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PubMed2004

First-perspective alignment effects in a computer-simulated environment.

In Experiment 1, participants explored two desktop, virtual environments (VEs), each comprising three city streets connected at right angles; for each participant one VE was open and one was enclosed. Following the first VE exploration, orientation estimates to remembered test locations were most accurate when participants imagined themselves aligned, rather than 90 degrees misaligned or 180 degrees or contra-aligned, with the first part of the route. In the second VE, the effect was attenuated and the data pattern conformed to that anticipated from an orientation-free memory. Experiment 2 followed the procedure of Experiment 1, but omitted the alignment tests after the first VE; following the second VE exploration, orientation estimates presented a similar pattern to those in first test of Experiment 1. These data are discussed in terms of cognitive load.

Adolescent↗

PubMed2002

Interaction and presence in the clinical relationship: virtual reality (VR) as communicative medium between patient and therapist.

The great potential offered by virtual reality (VR) to clinical psychologists derives prevalently from the central role, in psychotherapy, occupied by the imagination and by memory. These two elements, which are fundamental in our life, present absolute and relative limits to the individual potential. Using VR as an advanced imaginal system-an experience that is able to reduce the gap existing between imagination and reality-it is possible to transcend these limits. In this sense, VR can improve the efficacy of a psychological therapy for its capability of reducing the distinction between the computer's reality and the conventional reality. Two are the core characteristics of this synthetic imaginal experience: the perceptual illusion of nonmediation and the possibility of building and sharing a common ground. In this sense, experiencing presence in a clinical virtual environment (VE), such as a shared virtual hospital, requires more than reproduction of the physical features of external reality. It requires the creation and sharing of the cultural web that makes meaningful, and therefore visible, both people and objects populating the environment.

Communication↗

PubMed2006

A virtual reality scenario for all seasons: the virtual classroom.

Treatment and rehabilitation of the cognitive, psychological, and motor sequelae of central nervous system dysfunction often relies on assessment instruments to inform diagnosis and to track changes in clinical status. Typically, these assessments employ paper-and-pencil psychometrics, hands-on analog/computer tests, and rating of behavior within the context of real-world functional environments. Virtual reality offers the option to produce and distribute identical "standard" simulation environments in which performance can be measured and rehabilitated. Within such digital scenarios, normative data can be accumulated for performance comparisons needed for assessment/diagnosis and for treatment/rehabilitation purposes. In this manner, reusable archetypic virtual environments constructed for one purpose can also be applied for applications addressing other clinical targets. This article will provide a review of such a retooling approach using a virtual classroom simulation that was originally developed as a controlled stimulus environment in which attention processes could be systematically assessed in children with attention-deficit/hyperactivity disorder. This system is now being applied to other clinical targets including the development of tests that address other cognitive functions, eye movement under distraction conditions, social anxiety disorder, and the creation of an earthquake safety training application for children with developmental and learning disabilities.

Humans↗

PubMed2006

Large displays enhance optical flow cues and narrow the gender gap in 3-D virtual navigation.

OBJECTIVE: Existing reports suggest that males significantly outperform females in navigating 3-D virtual environments. Although researchers have recognized that this may be attributable to males and females possessing different spatial abilities, most work has attempted to reduce the gender gap by providing more training for females. In this paper, we explore using large displays to narrow the gender gap within these tasks. BACKGROUND: While evaluating various interaction techniques, we found that large displays affording wider fields of view seemed to improve virtual navigation performance in general and, additionally, to narrow the gender gap that existed on standard desktop displays. METHOD: We conducted two experiments (32 and 22 participants) exploring the individual contributions of display and geometric fields of view to the observed effects as well as isolating factors explaining performance increases seen on the large displays. RESULTS: We show that wider fields of view on large displays not only increase performance of all users on average but also benefit females to such a degree as to allow them to perform as well as males do. We further demonstrate that these benefits can be attributed to better optical flow cues offered by the large displays. CONCLUSION: These findings provide a significant contribution, including recommendations for the improved presentation of 3-D environments, backed by empirical data demonstrating performance benefits during navigation tasks. APPLICATION. Results can be used to design systems that narrow the gender gap in domains such as teleoperation and virtual environments for entertainment, virtual training, or information visualization.

Adolescent↗

PubMed2001

Three-dimensional planning and simulation of hip operations and computer-assisted construction of endoprostheses in bone tumor surgery.

OBJECTIVE: This article presents the VIRTOPS (VIRTual Operation Planning in Orthopaedic Surgery) software system for virtual preoperative planning and simulation of hip operations. The system is applied to simulate the endoprosthetic reconstruction of the hip joint with hemipelvic replacement, and supports the individual design of anatomically adaptable, modular prostheses in bone tumor surgery. The virtual planning of the operation and the construction of the individual implant are supported by virtual reality techniques. The central step of the operation planning procedure, the placement of the cutting plane in the hip bone, depends strongly on the tumor's position. Segmentation of the tumor and the bones in MR and CT data, as well as fusion of MR and CT image sequences, is necessary to visualize the tumor's position within the hip bone. MATERIALS AND METHODS: Three-dimensional models of the patient's hip are generated based on CT image data. A ROI-based segmentation algorithm enables the separation of the bone tumor in multispectral MR image sequences. A special registration method using segmentation results has been developed to transfer CT and MR data into one common coordinate system. During the 3D planning process, the surgeon simulates the operation and defines the position and geometry of the custom-made endoprosthesis. Stereoscopic visualization and 3D input devices facilitate navigation and 3D interaction in the virtual environment. Special visualization techniques such as texture mapping, color coding of quantitative parameters, and transparency support the determination of the correct position and geometry of the prosthesis. RESULTS AND CONCLUSIONS: The VIRTOPS system enables the complete virtual planning of hip operations with endoprosthetic reconstruction, as well as the optimal placement and design of endoprostheses. After the registration and segmentation of CT and MR data, 3D visualizations of the tumor within the bone are generated to support the surgeon during the planning procedure. In the virtual planning environment, individually adapted endoprostheses can be constructed without the need to generate expensive solid 3D models. Furthermore, different operation strategies can be compared easily. Three-dimensional images and digital movies generated during the virtual operation planning can be used for case documentation and patient information purposes.

Algorithms↗

PubMed2000

Virtual temporal bone: creation and application of a new computer-based teaching tool.

The human temporal bone is a 3-dimensionally complex anatomic region with many unique qualities that make anatomic teaching and learning difficult. Current teaching tools have proved only partially adequate for the needs of the aspiring otologic surgeon in learning this anatomy. We used a variety of computerized image processing and reconstruction techniques to reconstruct an anatomically accurate 3-dimensional computer model of the human temporal bone from serial histologic sections. The model is viewed with a specialized visualization system that allows it to be manipulated easily in a stereoscopic virtual environment. The model may then be interactively studied from any viewpoint, greatly simplifying the task of conceptualizing and learning this anatomy. The system also provides for simultaneous computer networking that can bring distant participants into a single shared virtual teaching environment. Future directions of the project are discussed.

Computer Simulation↗

PubMed2005

Anticipating the effects of gravity when intercepting moving objects: differentiating up and down based on nonvisual cues.

Intercepting an object requires a precise estimate of its time of arrival at the interception point (time to contact or "TTC"). It has been proposed that knowledge about gravitational acceleration can be combined with first-order, visual-field information to provide a better estimate of TTC when catching falling objects. In this experiment, we investigated the relative role of visual and nonvisual information on motor-response timing in an interceptive task. Subjects were immersed in a stereoscopic virtual environment and asked to intercept with a virtual racket a ball falling from above or rising from below. The ball moved with different initial velocities and could accelerate, decelerate, or move at a constant speed. Depending on the direction of motion, the acceleration or deceleration of the ball could therefore be congruent or not with the acceleration that would be expected due to the force of gravity acting on the ball. Although the best success rate was observed for balls moving at a constant velocity, we systematically found a cross-effect of ball direction and acceleration on success rate and response timing. Racket motion was triggered on average 25 ms earlier when the ball fell from above than when it rose from below, whatever the ball's true acceleration. As visual-flow information was the same in both cases, this shift indicates an influence of the ball's direction relative to gravity on response timing, consistent with the anticipation of the effects of gravity on the flight of the ball.

Attention↗

PubMed2004

Visual feedback control of hand movements.

We investigated what visual information contributes to on-line control of hand movements. It has been suggested that motion information predominates early in movements but that position information predominates for endpoint control. We used a perturbation method to determine the relative contributions of motion and position information to feedback control. Subjects reached to touch targets in a dynamic virtual environment in which subjects viewed a moving virtual fingertip in place of their own finger. On some trials, we perturbed the virtual fingertip while it moved behind an occluder. Subjects responded to perturbations that selectively altered either motion or position information, indicating that both contribute to feedback control. Responses to perturbations that changed both motion and position information were consistent with superimposed motion-based and position-based control. Results were well fit by a control model that optimally integrates noisy, delayed sensory feedback about both motion and position to estimate hand state.

Biomechanical Phenomena↗

PubMed2003

NeuroVRAC--a comprehensive approach to virtual reality-based neurological assessment and treatment systems.

We describe a comprehensive software-oriented approach to virtual reality-based neuroscientific systems in order to establish an easy to use framework for neuroscientific assessment and treatment. We have defined a process model and implemented the NeuroVRAC authoring tool for design and execution of experiments in virtual environments. Our system enables the modeling of virtual world objects and the definition of events, which are used to control the experimental process. We have included the virtual test person concept to enhance the sense of presence during the execution of virtual reality-based neuroscientific experiments.

Computer Simulation↗

PubMed2002

Stroke rehabilitation at home using virtual reality, haptics and telemedicine.

The objective of this pilot study is to identify the level of difficulty in which subjects with left hemisphere damage in the acute phase after stroke can start practicing in a virtual environment. Second, to test an application of Virtual Reality technology to existing occupational treatment methods in stroke rehabilitation and develop a platform for home rehabilitation controlled telemedically. The findings indicate that the system shows potential as an assessment and training device. The feasibility study setup is working well likewise the assessment method. Developing and increasing the complexity of the tasks must be based on the patient individual neurology, and that the cinematic motion patterns of the patient's are the basis for exercise design.

Adult↗

PubMed2002

Performance of a skilled motor task in virtual and real environments.

Three experiments compared the performances of adult participants (three groups of 10) on a perceptuo-motor task in both real world (RW) and virtual environments (VEs). The task involved passing a hoop over a bent wire course, and three versions of the task were used: a 3-D wire course with no background, a flattened version of the 3-D course (2(1/2)-D course) with no background, and the 2(1/2)-D course with added background to provide spatial context. In all three experiments the participants had to prevent the hoop from touching the wire as they moved it. In the first experiment, the VE condition produced about 18 times more errors than the RW task. The VE 2(1/2)-D task was found to be as difficult as the 3-D, and the 2(1/2)-D with the added background produced more errors than the other two experiments. Taken together, the experiments demonstrate the difficulty of performing fine motor tasks in VEs, a phenomenon that has not been given due attention in many previous studies of motor control in VEs.

Adolescent↗

PubMed2002

MAT3D: a virtual reality modeling language environment for the teaching and learning of mathematics.

Virtual Reality Modeling Language (VRML) is an independent platform language that allows the creation of nonimmersive virtual environments (VEs) and their use through the Internet. In these VEs, the viewer may navigate and interact with virtual objects, moving around and visualizing them from different angles. Students can benefit from this technology, because it permits them access to objects, which describe the topics covered in their studies in addition to oral and written information. In this work, we investigate the aspects involved in the use of VEs in teaching and learning and propose a conceptual model, called MAT3D, as a learning environment that can be used for the teaching and learning of mathematics. A case study is also presented, in which students use a virtual environment modeled in VRML. Data resulting from this study is analyzed statistically to evaluate the impact of this prototype when applied to the actual teaching and learning of mathematics.

Educational Technology↗

PubMed2003

Using the observer to analyze learning in virtual worlds.

In this study, we describe and analyze the ways in which high school students explored a virtual solar system (VSS). VSS is a nonimmersive virtual environment that affords visual manipulations of space by altering its frame of reference. The Observer software was used to code and analyze the participants' real-time free-exploration task. Two basic behaviors were identified across participants: establishing several home bases, and shifting between a still mode and a dynamic mode. Moreover, three overall exploration patterns emerged: the butterfly pattern represents a superficial mode of learning; the bee pattern represents an in-depth mode of studying the various celestial objects; and the eagle pattern represents a global approach of studying the complex system. This virtual reality environment promises to provide a setting in which to further study consistent patterns and individual differences in exploration strategies.

Adolescent↗

PubMed1998

Training environment for inferior vena caval filter placement.

This paper describes a Virtual Environment system designed to aid in training interventional radiologists in inferior vena cava filter placement. It is being developed as part of a VE simulator for a number of surgical and interventional radiology procedures at the Laboratory for Advanced Computer Applications in Medicine at the George Washington University. In this procedure a filter is placed in the inferior vena cava to prevent blood clots from the lower portion of the body from reaching the lungs and causing a pulmonary embolus. The simulation is designed to provide both tutorial and testing modes for the filter placement procedure.

Algorithms↗

PubMed2002

Virtual temporal bone dissection: an interactive surgical simulator.

OBJECTIVE: Our goal was to integrate current and emerging technology in virtual systems to provide a temporal bone dissection simulator that allows the user interactivity and realism similar to the cadaver laboratory. STUDY DESIGN: Iterative design and validation of a virtual environment for simulating temporal bone dissection. SETTING: University otolaryngology training program with interdisciplinary interaction in a high-performance computer facility. RESULTS: The system provides visual, force feedback (haptic), and aural interfaces. Unlike previous "fly through" virtual systems, this environment provides a richer emulation of surgical experience. CONCLUSION: The system provides a high level of functional utility and, through initial evaluations, demonstrates promise in adding to traditional training methods. SIGNIFICANCE: The system provides an environment to learn temporal bone surgery in a way similar to the experience with cadaver material where the subject is able to interact with the data without constraints (nondeterministic). Eventually, it may provide the "front end" to a large repository of various temporal bone pathologies that can be accessed through the Internet.

Algorithms↗

PubMed2006

Cognitive, emotional, and social processes in psychosis: refining cognitive behavioral therapy for persistent positive symptoms.

Psychosis used to be thought of as essentially a biological condition unamenable to psychological interventions. However, more recent research has shown that positive symptoms such as delusions and hallucinations are on a continuum with normality and therefore might also be susceptible to adaptations of the cognitive behavioral therapies found useful for anxiety and depression. In the context of a model of cognitive, emotional, and social processes in psychosis, the latest evidence for the putative psychological mechanisms that elicit and maintain symptoms is reviewed. There is now good support for emotional processes in psychosis, for the role of cognitive processes including reasoning biases, for the central role of appraisal, and for the effects of the social environment, including stress and trauma. We have also used virtual environments to test our hypotheses. These developments have improved our understanding of symptom dimensions such as distress and conviction and also provide a rationale for interventions, which have some evidence of efficacy. Therapeutic approaches are described as follows: a collaborative therapeutic relationship, managing dysphoria, helping service users reappraise their beliefs to reduce distress, working on negative schemas, managing and reducing stressful environments if possible, compensating for reasoning biases by using disconfirmation strategies, and considering the full range of evidence in order to reduce high conviction. Theoretical ideas supported by experimental evidence can inform the development of cognitive behavior therapy for persistent positive symptoms of psychosis.

Affect↗

PubMed2005

Modeling human behaviors and reactions under dangerous environment.

This paper describes the framework of a real-time simulation system to model human behavior and reactions in dangerous environments. The system utilizes the latest 3D computer animation techniques, combined with artificial intelligence, robotics and psychology, to model human behavior, reactions and decision making under expected/unexpected dangers in real-time in virtual environments. The development of the system includes: classification on the conscious/subconscious behaviors and reactions of different people; capturing different motion postures by the Eagle Digital System; establishing 3D character animation models; establishing 3D models for the scene; planning the scenario and the contents; and programming within Virtools Dev. Programming within Virtools Dev is subdivided into modeling dangerous events, modeling character's perceptions, modeling character's decision making, modeling character's movements, modeling character's interaction with environment and setting up the virtual cameras. The real-time simulation of human reactions in hazardous environments is invaluable in military defense, fire escape, rescue operation planning, traffic safety studies, and safety planning in chemical factories, the design of buildings, airplanes, ships and trains. Currently, human motion modeling can be realized through established technology, whereas to integrate perception and intelligence into virtual human's motion is still a huge undertaking. The challenges here are the synchronization of motion and intelligence, the accurate modeling of human's vision, smell, touch and hearing, the diversity and effects of emotion and personality in decision making. There are three types of software platforms which could be employed to realize the motion and intelligence within one system, and their advantages and disadvantages are discussed.

Artificial Intelligence↗

PubMed2003

Virtual reality and interactive 3D as effective tools for medical training.

CAVE-like displays allow a user to walk in to a virtual environment, and use natural movement to change the viewpoint of virtual objects which they can manipulate with a hand held device. This maps well to many surgical procedures offering strong potential for training and planning. These devices may be networked together allowing geographically remote users to share the interactive experience. This maps to the strong need for distance training and planning of surgeons. Our paper shows how the properties of a CAVE-Like facility can be maximised in order to provide an ideal environment for medical training. The implementation of a large 3D-eye is described. The resulting application is that of an eye that can be manipulated and examined by trainee medics under the guidance of a medical expert. The progression and effects of different ailments can be illustrated and corrective procedures, demonstrated.

Computer Simulation↗