Body Embodiment Research Articles

Investigation of the tissue displacement through textile pressure on soft avatar in Browzwear’s VStitcher software

Nowadays, soft avatars are used in various fields to simulate the behavior of human soft tissues in different applications. Likewise, they are also utilized in the garment industry in order to achieve a realistic testing of the fit and functionality of tight-fitting clothing. Therefore it is important that avatars in CAD programs for clothing conform to the mechanical properties of human soft tissue. The accuracy of the avatars' properties in simulating the change in shape of human tissue is crucial here, which is caused by the contact pressure that compressive or tight-fitting garments exert onto the body. In this study, Browzwear’s VStitcher soft avatar Sofia was investigated and different body shapes resulting from being influenced by a legging with different levels of negative ease values were compared with non-affected natural avatar body shape. The examination of the soft avatar simulation shows that although a fast estimation of the tissue displacement can be predicted, there are some shape changes limitations compared to the natural behavior of human soft tissue.

In Case of Doubt, One Follows One's Self: The Implicit Guidance of the Embodied Self-Avatar.

The sense of embodiment in virtual reality (VR) is commonly understood as the subjective experience that one's physical body is substituted by a virtual counterpart, and is typically achieved when the avatar's body, seen from a first-person view, moves like one's physical body. Embodiment can also be experienced in other circumstances (e.g., in third-person view) or with imprecise or distorted visuo-motor coupling. It was moreover observed, in various cases of small or progressive temporal and spatial manipulations of avatars' movements, that participants may spontaneously follow the movement shown by the avatar. The present work investigates whether, in some specific contexts, participants would follow what their avatar does even when large movement discrepancies occur, thereby extending the scope of understanding of the self-avatar follower effect beyond subtle changes of motion or speed manipulations. We conducted an experimental study in which we introduced uncertainty about which movement to perform at specific times and analyzed participants' movements and subjective feedback after their avatar showed them an incorrect movement. Results show that, when in doubt, participants were influenced by their avatar's movements, leading them to perform that particular error twice more often than normal. Importantly, results of the embodiment score indicate that participants experienced a dissociation with their avatar at those times. Overall, these observations not only demonstrate the possibility of provoking situations in which participants follow the guidance of their avatar for large motor distortions, despite their awareness about the avatar movement disruption and on the possible influence it had on their choice, and, importantly, exemplify how the cognitive mechanism of embodiment is deeply rooted in the necessity of having a body.

Examining the Proteus Effect in the Context of Healthy Food Choices and Intentions to Eat Healthy: The Role of Avatar Body Size, Avatar Allocation Type, and Visual Perspective

Abstract As avatars gain prominence in health-promoting applications, understanding how health-related avatar appearance characteristics could affect users’ behavior is crucial. Drawing upon the Proteus effect, avatars can positively and negatively affect health behaviors, depending on whether the avatar appearance is aligned with stereotypes about healthy or unhealthy behavior. Investigating avatar appearances is essential to understand potential negative health effects. Three experiments in a non-immersive virtual supermarket examined whether controlling an overweight avatar negatively affected (1) intentions to eat healthy and (2) food choice healthiness in the virtual supermarket, thereby investigating avatar allocation type (Study 1) and visual perspective (Study 2) as moderators. The studies employed 2 (Avatar body size: overweight vs. healthy weight) by 2 (Avatar allocation type: self-assigned vs. experimenter-assigned [Study 1]; Visual perspective: first-person vs. third-person [Studies 2 and 3]) between-subjects designs. None of the studies demonstrated the Proteus effect, and no moderating role of avatar allocation type was found (Study 1). Unexpectedly, controlling an overweight avatar resulted in stronger intentions to eat healthy from a third-person perspective only (Study 2), which led to the hypothesis that the overweight avatar functioned as a fear stimulus. To test this, a health message was added that highlighted obesity as a health risk (Study 3). The addition of this message did not affect intentions to eat healthy and food choice healthiness. The combination of fear appeal and self-perception theory as explanatory frameworks for behavioral responses to avatars opens avenues for new research, such as exploring specific conditions that trigger each effect.

Environmentally coupled gestures as a communicative resource in the word explanation activity: A multimodal analysis of interaction in social VR

This article contributes to our understanding of how participants use different resources to accomplish word explanations in social virtual reality (VR). The article draws on conversation analysis to examine audio-visual data of interaction on the Rec Room VR platform. A view of the physical space the participants inhabit has also been captured. There are twelve participants, and they have minimal experience with social VR. English is used as a lingua franca. The focus is on participants’ use of environmentally coupled gestures (EnCGs) during word explanation activity. The activity has two or more participants playing a word-guessing game, in which one participant explains a word using drawings and gesture as well as speech. Findings show that EnCGs that feature elements in the environment are more readily interpretable than EnCGs that feature elements over the avatar body. The latter can result in situations in which achieving the goal of a word explanation activity (correct guess) can be difficult. In addition, the explainer’s orientation to their physical body and the recipient’s orientation to the virtual body during the joint word explanation activity can create situations in which the gestures become difficult to interpret for the recipient. To conclude, the observations in this article reveal the importance of the alignment of virtual and physical gestures for the intelligibility of gesture in VR.

The Effects of Avatar’s Reality Level on Metaverse Application Compatibility and Use Intention

Objective: The aim of this study is to analyze metaverse application compatibility and application use intention depending on reality level of avatars and examine moderating effects of avatar-self-image identification and body ratio. Theoretical framework: The Proteus effect is the tendency for people to be affected by their digital representations, such as avatars. The Uncanny Valley effect is a hypothesized relation between an object's degree of resemblance to a human being and the emotional response to the object. Methodology: To test hypotheses, this study conducted an online and offline mixed survey to 219 respondents. To test validity and reliability of measurement tools, this study did factor analysis and reliability analysis. Hypotheses were tested with t-test and ANOVA analysis. To test mediating effects, it did mediating regression analysis. Results: The findings of data analysis were as follows. First, the lower the reality level of avatars is, the higher the higher metaverse application compatibility gets. Second, the moderating effect of avatar-self image identification was not statistically significant. Third, the moderating effect of avatar body ratio was confirmed. Forth, metaverse application compatibility was found to have positive effect on application use intention. Fifth, the mediating effect of application compatibility on the effect of reality level of avatars on application use intention was confirmed. Research, Practical & Social implications: The findings of this study will be good reference data for production of metaverse platforms using avatars, and scholastic and practical use of avatars. Originality/value: This study is an empirical analysis of outside characteristics of avatars based on Proteus effect and uncanny valley effect.

Exploring the Relationship Between Attribute Discrepancy and Avatar Embodiment in Immersive Social Virtual Reality.

Social virtual reality (VR) is an emerging set of platforms where users interact while embodying avatars. Given that VR headsets track real physical movements and map them onto one's avatar body, the nature of one's digital representation is an important aspect of social VR. However, little is known about how the visual proximity of an avatar to the self shapes user experience in naturalistic, social VR environments. In this article, we use this context to explore how embodiment is influenced by the perceived differences between the physical attributes of a user and the virtual attributes of their avatar. We selected a number of attributes for this measure that have been shown to be important for customization and representation in VR. Participants created an avatar, spent time in social VR, and reported on their experience in a questionnaire. Our results demonstrate a significant negative association between attribute discrepancy and avatar embodiment, the psychological experience of one's virtual body as their own body. We discuss implications for theories of self-representation and suggest urgency on the part of games and VR designers to improve the methods of creating avatars.

"Creepy Towards My Avatar Body, Creepy Towards My Body": How Women Experience and Manage Harassment Risks in Social Virtual Reality

Online harassment against women - particularly in gaming and virtual worlds contexts - remains a salient and pervasive issue, and arguably reflects the systems of offline structural oppression to control women's bodies and rights in today's world. Harassment in social Virtual Reality (VR) is also a growing new frontier of research in HCI and CSCW, particularly focusing on marginalized users such as women. Based on interviews with 31 women users of social VR, our findings present women's experiences of harassment risks in social VR as compared to harassment targeting women in pre-existing, on-screen online gaming and virtual worlds, along with strategies women employ to manage harassment in social VR with varying degrees of success. This study contributes to the growing body of literature on harassment in social VR by highlighting how women's marginalization online and offline impact their perceptions of and strategies to mitigate harassment in this unique space. It also provides a critical reflection on women's mitigation strategies and proposes important implications to rethink social VR design to better prevent harassment against women and other marginalized communities in the future metaverse.

Influence of Virtual Out-of-Body Experiences on Fear of Death

Virtual reality (VR) has a demonstrated capacity to embody participants in a virtual avatar and induce body ownership illusions. Previous research has leveraged avatar embodiment to create virtual out-of-body experiences (OBEs) for participants. These induced experiences have subsequently been linked to influencing participants’ fear of death (FOD). Because perceptions of mortality have important clinical implications for palliative and hospice care, there has been growing research interest in the efficacy of utilizing VR technologies to influence FOD. This exploratory study extends this line of research by examining the impact of VR OBEs on FOD in a between-groups experiment with three conditions: (1) a control condition where participants remained in control of the avatar body; (2) an out-of-body (OBE) experimental condition in which participants drifted out of the avatar body and lost visuotactile contact with their avatar; and (3) a “drifting body” (DBE) experimental condition in which participants drifted out of the avatar body but retained visuotactile contact with their avatar. Preliminary data analysis revealed non-significant reductions in FOD in the OBE and DBE experimental conditions. Furthermore, qualitative measures indicated that participants were more disturbed by the OBE condition than by the DBE condition. We provide a discussion of these results, as well as study limitations and future continuation of research under ideal conditions.

Reproducing Colonial Ideologies in Decolonization

Though James Cameron’s 2009 box office sensation Avatar overtly criticizes colonial capitalism, its conventional masculinist narrative reproduces ideologies that support colonialism. This essay analyzes the film using several post-colonial theorists to display its inability to engage in anti-colonial critique. In doing so, I outline the importance of considering the complexity of gender in literature that addresses colonial violence. Building upon the work of other scholars who have examined representations of gender in Avatar, this paper specifically addresses the masculinity of the protagonist, Jake Sully. Initially, I employ the work of Edward Said and Ann Laura Stoler to consider how the film reinscribes a stereotypical gender binary in its depiction of colonial contact between the humans and the Na’vi, thereby negating the intricate relationship between gender and colonialism. The paper then shifts to focus on the anti-colonial efforts of the Na’vi led by Jake in his Avatar body. Frantz Fanon and others assist in defining Avatar’s problematic appropriation of decolonization into Jake’s masculinity complex. This analysis determines that for creative works to consider colonial violence without contributing to it, they must avoid replicating dominating masculinity tropes formed within the contexts of colonialism.

Body Language of Avatars in VR Meetings as Communication Status Cue: Recommendations for Interaction Design and Implementation

Abstract While traditional videoconferencing causes privacy issues, virtual meetings are not yet widely used. Their communication quality still lacks usability and important non-verbal communication cues, such as body language, are underrepresented. We aim at exploring virtual avatars’ body language and how it can be used to indicate meeting attendees’ communication status. By comparing users’ perceptions of avatar behavior, we found that avatar body language across gender can be an indication of communication willingness. We derive resulting body language design recommendations and recommend using attentively behaving avatars as default body language and to indicate being busy through actions of the avatar, such as drinking, typing, or talking on a phone. These actions indicate that users are temporarily busy with another task, but still are attending the meeting. When users are unavailable, their avatars should not be displayed at all and in cases of longer meeting interruptions, the avatar of a user should leave the virtual meeting room.

Editorial Issue 33.2

This issue contains five papers. In the first paper, Ege Tekgün, Muhtar Çağkan Uludağlı, Hüseyin Akcan, and Burak Erdeniz, from Izmir University of Economics in Turkey assess the influence of virtual avatar anthropomorphism and the synchronicity of the visuo-tactile stimulation on self-location using a virtual reality (VR) full-body illusion (FBI) experiment. During the experiment, half of the 36 participants observed a gender-matched full-body humanoid avatar from a first-person perspective (1PP) and the other half observed a less anthropomorphic full-body cubical avatar from 1PP while they were receiving synchronous and asynchronous visuo-tactile stimulation. Results show a significant main effect of the synchronicity of the visuo-tactile stimulation and avatar body type on self-location but no significant interaction was found between them. Moreover, the results of the self-report questionnaire provide additional evidence showing that participants who received synchronous visuo-tactile stimulation, experienced not only greater changes in the feeling of self-location, but also, increased ownership, and referral of touch. In the second paper, Ke Li, Qian Zhang, Jinyuan Jia, from Tongji University in Shanghai, China, and Hantao Zhao, from Southeast University in Nanjing, all in China discuss the technology of presenting building information modeling (BIM) with an online platform and the difficulty to display large-scale BIM scenes in a flawless manner on mobile browsers, due to network bandwidth and browser performance limitations. The authors propose CEBOW, a Cloud-Edge-Browser Online architecture for visualizing BIM components with online solutions. The method combines transmission scheduling, cache management, and optimal initial loading into a single system architecture. For network transmission testing, BIM scenes are used, and the results show that their method effectively reduces scene loading time and networking delay while improving the visualization effect of large-scale scenes. In the third paper, Yuzhu Dong and Eakta Jain, from University of Florida in Gainesville, and Sophie Jörg, from Clemson University, all in United States discuss how the importance of eyes for virtual characters stems from the intrinsic social cues. They emphasize that the eye animation impacts the perception of an avatar's internal emotional state. They present three large scale experiments that investigate the extent to which viewers can identify if an avatar is scared. The authors find that participants can identify a scared avatar with 75% accuracy using cues in the eyes including pupil size variation, gaze, and blinks. Because eye trackers return pupil diameter in addition to gaze, their experiments inform practitioners that animating the pupil correctly will add expressiveness to a virtual avatar with negligible additional cost. These findings also have implications for creating expressive eyes in intelligent conversational agents and social robots. The fourth paper, by Osman Güler, from TUSAŞ Şehit Hakan Gülşen Vocational and Technical Anatolian High School in Ankara and Serkan Savaş, from Çankırı Karatekin Üniversitesi, both in Turkey present a study showing that Interactive Boards (IBs) have the necessary hardware to run Stereoscopic 3D (S3D) training materials, but the panel has not got an S3D imaging feature. Therefore, only the Anaglyph S3D imaging method can be applied to IBs. Thus, an Anaglyph S3D training material was prepared for the interaction of the skeletal system and interactive 3D material design for IBs with its effects in education was investigated. A Likert-type scale was developed to measure the usability of the training material on IBs and the material was evaluated by 20 experts. The data were analyzed by the SPSS statistical program and the results were interpreted. According to the results, educational material seems to be positive in terms of image characteristics, content, navigation, and ease of use, font sizes were moderate for readability, the feedback process and the help menu were moderately effective. The last paper by Alexandra Sierra, Marie Postma, from Tilburg University in Netherlands and Menno Van Zaanen, from North-West University in Potchefstroom, South Africa investigate whether the uncanny valley effect, which has already been found for the human-like appearance of virtual characters, can also be found for animal-like appearances. They conducted an online study in which six different animal designs were evaluated in terms of the following properties: familiarity, commonality, naturalness, attractiveness, interestingness, and animateness. The study participants differed in age (under 10–60 years) and origin (Europe, Asia, North America, and South America). For the evaluation of the results, the authors ranked the animal-likeness of the character using both expert opinion and participant judgments. They also investigated the effect of movement and morbidity. The results confirm the existence of the uncanny valley effect for virtual animals, especially with respect to familiarity and commonality, for both still and moving images. No uncanny valley effect was detected for interestingness and animateness.

Virtual body anthropomorphism increases drift in self‐location: Further support for the humanoid shape rule

AbstractPrevious studies on bodily self‐consciousness (BCS) have shown that self‐location and body ownership are prone to changes based on the perceptual appearances of the fake virtual body. In the current study with 36 participants, we assessed the influence of virtual avatar anthropomorphism and the synchronicity of the visuo‐tactile stimulation on self‐location using a virtual reality full‐body illusion experiment. During the experiment, half of the participants observed a gender‐matched full‐body humanoid avatar from a first‐person perspective (1PP) and the other half observed a less anthropomorphic full‐body cubical avatar from 1PP while they were receiving synchronous and asynchronous visuo‐tactile stimulation. Results showed a significant main effect of the synchronicity of the visuo‐tactile stimulation and avatar body type on self‐location but no significant interaction was found between them. Moreover, the results of the self‐report questionnaire provide additional evidence showing that participants who received synchronous visuo‐tactile stimulation, experienced not only greater changes in the feeling of self‐location, but also, increased ownership, and referral of touch. Our results provided further support for the previous findings that showed evidence for the effect of virtual avatar appearance on BCS.

Feeling of Ownership over an Embodied Avatar's Hand Brings About Fast Changes of Fronto-Parietal Cortical Dynamics.

When we look at our body parts, we are immediately aware that they belong to us and we rarely doubt about the integrity, continuity, and sense of ownership of our body. Despite this certainty, immersive virtual reality (IVR) may lead to a strong feeling of embodiment over an artificial body part seen from a first-person perspective (1PP). Although such feeling of ownership (FO) has been described in different situations, it is not yet understood how this phenomenon is generated at neural level. To track the real-time brain dynamics associated with FO, we delivered transcranial magnetic stimuli over the hand region in the primary motor cortex (M1) and simultaneously recorded electroencephalography (EEG) in 19 healthy volunteers (11 male/8 female) watching IVR renderings of anatomically plausible (full-limb) versus implausible (hand disconnected from the forearm) virtual limbs. Our data show that embodying a virtual hand is temporally associated with a rapid drop of cortical activity of the onlookers' hand region in the M1 contralateral to the observed hand. Spatiotemporal analysis shows that embodying the avatar's hand is also associated with fast changes of activity within an interconnected fronto-parietal circuit ipsilateral to the brain stimulation. Specifically, an immediate reduction of connectivity with the premotor area is paralleled by an enhancement in the connectivity with the posterior parietal cortex (PPC) which is related to the strength of ownership illusion ratings and thus likely reflects conscious feelings of embodiment. Our results suggest that changes of bodily representations are underpinned by a dynamic cross talk within a highly-plastic, fronto-parietal network.SIGNIFICANCE STATEMENT Observing an avatar's body part from a first-person perspective (1PP) induces an illusory embodiment over it. What remains unknown are the cortical dynamics underpinning the embodiment of artificial agents. To shed light on the physiological mechanisms of embodiment we used a novel approach that combines noninvasive stimulation of the cortical motor-hand area and whole-scalp electroencephalographic (EEG) recordings in people observing an embodied artificial limb. We found that just before the illusion started, there is a decrease of activity of the motor-hand area accompanied by an increase of connectivity with the parietal region ipsilateral to the stimulation that reflects the ratings of the embodiment illusion. Our results suggest that changes of bodily representations are underpinned by a dynamic cross talk within a fronto-parietal circuit.

One Ring Fit to Rule Them All? An Analysis of Avatar Bodies and Customization in Exergames.

With the growing popularity of exergames, researchers have noted the importance of presenting players with customizable avatars to encourage the long-term adoption of healthy behaviors offline. However, the “idealized” avatar bodies presented in avatar customization interfaces can represent limited body types and often problematically represent gender as binary. In this paper, we present a systematic analysis of the avatar customization interfaces of six console-based exergames. Results of our analysis indicate that customization options tend to be limited in exergames, especially with regard to body type and gender. Implications for avatar self-priming, self-identification, and healthy behavior adoption are discussed.

Head-Mounted Display with Increased Downward Field of View Improves Presence and Sense of Self-Location.

Common existing head-mounted displays (HMDs) for virtual reality (VR) provide users with a high presence and embodiment. However, the field of view (FoV) of a typical HMD for VR is about 90 to 110 [deg] in the diagonal direction and about 70 to 90 [deg] in the vertical direction, which is narrower than that of humans. Specifically, the downward FoV of conventional HMDs is too narrow to present the user avatar's body and feet. To address this problem, we have developed a novel HMD with a pair of additional display units to increase the downward FoV by approximately 60 ( 10+50) [deg]. We comprehensively investigated the effects of the increased downward FoV on the sense of immersion that includes presence, sense of self-location (SoSL), sense of agency (SoA), and sense of body ownership (SoBO) during VR experience and on patterns of head movements and cybersickness as its secondary effects. As a result, it was clarified that the HMD with an increased FoV improved presence and SoSL. Also, it was confirmed that the user could see the object below with a head movement pattern close to the real behavior, and did not suffer from cybersickness. Moreover, the effect of the increased downward FoV on SoBO and SoA was limited since it was easier to perceive the misalignment between the real and virtual bodies.

Exercising With a Six Pack in Virtual Reality: Examining the Proteus Effect of Avatar Body Shape and Sex on Self-Efficacy for Core-Muscle Exercise, Self-Concept of Body Shape, and Actual Physical Activity.

This study investigates the Proteus effect from the first-person perspective and during avatar embodiment in actual exercise. In addition to the immediate measurements of the Proteus effect, prolonged effects such as next-day perception and exercise-related outcomes are also explored. We theorized the Proteus effect as altered perceived self-concept and explored the association between virtual reality (VR) avatar manipulation and self-concept in the exercise context. While existing studies have mainly investigated the Proteus effect in a non-VR environment or after VR embodiment, we aim to contribute to the literature by addressing this concern to explore how the Proteus effect works in actual VR exercise. Through a 2 (avatar body shape: with a six pack vs. normal) × 2 (sex: male vs. female) between-subject experiment, the results partially support the Proteus effect. Regarding actual physical activity, embodying an avatar with a six pack during exercise creates fewer body movements. No significant effect was found for perceived exertion. We also explored the role of sex as a potential moderator in the association of the Proteus effect on exercise outcomes. The Proteus effect was supported by immediate and next-day self-efficacy for core-muscle exercise only among female participants. The between-subject design allowed us to probe how avatar manipulation of muscular body shape with a six pack as opposed to normal body shape influences participants’ self-concept and exercise outcomes, as limited VR studies have employed within-subject comparisons. This also contributes to the literature by providing an upward comparison (e.g., muscular with a six pack vs. normal) as opposed to the previous downward comparison regarding body fitness (e.g., normal vs. obese). The overall results supported the Proteus effect in the context of core-muscle exercise when comparing normal and ideal body shape avatars. However, the Proteus effect as an altered self-concept and its effects on self-efficacy for exercise were supported among females but not males. Whereas the female participants who embodied avatars with a six pack associated themselves more with the muscular concept than other people, the male participants who embodied avatars with a six pack perceived themselves as more normal than others. Theoretical and practical implications are discussed.

Changing your body changes your eating attitudes: embodiment of a slim virtual avatar induces avoidance of high-calorie food

The virtual-reality full-body illusion paradigm has been suggested to not only trigger the illusory ownership of the avatar's body but also the attitudinal and behavioral components stereotypically associated to that kind of virtual body. In the present study, we investigated whether this was true for stereotypes related to body size: body satisfaction and eating control behavior. Healthy participants underwent the full-body illusion paradigm with an avatar having either a larger or a slimmer body than their own, and were assessed for implicit attitudes towards body image and food calorie content at baseline and after each full-body illusion session. Results showed that the illusion emerged regardless of the avatar's body size, whereas the perceived dimension of the own body size changed according to the avatar's body size (i.e., participants felt to be slimmer after embodying their slim avatar and larger after embodying their large avatar). Crucially, we found that implicit attitudes towards food, but not those towards one's own body, were modulated by the size of the virtual body. Compared to baseline, ownership of a slimmer avatar increased the avoidance of high-calorie food, whereas ownership of a larger avatar did not induce changes. Our findings suggest that the illusory feeling of being slimmer drives also the food-related stereotypes associated with that body size, increasing the regulation of eating behaviors.

Multisensory integration of visual cues from first- to third-person perspective avatars in the perception of self-motion.

In the perception of self-motion, visual cues originating from an embodied humanoid avatar seen from a first-person perspective (1st-PP) are processed in the same way as those originating from a person's own body. Here, we sought to determine whether the user's and avatar's bodies in virtual reality have to be colocalized for this visual integration. In Experiment 1, participants saw a whole-body avatar in a virtual mirror facing them. The mirror perspective could be supplemented with a fully visible 1st-PP avatar or a suggested one (with the arms hidden by a virtual board). In Experiment 2, the avatar was viewed from the mirror perspective or a third-person perspective (3rd-PP) rotated 90° left or right. During an initial embodiment phase in both experiments, the avatar's forearms faithfully reproduced the participant's real movements. Next, kinaesthetic illusions were induced on the static right arm from the vision of passive displacements of the avatar's arms enhanced by passive displacement of the participant's left arm. Results showed that this manipulation elicited kinaesthetic illusions regardless of the avatar's perspective in Experiments 1 and 2. However, illusions were more likely to occur when the mirror perspective was supplemented with the view of the 1st-PP avatar's body than with the mirror perspective only (Experiment 1), just as they are more likely to occur in the latter condition than with the 3rd-PP (Experiment 2). Our results show that colocalization of the user's and avatar's bodies is an important, but not essential, factor in visual integration for self-motion perception.

Can I put myself in your shoes? Sharing peripersonal space reveals the simulation of the action possibilities of others.

The representation of the reachable space near the body or peripersonal space (PPS) plays an important role in action with objects and interaction with other people. Here we explored whether the representation of other people's PPS involves a simulation of their action possibility depending on the distance between the observer's body and the other person. We hypothesized that a simulation of action possibilities of others should be activated when they share the PPS of observers. In two experiments using Immersive Virtual Reality, the avatars were shown with their arms free or blocked (motor interference) at a reachable (i.e., Near/shared PPS) or not-reachable (i.e., Far/not-shared PPS) distance by the participants. Participants had to locate a glass in relation to the midline of the avatar's body, i.e., assuming the perspective of the avatar. To directly compare the representation of one's own and others' PPS, in Experiment 1 participants had to locate the glass in relation to themselves with their arms free or blocked. The glass was always within the PPS of either participants or avatars. The results showed that the localization of the glass from the avatar's perspective was slower with the blocked than free arm only when the avatar was in the near shared PPS, similar to the localization from one's own first-person perspective. Instead, there was no effect of motor interference in the far, not-shared PPS. This suggests that the representation of other people's PPS can involve motor simulation mechanisms when we share a common peripersonal area.

Towards a Common Framework for Mediated Embodiment

Mediated embodiment (ME) is the technologically generated illusion of substituting a person’s body with an avatar body. Virtual reality is the most representative technology of ME. However, other forms of embodiment are emerging and need to be examined. The inclusion of all ME technologies under a common paradigm would largely facilitate their study. Here, I develop a unified conceptual framework of ME and integrate robot embodiment as part of the phenomenon. I first describe the central component of ME: avatars. I extend the concept of avatar used in virtual reality to other forms of ME. I then outline the minimum conditions necessary to induce the embodiment illusion as well as the technical principles used to create this illusion. Next, I suggest that ME technologies can be regarded as tools that increase human capabilities in four directions: embodiment of a new self, expansion of traveling capabilities, expansion of body capabilities, and the reach of immortality. I connect the principal research conducted in the field to these categories and suggest potential research directions to promote the positive applied uses of ME. I conclude with the importance to also address ethical issues related to this phenomenon.