In our daily lives, we are exposed to various stressors, which, even in mild forms, can lead to serious health issues when prolonged. Dance Movement Therapy (DMT) uses bodily movement as psychotherapy to improve health and well-being; however, traditional DMT requires therapists, specific setups, and physical props, limiting daily accessibility. To address this, we conducted a formative study with 10 DMT experts and developed ImmersiveDMT, a VR application that provides real-time visual and auditory feedback in response to users’ movements. A user study with 56 participants examined how visual, auditory, and audiovisual feedback affect expressive movement and stress reduction compared to a non-responsive immersive baseline. Results showed that auditory and audiovisual conditions induced significantly more expressive movement compared to baseline. Both visual and auditory feedback achieved significant stress reduction below baseline (V: 17.1%, p=.004; A: 16.6%, p=.042), while combined audiovisual feedback led to less stress reduction. This research presents a novel approach to accessible daily stress management by integrating VR and DMT, demonstrating new possibilities for self-directed mental health support.

Augmented Reality (AR) is a growing technology that enables interaction with both virtual and real objects. However, in order to support the future development of efficient and usable AR interactions, there is still a lack of systematic knowledge establishing basic interaction performance across different conditions. Therefore, in this paper, we report a user study measuring the impact of objects' physicalization (object's set composed of (i) virtual, (ii) real, or (iii) a composite mix of real and virtual objects) and hand appearance (hand's appearance displayed as (i) the real hand, (ii) an avatar, or (iii) dynamically adapting to the surrounding objects' physicalization) on the speed performance of a pick-and-place task. Overall, our results reveal that objects' physicalization plays a significant role in interaction performance, with the more real objects in a set the better the performance. Moreover, our results also suggest that pick-and-place interaction performances are mostly unaffected by the hand appearance. Interestingly, we also observed that interactions with real objects were less efficient as the object condition required the user to alternate between interactions with virtual and real objects (object condition (iii)), which provides novel insights into an important - mostly AR-specific - factor to consider for designing future AR interactions. Taken together, our results provide a rich characterization of different factors influencing different phases of a pick-and-place interaction, which could be employed to improve the design of future AR applications.

Abstract One singularity of VR is its capacity to generate a strong sensation of being present in a dangerous environment, without risking the physical consequences. However, this absence of consequences when interacting with virtual dangers might also limit the induction of realistic responses, such as avoidance behaviors, which are a key factor of various VR applications (e.g., training, journalism, or exposure therapies). To address this limitation, we propose avatar-centered feedback, a novel, device-free approach, consisting of dynamically altering the avatar’s appearance and movements to offer coherent feedback from interactions with the virtual environment, including dangers. To begin with, we present a design space clarifying the range of potential implementations for this approach. Then, we tested this approach in a metallurgy scenario, where participants’ virtual hands would redden and display burns as they got closer to a virtual fire (appearance alteration), and simulate short withdrawal reflexes movements when a spark burst next to them (movement alteration). Our results show that in comparison to a control group, participants receiving avatar-centered feedback demonstrated significantly more avoidance behaviors to the virtual fire. Interestingly, we also found that experiencing avatar-centered feedback of fire significantly increased avoidance behaviors toward a following danger of different nature (a circular saw). These results suggest that avatar-centered feedback can also impact the general perception of the avatar vulnerability to the virtual environment.

In Mixed Reality (MR), users' heads are largely (if not completely) occluded by the MR Head-Mounted Display (HMD) they are wearing. As a consequence, one cannot see their facial expressions and other communication cues when interacting locally. In this paper, we investigate how displaying virtual avatars' heads on-top of the (HMD-occluded) heads of participants in a Video See-Through (VST) Mixed Reality local collaborative task could improve their collaboration as well as social presence. We hypothesized that virtual heads would convey more communicative cues (such as eye direction or facial expressions) hidden by the MR HMDs and lead to better collaboration and social presence. To do so, we conducted a between-subject study ($\mathrm{n}=88$) with two independent variables: the type of avatar (CartoonAvatar/RealisticAvatar/NoAvatar) and the level of facial expressions provided (HighExpr/LowExpr). The experiment involved two dyadic communication tasks: (i) the "20-question" game where one participant asks questions to guess a hidden word known by the other participant and (ii) a urban planning problem where participants have to solve a puzzle by collaborating. Each pair of participants performed both tasks using a specific type of avatar and facial animation. Our results indicate that while adding an avatar's head does not necessarily improve social presence, the amount of facial expressions provided through the social interaction does have an impact. Moreover, participants rated their performance higher when observing a realistic avatar but rated the cartoon avatars as less uncanny. Taken together, our results contribute to a better understanding of the role of partial avatars in local MR collaboration and pave the way for further research exploring collaboration in different scenarios, with different avatar types or MR setups.

Embodying a virtual creature or animal in Virtual Reality (VR) is becoming common, and can have numerous beneficial impacts. For instance, it can help actors improve their performance of a computer-generated creature, or it can endow the user with empathy towards threatened animal species. However, users must feel a sense of embodiment towards their virtual representation, commonly achieved by providing congruent sensory feedback. Providing effective visuo-motor feedback in dysmorphic bodies can be challenging due to human-animal morphology differences. Thus, the purpose of this study was to experiment with the inclusion of audio and audio-tactile feedback to begin unveiling their influence towards animal avatar embodiment. Two experiments were conducted to examine the effects of different sensory feedback on participants’ embodiment in a dog avatar in an Immersive Virtual Environment (IVE). The first experiment (n= 24) included audio, tactile, audio-tactile, and baseline conditions. The second experiment (n= 34) involved audio and baseline conditions only.

In virtual reality, the avatar - the user's digital representation - is an important element which can drastically influence the immersive experience. In this paper, we especially focus on the use of "dissimilar" avatars i.e., avatars diverging from the real appearance of the user, whether they preserve an anthropomorphic aspect or not. Previous studies reported that dissimilar avatars can positively impact the user experience, in terms for example of interaction, perception or behaviour. However, given the sparsity and multi-disciplinary character of research related to dissimilar avatars, it tends to lack common understanding and methodology, hampering the establishment of novel knowledge on this topic. In this paper, we propose to address these limitations by discussing: (i) a methodology for dissimilar avatars characterization, (ii) their impacts on the user experience, (iii) their different fields of application, and finally, (iv) future research direction on this topic. Taken together, we believe that this paper can support future research related to dissimilar avatars, and help designers of VR applications to leverage dissimilar avatars appropriately.

In Virtual Reality, self-touch (ST) stimulation is a promising method of sense of body ownership (SoBO) induction that does not require an external effector. However, its applicability to dysmorphic bodies has not been explored yet and remains uncertain due to the requirement to provide incongruent visuomotor sensations. In this, paper, we studied the effect of ST stimulation on dysmorphic hands via haptic retargeting, as compared to a classical external-touch (ET) stimulation, on the SoBO. Our results indicate that ST can induce similar levels of dysmorphic SoBO than ET stimulation, but that some types of dysmorphism might decrease the ST stimulation accuracy due to the nature of the re-targeting that they induce.

Advancements in real-time rendering technology have continued to develop rapidly over the course of the last decade. Consequently, human likenesses have been represented virtually with increasingly impressive detail. There is evidence that this increased resemblance to real humans has an observable and wide-ranging set of effects on human perception, cognition and action in situations that involve digital characters. Studies that seek to advance the science of synthetic animated people have consistently aimed to measure and quantify changes in perceived emotional content mediated through artificial human likenesses. The present study has been built off of this work. The experiment outlined here was constructed to define and measure responses from human participants towards state-of-the-art photorealistic virtual humans under affected conditions. In particular, we sought evidence for changes in perceptions of human likeness, eeriness and attractiveness that could be observably dependent on conditions of photorealism and character representation.

The main use of Augmented Reality (AR) today for the general public is in applications for smartphones. In particular, social network applications allow the use of many AR filters, modifying users’ environments but also their own image. These AR filters are increasingly and frequently being used and can distort in many ways users’ facial traits. Yet, we still do not know clearly how users perceive their faces augmented by these filters. In this paper, we present a study that aims to evaluate the impact of different filters, modifying several facial features such as the size or position of the eyes, the shape of the face or the orientation of the eyebrows, or adding virtual content such as virtual glasses. These filters are evaluated via a self-evaluation questionnaire, asking the participants about the personality, emotion, appeal and intelligence traits that their distorted face conveys. Our results show relative effects between the different filters in line with previous results regarding the perception of others. However, they also reveal specific effects on self-perception, showing, inter alia, that facial deformation decreases participants’ credence towards their image. The findings of this study covering multiple factors allow us to highlight the impact of face deformation on user perception but also the specificity related to this use in AR, paving the way for new works focusing on the psychological impact of such filters.

In this article, we introduce a concept called "virtual co-embodiment", which enables a user to share their virtual avatar with another entity (e.g., another user, robot, or autonomous agent). We describe a proof-of-concept in which two users can be immersed from a first-person perspective in a virtual environment and can have complementary levels of control (total, partial, or none) over a shared avatar. In addition, we conducted an experiment to investigate the influence of users' level of control over the shared avatar and prior knowledge of their actions on the users' sense of agency and motor actions. The results showed that participants are good at estimating their real level of control but significantly overestimate their sense of agency when they can anticipate the motion of the avatar. Moreover, participants performed similar body motions regardless of their real control over the avatar. The results also revealed that the internal dimension of the locus of control, which is a personality trait, is negatively correlated with the user's perceived level of control. The combined results unfold a new range of applications in the fields of virtual-reality-based training and collaborative teleoperation, where users would be able to share their virtual body.

In Virtual Reality, a number of studies have been conducted to assess the influence of avatar appearance, avatar control and user point of view on the Sense of Embodiment (SoE) towards a virtual avatar. However, such studies tend to explore each factor in isolation. This paper aims to better understand the inter-relations among these three factors by conducting a subjective matching experiment. In the presented experiment ( n=40), participants had to match a given "optimal" SoE avatar configuration (realistic avatar, full-body motion capture, first-person point of view), starting by a "minimal" SoE configuration (minimal avatar, no control, third-person point of view), by iteratively increasing the level of each factor. The choices of the participants provide insights about their preferences and perception over the three factors considered. Moreover, the subjective matching procedure was conducted in the context of four different interaction tasks with the goal of covering a wide range of actions an avatar can do in a VE. The paper also describes a baseline experiment ( n=20) which was used to define the number and order of the different levels for each factor, prior to the subjective matching experiment (e.g. different degrees of realism ranging from abstract to personalised avatars for the visual appearance). The results of the subjective matching experiment show that point of view and control levels were consistently increased by users before appearance levels when it comes to enhancing the SoE. Second, several configurations were identified with equivalent SoE as the one felt in the optimal configuration, but vary between the tasks. Taken together, our results provide valuable insights about which factors to prioritize in order to enhance the SoE towards an avatar in different tasks, and about configurations which lead to fulfilling SoE in VE.

With the increasing use of avatars (i.e. the virtual representation of the user in a virtual environment) in virtual reality, it is important to identify the factors eliciting the sense of embodiment or the factors that can disrupt this feeling. This paper reports an exploratory study aiming at identifying internal factors (personality traits and body awareness) that might cause either a resistance or a predisposition to feel a sense of embodiment towards a virtual avatar. To this purpose, we conducted an experiment (n=123) in which participants were immersed in a virtual environment and embodied in a gender-matched generic virtual avatar through a head-mounted display. After an exposure phase in which they had to perform a number of visuomotor tasks (during 2 minutes) a virtual character entered the virtual scene and stabbed the participants' virtual hand with a knife. The participants' sense of embodiment was measured, as well as several personality traits (Big Five traits and locus of control) and body awareness, to evaluate the influence of participants' personality on the acceptance of the virtual body. The major finding of the experiment is that the locus of control is linked to several components of embodiment: the sense of agency is positively correlated with an internal locus of control and the sense of body ownership is positively correlated with an external locus of control. Interestingly, both components are not influenced by the same traits, which confirms that they can appear independently. Taken together our results suggest that the locus of control could be a good predictor of the sense of embodiment when the user embodies an avatar with a similar physical appearance. Yet, further studies are required to confirm these results.

In this paper, we present the design of ten different 3D user interactions using passive haptics and embedded in an escape game scenario in which users have to escape from a pyramid in a limited time. Our solution is innovative by its modularity, allowing interactions with virtual objects using tangible props manipulated either directly using the hands and feet or indirectly through a single prop held in the hand, in order to perform several interactions with the virtual environment (VE). We also propose a navigation technique based on the “impossible spaces” design, allowing users to naturally walk through several overlapping rooms of the VE. All together, our different interaction techniques allow the users to solve several enigmas built into a challenging scenario inside a pyramid.

In this paper, we propose 3D user interfaces (3DUI) that are adapted to specific Virtual Reality (VR) tasks: climbing a ladder using a puppet metaphor, piloting a drone thanks to a 3D virtual compass and stacking 3D objects with physics-based manipulation and time control. These metaphors have been designed to provide the user with an intuitive, playful and efficient way to perform each task.

In this paper, we explore the influence of sharing a virtual environment with another user on the sense of embodiment in virtual reality. For this aim, we conducted an experiment where users were immersed in a virtual environment while being embodied in an anthropomorphic virtual representation of themselves. To evaluate the influence of the presence of another user, two situations were studied: either users were immersed alone, or in the company of another user. During the experiment, participants performed a virtual version of the well-known whac-a-mole game, therefore interacting with the virtual environment, while sitting at a virtual table. Our results show that users were significantly more “efficient” (i.e., faster reaction times), and accordingly more engaged, in performing the task when sharing the virtual environment, in particular for the more competitive tasks. Also, users experienced comparable levels of embodiment both when immersed alone or with another user. These results are supported by subjective questionnaires but also through behavioural responses, e.g. users reacting to the introduction of a threat towards their virtual body. Taken together, our results show that competition and shared experiences involving an avatar do not influence the sense of embodiment, but can increase user engagement. Such insights can be used by designers of virtual environments and virtual reality applications to develop more engaging applications.