Psychological and physiological responses to stressful situations in immersive virtual reality: Differences between users who practice mindfulness meditation and controls

Several studies in the literature have shown positive psychophysical effects during or immediately after mindfulness meditation. However, the extent to which such positive effects are maintained in real-life, stressful contexts, remains unclear. This paper investigates the effects of an 8-week mindfulness-oriented meditation (MOM) program on the psychological and physiological responses evoked by immersive virtual environments (IVEs) that simulate emergency situations that may occur in life. Before and after the 8-week period, healthy MOM participants and a group of controls not involved in any meditation course were administered self-report measures of mindfulness and anxiety, and acted in the IVEs while a set of physiological parameters were recorded. Responses of MOM participants to the immersive virtual experiences were different from those of controls. MOM participants showed increased mindfulness and decreased anxiety levels. They also showed decreased heart rate and corrugator muscle activity while facing IVEs. We explain these results in terms of the awareness and acceptance components of mindfulness. More generally, the present experimental methods could also open up new lines of research that combine psychological and physiological indices with ecologically valid stimuli provided by IVEs in an effort to increase understanding of the impact of mindfulness meditation on realistic life situations.     

Estimation of Detection Thresholds for Redirected Walking Techniques

In immersive virtual environments (IVEs), users can control their virtual viewpoint by moving their tracked head and walking through the real world. Usually, movements in the real world are mapped one-to-one to virtual camera motions. With redirection techniques, the virtual camera is manipulated by applying gains to user motion so that the virtual world moves differently than the real world. Thus, users can walk through large-scale IVEs while physically remaining in a reasonably small workspace. In psychophysical experiments with a two-alternative forced-choice task, we have quantified how much humans can unknowingly be redirected on physical paths that are different from the visually perceived paths. We tested 12 subjects in three different experiments: (E1) discrimination between virtual and physical rotations, (E2) discrimination between virtual and physical straightforward movements, and (E3) discrimination of path curvature. In experiment E1, subjects performed rotations with different gains, and then had to choose whether the visually perceived rotation was smaller or greater than the physical rotation. In experiment E2, subjects chose whether the physical walk was shorter or longer than the visually perceived scaled travel distance. In experiment E3, subjects estimate the path curvature when walking a curved path in the real world while the visual display shows a straight path in the virtual world. Our results show that users can be turned physically about 49 percent more or 20 percent less than the perceived virtual rotation, distances can be downscaled by 14 percent and upscaled by 26 percent, and users can be redirected on a circular arc with a radius greater than 22 m while they believe that they are walking straight.     

Playing in the mud: Virtual worlds are real places

This paper is about how developers will know whether intelligent virtual environments (IVEs) are appropriate for the tasks set to them. There are several important research questions that need to be answered before they can even begin to build IVEs for some of the more promising applications, such as entertainment, education, collaboration on research and development, military, and other training. The main technical point is that every aspect of any IVE involves model, and the modeling needs to be addressed very directly and explicitly. This paper is more for the developers of such systems and the potential customers, than for the users. More is written about what is important to consider as one contemplates, for example, a difficult collaborative task, than about what it will be like to live in these IVEs. The authors believe that IVEs must be expanded to become virtual worlds (VWs), and that the modeling sophistication required for any of the serious applications described above is much more than is currently available in the VWs seen, even the ones with good graphics. Finally, the connection between Virtual Reality and CyberSpace is made, and the authors explain their expectations will be explained for the future of CyberSpace.     

Cognitive and synthetic behavior of avatars in intelligent virtual environments

In intelligent virtual environments (IVEs), it is a challenging research issue to provide the intelligent virtual actors (or avatars) with the ability of visual perception and rapid response to virtual world events. Modeling an avatar’s cognitive and synthetic behavior appropriately is of paramount important in IVEs. We propose a new cognitive and behavior modeling methodology that integrates two previously developed complementary approaches. We present expression cloning, walking synthetic behavior modeling, and an autonomous agent cognitive model for driving an avatar’s behavior. Facial expressions are generated using our own-developed rule-based state transition system. Facial expressions are further personalized for individuals by expression cloning. An avatar’s walking behavior is modeled using a skeleton model that is implemented by seven-motion sequences and finite state machines (FSMs). We discuss experimental results demonstrating the benefits of our approach.     

Internet-Based Support for Process-Oriented Instant Virtual Enterprises

The ever-increasing complexity of contemporary products and services demands business supply chains that ultimately involve a large number of autonomous organizations. Competitive markets require these chains to be highly agile, effective, and efficient, which organizations can achieve by forming dynamic virtual enterprises within supplier networks, called instant virtual enterprises (IVEs). The authors present the CrossWork system, which helps these organizations efficiently create and operate IVEs by providing automated, Internet-based support for the composition, setup, and execution of global business processes. This article uses the automotive domain to illustrate the system's optimal use.     

Acceptability of a custom-designed game,CityQuest, aimed at improving balance confidence and spatial cognition in fall-prone and healthy older adults

Virtual reality or video games show great potential as low-cost and effective interventions for improving balance and cognitive function in older adults. This research describes the design and acceptability of a serious game (CityQuest) aimed at improving balance confidence, spatial navigation, and perceptual function in older adults with the use of a virtual environment and a balance board. Community-dwelling healthy (N?=?28) and fall-prone (N?=?28) older adults were pseudo-randomly assigned to train with CityQuest or one of two control games developed to evaluate the specific effects of the CityQuest game. Following completion of 10 training sessions, participants completed questionnaires measuring their acceptability of the game as a falls-related intervention, game experience, and subjective cognitive or balance confidence changes associated with the game. The results revealed high acceptance scores of the game and positive game experiences for all three game conditions. Older adults prone to falls reported a greater reduction in fear of falling and greater improvement in vigilance following training, compared to healthy older adults. These findings suggest that a serious game based on VR technology that trains both motor and cognitive processes is perceived to be beneficial and acceptable to healthy and fall-prone older adults.     

Where Am I? How Can I Get There? Impact of Navigability and Narrative Transportation on Spatial Presence

From video games to virtual worlds on the World Wide Web, modern media are becoming increasingly spatial, with users traversing artificial spaces and experiencing a kind of immersion known as “spatial presence.” But how do these media induce spatial presence? Are the affordances for movement provided by these technologies responsible for this illusion? Or do narratives that accompany them persuade us to suspend disbelief and transport ourselves into a virtual space? We explore these theoretical questions by pitting the navigability affordances of a video game against narrative transportation and examining their relative contributions to the formation of spatial presence in a virtual reality context. Results from a large experiment (N = 240) reveal that the narrative actually detracts from spatial presence while traversibility (in the form of greater degrees of steering motion) enhances it even without invoking a mental model of the portrayed environment. Theoretical and practical implications are discussed.     

A new approach to model virtual channels in interconnection networks

Dealing with virtual channels has always been a critical issue in developing analytical performance models for interconnection networks. Almost all previous studies relied on a method proposed by Dally to capture the effect of virtual channels multiplexing in the performance of interconnection networks. This paper presents a new method to model the effect of virtual channel multiplexing in high-speed wormhole-switched interconnection networks. Dally's method loses its accuracy as the traffic load increases due to blocking nature of wormhole-switched networks. Our new method is based on a finite capacity queue, M/G/1/V and comparing to Dally's method achieves a higher degree of accuracy under low, moderate and high traffic loads. Furthermore, its simplicity eases its employment under different network conditions and setup. The presented model is validated by means of an event driven simulator and a detailed comparison with Dally's method is presented.     

自然保护区海量视频数据快速分析与检索

近年来,随着视频监控系统在自然保护区的大量部署,如何有效利用日益增加的海量视频监控数据成为亟待解决的难题.通过基于图像相似度的关键帧提取算法对海量视频数据进行清洗和压缩,同时利用基于深度学习的目标检测算法提取关键帧中的有效视频信息,并提供多种基于内容的视频检索方式,自动对用户提交的检索内容进行分析与处理,从而快速检索出感兴趣的视频.通过对青海湖野生动物视频监控数据进行分析与检索,验证了该系统的有效性.     

Mixing virtual and real scenes in the site of ancient Pompeii

This paper presents an innovative 3D reconstruction of ancient fresco paintings through the real‐time revival of their fauna and flora, featuring groups of virtual animated characters with artificial‐life dramaturgical behaviours in an immersive, fully mobile augmented reality (AR) environment. The main goal is to push the limits of current AR and virtual storytelling technologies and to explore the processes of mixed narrative design of fictional spaces (e.g. fresco paintings) where visitors can experience a high degree of realistic immersion. Based on a captured/real‐time video sequence of the real scene in a video‐see‐through HMD set‐up, these scenes are enhanced by the seamless accurate real‐time registration and 3D rendering of realistic complete simulations of virtual flora and fauna (virtual humans and plants) in a real‐time storytelling scenario‐based environment. Thus the visitor of the ancient site is presented with an immersive and innovative multi‐sensory interactive trip to the past. Copyright © 2005 John Wiley & Sons, Ltd.     

Towards video-based immersive environments

Video provides a comprehensive visual record of environment activity over time. Thus, video data is an attractive source of information for the creation of virtual worlds which require some real-world fidelity. This paper describes the use of multiple streams of video data for the creation of immersive virtual environments. We outline our multiple perspective interactive video (MPI-Video) architecture which provides the infrastructure for the processing and analysis of multiple streams of video data. Our MPI-Video system performs automated analysis of the raw video and constructs a model of the environment and object activity within this environment. This model provides a comprehensive representation of the world monitored by the cameras which, in turn, can be used in the construction of a virtual world. In addition, using the information produced and maintained by the MPI-Video system, our immersive video system generates virtual video sequences. These are sequences of the dynamic environment from an arbitrary view point generated using the real camera data. Such sequences allow a user to navigate through the environment and provide a sense of immersion in the scene. We discuss results from our MPI-Video prototype, outline algorithms for the construction of virtual views and provide examples of a variety of such immersive video sequences.     

Energy shaping,interconnection and damping assignment,and integral control in the bond graph domain

This paper presents a methodology to perform energy shaping and interconnection and damping assignment in the bond graph domain, and addresses a new result on integral action control which improves the robustness of these passivity based control methods, which were first introduced on the port-controlled Hamiltonian systems with dissipation formalism. The methods perform expressing the desired closed-loop energy, interconnection and damping properties on a so-called target bond graph, which is built as follows on the plant bond graph: (i) adding virtual storage elements enforces a minimum on the target bond graph energy at a prespecified stable closed-loop equilibrium state, (ii) changing the R-field and its interconnection with the rest of the graph assigns a new dissipation function, and (iii) suitably inserting of power conserving elements (bonds and other structural BG-elements) among junctions yields the desired power conserving interconnection structure. The control law is then determined developing physically based heuristics and formal techniques on the target and plant bond graphs, which deliver a set of partial differential equations to be solved. The method to achieve integral control consists in adding to the target bond graph virtual elements representing the integral action and a change of variables, and then computing the integral control law with standard BG equation-reading procedures. These BG heuristics and prototyping allow to provide integral action on outputs of relative degree greater than one, a contribution of this work not previously available in the literature. This shows that the physical properties of bond graphs are beneficial not only to expediently perform methods contributed by control theory, but also to derive new theoretical results.     

Using activity theory to understand intergenerational play: The case of Family Quest

We implemented a five-week family program called Family Quest where parents and children ages 9 to 13 played Quest Atlantis, a multiuser 3D educational computer game, at a local after-school club for 90-minute sessions. We used activity theory as a conceptual and an analytical framework to study the nature of intergenerational play, the collaborative activity between parents and children in the context of role-playing virtual game environment, and the opportunities and challenges of bringing parents and children together around an educational video game. Our analyses of five parent-child dyads revealed that the nature of intergenerational play is different for different parent-child dyads, but has positive outcomes. Implications of the study for supporting family learning and bonding through video games are discussed.     

The impact of a character posture model on the communication of affect in an immersive virtual environment

This paper presents the quantitative and qualitative findings from an experiment designed to evaluate a developing model of affective postures for full-body virtual characters in immersive virtual environments (IVEs). Forty-nine participants were each requested to explore a virtual environment by asking two virtual characters for instructions. The participants used a CAVE-like system to explore the environment. Participant responses and their impression of the virtual characters were evaluated through a wide variety of both quantitative and qualitative methods. Combining a controlled experimental approach with various data-collection methods provided a number of advantages such as providing a reason to the quantitative results. The quantitative results indicate that posture plays an important role in the communication of affect by virtual characters. The qualitative findings indicated that participants attribute a variety of psychological states to the behavioral cues displayed by virtual characters. In addition, participants tended to interpret the social context portrayed by the virtual characters in a holistic manner. This suggests that one aspect of the virtual scene colors the perception of the whole social context portrayed by the virtual characters. We conclude by discussing the importance of designing holistically congruent virtual characters especially in immersive settings.     

User models of subjective image quality assessment on virtual viewpoint in free-viewpoint video system

In this paper, we present a user model of subjective quality assessment on virtual viewpoint image (VVI) for free-viewpoint video system. VVIs are rendered through neighbor viewpoint color and depth images, and it is a new type of image that generated for human-computer interaction (HCI) in free-viewpoint video system. In this system, a natural scene is captured by multi-viewpoint cameras, and users can view the scene from any desired viewpoint, regardless the real or virtual one. The subjective quality of VVIs is crucial for the quality of experiences for HCI, because the magnitude of VVI is much greater than the real. In order to find the user model of VVI quality assessment, we organize three sets of stimuli, including Symmetric Stimuli, Asymmetric Stimuli Part I and Part II, to reveal the psychological responses of participants. A psychometric function is consequently obtained to determine the relationship between stimulus and psychological responses. Further discussions on the factors of distortion level, gender, age and academic background are examined to find the influence on the user model. We find that the distortion level of neighbor viewpoint color images has the dominant impact on the user model, while other factors contribute little.     

虚拟现实全景流体绘画系统的可用性研究

虚拟现实环境给三维空间场景应用带来更强的真实感和身临其境的体验。在虚拟现实场景中经 常需要使用 360全景图像生成沉浸式环境背景,其中全景流体动力学绘画系统提供了一个新的全景图绘制方 法。在调研虚拟现实技术在流体绘画领域应用的适用性测试中,本文综合运用用户测试法、操作日志分析法、 事后问卷调查法和访谈法,对基于虚拟现实的全景式流体绘画创作系统进行可用性评估,并创意性地使用可视 化方法辅助日志分析。所有的受试者均认为系统的可用性不低于一般水平,利用该系统完成流体绘画的创作工 作不需要受试者具有专业绘画经验。受试者对系统的功能效果持积极肯定的意见,并期待尝试用其他交互形式 代替手柄类交互方式以促进艺术创作的表达。其研究方法和结果将为同类系统的开发和评估提供参考。     

Altered Visual Perception in Game Transfer Phenomena: An Empirical Self-Report Study

The aim of this study was to identify, classify, and explain gamers’ perceptual experiences referred to as Visual Game Transfer Phenomena (VGTP) to contribute to the understanding of the effects of post-video-game playing and encourage healthy and safe gaming. A total of 656 experiences from 483 gamers were collected from 54 online gaming forums. The findings suggest that intensive playing can result in misperceptions and visual distortions of real-life objects and environments, stereotypical visual experiences that arise from mind visualization, and pseudo-hallucinatory experiences with video game content. Gamers’ experiences can be explained by the interplay of physiological, perceptual, and cognitive mechanisms. Observation of video game features suggests that in most cases a relationship between the games’ structural characteristics, gamers’ VGTP experiences, and gamers’ playing habits appeared relevant. VGTP can occur while gaming, immediately after stopping play, or after some delay. Further VGTP characteristics and their psychosocial implications are discussed.     

Stochastic Analysis of Deterministic Routing Algorithms in the Presence of Self-Similar Traffic

Many performance models for deterministic routing in multicomputer interconnection networks have been derived and analyzed under the assumption of the traditional Poisson stochastic arrival process, which is inherently unable to capture traffic self-similarity revealed by many real-world parallel applications. In an effort towards understanding the network performance under various traffic loads and different design alternatives, this paper presents an analytical model for dimension-ordered routing in k-ary n-cubes when subjected to self-similar traffic. As the service time, blocking probability and waiting time experienced by a message vary from a dimension to another, the design of such a model for dimension-ordered routing poses greater challenges. The developed analytical model is then used to investigate the efficiency of two different ways to organize virtual channels for deterministic routing and to evaluate the impact of self-similar traffic with various Hurst parameters on network performance.     

I-Portrait: An Interactive Photograph System for Enhancing Social Presence

ABSTRACT

People often strive to “externalize” memories for long-term saving or sharing with others using different forms of media. We devised a new interactive photograph system, I-Portrait, which enables interactive experiences with figures in a photograph. I-Portrait comprises short video clips that are recorded and played upon user interactions such as touch, voice, gestures, and facial expressions, providing users with the virtual experience of interaction with the figure. We evaluated the system by surveying 40 university students (age 20–29 years) on the level of social presence of the photograph (mutual awareness, emotional connectedness, and awareness of co-location) and users’ satisfaction, and comparing these measures between the I-Portrait system and traditional portraits. We found significant differences in all aspects of social presence suggesting that the interactivity of the I-Portrait system may significantly increase the social presence of physically distant others.