Abstract
With the consistent adoption of iVR and growing research on the topic, it becomes fundamental to understand how the perception of Realism plays a role in the potential of iVR. This work puts forwards a hypothesis-driven theoretical model of how the perception of each multisensory stimulus (Visual, Audio, Haptic and Scent) is related to the perception of Realism of the whole experience (Subjective Realism) and, in turn, how this Subjective Realism is related to Involvement and Presence. The model was validated using a sample of 216 subjects in a multisensory iVR experience. The results indicated a good model fit and provided evidence on how the perception of Realism of Visual, Audio and Scent individually is linked to Subjective Realism. Furthermore, the results demonstrate strong evidence that Subjective Realism is strongly associated with Involvement and Presence. These results put forwards a validated questionnaire for the perception of Realism of different aspects of the virtual experience and a robust theoretical model on the interconnections of these constructs. We provide empirical evidence that can be used to optimise iVR systems for Presence, Involvement and Subjective Realism, thereby enhancing the effectiveness of iVR experiences and opening new research avenues.

Abstract
We experience the world around us using all our senses, however, multimedia content still relies majorly on audiovisual stimuli. With technology advancements, multisensory stimuli started to be introduced in multimedia experiences. Still, very few contemplate a wide range of different modalities simultaneously, approaching the stimulation one would receive in reality. This paper explores the effects of trimodal multisensory stimuli on the sense of Presence, Perceptual Realism, and Quality of Experience (QoE) during video visualisation. Namely, we study the impact of heat, wind, and smell during video visualization to investigate how each stimulus contributes to the QoE. A correlational analysis was also performed to understand better how the different variables interact. The results indicate that multisensory stimulation improved significantly the sense of presence satisfaction and perceptual realism. Furthermore, smell contributed the most to the QoE, followed by heat and wind. We highlight the use of multisensory stimulation on video visualization over audiovisual only, as it benefits substantially the user experience. © 2023 IEEE.

Abstract
Currently, it is standard to use tracked handheld controllers for interaction in immersive virtual reality (VR). However, since VR interactions are becoming more natural with hand tracking, it is important to provide hands-free alternatives for selection and system control tasks. As such, this study aims to provide an exploratory evaluation of the effectiveness and efficiency of commonly used hands-free interfaces in selection and system control tasks. Nine interaction methods were evaluated while performing a Fitts' law task with nine advanced users of VR in a within-subject experiment. We evaluated handheld controllers as a baseline, against head gaze, eye gaze, and voice commands for pointing at the targets, and dwell time and voice commands to confirm selections. We found that using eye gaze with a 500 ms dwell time proved to be the hand-free method with the highest performance, matching the handheld controllers and being preferred by users. The evaluation also showed that using a multimodal approach to selection, especially using the voice, decreases performance, but increases effectiveness. Moreover, we verified that Fitts' law can be applied to hands-free methods, but its usage is limited when the methods have very short travel times. We then suggest selections per minute as a more robust comparative performance metric. Further studies should expand the audience and interaction tasks and focus on the confirmatory method of selection.

Abstract
The sense of presence is an important aspect of virtual reality experiences, being increasingly researched in educational contexts for its potential association with learning outcomes. A panorama of how these investigations have been conducted could help researchers and practitioners to harness this potential and find new directions. A systematic literature review was conducted to contribute to this perspective, with a comprehensive analysis of 140 primary studies recovered from five worldwide databases. The results show an overview of 24 years of research, with a summarization of areas, factors, and methodological approaches that have been the focus of investigation when these three variables of interest (VR, sense of presence, and learning) are together. We conclude with a list of research gaps that need to be addressed and a research agenda, identifying current and emerging challenges.

Abstract
This paper investigates the impact of different immersive Virtual Reality (iVR) technological approaches in teaching and learning English as a Foreign Language (EFL). Specifically, this paper explores the passive iVR and interactive iVR in a real authentic learning context as didactic possibilities compared to the conventional method of listening, consisting of audio-only listening exercises. The study was conducted using university students of B1 level EFL classes. The dependent variables considered in the study were Knowledge Retention, Presence, User Satisfaction, Cybersickness, and Preferred Technology. Results indicated that users showed significant satisfaction and preference for using this technology for learning, revealing enjoyment and motivation which are vital factors when learning a foreign language. However, no significant differences were found between learning via traditional listening exercises or the virtual system. Correlation tests were conducted between the questionnaire subscales to understand better which elements can influence learning. The study concludes that using iVR-based learning tools to learn a foreign language as an alternative to audio listening can only produce a broader positive impact and greater motivation. The results also suggest that iVR can be a valuable tool in the education field for knowledge transfer and motivation when learning foreign languages.