Viewing medium affects arm motor performance in 3D virtual environments

Virtual reality (VR) is being used increasingly in many fields of medicine, including rehabilitation. Both 2D and 3D virtual environments (VEs) can be viewed either through a head mounted display (HMD) or on a screen (computer monitor and rear projection system, SPS). However, the question of whether the medium through which the environment is viewed affects motor performance has not been addressed. The objective of our study was to determine whether movement patterns were different when movements were performed in a 3D fully immersive VE viewed via an HMD or SPS. Two groups of subjects were recruited (stroke, healthy). They performed pointing movements to targets placed in the ipsilateral, central and contralateral arm workspaces in a VE. The VE, designed to resemble the interior of an elevator, was viewed via an HMD or a SPS. Arm motor impairment and spasticity were evaluated in both groups of subjects. The kinematics of the pointing movements were recorded using an optical tracking system (Optotrak Certus, 100 Hz, 6 markers). Arm motor performance (speed, precision and trajectory straightness) and movement quality outcomes (elbow and shoulder ranges of motion and trunk forward displacement) were analyzed using 2 way ANOVAs. Preliminary results suggest that the control group had straighter movements and used more shoulder flexion as compared to the stroke group. When the VE was viewed via both media, there were no differences in terms of endpoint precision and speed, elbow and shoulder ranges of motion and trunk forward displacement in both groups. Both groups reported that they completely enjoyed performing the movements when viewing them via both media. All subjects in the control group and 80% of subjects in the stroke group reported that VE was engaging, that it felt real and that the movements performed were similar to those made in the physical world. The results of this study have implications for the design of rehabilitation applications using VR aimed at improving arm motor activity and function.

Kinematics of Pointing Movements Made in a Virtual Versus a Physical 3-Dimensional Environment in Healthy and Stroke Subjects

Upper Extremity Rehabilitation Using Fully Immersive Virtual Reality Games With a Head Mount Display: A Feasibility Study.

Virtual environments are increasingly being used for upper limb rehabilitation in post-stroke patients. However, still there is no clear evidence that the movements performed in virtual reality are comparable to those performed in the physical world from the kinematic point-of-view. The goal of the proposed study is thus to determine if aimed reaching movements made in a 3D ecological and immersive virtual environment – displayed through a Head Mounted Display (HMD) – are comparable to movements performed in the real world. The study foresees the realization of two comparable environmental settings representing the shelf of a supermarket. Three different groups of subjects (healthy young adults, healthy elderly, and post-stroke subjects, n=15 each) are asked to reach 5 times toward 9 targets in 3 different conditions: virtual reality, physical reality, and physical reality while holding a controller. Their movements are tracked with a stereo-photogrammetric motion capture system; movement times, peak velocities, and joint angles are then extracted for analysis. This protocol will allow comparing reaching movements, and also excluding of the effects related to holding a controller. A preliminary trial reveled the feasibility of the protocol, thus the experiment will be carried out in the next months. If results will be encouraging, VR should be considered in rehabilitative treatments as a useful means to elicit patients’ motivation, but also appropriate movement synergies, thus promoting a better recovery of upper limb functions.

Virtual reality technologies, including head-mounted displays (HMD), can provide benefits to psychological research by combining high degrees of experimental control with improved ecological validity. This is due to the strong feeling of being in the displayed environment (presence) experienced by VR users. As of yet, it is not fully explored how using HMDs impacts basic perceptual tasks, such as object perception. In traditional display setups, the congruency between background environment and object category has been shown to impact response times in object perception tasks. In this study, we investigated whether this well-established effect is comparable when using desktop and HMD devices. In the study, 21 participants used both desktop and HMD setups to perform an object identification task and, subsequently, their subjective presence while experiencing two-distinct virtual environments (a beach and a home environment) was evaluated. Participants were quicker to identify objects in the HMD condition, independent of object-environment congruency, while congruency effects were not impacted. Furthermore, participants reported significantly higher presence in the HMD condition.

Downstairs resident classification characteristics for upstairs walking vibration noise in an apartment building under virtual reality environment

Head-mounted displays (HMDs) offer immersion and binocular disparity. This study investigated whether an HMD yields better object-alignment performance than a conventional monitor in virtual environments that are rich in pictorial depth cues. To determine the effects of immersion and disparity separately, three hardware setups were compared: 1) a conventional computer monitor, yielding low immersion, 2) an HMD with binocular-vision settings (HMD stereo), and 3) an HMD with the same image presented to both eyes (HMD mono). Two virtual environments were used: a street environment in which two cars had to be aligned (target distance of about 15 m) and an office environment in which two books had to be aligned (target distance of about 0.7 m, at which binocular depth cues were expected to be important). Twenty males (mean age = 21.2, SD age = 1.6) each completed 10 object-alignment trials for each of the six conditions. The results revealed no statistically significant differences in object-alignment performance between the three hardware setups. A self-report questionnaire showed that participants felt more involved in the virtual environment and experienced more oculomotor discomfort with the HMD than with the monitor.

The purpose of this case study was to determine if learning occurred within a 3D virtual learning environment by determining if elements of collaboration and Nonaka and Takeuchi's (1995) knowledge spiral were present. A key portion of this research was the creation of a Virtual Learning Environment. This 3D VLE utilized the Torque Game Engine provided by Garage Games and a content pack created by BraveTree Productions, LLC. By creating this 3D didactic constructivist virtual environment, conversations were observed for collaborative and knowledge creation elements. Data for this mixed-design case study were gathered through three sources: the 3D virtual environment; a survey created by the researchers; and follow-up interviews. Findings revealed that the five forms of collaboration (Elementary Clarification, In-Depth Clarification, Inference, Judgment, and Application) amplified the knowledge creation process and indeed occurred within the virtual learning environment. It was also determined that all four modes for knowledge creation (socialization, externalization, combination, and internalization) were observed as well.

Extended-Reality Technologies: An Overview of Emerging Applications in Medical Education and Clinical Care.

This chapter aimed to reveal how the analysis, design, and development processes should be carried out while history teaching environments are being developed in 3D virtual environments and to set a concrete definition of teaching process in 3D virtual environments. In the history teaching session, the participants were represented in the 3D virtual environment developed in OpenSim simultaneously with their own avatars. They role-played the historical characters and actively participated in the events of that period by using historical reenactment technique in historical spaces. Additionally, this chapter describes the development process of a 3D virtual teaching environment from the design of the teaching process to the implementation. The procedures performed during the preparation of the 3D virtual teaching environment are presented with a flowchart. It is expected that this flowchart, suggested as a 3D virtual instructional design model, will guide researchers through the process of developing teaching implementations in 3D virtual environments in future studies.

In this paper, an immersive virtual roller coaster is introduced. A three Degree-Of-Freedom (3DOF) computer controlled simulator with special effects is designed, implemented, and tested. The simulator platform moves in response to control signals generated by a three-dimensional (3D) virtual gaming environment. In order to add more reality to the gaming environment, external effects, that represent a fourth dimension to virtual environment, are added to the simulator environment such as smell, sound, light, and sense of temperature (heat or cold) that are synchronized with the events happening in the 3D virtual gaming environment. The controlled simulator is developed for entertainment purposes and to suit all ages. The proposed system was tested and verified in the sense that the platform interacts with all events occur in the 3D virtual environment and external effects. The proposed 4D entertainment machine can be used in amusement parks and family entertainment centers and malls.

Research has shown that people are able to judge distances accurately in full-cue, real-world environments using visually directed actions. However, in virtual environments viewed with head-mounted display (HMD) systems, there is evidence that people act as though the virtual space is smaller than intended. This is a surprising result given how well people act in real environments. The behavior in the virtual setting may be linked to distortions in the available visual cues or to a person's ability to locomote without vision. Either could result from issues related to added mass, moments of inertia, and restricted field of view in HMDs. This article describes an experiment in which distance judgments based on normal real-world and HMD viewing are compared with judgments based on real-world viewing while wearing two specialized devices. One is a mock HMD, which replicated the mass, moments of inertia, and field of view of the HMD and the other an inertial headband designed to replicate the mass and moments of inertia of the HMD, but constructed to not restrict the field of view of the observer or otherwise feel like wearing a helmet. Distance judgments using the mock HMD showed a statistically significant underestimation relative to the no restriction condition but not of a magnitude sufficient to account for all the distance compression seen in the HMD. Indicated distances with the inertial headband were not significantly smaller than those made with no restrictions.

Combining immersive virtual reality (VR) using head-mounted displays (HMDs) with assisting robotic devices might be a promising procedure to enhance neurorehabilitation. However, it is still an open question how immersive virtual environments (VE) should be designed when interacting with rehabilitation robots. In conventional training, the robot is usually not visually represented in the VE, resulting in a visuo-haptic sensory conflict between what users see and feel. This study aimed to investigate how motivation, embodiment, and presence are affected by this visuo-haptic sensory conflict. Using an HMD and a rehabilitation robot, 28 healthy participants performed a path-tracing task, while the robot was either visually reproduced in the VE or not and while the robot either assisted the movements or not. Participants' performance and visual attention were measured during the tasks, and after each visibility/assistance condition, they reported their motivation, presence, and embodiment with questionnaires. We found that, independently of the assistance, the robot visibility did not affect participants' motivation, presence, embodiment, nor task performance. We only found a greater effort/importance reported when the robot was visible. The visual attention was also slightly affected by the robot's visibility. Importantly, we found that the robotic assistance hampered presence and embodiment, but improved motivation. Our results indicate no disadvantage of not reproducing robotic devices in VEs when using HMDs. However, caution must be put when developing assisting controllers, as they might hamper users' affect.

The sense of agency (SoA) describes the feeling of being the author and in control of one's movements. It is closely linked to automated aspects of sensorimotor control and understood to depend on one's ability to monitor the details of one's movements. As such SoA has been argued to be a critical component of self-awareness in general and contribute to presence in virtual reality environments in particular. A common approach to investigating SoA is to ask participants to perform goal-directed movements and introducing spatial or temporal visuomotor mismatches in the feedback. Feedback movements are traditionally either switched with someone else's movements using a 2D video-feed or modified by providing abstracted feedback about one's actions on a computer screen. The aim of the current study was to quantify conscious monitoring and the SoA for ecologically valid, three dimensional feedback of the participants' actual limb and movements. This was achieved by displaying an Infra-Red (IR) feed of the participants' upper limbs in an augmented virtuality environment (AVE) using a head-mounted display (HMD). Movements could be fed back in real-time (46ms system delay) or with an experimental delay of up to 570ms. As hypothesized, participant's SoA decreased with increasing temporal visuomotor mismatches (p<.001), replicating previous findings and extending them to AVEs. In-line with this literature, we report temporal limits of 222±60ms (50% psychometric threshold) in N=28 participants. Our results demonstrate the validity of the experimental platform by replicating studies in SoA both qualitatively and quantitatively. We discuss our findings in relation to the use of virtual and mixed reality in research and implications for neurorehabilitation therapies.

Modeling physiological and perceived responses in remote collaborative virtual environments: A comparative study of HMD and desktop platforms