Multiple Self-Avatar Effect: Effects of Using Diverse Self-Avatars on Memory Acquisition and Retention of Sign-Language Gestures.

This study proposes a new learning method that employs multiple embodied self-avatars during learning, to use the potential benefit of virtual reality (VR) for effective learning and training. In this study, by taking advantage of the benefit of virtual reality (VR), we propose a new learning method that employs multiple embodied self-avatars during learning. Based on the multiple-context effect, which posits that learning in diverse situations can prevent forgetting and enhance memory retention, we conducted a between-participants study under two conditions: the varied avatar condition, in which participants learned sign languages with different self-avatars in six iterations, and the constant avatar condition, in which the same self-avatar was used consistently. We employed sign language as a learning material that naturally draws attention to self-avatars and is suitable for investigating the effects of varying self-avatars. Initially, the varied avatar condition performed worse than the constant avatar condition. However, in a test conducted after one week in the real world, the varied avatar condition showed significantly less forgetting and better retention than the constant avatar condition. Furthermore, our results suggested a positive correlation between the degree of embodiment toward the avatars and the effectiveness of the proposed method. This study presents an innovative design approach for the use of self-avatars in VR-based education.

Reduction of Forgetting by Contextual Variation During Encoding Using 360-Degree Video-Based Immersive Virtual Environments.

Recall impairment in a different environmental context from learning is called context-dependent forgetting. Two learning methods have been proposed to prevent context-dependent forgetting: reinstatement and decontextualization. Reinstatement matches the environmental context between learning and retrieval, whereas decontextualization involves repeated learning in various environmental contexts and eliminates the context dependency of memory. Conventionally, these methods have been validated by switching between physical rooms. However, in this study, we use immersive virtual environments (IVEs) as the environmental context assisted by virtual reality (VR), which is known for its low cost and high reproducibility compared to traditional manipulation. Whereas most existing studies using VR have failed to reveal the reinstatement effect, we test its occurrence using a 360-degree video-based IVE with improved familiarity and realism instead of a computer graphics-based IVE. Furthermore, we are the first to address decontextualization using VR. Our experiment showed that repeated learning in the same constant IVE as retrieval did not significantly reduce forgetting compared to repeated learning in different constant IVEs. Conversely, repeated learning in various IVEs significantly reduced forgetting than repeated learning in constant IVEs. These findings contribute to the design of IVEs for VR-based applications, particularly in educational settings.

Virtual Reality Self Co-Embodiment: An Alternative to Mirror Therapy for Post-Stroke Upper Limb Rehabilitation.

We present Virtual Reality Self Co-embodiment, a new method for post-stroke upper limb rehabilitation. It is inspired by mirror therapy, where the patient's healthy arm is involved in recovering the affected arm's motion. By tracking the user's head, wrists, and fingers' positions, our new approach allows the handicapped arm to control a digital avatar in order to pursue a reaching task. We apply the concept of virtual co-embodiment to use the information from the unaffected arm and complete the affected limb's impaired motion, which is our added unique feature. This requires users to mechanically involve the incapacitated area as much as possible, prioritizing actual movement rather than the sole imagination of it. As a result, subjects will see a seemingly normally functional virtual arm primarily controlled by their handicapped extremity, but with the constant support of their healthy limb's motion. Our experiment compares the task execution performance and embodiment perceived when interacting with both mirror therapy and our proposed technique. We found that our approach's provided sense of ownership is mildly impacted by users' motion planning response times, which mirror therapy does not exhibit. We also observed that mirror therapy's sense of ownership is moderately affected by the subject's proficiency while executing the assigned task, which our new method did not display. The results indicate that our proposed method provides similar embodiment and rehabilitation capabilities to those perceived from existing mirror therapy. This experiment was performed in healthy individuals to have an unbiased comparison of how mirror therapy's and VRSelfCo's task performance and degree of virtual embodiment compare, but future work explores the possibility of applying this new approach to actual post-stroke patients.

Rotational Motion Due to Skin Shear Deformation at Wrist and Elbow.

The hanger reflex is an illusion phenomenon that induces strong force perception and rotational motion, and it occurs in multiple parts of the body. A potential application of this phenomenon is in upper limb rehabilitation for patients with upper-limb paralysis involving arm rotation. However, the only upper limb movements that have been confirmed in this phenomenon are the inward and outward movements of the wrist, which limits the applicable tasks. Therefore, we attempted to apply the hanger reflex to the elbow and use it simultaneously with the wrist. This phenomenon occurs due to shear deformation of the skin, so shear deformation was presented to the skin on the elbow. When shear deformation of the skin was presented to the elbow in the same manner as in previous studies applied to the wrist, movement and force perception of pronation and supination of the elbow were confirmed. The results of an experiment in which the hanger reflex was simultaneously presented to the elbow and wrist showed that each region independently perceived motion and force.

Investigation of the Effect of Students' Nodding on Their Arousal Levels in On-Demand Lectures.

Due to COVID-19, various lecture styles are being explored. On-demand lectures are attracting increasing attention due to advantages such as being able to watch without restrictions due to location and time. In contrast, on-demand lectures have disadvantages, such as no interaction with the lecturer, so the quality of on-demand lectures should be improved. Our previous study showed that when participants nod without showing their faces in a real-time remote lecture, their heart rate state changes to arousal and nodding can increase arousal. In this paper, we hypothesize that nodding during on-demand lectures increases participants' arousal levels, and we investigate the relationship between natural and forced nodding and the level of arousal based on heart rate information. Students taking on-demand lectures rarely nod naturally, so we used entrainment to encourage nodding by showing a video of another participant nodding, and by forcing the participants to nod when the other participant nodded in the video. The results showed that only participants who nodded spontaneously changed the value of pNN50, an index of the arousal level, which reflected a state of high arousal after one minute. Thus, participants' nodding in on-demand lectures can increase their arousal levels; however, the nodding must be spontaneous, not forced.

Effects of the Visual Fidelity of Virtual Environments on Presence, Context-dependent Forgetting, and Source-monitoring Error.

Advances in virtual reality technology have enabled the creation of virtual environments (VEs) with significantly high visual fidelity when compared to real environments (REs). In this study, we use a high-fidelity VE to examine two effects caused by alternating VE and RE experiences: "context-dependent forgetting" and "source-monitoring errors." The former effect is that memories learned in VEs are more easily recalled in VEs than in REs, whereas memories learned in REs are more easily recalled in REs than in VEs. The source-monitoring error is that memories learned in VEs are easily confused with those learned in REs, making discriminating the source of the memory difficult. We hypothesized that the visual fidelity of VEs is responsible for these effects and conducted an experiment using two types of VEs: a high-fidelity VE created using photogrammetry techniques and low-fidelity VE created with primitive shapes and materials. The results show that the high-fidelity VE significantly improved the sense of presence. However, the level of the visual fidelity of the VEs did not show any effect on context-dependent forgetting and source-monitoring errors. Notably, the null results of the context-dependent forgetting between the VE and RE were strongly supported by Bayesian analysis. Thus, we indicate that context-dependent forgetting does not necessarily occur, which will be helpful for VR-based education and training.

Redirected Walking using Continuous Curvature Manipulation.

In this paper, we propose a novel redirected walking (RDW) technique that applies dynamic bending and curvature gains so that users perceive less discomfort than existing techniques that apply constant gains. Humans are less likely to notice continuous changes than those that are sudden. Therefore, instead of applying constant bending or curvature gains to users, we propose a dynamic method that continuously changes the gains. We conduct experiments to investigate the effect of dynamic gains in bending and curvature manipulation with regards to discomfort. The experimental results show that the proposed method significantly suppresses discomfort by up to 16 and 9% for bending and curvature manipulations, respectively.

Remote support for emergency medicine using a remote-control laser pointer.

We have developed a laser pointing system, the GestureLaser, which allows a remote operator to control a videocamera and a laser beam via a networked personal computer. The laser spot can be moved by the mouse cursor controlled by the remote instructor. The system was tested by giving remote instruction in thoracentesis to inexperienced operators using a training mannekin. Seven medical students received instructions using the laser pointer and another seven received instruction without the laser pointer. All operators completed the task correctly. The laser pointer group correctly identified the centesis space and performed the task on the first trial. When the laser pointer was not used, four operators (57%) made a mistake in selecting the centesis space at the first trial. The mean times for both stage 1--verbal versus GestureLaser 59 s (SD 13) versus 44 s (SD 5), p = 0.015 - and stage 2--verbal versus GestureLaser 98 s (SD 20) versus 64 s (SD 7), P = 0.002 - were significantly shorter when the GestureLaser was used. The study shows that the laser pointing system can be used to remotely instruct a novice operator in performing thoracentesis. It could improve collaboration between geographically separated sites.