Embodied Conversational Agents (ECAs) can influence users through verbal and nonverbal social cues. Focusing on dominance, we examine how verbal and nonverbal dominance cues influence users’ decision-making and perceptions of the agent in VR. We conducted a user study using a 2 (verbal: dominant vs. submissive) × 2 (nonverbal: dominant vs. submissive) full factorial design, operationalized through a route-selection task at a virtual crossroads. Results indicated that verbal dominance cues shaped participants’ dominance perception but did not influence decision-making, while nonverbal dominance cues affected route-selection behavior without altering perceived dominance. Both verbal and nonverbal cues also affected broader social evaluations of the agent (e.g., intelligence, competence, warmth, and trustworthiness), with nonverbal cues uniquely affecting likability and social presence. These findings highlight the complementary roles of verbal and nonverbal dominance cues in human–agent interaction in VR and inform the design of context-sensitive, dominance-calibrated ECAs for training, education, and decision support.

Mixed Reality Agents (MiRAs) have been extensively studied to enhance virtual-physical interactions, using their ability to exist in both virtual and physical environments. However, little research has focused on enhancing perceived empathy in MiRAs, despite its potential for agent-assisted therapy, education, and training. To fill this gap, we investigate the impact of an Empathic Mixed Reality agent (EMiRA) that adapts to users' physiological states and physical events in a shooting game. We found that this adaptation enhanced users' social perceptions of the agent, including social presence, social connectedness, and perceived empathy. Physiological adaptation increased paternalism and reduced user dominance, while physical adaptation had no such effect. We discuss these findings and provide design implications for future EMiRAs.

This study explores a streamlined facial data collection method for conversational contexts, addressing the limitations of existing approaches that often require extensive datasets and prioritize technical metrics over user perception and experience. We systematically investigate which facial expression data are essential for reconstructing photorealistic avatars and how they can be captured efficiently. Our research employs a two-phase methodology to identify efficient facial data collection strategies and evaluate their effectiveness. In the first phase, we conduct facial data acquisition and evaluate reconstruction performance using utterance data and emotional data. In the second phase, we carry out a comprehensive user evaluation comparing three progressive conditions: utterance only, utterance and emotional data, and a control condition involving extensive data. Findings from 24 participants engaged in simulated face-to-face conversations reveal that targeted utterance and emotional data achieve comparable levels of perceived realism, naturalness, and telepresence, while reducing training time and data usage when compared to the extensive data collection approach. These results demonstrate that targeted data inputs can enable efficient avatar face reconstruction, offering practical guidelines for real-time applications such as AR/VR telepresence and highlighting the trade-off between data quantity and perceived quality.

Room-scale locomotion in VR can promote physical movement to combat the negative effects of a sedentary lifestyle. Therefore, it is useful to investigate factors which may motivate users to walk instead of teleport. In a within-subjects study with 24 participants, we investigated the effects of avatar appearance and target distance on users' locomotion behavior, when given the option to either walk or teleport. In particular, we manipulated three aspects of avatar appearance-body completeness (full-body vs upper-body only), body weight (normal vs obese), and clothing (casual vs superhero armor), and we provided three target distances (1.5 meters, 3.0 meters, and 4.5 meters). We found that avatar obesity decreased willingness to walk, but only for full-body avatars. We also found that close target distances encouraged more walking than teleporting, up to a certain threshold distance. Additionally, we found that users' perceived similarity to their avatar correlated with their willingness to walk. Our findings can be applied to motivate users to walk more in VR, such as in VR exergames.

Immersive technologies such as virtual and augmented reality (VR/AR) enable people to own and interact with virtual pets, offering an alternative for those who are unable to care for real pets due to spatial, physical, or financial constraints. However, how users form social bonds and emotional connections with virtual pets remains unclear and underexplored. Most virtual pet systems rely primarily on visual and auditory cues, overlooking one critical modality for emotional bonding�touch. Touch plays a fundamental role in emotional communication and social presence, particularly in human-animal interactions. Haptic feedback can fill the role of providing touch cues for users of virtual pet systems. This paper investigates how different haptic feedback modalities can influence emotional communication between users and virtual pets. We compare active haptic feedback�more specifically vibrotactile feedback�delivered through haptic gloves that respond to user interactions with a virtual dog, and passive haptic feedback, provided through a physical plush toy dog that represents the dog's body in physical space. In a within-subjects study with 32 participants, results revealed that passive haptic feedback significantly enhanced emotional bonding, social presence, and perceptions of realism, while active vibrotactile feedback contributed meaningfully in the absence of passive cues, especially in increasing behavioral engagement. These findings offer valuable design insights for emotionally resonant virtual pet systems, suggesting that passive haptics anchor affective realism, while active vibrotactile haptics enhance interactivity and compensate for reduced physical embodiment in immersive environments.

Incorporating multi-sensory cues into Virtual Reality (VR) can significantly enhance user experiences, mirroring the multi-sensory interactions we encounter in the real-world. Olfaction plays a crucial role in shaping impressions when engaging with others. This study examines how non-verbal cues from virtual agents-specifically olfactory cues, emotional expressions, and gender-influence user perceptions during encounters with virtual agents. Our findings indicate that in unscented, woodsy, and floral scent conditions, participants primarily relied on visually observable cues to form their impressions of virtual agents. Positive emotional expressions, conveyed through facial expressions and gestures, contributed to more favorable impressions, with this effect being stronger for the female agent than the male agent. However, in the unpleasant scent condition, participants consistently formed negative impressions, which overpowered the influence of emotional expressions and gender, suggesting that aversive olfactory stimuli can detrimentally impact user perceptions. Our results emphasize the importance of carefully selecting olfactory stimuli when designing immersive and engaging VR interactions. Finally, we present our findings and outline future research directions for effectively integrating olfactory cues into virtual agents.

As augmented reality (AR) technologies become more integrated into everyday tasks, the design of notification systems that minimize disruption while enhancing user awareness is increasingly important. This study investigates how crossmodal interference between notification modality (visual, audio, tactile) and primary task modality (also visual, auditory, tactile) affects user perception and performance in AR environments. Through a controlled user study ($N=36$), participants engaged in modality-specific pattern recognition tasks while responding to spatial directional notifications delivered via different sensory channels. By analyzing notification awareness time, reaction time, task accuracy, and subjective measures, such as cognitive load and user preference, the study reveals how congruency or mismatch between task and notification modalities can either facilitate or hinder attention redirection and multi-tasking efficiency. The findings contribute to the design of adaptive AR notification systems that are less intrusive and better aligned with users' perceptual and cognitive states.

As immersive virtual environments become more prevalent, avatars serve as critical social interfaces. This study explores how combinations of visual appearance, vocal characteristics, and informed identity influence users' initial impressions and partner preferences in four distinct XR scenarios: physical, intellectual, social, and romantic. A within-subject experiment with 40 participants assessed perceived warmth, competence, uncanniness, and selection preferences across diverse avatar configurations. Results indicate that vocal cues had a particularly strong impact on social perception, often shaping feelings of approachability and clarity in communication. While some cue alignments enhanced perceived social comfort and engagement, inconsistencies across gender-related cues occasionally led to increased perceptions of uncanniness, especially in emotionally sensitive contexts. These findings highlight the importance of designing avatars that thoughtfully adapt to different interaction contexts, supporting inclusive and responsive user experiences in social XR platforms.

According to Hall’s theory, the space individuals maintain between one another depends on relational closeness and situational context. Prior research suggests that interpersonal distance (IPD) varies not only between virtual and real humans, but also among virtual humans depending on their perceived agency. However, little is known about how people spatially negotiate entry into mixed groups comprising different types of agents in extended reality (XR) settings. In this study, we examine participants’ entry behavior as they join a circular F-formation composed of three distinct entities: an agent, an avatar, and a real human. Specifically, we investigate how participants position themselves relative to each entity, analyzing their preferences and behaviors in terms of IPD and entry dynamics. Our findings reveal that participants maintained the greatest IPD from the real human, followed by the avatar and the agent, suggesting nuanced social distinctions among these three entities. Furthermore, when the real human was absent, participants tended to maintain a greater distance from the avatar compared to the agent. These results offer valuable insights for the design of XR collaboration environments and for understanding social dynamics in multi-agent interactions.

Accurate and real-time three-dimensional (3D) pose estimation is challenging in resource-constrained and dynamic environments owing to its high computational complexity. To address this issue, this study proposes a novel cooperative inference method for real-time 3D human pose estimation in mobile edge computing (MEC) networks. In the proposed method, multiple end devices equipped with lightweight inference models employ dual confidence thresholds to filter ambiguous images. Only the filtered images are offloaded to an edge server with a more powerful inference model for re-evaluation, thereby improving the estimation accuracy under computational and communication constraints. We numerically analyze the performance of the proposed inference method in terms of the inference accuracy and end-to-end delay and formulate a joint optimization problem to derive the optimal confidence thresholds and transmission time for each device, with the objective of minimizing the mean per-joint position error (MPJPE) while satisfying the required end-to-end delay constraint. To solve this problem, we demonstrate that minimizing the MPJPE is equivalent to maximizing the sum of the inference accuracies for all devices, decompose the problem into manageable subproblems, and present a low-complexity optimization algorithm to obtain a near-optimal solution. The experimental results show that a trade-off exists between the MPJPE and end-to-end delay depending on the confidence thresholds. Furthermore, the results confirm that the proposed cooperative inference method achieves a significant reduction in the MPJPE through the optimal selection of confidence thresholds and transmission times, while consistently satisfying the end-to-end delay requirement in various MEC environments.

As avatars have evolved from simple digital representations into extensions of our identities, they offer unprecedented opportunities for self-expression and customization beyond the physical world limitations. While virtual platforms foster new forms of identity exploration, social norms still play a crucial role in defining what is considered appropriate in these environments. In this study, we surveyed 150 participants to investigate social norms surrounding avatar modifications, examining how perspectives, contexts, and personality traits influence attitudes toward appropriateness. Our findings reveal that avatar modifications are generally viewed as more appropriate when considered from a partner's perspective, especially for changeable attributes. However, these modifications are perceived as less acceptable in professional settings such as workplaces. Additionally, individuals with high self-monitoring tendencies tend to be more resistant to changes, while those scoring higher on Machiavellianism are more accepting of changes, particularly regarding unchangeable attributes and emotional expressions. These findings provide valuable insights for platform developers and designers, highlighting the importance of implementing context-aware customization options that balance core identity elements with personality-driven preferences, thereby enhancing user experiences while respecting social norms.

As virtual reality (VR) continues to expand, particularly in social VR platforms and immersive gaming environments, understanding the factors that shape user experience is becoming increasingly important. Avatars and locomotion methods play central roles in influencing how users identify with their virtual representations and navigate virtual spaces. Despite extensive research on these elements individually, their relationship remains underexplored. In particular, little is known about how congruence between avatar appearance and locomotion method affects user perceptions. This study investigates the impact of avatar-locomotion congruence on user experience and avatar identification in VR. We conducted a within-subjects experiment with 30 participants, employing two visually distinct avatar types (human and gorilla) and two locomotion methods (human-like arm-swinging and gorilla-like arm-rolling), to assess their individual and combined effects. Our results indicate that congruence between avatar appearance and locomotion method enhances both avatar identification and user experience. These findings contribute to the understanding of the relationship between avatars and locomotion in VR, with potential applications in enhancing user experience in immersive gaming, social VR, and gamified remote physical therapy.

This paper presents a scoping review of immersive virtual nature experiences delivered via head-mounted displays (HMDs) and their role in promoting well-being, psychological restoration, cognitive performance, and nature connectedness. As access to natural environments becomes increasingly constrained by urbanization, technological lifestyles, and environmental change, immersive technologies offer a scalable and accessible alternative for engaging with nature. Guided by three core research questions, this review explores how HMD-mediated immersive technologies have been used to promote nature connectedness and well-being, what trends and outcomes have been observed across applications, and what methodological gaps or limitations exist in this growing body of work. Fifty-five peer-reviewed studies were analyzed and categorized into six key implication areas: emotional well-being, stress reduction, cognitive performance, attention recovery, restorative benefits, and nature connectedness. The review identifies immersive virtual nature as a promising application of extended reality (XR) technologies, with potential across healthcare, education, and daily life, while also emphasizing the need for more consistent methodologies and long-term research.

This paper explores the impact of an augmented reality (AR) virtual dog, designed to mimic user behavior, on the exercise experience in both solo and group settings. Focusing on the virtual pet's role as a companion during physical activity, we conducted a human-subject experiment comparing three conditions: a mimicking virtual dog, a randomly behaving virtual dog, and no virtual dog. Participants exercised either solo or in groups, specifically in pairs, allowing for a detailed analysis of how the behavior and physical presence of the virtual dog influenced users' exercise experience and social connections. The findings demonstrate that the mimicking virtual dog significantly enhanced the exercise experience, especially in solo settings, by fostering a stronger sense of companionship. In group exercises, the virtual dog acted as a social facilitator, improving group cohesion and interaction. This research highlights the potential of behavior-mimicking virtual pets to enhance both individual and group exercise experiences and offers valuable insights for developing AR-based fitness applications.

Immersive technologies such as virtual and augmented reality (VR/AR) allow remote users to meet and interact in a shared virtual space using embodied virtual avatars, creating a sense of co-presence. However, asynchronous communication-essential in many real-world contexts-remains underexplored in these environments. Traditional playback-based systems lack interactivity and often fail to preserve critical contextual cues necessary for effective asynchronous communication. In this paper, we introduce AVAGENTs, AI-powered virtual avatars that replicate users' verbal and nonverbal cues from recordings of past meetings. Avagents can interpret meeting context and generate appropriate responses to questions posed by asynchronous viewers. Through a user study (N = 30), we evaluated Avagents against a traditional playback method and a voice-based AI assistant across two asynchronous meeting scenarios: analytic reasoning and affective resonance. Results showed that Avagents enhance the asynchronous communication experience by increasing social presence, sense of belonging, emotional intimacy, and other user perceptions. We discuss the findings and their implications for designing effective AI-driven asynchronous communication tools in VR/AR environments.

In human-agent interaction, establishing trust and a social bond with the agent is crucial to improving communication quality and performance in collaborative tasks. This paper investigates how a Mixed Reality Agent’s (MiRA) ability to acknowledge a user’s physiological state affects perceptions such as empathy, social connectedness, presence, and trust. In a within-subject study with 24 subjects, we varied the companion agent’s awareness during a mixed-reality first-person shooting game. Three agents provided feedback based on the users’ physiological states: (1) No Awareness Agent (NAA), which did not acknowledge the user’s physiological state; (2) Random Awareness Agent (RAA), offering feedback with varying accuracy; and (3) Accurate Awareness Agent (AAA), which provided consistently accurate feedback. Subjects reported higher scores on perceived empathy, social connectedness, presence, and trust with AAA compared to RAA and NAA. Interestingly, despite exceeding NAA in perception scores, RAA was the least favored as a companion. The findings and implications for the design of MiRA interfaces are discussed, along with the limitations of the study and directions for future work.

Understanding gender differences in facial and spatial recognition is crucial for enhancing avatar-mediated communication. However, there remains a gap in understanding how participant gender influences perceptions of avatar facial expressions and spatial dynamics in Mixed Reality communication. Therefore, our study investigates how avatar non-verbal cues interact with gender differences to affect user experience and understanding in MR environments. To examine these complex relationships, we conducted a user study comparing the effects of various avatar facial expressions (Full, Mouth-Only, and Emotion-based) and interpersonal distances (Closer vs. Farther) on facial animation realism and social presence, with a focus on gender-balanced participant groups. Our findings revealed that female participants were particularly sensitive to the avatar’s proximity and facial expressions, reporting significantly higher perceptions of facial animation realism, copresence, message understanding, and affective understanding at farther distances compared to male participants. They also perceived higher copresence and message understanding when exposed to emotion-based facial expressions, as opposed to a mouth-only condition-a distinction not observed among male participants. Based on our findings, we advocate for avatar design strategies that accommodate gender differences in perception and preference, potentially through customizable levels of expressiveness to cater to diverse user needs and contexts.

In avatar-mediated remote communication, avatars’ facial expressions can be dynamically adjusted according to each user’s computational and device constraints, highlighting the importance of varied expressions and their impact on user perception. However, there is a lack of research on how variations in avatar facial expressions, especially when simplified, influence user perception, particularly in terms of social presence. To address this, we examine the impact of various facial expression combinations on social presence in avatar-mediated communication scenarios, ranging from informative speeches to emotional conversations. Our approach involves prioritizing avatar facial blendshape combinations using two main approaches: (1) commonly activated expressions that reflect the active facial movements observed during casual conversations, and (2) emotion-based expressions derived from Facial Action Coding System (FACS). These combinations were compared against minimal baseline and full blendshape conditions through a comprehensive study involving 32 participants. Our findings reveal that emotion-based condition achieves comparable levels of social presence and communication quality to the full condition, in both informative speeches and emotional conversations. This highlights the effectiveness of prioritizing emotion-based expressions and adopting a streamlined approach to avatar facial control. By focusing on emotional expressions while optimizing resources, this approach shows potential for enhancing the avatar-mediated communication experience, accommodating the diverse users’ contexts.

The proliferation of personalized video content consumption, amplified by advances in virtual reality (VR) and augmented reality (AR), has introduced new paradigms in media engagement.This paper presents the development and evaluation of “Watch Buddy,” an expressive virtual agent designed to enhance the video-watching experience within an AR environment. The research assesses the impact of the agent’s presence and expressiveness on user satisfaction, technology acceptance, social presence, and emotional intimacy. A comparative user study with 30 participants reveals that the expressive agent significantly improves the viewing experience, as well as the perceived social connection between users and the agent, compared with an inexpressive agent and no agents at all. This paper contributes to VR/AR and human-agent interaction by demonstrating how virtual companions can influence media consumption and foster social connections, particularly for isolated demographics like the elderly or those living alone.

Immersive and simulation technologies, such as Augmented Reality (AR), Virtual Reality (VR), Mixed Reality (MR), and Digital Twins (DTs), have proven effective in enhancing decision-making, streamlining operations, and improving safety through intuitive visualizations. Unsurprisingly, the oil and gas (O&G) pipeline industry is increasingly turning to these technologies to tackle complex construction and resource management challenges. This paper reviews the applications, benefits, and future trends of these technologies, focusing on integration and emerging trends in monitoring, training, maintenance, and testing. It identifies potential gaps, offers guidance for future research, and emphasizes adapting to technological evolution, providing insights to improve system reliability and sustainability in O&G pipeline operations using immersion and simulation methods.

Augmented reality (AR) provides users with a unique social space where virtual objects are natural parts of the real world. The users can interact with 3D virtual objects and virtual humans projected onto the physical environment. This work examines perceived ownership based on the reality of objects and partners, as well as object controllability in a shared AR setting. Our formal user study with 28 participants shows a sense of possession, control, separation, and partner presence affect their perceived ownership of a shared object. Finally, we discuss the findings and present a conclusion.

In our lives, we encounter various stressors that may cause negative mental and bodily reactions to make us feel frustrated, angry, or irritated. Effective methods to manage or reduce stress and anxiety are essential for a healthy life, and several stress-management approaches are found to be useful for stress relief, such as meditation, taking a rest, walking around nature, or even breaking things in a smash room. Previous research has revealed that certain experiences in virtual reality (VR) are effective for reducing stress as traditional real-world methods. However, it is still unclear how the stress relief effects are associated with other factors like individual user profile in terms of different treatment activities. In this paper, we report our findings from a formal user study that investigates the effects of two virtual activities: (1) VR Meditation and (2) VR Smash Room experience, compared with a traditional Sitting-in-Silence method. Our results show that VR Meditation has a better stress relief effect compared to VR Smash Room and Sitting-in-Silence, and the effects of the treatments are correlated with the participants’ personalities. We discuss the findings and implications addressing potential benefits/impacts of different stress-relief activities in VR.

Extended reality (XR) technologies, such as virtual reality (VR) and augmented reality (AR), provide users, their avatars, and embodied agents a shared platform to collaborate in a spatial context. Although traditional face-to-face communication is limited by users’ proximity, meaning that another human’s non-verbal embodied cues become more difficult to perceive the farther one is away from that person, researchers and practitioners have started to look into ways to accentuate or amplify such embodied cues and signals to counteract the effects of distance with XR technologies. In this article, we describe and evaluate the Big Head technique, in which a human’s head in VR/AR is scaled up relative to their distance from the observer as a mechanism for enhancing the visibility of non-verbal facial cues, such as facial expressions or eye gaze. To better understand and explore this technique, we present two complimentary human-subject experiments in this article. In our first experiment, we conducted a VR study with a head-mounted display to understand the impact of increased or decreased head scales on participants’ ability to perceive facial expressions as well as their sense of comfort and feeling of “uncannniness” over distances of up to 10 m. We explored two different scaling methods and compared perceptual thresholds and user preferences. Our second experiment was performed in an outdoor AR environment with an optical see-through head-mounted display. Participants were asked to estimate facial expressions and eye gaze, and identify a virtual human over large distances of 30, 60, and 90 m. In both experiments, our results show significant differences in minimum, maximum, and ideal head scales for different distances and tasks related to perceiving faces, facial expressions, and eye gaze, and we also found that participants were more comfortable with slightly bigger heads at larger distances. We discuss our findings with respect to the technologies used, and we discuss implications and guidelines for practical applications that aim to leverage XR-enhanced facial cues.

Immersive virtual reality (VR) simulations become more and more popular for basic nursing skills training in a realistic VR environment. However, there is still a gap of research that specifically focuses on pediatric nursing interventions where nurse trainees should be able to recognize and deal with the patient parent’s emotional responses appropriately. In this paper, we propose a novel nursing intervention analysis framework that evaluates the user’s nursing performance, by analyzing not only their momentary multimodal (verbal and nonverbal) behaviors, but also accumulated intervention behaviors that capture the overall nursing context. Based on the proposed framework, we developed an immersive VR-based nursing education system with an emotionally responsive virtual parent, and designed a realistic pediatric nursing intervention scenario in collaboration with a subject-matter expert (a nursing faculty in our university). An expert-evaluation study with professional nurses was conducted to assess the potential of the developed system—in particular, the effects of the emotionally responsive virtual parent— as an effective education tool, by comparing with an emotionally static/neutral virtual parent. Several factors of learning experience, e.g., immersion, realism, learning efficacy, and usefulness, were examined through a subjective questionnaire, and the results support the effectiveness of our system in clinical practice or educational settings. We discuss the findings and implications of our research with the nurse participants’ qualitative feedback, while also addressing possible limitations and future research directions.

Mutual gaze is one of the most significant, reliable, and observable social cues that we can use for establishing and maintaining successful social interactions. This cue has been actively used to assess the level of social behavior in the context of autism therapy. However, collecting gaze data manually and evaluating them is so challenging, which requires a lot of time and effort from therapy experts. To address these issues, in this paper, we introduce an automated mutual gaze detection framework, grounded based on previous works on automated gaze detection, as an effective predictive model for social visual behavior analysis and assessment in autism therapy. To evaluate the proposed gaze prediction framework, we prepare an in-house video dataset that captures social interactions between children with autism and their therapy trainers (N = 10, 30 video recordings). We estimate the mutual gaze ratio of children using our prediction model, then compared it with the social visual behavior scores that therapy experts manually annotated. The results showed that our framework provided mutual gaze ratio scores that reliably represent (or even replace) the therapy experts’ hand-coded social visual behavior scores through different analysis approaches: descriptive comparisons, correlation analysis, and regression prediction. We report our findings and discuss the implications of the proposed work in the context of visual behavior analysis for children with autism.

The closed design of virtual reality (VR) head-mounted displays substantially limits users’ awareness of their real-world surroundings. This presents challenges when another person in the same physical space needs to interrupt the VR user for a brief conversation. Such interruptions, e.g., tapping a VR user on the shoulder, can cause a disruptive break in presence (BIP), which affects their place and plausibility illusions, and may cause a drop in performance of their virtual activity. Recent findings related to the concept of diegesis, which denotes the internal consistency of an experience/story, suggest potential benefits of integrating registered virtual representations for physical interactors, especially when these appear internally consistent in VR. In this paper, we present a human-subject study we conducted to compare and evaluate five different diegetic and non-diegetic methods to facilitate cross-reality interruptions in a virtual office environment, where a user’s task was briefly interrupted by a physical person. We created a Cross-Reality Interaction Questionnaire (CRIQ) to capture the quality of the interaction from the VR user’s perspective. Our results show that the diegetic representations afforded reasonably high senses of co-presence, the highest quality interactions, the highest place illusions, and caused the least disruption of the participants’ virtual experiences. We discuss our findings as well as implications for practical applications that aim to leverage virtual representations to ease cross-reality interruptions.

Previous research on distance estimation in virtual reality (VR) has well established that even for geometrically accurate virtual objects and environments users tend to systematically mis-estimate distances. This has implications for Social VR, where it introduces variables in personal space and proxemics behavior that change social behaviors compared to the real world. One yet unexplored factor is related to the trend that avatars' embodied cues in Social VR are often scaled, e.g., by making one's head bigger or one's voice louder, to make social cues more pronounced over longer distances. In this paper we investigate how the perception of avatar distance is changed based on two means for scaling embodied social cues: visual head scale and verbal volume scale. We conducted a human-subject study employing a mixed factorial design with two Social VR avatar representations (full-body, head-only) as a between factor as well as three visual head scales and three verbal volume scales (up-scaled, accurate, down-scaled) as within factors. For three distances from social to far-public space, we found that visual head scale had a significant effect on distance judgments and should be tuned for Social VR, while conflicting verbal volume scales did not, indicating that voices can be scaled in Social VR without immediate repercussions on spatial estimates. We discuss the interactions between the factors and implications for Social VR.

Light-on-dark color schemes, so-called “Dark Mode,” are becoming more and more popular over a wide range of display technologies and application fields. Many people who have to look at computer screens for hours at a time, such as computer programmers and computer graphics artists, indicate a preference for switching colors on a computer screen from dark text on a light background to light text on a dark background due to perceived advantages related to visual comfort and acuity, specifically when working in low-light environments. In this article, we investigate the effects of dark mode color schemes in the field of optical see-through head-mounted displays (OST-HMDs), where the characteristic “additive” light model implies that bright graphics are visible but dark graphics are transparent . We describe two human-subject studies in which we evaluated a normal and inverted color mode in front of different physical backgrounds and different lighting conditions. Our results indicate that dark mode graphics displayed on the HoloLens have significant benefits for visual acuity and usability, while user preferences depend largely on the lighting in the physical environment. We discuss the implications of these effects on user interfaces and applications.

360-degree experiences such as cinematic virtual reality and 360-degree videos are becoming increasingly popular. In most examples, viewers can freely explore the content by changing their orientation. However, in some cases, this increased freedom may lead to viewers missing important events within such experiences. Thus, a recent research thrust has focused on studying mechanisms for guiding viewers' attention while maintaining their sense of presence and fostering a positive user experience. One approach is the utilization of diegetic mechanisms, characterized by an internal consistency with respect to the narrative and the environment, for attention guidance. While such mechanisms are highly attractive, their uses and potential implementations are still not well understood. Additionally, acknowledging the user in 360-degree experiences has been linked to a higher sense of presence and connection. However, less is known when acknowledging behaviors are carried out by attention guiding mechanisms. To close these gaps, we conducted a within-subjects user study with five conditions of no guide and virtual arrows, birds, dogs, and dogs that acknowledge the user and the environment. Through our mixed-methods analysis, we found that the diegetic virtual animals resulted in a more positive user experience, all of which were at least as effective as the non-diegetic arrow in guiding users towards target events. The acknowledging dog received the most positive responses from our participants in terms of preference and user experience and significantly improved their sense of presence compared to the non-diegetic arrow. Lastly, three themes emerged from a qualitative analysis of our participants' feedback, indicating the importance of the guide's blending in, its acknowledging behavior, and participants' positive associations as the main factors for our participants' preferences.

Virtual reality (VR) technologies provide a shared platform for collaboration among users in a spatial context. To enhance the quality of social signals during interaction between users, researchers and practitioners started augmenting users’ interpersonal space with different types of virtual embodied social cues. A prominent example is commonly referred to as the "Big Head" technique, in which the head scales of virtual interlocutors are slightly increased to leverage more of the display’s visual space to convey facial social cues. While beneficial in improving interpersonal social communication, the benefits and thresholds of human perception of facial cues and comfort in such Big Head environments are not well understood, limiting their usefulness and subjective experience.In this paper, we present a human-subject study that we conducted to understand the impact of an increased or decreased head scale in social VR on participants’ ability to perceive facial expressions as well as their sense of comfort and feeling of "uncanniness." We explored two head scaling methods and compared them with respect to perceptual thresholds and user preferences. We further show that the distance to interlocutors has an important effect on the results. We discuss implications and guidelines for practical applications that aim to leverage VR-enhanced social cues.

Current virtual reality (VR) head-mounted displays (HMDs) are characterized by a low angular resolution that makes it difficult to make out details, leading to reduced legibility of text and increased visual fatigue. Light-on-dark graphics modes, so-called "dark mode" graphics, are becoming more and more popular over a wide range of display technologies, and have been correlated with increased visual comfort and acuity, specifically when working in low-light environments, which suggests that they might provide significant advantages for VR HMDs.In this paper, we present a human-subject study investigating the correlations between the color mode and the ambient lighting with respect to visual acuity and fatigue on VR HMDs. We compare two color schemes, characterized by light letters on a dark background (dark mode), or dark letters on a light background (light mode), and show that the dark background in dark mode provides a significant advantage in terms of reduced visual fatigue and increased visual acuity in dim virtual environments on current HMDs. Based on our results, we discuss guidelines for user interfaces and applications.

Collaboration in a group has the potential to achieve more effective solutions for challenging problems, but collaboration per se is not an easy task, rather a stressful burden if the collaboration partners do not communicate well with each other. While Intelligent Virtual Assistants (IVAs), such as Amazon Alexa, are becoming part of our daily lives, there are increasing occurrences in which we collaborate with such IVAs for our daily tasks. Although IVAs can provide important support to users, the limited verbal interface in the current state of IVAs lacks the ability to provide effective non-verbal social cues, which is critical for improving collaborative performance and reducing task load.In this paper, we investigate the effects of IVA embodiment on collaborative decision making. In a within-subjects study, participants performed a desert survival task in three conditions: (1) performing the task alone, (2) working with a disembodied voice assistant, and (3) working with an embodied assistant. Our results show that both assistant conditions led to higher performance over when performing the task alone, but interestingly the reported task load with the embodied assistant was significantly lower than with the disembodied voice assistant. We discuss the findings with implications for effective and efficient collaborations with IVAs while also emphasizing the increased social presence and richness of the embodied assistant.

Human gaze awareness is important for social and collaborative interactions. Recent technological advances in augmented reality (AR) displays and sensors provide us with the means to extend collaborative spaces with real-time dynamic AR indicators of one's gaze, for example via three-dimensional cursors or rays emanating from a partner's head. However, such gaze cues are only as useful as the quality of the underlying gaze estimation and the accuracy of the display mechanism. Depending on the type of the visualization, and the characteristics of the errors, AR gaze cues could either enhance or interfere with collaborations. In this paper, we present two human-subject studies in which we investigate the influence of angular and depth errors, target distance, and the type of gaze visualization on participants' performance and subjective evaluation during a collaborative task with a virtual human partner, where participants identified targets within a dynamically walking crowd. First, our results show that there is a significant difference in performance for the two gaze visualizations ray and cursor in conditions with simulated angular and depth errors: the ray visualization provided significantly faster response times and fewer errors compared to the cursor visualization. Second, our results show that under optimal conditions, among four different gaze visualization methods, a ray without depth information provides the worst performance and is rated lowest, while a combination of a ray and cursor with depth information is rated highest. We discuss the subjective and objective performance thresholds and provide guidelines for practitioners in this field.

An advanced approach to the waypoint-based navigation for near-bottom survey of a cruising AUV is presented. Pursuing vehicle safety as well as high-definition bottom survey data, we apply GDS-based optimization technique for achieving waypoint-based minimum-altitude flight of an underactuated cruising AUV. While the objective of our optimization is minimizing average altitude of a vehicle throughout its flight interval, depth or altitude references on waypoints are used as control inputs. In our optimization, bottom bathymetry is incorporated as a constraint used for bottom collision avoidance. As another constraint, dynamic model of an AUV is included. By solving the dynamic model in time domain, motion responses of the vehicle following reference waypoints are derived. Our approach of the optimal waypoint navigation is validated by not only simulation but also actual at-sea deployment of an AUV.

Modern augmented reality (AR) head-mounted displays comprise a multitude of sensors that allow them to sense the environment around them. We have extended these capabilities by mounting two heat-wavelength infrared cameras to a Microsoft HoloLens, facilitating the acquisition of thermal data and enabling stereoscopic thermal overlays in the user's augmented view. The ability to visualize live thermal information opens several avenues of investigation on how that thermal awareness may affect a user's thermoception. We present a human-subject study, in which we simulated different temperature shifts using either heat vision overlays or 3D AR virtual effects associated with thermal cause-effect relationships (e.g., flames burn and ice cools). We further investigated differences in estimated temperatures when the stimuli were applied to either the user's body or their environment. Our analysis showed significant effects and first trends for the AR virtual effects and heat vision, respectively, on participants' temperature estimates for their body and the environment though with different strengths and characteristics, which we discuss in this paper.

Domestic animals have a long history of enriching human lives physically and mentally by filling a variety of different roles, such as service animals, emotional support animals, companions, and pets. Despite this, technological realizations of such animals in augmented reality (AR) are largely underexplored in terms of their behavior and interactions as well as effects they might have on human users' perception or behavior. In this paper, we describe a simulated virtual companion animal, in the form of a dog, in a shared AR space. We investigated its effects on participants' perception and behavior, including locomotion related to proxemics, with respect to their AR dog and other real people in the environment. We conducted a 2 by 2 mixed factorial human-subject study, in which we varied (i) the AR dog's awareness and behavior with respect to other people in the physical environment and (ii) the awareness and behavior of those people with respect to the AR dog. Our results show that having an AR companion dog changes participants' locomotion behavior, proxemics, and social interaction with other people who can or can not see the AR dog. We also show that the AR dog's simulated awareness and behaviors have an impact on participants' perception, including co-presence, animalism, perceived physicality, and dog's perceived awareness of the participant and environment. We discuss our findings and present insights and implications for the realization of effective AR animal companions.

Intelligent Virtual Agents (IVAs) are becoming part of our everyday life, thanks to artificial intelligence technology and Internet of Things devices. For example, users can control their connected home appliances through natural voice commands to the IVA. However, most current-state commercial IVAs, such as Amazon Alexa, mainly focus on voice commands and voice feedback, and lack the ability to provide non-verbal cues which are an important part of social interaction. Augmented Reality (AR) has the potential to overcome this challenge by providing a visual embodiment of the IVA. In this paper we investigate how visual embodiment and social behaviors influence the perception of the IVA. We hypothesize that a user's confidence in an IVA's ability to perform tasks is improved when imbuing the agent with a human body and social behaviors compared to the agent solely depending on voice feedback. In other words, an agent's embodied gesture and locomotion behavior exhibiting awareness of the surrounding real world or exerting influence over the environment can improve the perceived social presence with and confidence in the agent. We present a human-subject study, in which we evaluated the hypothesis and compared different forms of IVAs with speech, gesturing, and locomotion behaviors in an interactive AR scenario. The results show support for the hypothesis with measures of confidence, trust, and social presence. We discuss implications for future developments in the field of IVAs.

The field of intelligent virtual agents (IVAs) has evolved immensely over the past 15 years, introducing new application opportunities in areas such as training, health care, and virtual assistants. In this survey paper, we provide a systematic review of the most influential user studies published in the IVA conference from 2001 to 2015 focusing on IVA development, human perception, and interactions. A total of 247 papers with 276 user studies have been classified and reviewed based on their contributions and impact. We identify the different areas of research and provide a summary of the papers with the highest impact. With the trends of past user studies and the current state of technology, we provide insights into future trends and research challenges.

In 2008, Zhou et al. presented a survey paper summarizing the previous ten years of ISMAR publications, which provided invaluable insights into the research challenges and trends associated with that time period. Ten years later, we review the research that has been presented at ISMAR conferences since the survey of Zhou et al., at a time when both academia and the AR industry are enjoying dramatic technological changes. Here we consider the research results and trends of the last decade of ISMAR by carefully reviewing the ISMAR publications from the period of 2008-2017, in the context of the first ten years. The numbers of papers for different research topics and their impacts by citations were analyzed while reviewing them-which reveals that there is a sharp increase in AR evaluation and rendering research. Based on this review we offer some observations related to potential future research areas or trends, which could be helpful to AR researchers and industry members looking ahead.

In this paper we report on an investigation of the effects of a self-avatar's visual similarity to a user's actual appearance, on their perceptions of the avatar in an immersive virtual reality (IVR) experience. We conducted a user study to examine the participant's sense of body ownership, presence and visual realism under three levels of avatar-owner visual similarity: (L1) an avatar reconstructed from real imagery of the participant's appearance, (L2) a cartoon-like virtual avatar created by a 3D artist for each participant, where the avatar shoes and clothing mimic that of the participant, but using a low-fidelity model, and (L3) a cartoon-like virtual avatar with a pre-defined appearance for the shoes and clothing. Surprisingly, the results indicate that the participants generally exhibited the highest sense of body ownership and presence when inhabiting the cartoon-like virtual avatar mimicking the outft of the participant (L2), despite the relatively low participant similarity. We present our experiment and main findings, also, discuss the potential impact of a self-avatar's visual differences on human perceptions in IVR.

Augmented reality (AR) enables the illusion of computer-generated virtual objects and humans co-existing with us in the real world. Virtual humans (VHs) in AR can further induce an illusion of physicality in the real world due to their form of presentation and their behavior, such as showing awareness of their surroundings. However, certain behaviors can cause a conflict that breaks this illusion, for example, when we see a VH passing through a physical object.

Abstract In augmented reality, people can feel the illusion of virtual humans (VHs) integrated into a real (physical) space. However, affordances of the real world and virtual contents might conflict, for example, when the VHs and real objects “collide” by occupying the same space. This implausible conflict can cause a break in presence in real–virtual human interactions. In this paper, we address an effort to avoid this conflict by maintaining the VH's spatial and behavioral coherence with respect to the physical objects or events (e.g., natural occlusions and appropriate help‐requesting behaviors to avoid implausible physical–virtual collisions). We present a human subject experiment examining the effects of the physical–virtual coherence on human perceptions, such as social/copresence and behaviors with the VH. The basic ideas, experimental design, and results supporting the benefit of the VH's spatial and behavioral coherence are presented and discussed.

We explore whether a peripheral observation of apparent mutual social presence between a real human (RH) and a virtual human (VH) can in turn increase a subject's sense of social presence with the VH. In other words, we explore whether social presence can “transfer” from one RH-VH interaction to another. Specifically, we carried out an experiment where human subjects were asked to play a game with a VH. As they entered the game room, approximately half of the subjects were exposed to a brief but apparently engaging conversation between an RH and the VH. The subjects who were exposed to the brief RH-VH interaction had significantly higher measures of both emotional connection and the attentional allocation dimension of social presence for the VH, compared to those who were not. We describe the motivation, the experiment, and the results.

While performing everyday interactions, we often incidentally touch and move objects in subtle ways. These objects are not necessarily directly related to the task at hand, and the movement of an object might even be entirely unintentional. If another person is touching the object at the same time, the movement can transfer through the object and be experienced — however subtly — by the other person. For example, when one person hands a drink to another, at some point both individuals will be touching the glass, and consequently exerting small (often unnoticed) forces on the other person. Despite the frequency of such subtle incidental movements of shared objects in everyday interactions, few have examined how these movements affect human-virtual human (VH) interaction. We ran an experiment to assess how presence and social presence are affected when a person experiences subtle, incidental movement through a shared real-virtual object. We constructed a real-virtual room with a table that spanned the boundary between the real and virtual environments. The participant was seated on the real side of the table, which visually extended into the virtual world via a projection screen, and the VH was seated on the virtual side of the table. The two interacted by playing a game of “Twenty Questions,” where one player asked the other a series of 20 yes/no questions to deduce what object the other player was thinking about. During the game, the “wobbly” group of subjects experienced subtle incidental movements of the real-virtual table: the entire real-virtual table tilted slightly away/toward the subject when the virtual/real human leaned on it. The control group also played the same game, except the table did not wobble. Results indicate that the wobbly group had higher presence and social presence with the virtual human in general, with statistically significant increases in presence, co-presence, and attentional allocation. We present the experiment and results, and discuss some potential implications for virtual human systems and some potential future studies.

Optimal and quasi-optimal navigations of an AUV achieved by the minimum time guidance in undersea area of sea currents are presented. When an AUV is to transfer to a given destination within an area of sea current disturbance, ingenious guidance enables the minimization of navigation time. In this study, a numerical procedure to obtain solution of the optimal guidance law in undersea area of sea current disturbances is presented. Simulated optimal and quasi-optimal navigations by minimum time guidance are realized based on the dynamics of an AUV ldquor2D4rdquo. The r2D4 is a deep ocean exploring AUV developed by Institute of Industrial Science, the University of Tokyo. The developed algorithm never fails to derive the optimal headings for minimum time navigation, if only the distribution of current velocity in navigation region is deterministic.