

Adolescent↗

PubMed2001

Evaluation for the design of experience in virtual environments: modeling breakdown of interaction and illusion.

New and emerging media technologies have the potential to induce a variety of experiences in users. In this paper, it is argued that the inducement of experience presupposes that users are absorbed in the illusion created by these media. Looking to another successful visual medium, film, this paper borrows from the techniques used in "shaping experience" to hold spectators' attention in the illusion of film, and identifies what breaks the illusion/experience for spectators. This paper focuses on one medium, virtual reality (VR), and advocates a transparent or "invisible style" of interaction. We argue that transparency keeps users in the "flow" of their activities and consequently enhances experience in users. Breakdown in activities breaks the experience and subsequently provides opportunities to identify and analyze potential causes of usability problems. Adopting activity theory, we devise a model of interaction with VR--through consciousness and activity--and introduce the concept of breakdown in illusion. From this, a model of effective interaction with VR is devised and the occurrence of breakdown in interaction and illusion is identified along a continuum of engagement. Evaluation guidelines for the design of experience are proposed and applied to usability problems detected in an empirical study of a head-mounted display (HMD) VR system. This study shows that the guidelines are effective in the evaluation of VR. Finally, we look at the potential experiences that may be induced in users and propose a way to evaluate user experience in virtual environments (VEs) and other new and emerging media.

Humans↗

PubMed2001

Real-time monitoring of brain activity in patients with specific phobia during exposure therapy, employing a stereoscopic virtual environment.

Exposure therapy is a behavioral technique that is reported to be the most effective, long-lasting treatment for patients suffering from specific phobia. During the performance in enclosed spaces, the patients show a strong psychophysiological response to the phobic stimulus that is normally avoided. This psychophysiological response changes characteristically during the course of exposure. We implemented an electroencephalographic monitoring focusing on event-related potentials to resolve the modulation of preattentive information processing by the anxiety state of the subject. Therefore, mismatch-negativity (MMN) was chosen as parameter using a passive auditory oddball paradigm that does not interfere with performance in the virtual environment. The results of this neurophysiological monitoring are demonstrated in one patient suffering from claustrophobia.

Adult↗

PubMedDate not supplied

Low-cost telepresence for collaborative virtual environments.

We present a novel low-cost method for visual communication and telepresence in a CAVE -like environment, relying on 2D stereo-based video avatars. The system combines a selection of proven efficient algorithms and approximations in a unique way, resulting in a convincing stereoscopic real-time representation of a remote user acquired in a spatially immersive display. The system was designed to extend existing projection systems with acquisition capabilities requiring minimal hardware modifications and cost. The system uses infrared-based image segmentation to enable concurrent acquisition and projection in an immersive environment without a static background. The system consists of two color cameras and two additional b/w cameras used for segmentation in the near-IR spectrum. There is no need for special optics as the mask and color image are merged using image-warping based on a depth estimation. The resulting stereo image stream is compressed, streamed across a network, and displayed as a frame-sequential stereo texture on a billboard in the remote virtual environment.

Algorithms↗

PubMed2005

Height effects in real and virtual environments.

The study compared human perceptions of height, danger, and anxiety, as well as skin conductance and heart rate responses and postural instability effects, in real and virtual height environments. The 24 participants (12 men, 12 women), whose average age was 23.6 years, performed "lean-over-the-railing" and standing tasks on real and comparable virtual balconies, using a surround-screen virtual reality (SSVR) system. The results indicate that the virtual display of elevation provided realistic perceptual experience and induced some physiological responses and postural instability effects comparable to those found in a real environment. It appears that a simulation of elevated work environment in a SSVR system, although with reduced visual fidelity, is a valid tool for safety research. Potential applications of this study include the design of virtual environments that will help in safe evaluation of human performance at elevation, identification of risk factors leading to fall incidents, and assessment of new fall prevention strategies.

Accidental Falls↗

PubMed2003

An investigation of road crossing in a virtual environment.

The reported study employed a virtual reality (VR) system, using a head mounted display (HMD), to investigate road crossing behavior in children and young adults. Younger children (aged 5-9 years) made the greatest number of unsafe road crossings and the oldest participants (aged >19 years) the fewest. Overall performance was better (fewer unsafe road crossings) in uniform speed than uniform distance trials, consistent with previous research suggesting that pedestrians base road crossing decisions on inter-vehicle distance rather than vehicle speed. Results are discussed in terms of road crossing behavior and the use of VR simulations in the study of pedestrian behavior.

Accidents, Traffic↗

PubMed2006

Integrating haptic-tactile feedback into a video-capture-based virtual environment for rehabilitation.

Video-capture virtual reality (VR) systems are gaining popularity as intervention tools. To date, these platforms offer visual and audio feedback but do not provide haptic feedback. We contend that adding haptic feedback may enhance the quality of intervention for various theoretical and empirical reasons. This study aims to integrate haptic-tactile feedback into a video capture system (GX VR), which is currently applied for rehabilitation. The proposed multi-modal system can deliver audio-visual as well as vibrotactile feedback. The latter is provided via small vibratory discs attached to the patient's limbs. This paper describes the system, the guidelines of its design, and the ongoing usability study.

Computer Simulation↗

PubMed2002

A user interface model for navigation in virtual environments.

One of the most complicated tasks when working with three-dimensional virtual worlds is the navigation process. Usually, this process requires the use of buttons and key-sequences and the development of interaction metaphors that frequently make the interaction process artificial and inefficient. In these environments, very simple tasks, such as looking upward and downward, can became extremely complicated. To overcome these obstacles, this work presents an interaction model for three-dimensional virtual worlds, based on the interpretation of the natural gestures of a real user while he/she is walking in a real world. This model is an example of a non-WIMP (Window, Icon, Menu, Pointer) interface. To test this model, we created a device named "virtual bike." With this device, the user can navigate through the virtual environment exactly as if he were riding a real bike.

Computers↗

PubMed2003

Experience with V-STORE: considerations on presence in virtual environments for effective neuropsychological rehabilitation of executive functions.

The paper discusses the use of immersive virtual reality systems for the cognitive rehabilitation of dysexecutive syndrome, usually caused by prefrontal brain injuries. With respect to classical P&P and flat-screen computer rehabilitative tools, IVR systems might prove capable of evoking a more intense and compelling sense of presence, thanks to the highly naturalistic subject-environment interaction allowed. Within a constructivist framework applied to holistic rehabilitation, we suggest that this difference might enhance the ecological validity of cognitive training, partly overcoming the implicit limits of a lab setting, which seem to affect non-immersive procedures especially when applied to dysexecutive symptoms. We tested presence in a pilot study applied to a new VR-based rehabilitation tool for executive functions, V-Store; it allows patients to explore a virtual environment where they solve six series of tasks, ordered for complexity and designed to stimulate executive functions, programming, categorical abstraction, short-term memory and attention. We compared sense of presence experienced by unskilled normal subjects, randomly assigned to immersive or non-immersive (flat screen) sessions of V-Store, through four different indexes: self-report questionnaire, psychophysiological (GSR, skin conductance), neuropsychological (incidental recall memory test related to auditory information coming from the "real" environment) and count of breaks in presence (BIPs). Preliminary results show in the immersive group a significantly higher GSR response during tasks; neuropsychological data (fewer recalled elements from "reality") and less BIPs only show a congruent but yet non-significant advantage for the immersive condition; no differences were evident from the self-report questionnaire. A larger experimental group is currently under examination to evaluate significance of these data, which also might prove interesting with respect to the question of objective-subjective measures of presence.

Cognition Disorders↗

PubMed2005

Cognitive ergonomics in virtual environments: development of an intuitive and appropriate input device for navigating in a virtual maze.

For patients suffering from mild cognitive impairments, the navigation through a virtual maze should be as intuitive and efficient as possible in order to minimize cognitive and physical strain. This paper discusses the appropriateness of interaction devices for being used for easy navigation tasks. Information gained from human centered evaluation was used to develop an intuitive and ergonomic interaction device. Two experiments examined the usability of tracked interaction devices. Usability problems with the devices are discussed. The findings from the experiments were translated into general design guidance, in addition to specific recommendations. A new device was designed on the basis of these recommendations and its usability was evaluated in a second experiment. The results were used to develop a lightweight interaction device for navigation in the virtual maze.

Cognition Disorders↗

PubMed2001

A virtual therapeutic environment with user projective agents.

Today, we see the Internet as more than just an information infrastructure, but a socializing place and a safe outlet of inner feelings. Many personalities develop aside from real world life due to its anonymous environment. Virtual world interactions are bringing about new psychological illnesses ranging from netaddiction to technostress, as well as online personality disorders and conflicts in multiple identities that exist in the virtual world. Presently, there are no standard therapy models for the virtual environment. There are very few therapeutic environments, or tools especially made for virtual therapeutic environments. The goal of our research is to provide the therapy model and middleware tools for psychologists to use in virtual therapeutic environments. We propose the Cyber Therapy Model, and Projective Agents, a tool used in the therapeutic environment. To evaluate the effectiveness of the tool, we created a prototype system, called the Virtual Group Counseling System, which is a therapeutic environment that allows the user to participate in group counseling through the eyes of their Projective Agent. Projective Agents inherit the user's personality traits. During the virtual group counseling, the user's Projective Agent interacts and collaborates to recover and increase their psychological growth. The prototype system provides a simulation environment where psychologists can adjust the parameters and customize their own simulation environment. The model and tool is a first attempt toward simulating online personalities that may exist only online, and provide data for observation.

Behavior, Addictive↗

PubMed2006

Does walking in a virtual environment induce unstable gait? An examination of vertical ground reaction forces.

Virtual reality (VR) can induce postural instability in standing and walking, as quantified with kinematic parameters. This study examines the effect of a VR environment on kinetic gait parameters. Ten healthy volunteers walked on an instrumented treadmill in a VR environment and a non-VR environment. In the VR environment, a corridor with colored vertical stripes comprising the walls was projected onto a concave screen placed in front of the treadmill. The speed of the moving image was perceptually equivalent to the speed of the treadmill, creating an illusion that subjects walked through the corridor. Vertical ground reaction forces were sampled. Kinetic parameters that reflect gait stability (weight acceptance peak force, weight acceptance rate, push-off peak force and push-off rate) were compared between the VR and non-VR environments. Subjects walked in the VR environment with increased magnitudes and rates of weight acceptance force and with increased rates of push-off force. Variability in weight acceptance rates and peak forces, and variability in push-off peak forces, were also increased in the VR environment. The gait deviations reflect a compensatory response to visual stimulation that occurs in the VR environment, suggesting that walking in a VR environment may induce gait instability in healthy subjects.

Adult↗

PubMed1997

Cubby. A medical virtual environment based on multiscreen movement parallax.

In this paper a desktop virtual reality system named Cubby is described. Cubby is based on self-induced, head-coupled movement parallax on three orthogonal screens. It is argued that this system is better suited to medical practice than Immersive VR solutions or single screen Desktop VR systems. Whilst Cubby is currently limited to visualisation it opens up possibilities of direct instrumental manipulation and as such could prove useful as a medical simulator.

Computer Simulation↗

PubMed2004

Human foraging behavior in a virtual environment.

We have developed an experimental platform that allows a large number of human participants to interact in real time within a common virtual world. Within this environment, human participants foraged for resources distributed in two spatially separated pools. In addition to varying the relative replenishment rate for the two pools (50-50, 65-35, or 80-20), we manipulated whether the participants could see each other and the entire resource distribution or had their vision restricted to resources at their own location. Two empirical deviations from an optimal distribution of the participants were found. First, the participants were more scattered within a resource pool than the resources were themselves. Second, there was systematic underutilization of the richer pool. For example, the participants distributed themselves 73% and 27% to resource pools that had replenishment rates of 80% and 20%, respectively. In addition, there were oscillations in the harvesting rate of the pools across time, revealed by a Fourier analysis with prominent power near 50 sec per cycle. The suboptimalities and oscillations were more apparent when the locations of the participants and the food were not visible. Individual participant knowledge thus affects the efficiency with which a population of participants harvests resources.

Feeding Behavior↗