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PubMed1998

Contributions of proprioception to navigation in virtual environments.

Users immersed in virtual environments (VEs) are prone to disorientation and have difficulty transferring spatial knowledge to the real world. A single experiment investigated the contribution of inadequate proprioception to this problem by providing participants with interfaces to a virtual environment that either did (a walking interface) or did not (a joystick) afford proprioceptive feedback similar to that obtained during real walking. The 2 groups explored a large, complex building using a low-resolution head-mounted display. Later, their navigational abilities within the actual building were compared with those of control groups who either studied a map of the building, walked through the real building, or received no prior training. The walking interface conveyed no benefit on an orientation task performed during training in the VE, but it did benefit participants when they tried to find objects in the real world. Actual or potential applications include simulations of environments that are normally explored on foot but cannot be readily visited, such as infantry battlefields and facilities contaminated with chemical, biological, or radiological materials.

Adolescent↗

PubMed1996

The expert surgical assistant. An intelligent virtual environment with multimodal input.

Virtual Reality has made computer interfaces more intuitive but not more intelligent. This paper shows how an expert system can be coupled with multimodal input in a virtual environment to provide an intelligent simulation tool or surgical assistant. This is accomplished in three steps. First, voice and gestural input is interpreted and represented in a common semantic form. Second, a rule-based expert system is used to infer context and user actions from this semantic representation. Finally, the inferred user actions are matched against steps in a surgical procedure to monitor the user's progress and provide automatic feedback. In addition, the system can respond immediately to multimodal commands for navigational assistance and/or identification of critical anatomical structures. To show how these methods are used we present a prototype sinus surgery interface. The approach described here may easily be extended to a wide variety of medical and non-medical training applications by making simple changes to the expert system database and virtual environment models. Successful implementation of an expert system in both simulated and real surgery has enormous potential for the surgeon both in training and clinical practice.

Artificial Intelligence↗

PubMed1999

Virtual environments applications and applied ergonomics.

The usability of virtual environments has attracted considerable efforts from ergonomists. Work has included studies of the side or after effects of participation in a virtual environment (VE) as well as the appropriateness of the Virtual Reality hardware and software interfaces and the understanding of factors which determine participant performance. Equally important for applied ergonomics is to understand how best to specify, build, implement and evaluate virtual environment solutions to everyday industrial, commercial, educational and medical problems. The potential value of ergonomics applied to virtual environments, and vice versa, are discussed. Two particular instances of VE development relevant to applied ergonomics are described - structured development and evaluation of industrial training and participatory redesign of workplaces. This paper is one of a number of contributions to a special issue on ergonomics in the study and use of virtual environments.

Ergonomics↗

PubMed2002

The tolerance for visual feedback distortions in a virtual environment.

We are interested in using a virtual environment with a robotic device to extend the strength and mobility of people recovering from strokes by steering them beyond what they had thought they were capable of doing. Previously, we identified just noticeable differences (JND) of a finger's force production and position displacement in a virtual environment. In this paper, we extend this investigation by identifying peoples' tolerance for distortions of visual representations of force production and positional displacement in a virtual environment. We determined that subjects are not capable of reliably detecting inaccuracies in visual representation until there is 36% distortion. This discrepancy between actual and perceived movements is significantly larger than the JNDs reported in the past, indicating that a virtual robotic environment could be a valuable tool for steering actual movements further away from perceived movements. We believe this distorted condition may allow people recovering from strokes, even those who have perceptual or cognitive deficits, to rehabilitate with greater ease.

Adult↗

PubMed2004

The use and understanding of virtual environments by adolescents with autistic spectrum disorders.

The potential of virtual environments for teaching people with autism has been positively promoted in recent years. The present study aimed to systematically investigate this potential with 12 participants with autistic spectrum disorders (ASDs), each individually matched with comparison participants according to either verbal IQ or performance IQ, as well as gender and chronological age. Participants practised using a desktop 'training' virtual environment, before completing a number of tasks in a virtual café. We examined time spent completing tasks, errors made, basic understanding of the representational quality of virtual environments and the social appropriateness of performance. The use of the environments by the participants with ASDs was on a par with their PIQ-matched counterparts, and the majority of the group seemed to have a basic understanding of the virtual environment as a representation of reality. However, some participants in the ASD group were significantly more likely to be judged as bumping into, or walking between, other people in the virtual scene, compared to their paired matches. This tendency could not be explained by executive dysfunction or a general motor difficulty. This might be a sign that understanding personal space is impaired in autism. Virtual environments might offer a useful tool for social skills training, and this would be a valuable topic for future research.

Adolescent↗

PubMed2000

G2H--graphics-to-haptic virtual environment development tool for PC's.

For surgical training and preparations, the existing surgical virtual environments have shown great improvement. However, these improvements are more in the visual aspect. The incorporation of haptics into virtual reality base surgical simulations would enhance the sense of realism greatly. To aid in the development of the haptic surgical virtual environment we have created a graphics to haptic, G2H, virtual environment developer tool. G2H transforms graphical virtual environments (created or imported) to haptic virtual environments without programming. The G2H capability has been demonstrated using the complex 3D pelvic model of Lucy 2.0, the Stanford Visible Female. The pelvis was made haptic using G2H without any further programming effort.

Computer Graphics↗

PubMed1998

Virtual environments in brain damage rehabilitation: a rationale from basic neuroscience.

The potential of virtual environments in assessment and training of cognitive function is a more than adequate reason for their application to neurorehabilitation. However, there is a more fundamental justification, and one which is firmly rooted in the neuroscience literature. Over the last half century there has been a wealth of published evidence that enriching the environments of laboratory rats stimulates neuroplastic change in the cerebral cortex, enhances learning and problem solving in normal rats and reduces cognitive impairment in brain damaged rats. Central to all three effects of enrichment are the increased levels of interaction with the physical environment engendered by enrichment. Placing humans who have damaged brains in virtual environments is one way of enhancing their levels of environmental interaction which, because of cognitive impairments and sensory and motor disabilities, is otherwise difficult to achieve. In this chapter we explore the potential of virtual environments as enriched environments within the rehabilitation regime. The underlying assumption, that interaction with a virtual environment is functionally equivalent to interaction with a real environment, is examined. Three lines of relevant evidence are reviewed, neuroimaging studies and psychophysiological studies of people in virtual environments and studies of transfer of training from virtual to real tasks. An agenda for future research in this are is proposed.

Animals↗

PubMed2004

Navigation in virtual environment by the macaque monkey.

To determine whether monkeys can navigate a virtual environment, and whether they can represent a virtual environment in their brain, we trained two macaque monkeys to perform a navigation task in a virtual building and conducted behavioral analyses. After learning the task from the first starting point, they were trained to perform the navigation task from a second starting point which is already familiar to them during the first training session. The second training was completed faster than the first one. Furthermore, we found that the time required for a free-way-finding test from a novel starting point was shortened after the second training. These results suggest that monkeys can navigate a virtual environment and can construct a flexible representation of a virtual environment in their brain.

Animals↗

PubMed1999

The specificity of memory enhancement during interaction with a virtual environment.

Two experiments investigated differences between active and passive participation in a computer-generated virtual environment in terms of spatial memory, object memory, and object location memory. It was found that active participants, who controlled their movements in the virtual environment using a joystick, recalled the spatial layout of the virtual environment better than passive participants, who merely watched the active participants' progress. Conversely, there were no significant differences between the active and passive participants' recall or recognition of the virtual objects, nor in their recall of the correct locations of objects in the virtual environment. These findings are discussed in terms of subject-performed task research and the specificity of memory enhancement in virtual environments.

Humans↗

PubMed1998

The clinical advantages of editable real-time volume rendering in a medical virtual environment: VolMed.

Segmentation for a medical virtual environment is a process of image diagnosis. It should be performed by clinical doctors, otherwise the data may be meaningless for using clinical purposes. At the National Cancer Center, in Japan, we have recently developed interactive, editable real-time volume rendering software (VolMed), based on Volren-6 software, with the ability to interactively edit the 3D images of a patient's virtual cancer and virtual organs, in a virtual environment. Doctors can see proposed solutions to clinical problems as 3D images, using real-time volume rendering. We conclude that interactive editing is very important for clinical use, and also decreases the time required to create the virtual cancer images used for surgical simulation, pre-surgical planning and 3D invasion diagnoses.

Algorithms↗

PubMed2002

Combined and interacting effects of hand and head movement delays on discrete manual performance in a virtual environment.

Transmission delays occur when a virtual environment responds to the hand and head movements of an operator. The effects of hand and head-related delays on discrete manual performance was investigated experimentally and compared. Imposed hand and head-related pure delays equal to or greater than 110 ms and 220 ms, respectively, significantly increased hand Movement Time (MT). The effect of hand-related delays was greater than that of head-related delays of the same magnitude. A regression model describing the combined effects of both delays on MT is reported (R(2) = 0.95). Analyses of the interactions among delays, target width, and distances have shown the need to adopt the traditional classification of delays into (1) control delay, and (2) display delay. The use of this taxonomy and the regression analyses to describe and explain the effects of individual and combined effects of delays on discrete target-reaching task performance in virtual environments are discussed.

Ergonomics↗

PubMed1999

Immersive virtual environment technology as a basic research tool in psychology.

Immersive virtual environment (IVE) technology has great promise as a tool for basic experimental research in psychology. IVE technology gives participants the experience of being surrounded by the computer-synthesized environment. We begin with a discussion of the various devices needed to implement immersive virtual environments, including object manipulation and social interaction. We review the benefits and drawbacks associated with virtual environment technology, in comparison with more conventional ways of doing basic experimental research. We then consider a variety of examples of research using IVE technology in the areas of perception, spatial cognition, and social interaction.

Cognition↗

PubMedDate not supplied

An exploratory investigation into the usability and usefulness of training people with learning disabilities in a virtual environment.

PURPOSE: Two studies sought to answer the following questions. Are people with learning disabilities capable of using a virtual environment? Are they motivated to learn using this training method? Do they show any benefit from using a virtual environment? Does any benefit transfer to improved real world performance? METHOD: In the first study, 30 students with learning disabilities were sequentially allocated to an active or a passive experimental group. Active participants explored a virtual bungalow searching for a toy car. Passive participants watched the exploration undertaken by the preceding active participant and searched for the toy car. All participants then performed spatial and object recognition tests of their knowledge of the virtual environment. In the second study, the errors of 45 participants on a real steadiness tester task were noted before they were randomly allocated to three groups-a real training group, a virtual training group and a no training group. After training, the participants performed a second test trial on the real steadiness tester. RESULTS: The students were capable of using a virtual environment and were motivated to use this training method. Active exploration of a virtual environment was found to enhance their memory of the spatial layout of the bungalow but not their memory of the virtual objects. In the second study, virtual training was found to transfer to real task performance. CONCLUSIONS: These two laboratory-based studies provide answers to four important questions concerning virtual training of people with learning disabilities. Hopefully, the findings will encourage this training aid to be used more widely.

Achievement↗

PubMed2004

Evaluation of glucose controllers in virtual environment: methodology and sample application.

OBJECTIVE: Adaptive systems to deliver medical treatment in humans are safety-critical systems and require particular care in both the testing and the evaluation phase, which are time-consuming, costly, and confounded by ethical issues. The objective of the present work is to develop a methodology to test glucose controllers of an artificial pancreas in a simulated (virtual) environment. MATERIAL AND METHODS: A virtual environment comprising a model of the carbohydrate metabolism and models of the insulin pump and the glucose sensor is employed to simulate individual glucose excursions in subjects with type 1 diabetes. The performance of the control algorithm within the virtual environment is evaluated by considering treatment and operational scenarios. RESULTS: The developed methodology includes two dimensions: testing in relation to specific life style conditions, i.e. fasting, post-prandial, and life style (metabolic) disturbances; and testing in relation to various operating conditions, i.e. expected operating conditions, adverse operating conditions, and system failure. We define safety and efficacy criteria and describe the measures to be taken prior to clinical testing. The use of the methodology is exemplified by tuning and evaluating a model predictive glucose controller being developed for a wearable artificial pancreas focused on fasting conditions. CONCLUSION: Our methodology to test glucose controllers in a virtual environment is instrumental in anticipating the results of real clinical tests for different physiological conditions and for different operating conditions. The thorough testing in the virtual environment reduces costs and speeds up the development process.

Algorithms↗

PubMed2003

[Effects of field viewing angles on object judgement [correction of jubgerent] in virtual environment].

OBJECT: To investigate the effect of viewing angle on human judgement reliability for objects in virtual environment. METHOD: Firstly, pre-tests were done with the PC virtual reality ergonomic system to determine difference among observed object and values of viewing angle. Then, one factor, 4-levels full random experiments were done with 45 health human subjects (male and female nearly 1:1). RESULT: It was shown that the reliability of human judgement was significantly influenced by the setting of the viewing angle of virtual environment, and the object judgement including size and angle judgement was the best when the viewing angle of virtual environment was 60 degrees. CONCLUSION: When virtual reality was used in ergonomic design, operation training and other related research, the effect of field viewing angle should be taken into consideration, and 60 degrees is recommended to be optimal for human judgment task.

Adult↗

PubMed2001

Vestibulo-ocular reflex modification after virtual environment exposure.

Immersion in an illusory world is possible by means of virtual reality (VR), where environmental perception is modified by artificial sensorial stimulation. The application of VR for the assessment and rehabilitation of pathologies affecting the vestibular system, in terms of both diagnosis and care, could represent an interesting new line of research. Our perception of reality is in fact based on static and dynamic spatial information perceived by our senses. During head movements in a virtual environment the images on the display and the labyrinthine information relative to the head angular accelerations differ and therefore a visuo-vestibular conflict is present. It is known that mismatches between visual and labyrinthine information may modify the vestibulo-oculomotor reflex (VOR) gain. We studied the post-immersion modifications in 20 healthy subjects (mean age 25 years) exposed to a virtual environment for 20 min by wearing a head-mounted display. VOR gain and phase were measured by means of harmonic sinusoidal stimulation in the dark before, at the end of and 30 min after VR exposure. A VOR gain reduction was observed in all subjects at the end of VR exposure which disappeared after 30 min. Our data show that exposure to a virtual environment can induce a temporary modification of the VOR gain. This finding can be employed to enable an artificial, instrumental modification of the VOR gain and therefore opens up new perspectives in the assessment and rehabilitation of vestibular diseases.

Adult↗

PubMed1998

Personal stories within virtual environments: creating three experiences in cancer information software.

Virtual environments can create a relaxed mood, increasing a patient's receptivity to learning. Personal stories and an individual approach to the content, rather than abstract facts, make the CD-generated experience vivid and informative. With the user in control, selecting content and interacting constantly with the program, the virtual experience is more meaningful than the one created by simply retrieving information. This chapter explains how three CD-ROMs containing cancer information--Breast Cancer Lighthouse, Easing Cancer Pain and Cancer Prevention Park--embody personal stories and medical information in virtual environments.

Breast Neoplasms↗

PubMed2005

Stimulation of cortisol during mental task performance in a provocative virtual environment.

Fully immersive and stereoscopic Virtual Environments (VE) represent a powerful multimedia tool for laboratory-based simulations of distinct scenarios including scenarios for evaluating stressful situations resembling reality. Thus far, cortisol secretion as a neuroendocrine parameter of stress has not been evaluated within a Virtual Reality (VR)-based paradigm. In this study 94 healthy volunteers were subjected to a provocative VR-paradigm and a cognitive stress task. Provocative in this context means the VE was designed to provoke physiological reactions (cortisol secretion) within the respective users by purpose. It was tested (a) if a fully dynamic VE as opposed to a static VE can be regarded as a stressor and (b) if such a fully dynamic VE can modify an additional response to a cognitive stressor presented within the VE additionally. Furthermore, possible gender-related impacts on cortisol responses were assessed. A significant cortisol increase was observed only after the combined application of the fully dynamic VE and the cognitive stressor, but not after application of the dynamic VE or the cognitive stressor alone. Cortisol reactivity was greater for men than for women. We conclude that a fully dynamic VE does not affect cortisol secretion per se, but increases cortisol responses to a dual task paradigm that includes performance of a stressful mental task. This provides the basis for the application of VR-based technologies in neuroscientific research, including the assessment of the human Hypothalamus-Pituitary-Adrenal (HPA) axis regulation.

Adult↗