Effective collaboration in Virtual Reality depends on users' ability to accurately perceive the affordances of others within a shared space. This paper presents the first empirical investigation of how people judge others' reaching capabilities in Immersive Virtual Environments (IVEs). We examined whether observers can reliably estimate the maximum horizontal reach distance of virtual actors, how different actor representations influence these perceptual judgments, and whether calibration feedback can improve estimation accuracy. Participants (N=35) judged the reachability of objects for virtual actors across three visual fidelity conditions: high-fidelity, low-fidelity, and end-effector-only representations. Results demonstrate that users can successfully estimate others' horizontal reachability in IVEs, though with overestimation. Calibration through action feedback significantly improved estimation accuracy, with overestimation decreasing across trials. Visual fidelity showed no main effect on initial reachability judgments but significantly affected postcalibration performance, with low-fidelity representations demonstrating significantly better calibration outcomes compared to high-fidelity avatars, while end-effector-only representations showed no significant difference from either condition. The findings contribute to the social perception literature in Virtual Reality (VR) and to provide design guidelines for avatar systems in collaborative virtual environments, where spatial coordination and shared action planning are critical.

Immersive Virtual Environments (IVEs) incorporating tangible graspable objects are becoming more accessible for training and other applications. Visual and proprioceptive information has been shown to be important for accurate distance and size perception. However, previous research has shown that users overestimate the size of tangible objects in IVEs. To address this issue, researchers have demonstrated the use of calibration to alter users' perceptions. In this study, we examined the carryover effects of calibration on the perceived size of graspable dials in IVEs. Participants wore head-mounted displays and experienced two calibration perturbations: Divergent Plus (physical dials 10% larger than virtual) and Divergent Minus (physical dials smaller than virtual). These were compared to the baseline Convergent condition (equal diameters). The results showed significant effects of the calibration on the accuracy of diameter estimates. Overall, a higher overestimation of dial sizes for the haptics-only condition was observed as compared to the vision-only condition. Additionally, participants' estimations worsened when haptic information was added to the vision during calibration but improved when vision information was added to the haptics-only condition during calibration. These findings highlight the importance of calibration in improving the accuracy of size perception in IVEs and contribute to our understanding of how tangible graspable objects are perceived in immersive virtual environments.

Direct perception, as part of the ecological approach to perception, defines a relationship between an organism and their environment that is specified by lawful information.Researchers can apply the ecological approach to eXtended Reality (XR) work to obtain a richer understanding of users' perception-action coordination in novel virtual settings.To encourage widespread adoption of this theoretical framework, this methodological paper introduces four major concepts from the ecological approach that are highly relevant to XR applications.We also provide an overview of existing literature to illustrate how those concepts may be used to inform and test their designs.These elements include the study of calibration and attunement, affordances, action based responses, and intrinsic scaling for measurements.The goal of this work is to increase awareness of the value of the ecological approach, and to provide a practical, evidence-based reference for researchers interested in applying these techniques in XR research.

In immersive virtual environments (IVEs), accurate size perception is critical, especially in training simulations designed to mimic real-world tasks, such as, nuclear power plant control room or medical procedures. These simulations have dials or instruments of varying sizes. Visual information of the objects alone, often fails to capture subtle size differences in virtual reality (VR). However, integrating haptic and hand-avatars may potentially improve accuracy and performance. This improvement could be especially beneficial for real-world scenarios where hand(s) are intermittently visible or obscured. To investigate how this intermittent presence or absence of body-scaled hand-avatars affects size perception when integrated with haptic information, we conducted 2x2 mixed-factorial experiment design using a near-field, size-estimation task in VR. The experiment conditions compared size estimations with or without virtual hand visibility in the perception and reporting phases. The task involved 16 graspable objects of varying sizes and randomly repeated 3 times across 48 trials per participant (total 80 participants). We employed Linear Mixed Models (LMMs) analysis to objective measures: perceived size, residual error and proportional errors. Results revealed that as the tangible-graspable size increases, overestimation reduces if the hand-avatars are visible in the reporting phase. Also, overestimation reduces as the number of trials increases, if the hand-avatars are visible in the reporting phase. Thus, the presence of hand-avatars facilitated perceptual calibration. This novel study, with different combinations of hand-avatar visibility, taking perception and reporting of size as two separate phases, could open future research directions in more complex scenarios for refined integration of sensory modalities and consequently enhance real-world application performance.

Various experiments have led to a better understanding of how the surrounding environment influences long-term memory and spatial cognition, including those indicating how environmental context is encoded. However, specific external environment characteristics that may impact cognitive memory and performance remain unclear. Using an immersive Virtual Reality (VR) environment, we investigated the effects of color congruency on object placement accuracy, recall speed, and recognition.

Self-overlapping spaces, also known as impossible spaces, are a design mechanic in virtual reality (VR) that allows a user to naturally walk through an environment that is larger than the physical space available to them. Prior work has focused on generating these spaces and evaluating when their self-overlapping nature is detectable. Comparatively, little work has evaluated how the self-overlapping nature of these spaces impacts users’ spatial understanding and whether any misperceptions carry over into altered action judgments. We present a study evaluating how self-overlapping spaces influence action judgments related to relative distances within the virtual environment. Participants were presented with a variety of self-overlapping spaces and, after exploring them, were asked to judge which of the two locations was closer to their current position in the environment. Participants’ were more likely to make correct decisions as the relative difference in distance between the two locations increased; however, this effect was affected by both the amount of overlap present in a particular environment and by the relative position from which they made their decision.

Mixed reality (MR) interactions feature users interacting with a combination of virtual and physical components. Inspired by research investigating aspects associated with near-field interactions in augmented and virtual reality (AR & VR), we investigated how avatarization, the physicality of the interacting components, and the interaction technique used to manipulate a virtual object affected performance and perceptions of user experience in a mixed reality fundamentals of laparoscopic peg-transfer task wherein users had to transfer a virtual ring from one peg to another for a number of trials. We employed a 3 (Physicality of pegs) X 3 (Augmented Avatar Representation) X 2 (Interaction Technique) multi-factorial design, manipulating the physicality of the pegs as a between-subjects factor, the type of augmented self-avatar representation, and the type of interaction technique used for object-manipulation as within-subjects factors. Results indicated that users were significantly more accurate when the pegs were virtual rather than physical because of the increased salience of the task-relevant visual information. From an avatar perspective, providing users with a reach envelope-extending representation, though useful, was found to worsen performance, while co-located avatarization significantly improved performance. Choosing an interaction technique to manipulate objects depends on whether accuracy or efficiency is a priority. Finally, the relationship between the avatar representation and interaction technique dictates just how usable mixed reality interactions are deemed to be.

Active exploration in virtual reality (VR) involves users navigating immersive virtual environments, going from one place to another. While navigating, users often engage in secondary tasks that require attentional resources, as in the case of distracted driving. Inspired by research generally studying the effects of task demands on cybersickness (CS), we investigated how the attentional demands specifically associated with secondary tasks performed during exploration affect CS. Downstream of this, we studied how increased attentional demands from secondary tasks affect spatial memory and navigational performance. We discuss the results of a multi-factorial between-subjects study, manipulating a secondary task's demand across two levels and studying its effects on CS in two different sickness-inducing levels of an exploration experience. The secondary task's demand was manipulated by parametrically varying $n$ in an aural $n$-back working memory task and the provocativeness of the experience was manipulated by varying how frequently users experienced a yaw-rotational reorientation effect during the exploration. Results revealed that increases in the secondary task's demand increased sickness levels, also resulting in a higher temporal onset rate, especially when the experience was not already highly sickening. Increased attentional demand from the secondary task also vitiated navigational performance and spatial memory. Overall, increased demands from secondary tasks performed during navigation produce deleterious effects on the VR experience.

Cybersickness (CS) is one of the challenges that has hindered the widespread adoption of Virtual Reality (VR). Consequently, researchers continue to explore novel means to mitigate the undesirable effects associated with this affliction, one that may require a combination of remedies as opposed to a solitary stratagem. Inspired by research probing into the use of distractions as a means to control pain, we investigated the efficacy of this countermeasure against CS, studying how the introduction of temporally time-gated distractions affects this malady during a virtual experience featuring active exploration. Downstream of this, we studied how other aspects of the VR experience are affected by this intervention. We discuss the results of a between-subjects study manipulating the presence, sensory modality, and nature of periodic and short-lived (5-12 seconds) distractor stimuli across four experimental conditions: 1) no-distractors (ND); 2) auditory distractors (AD); 3) visual distractors (VD); 4) cognitive distractors (CD). Two of these conditions (VD and AD) formed a yoked control design wherein every matched pair of 'seers' and 'hearers' was periodically exposed to distractors that were identical in terms of content, temporality, duration, and sequence. In the CD condition, each participant had to periodically perform a 2-back working memory task, the duration and temporality of which was matched to distractors presented in each matched pair of the yoked conditions. These three conditions were compared to a baseline control group featuring no distractions. Results indicated that the reported sickness levels were lower in all three distraction groups in comparison to the control group. The intervention also increased the amount of time users were able to endure the VR simulation and avoided causing detriments to spatial memory and virtual travel efficiency. Overall, it appears that it may be possible to make users less consciously aware and bothered by the symptoms of CS, thereby reducing its perceived severity.

Over the past two decades self-avatars have been shown to affect the perception of both oneself and of environmental properties including the sizes and distances of elements in immersive virtual environments. However, virtual avatars that accurately match the body proportions of their users remain inaccessible to the general public. As such, most virtual experiences that represent the user have a generic avatar that does not fit the proportions of the users' body. This can negatively affect judgments involving affordances, such as passability and maneuverability, which pertain to the relationship between the properties of environmental elements relative to the properties of the user providing information about actions that can be enacted. This is especially true when the task requires the user to maneuver around moving objects like in games. Therefore, it is necessary to understand how different sized self-avatars affect the perception of affordances in dynamic virtual environments. To better understand this, we conducted an experiment investigating how a self-avatar that is either the same size, 20% shorter, or 20% taller, than the user's own body affects passability judgments in a dynamic virtual environment. Our results suggest that the presence of self-avatars results in better regulatory and safer road crossing behavior, and helps participants synchronize self-motion to external stimuli quicker than in the absence of self-avatars.

No abstract available.

Little research has studied how people use Virtual Reality (VR) changes as they experience VR. This article reports the results of an experiment investigating how users’ behavior with two locomotion methods changed over 4 weeks: teleportation and joystick-based locomotion. Twenty novice VR users (with no more than 1 hour prior experience with any form of walking in VR) were recruited. They loaned an Oculus Quest for 4 weeks on their own time, including an activity we provided them with. Results showed that the time required to complete the navigation task decreased faster for joystick-based locomotion. Spatial memory improved with time, particularly when using teleportation (which starts disadvantaged to joystick-based locomotion). In addition, overall cybersickness decreased slightly over time; however, two dimensions of cybersickness (nausea and disorientation) increased notably over time using joystick-based navigation.

With the popularity of Virtual Reality (VR) on the rise, creators from a variety of fields are building increasingly complex experiences that allow users to express themselves more naturally. Self-avatars and object interaction in virtual worlds are at the heart of these experiences. However, these give rise to several perception based challenges that have been the focus of research in recent years. One area that garners most interest is understanding the effects of self-avatars and object interaction on action capabilities or affordances in VR. Affordances have been shown to be influenced by the anthropometric and anthropomorphic properties of the self-avatar embodied. However, self-avatars cannot fully represent real world interaction and fail to provide information about the dynamic properties of surfaces in the environment. For example, pressing against a board to feel its rigidity. This lack of accurate dynamic information can be further amplified when interacting with virtual handheld objects as the weight and inertial feedback associated with them is often mismatched. To investigate this phenomenon, we looked at how the absence of dynamic surface properties affect lateral passability judgments when carrying virtual handheld objects in the presence or absence of gender matched body-scaled self-avatars. Results suggest that participants can calibrate to the missing dynamic information in the presence of self-avatars to make lateral passability judgments, but rely on their internal body schema of a compressed physical body depth in the absence of self-avatars.

User representations are critical to the virtual experience, and involve both the input device used to support interactions as well as how the user is virtually represented in the scene. Inspired by previous work that has shown effects of user representations on the perceptions of relatively static affordances, we attempt to investigate how end-effector representations affect the perceptions of affordances that dynamically change over time. Towards this end, we empirically evaluated how different virtual hand representations affect users' perceptions of dynamic affordances in an object retrieval task wherein users were tasked with retrieving a target from a box for a number of trials while avoiding collisions with its moving doors. We employed a 3 (virtual end-effector representation) X 13 (frequency of moving doors) X 2 (target object size) multi-factorial design, manipulating the input modality and its concomitant virtual end-effector representation as a between-subjects factor across three experimental conditions: (1) Controller (using a controller represented as a virtual controller); (2) Controller-hand (using a controller represented as a virtual hand); (3) Glove (using a hand tracked hi-fidelity glove represented as a virtual hand). Results indicated that the controller-hand condition produced lower levels of performance than both the other conditions. Furthermore, users in this condition exhibited a diminished ability to calibrate their performance over trials. Overall, we find that representing the end-effector as a hand tends to increase embodiment but can also come at the cost of performance, or an increased workload due to a discordant mapping between the virtual representation and the input modality used. It follows that VR system designers should carefully consider the priorities and target requirements of the application being developed when choosing the type of end-effector representation for users to embody in immersive virtual experiences.

Inspired by previous works showing promise for AR self-avatarization - providing users with an augmented self avatar, we investigated whether avatarizing users' end-effectors (hands) improved their interaction performance on a near-field, obstacle avoidance, object retrieval task wherein users were tasked with retrieving a target object from a field of non-target obstacles for a number of trials. We employed a 3 (Augmented hand representation) X 2 (density of obstacles) X 2 (size of obstacles) X 2 (virtual light intensity) multi-factorial design, manipulating the presence/absence and anthropomorphic fidelity of augmented self-avatars overlaid on the user's real hands, as a between subjects factor across three experimental conditions: (1) No-Augmented Avatar (using only real hands); (2) Iconic-Augmented Avatar; (3) Realistic Augmented Avatar. Results indicated that self-avatarization improved interaction performance and was perceived as more usable regardless of the anthropomorphic fidelity of avatar. We also found that the virtual light intensity used in illuminating holograms affects how visible one's real hands are. Overall, our findings seem to indicate that interaction performance may improve when users are provided with a visual representation of the AR system's interacting layer in the form of an augmented self-avatar.

Walking through immersive virtual environments is one of the important parts of Virtual Reality (VR) applications. Prior research has established that users’ gait in virtual and real environments differs; however, little research has evaluated how users’ gait differs as users gain more experience with VR. We conducted experiments measuring novice and experienced subjects’ gait parameters in VR and real environments. Results showed that subjects’ performance in VR and Real World was more similar in the last trials than in the first trials; their walking dissimilarity in the start trials diminished by walking more trials. We found trial as a significant variable affecting the walking speed, step length, and trunk angle for both groups of users. While the main effect of expertise was not observed, an interaction effect between expertise and the trial number was shown. Trunk angle increased over time for novices but decreased for experts.

This work explored how users’ sensitivity to offsets in their avatars’ virtual hands changes as they gain exposure to virtual reality. We conducted an experiment using a two-alternative forced choice (2-AFC) design over the course of 4 weeks, split into four sessions. The trials in each session had a variety of eight offset distances paired with eight offset directions (across a two-dimensional plane). While we did not find evidence that users became more sensitive to the offsets over time, we did find evidence of behavioral changes. Specifically, participants’ head–hand coordination and completion time varied significantly as the sessions went on. We discuss the implications of both results and how they could influence our understanding of long-term calibration for perception-action coordination in virtual environments.

Redirected walking techniques use rotational gains to guide users away from physical obstacles as they walk in a virtual world, effectively creating the illusion of a larger virtual space than is physically present. Designers often want to keep users unaware of this manipulation, which is made possible by limitations in human perception that render rotational gains imperceptible below a certain threshold. Many aspects of these thresholds have been studied; however, no research has yet considered whether these thresholds may change over time as users gain more experience with them. To study this, we recruited 20 novice VR users (no more than 1 hour of prior experience with an HMD) and provided them with an Oculus Quest to use for 4 weeks on their own time. They were tasked to complete an activity assessing their sensitivity to rotational gain once each week, in addition to whatever other activities they wanted to perform. No feedback was provided to participants about their performance during each activity, minimizing the possibility of learning effects accounting for any observed changes over time. We observed that participants became significantly more sensitive to rotation gains over time, underscoring the importance of considering prior user experience in applications involving rotational gain, as well as how prior user experience may affect other, broader applications of VR.

The availability of new and improved display, tracking and input devices for Virtual Reality experiences has facilitated the use of partial and full body self-avatars in interaction with virtual objects in the environment. However, scaling the avatar to match the user's body dimensions remains to be a cumbersome process. Moreover, the effect of body-scaled self-avatars on size perception of virtual handheld objects and related action capabilities has been relatively unexplored. To this end, we present an empirical evaluation investigating the effect of the presence or absence of body-scaled self-avatars and visuo-motor calibration on frontal passability affordance judgments when interacting with virtual handheld objects. The self-avatar's dimensions were scaled to match the participant's eyeheight, arms length, shoulder width and body depth along the mid section. The results indicate that the presence of body-scaled self-avatars produce more realistic judgments of passability and aid the calibration process when interacting with virtual objects. Also, participants rely on the visual size of virtual objects to make judgments even though the kinesthetic and proprioceptive feedback of the object is missing or mismatched.

Prior research in depth perception and perceptuo-motor calibration have primarily focused on participants completing experiments in single sessions and therefore do not empirically evaluate changes over time. Further, these studies do not typically take into account the amount of experience that the participants have in virtual reality (VR) prior to participation, the role of experience during participation, or calibration that may occur throughout the experiment session. In this contribution, we conducted a novel empirical evaluation of how calibration affects perception-action coordination over time. We recruited novice VR users and they completed eight sessions of a depth perception reaching experiment over the course of 12 weeks. During these experiments, we examined how participants' ability to estimate depth in a virtual environment changed as they gradually gained experience. While previous literature has shown that participants tend to underestimate distances, we found that this underestimation diminished over time as they gained experience in the virtual environment. Our study highlights the need for carrying out VR studies over time and the influence that longitudinal calibration can have on spatial perception in long-term VR experiences.

Social virtual reality (VR) has emerged as a popular online space for teenagers to interact and socialize. It attracts teens due to the broad range of immersive activities and social engagement opportunities, along with diverse users in terms of age and interest. Yet, little is known about teenagers’ experiences and understandings of this emerging online social space, especially regarding what aspects may attract or dissuade them to social VR. To explore this question, we conducted in-depth interviews with 20 teenagers (e.g., ages 13-18) and reported findings regarding what attracted them to engage in social VR and challenges with social VR that may dissuade them from using it. Our findings contribute to the growing body of scholarship on teenagers’ experiences in emerging, novel online social spaces and highlight potential design implications for creating safer and more fulfilling social VR experiences for teenagers.

In virtual reality (VR), Impossible Spaces allow rooms to overlap each other in physical space, enabling developers to better utilize the limited space available for VR systems. Prior work has explored detect thresholds for an impossible spaces, but little work has considered how impossible spaces affect users’ understandings of spatial relationships within virtual environments. We present a study evaluating how impossible spaces affected participants’ judgments of a room’s width, and how this was impacted by whether participants considered each room individually, or within the context of the entire space. Participants’ judgments of single rooms was not impacted by being in an impossible space, however judgments were significantly smaller when considering an impossible space as a whole. Even so, participants’ judgments preserved the respective ratio between overlapping rooms, indicating that the relative sizes of different rooms is preserved in impossible spaces. This suggests that while absolute spatial information may be disrupted by impossible spaces, important relative information can be preserved. However, it is not yet clear how much of this effect can be attributed to lower-level perception and higher-level cognition.

Immersive Virtual Environments (IVEs) incorporating tangibles are becoming more accessible. The success of applications combining 3D printed tangibles and VR often depends on how accurately size is perceived. Research has shown that visuo-haptic perceptual information is important in the perception of size. However, it is unclear how these sensory-perceptual channels are affected by immersive virtual environments that incorporate tangible objects. Towards understanding the effects of different sensory information channels in the near field size perception of tangibles of graspable sizes in IVEs, we conducted a between-subjects study evaluating the accuracy of size perception across three experimental conditions (Vision-only, Haptics-only, Vision and Haptics). We found that overall, participants consistently over-estimated the size of the dials regardless of the type of perceptual information that was presented. Participants in the haptics only condition overestimated diameters to a larger degree as compared to other conditions. Participants were most accurate in the vision only condition and least accurate in the haptics only condition. Our results also revealed that increased efficiency in reporting size over time was most pronounced in the visuo- haptic condition.

As Virtual Reality (VR) devices become more accessible, a multitude of VR applications engage users in highly immersive virtual environments that feature realistic graphics, real-life scenarios, and self-avatars. Many of these simulations require users to make spontaneous affordance judgments such as stepping over obstacles, passing through gaps, etc. which are shown to be affected by the nature of our self-representation in the virtual world. As the technology for creating self-avatars becomes more widely available, it is important to explore how various affordance judgments are affected by the presence of self-avatars. In this work, we investigate the effects of body-scaled self-avatars on the affordance of passability in a natural setting. We implemented a gender-matched body-scaled self-avatar using HTC Vive trackers and evaluated how passability judgments for a sliding doorway in VR, with and without an avatar, compared to the real world judgments. The results suggest that passability judgments are more conservative in VR as compared to the real world. However, the presence of a self-avatar does not significantly affect passability judgments made in VR. This does not align with previous findings which show that having a self-avatar improves judgments and estimates.

In this paper, we consider the effect of different types of virtual annotations on performance during a navigation task in virtual reality. Two major types of annotations were shown to users: screen-fixed annotations that remained fixed in the user’s field of view, and world- fixed annotations that are linked to specific locations in the world. We also considered three different levels of navigation information, including destination markers, maps visualizing the layout of the space being navigated, and path markers showing the optimal route to the destination. We ran a within-subjects study where participants completed three trials with each of the six combinations of annotation type and information level, for a total of 18 trials in a virtual environment. Average speed, distance traveled, and the time taken to reach the destination were recorded during each trial. Participants were also asked to point back to where they started the trial upon reaching the destination, as a measure of spatial memory. Finally, participants were tasked with completing a secondary activity while navigating, so as to assess what effect annotation types had on multitasking performance. Participants navigated significantly more quickly when using world-fixed annotations; however an interaction effect was observed between the type of annotation and the level of information, which suggests that world-fixed annotations are not inherently better than screen-fixed annotations; instead, it is important to consider both the type of annotation and what information it displays.

The commercialization and lowering costs of consumer grade Virtual Reality (VR) devices has made the technology increasingly accessible to users around the world. The usage of VR technology is often accompanied by an undesirable side effect called cybersickness. Cyber-sickness is the feeling of discomfort that occurs during VR experiences, producing symptoms similar to those of motion sickness. It continues to remain one of the biggest hurdles to the widespread adoption of VR, making it increasingly important to explore and understand the factors that influence its onset. In this work, we investigated the influence of the presence/absence of motion control on the onset and severity of cybersickness in an HMD based VR driving simulation employing steering as a travel metaphor. Towards this end, we conducted a between subjects study manipulating the presence of control between three experimental conditions, two of which (Driving condition and Yoked Pair condition) formed a yoked control design where every pair of drivers and their yoked pairs were exposed to identical vehicular motion stimuli created by participants in the driving condition. In the other condition (Autonomous Car condition), participants experienced a program driven autonomous vehicle simulation. Results indicated that participants in the Driving condition experienced higher levels of cybersickness than participants in the Yoked Pair condition. While these results don’t conform to findings from previous research which suggests that having control over motion reduces cybersickness, it seems to point towards the importance of the fidelity of the control metaphor’s feedback response in alleviating cybersickness. Simply allowing one control their motion may not readily alleviate cybersickness but could instead increase it in such HMD based VR driving simulations. It may hence be important to consider how well the control metaphor and its feedback matches users’ expectations if we want to successfully mitigate cybersickness.

Impossible spaces have been used to increase the amount of virtual space available for real walking within a constrained physical space. In this technique, multiple virtual rooms are allowed to occupy overlapping portions of the physical space, in a way which is not possible in real euclidean space. Prior work has explored detection thresholds for impossible spaces, however very little work has considered other aspects of how impossible spaces alter participants’ perception of spatial relationships within virtual environments. In this paper, we present a within-subjects study (n = 30) investigating how impossible spaces altered participants perceptions of the location of objects placed in different rooms. Participants explored three layouts with varying amounts of overlap between rooms and then pointed in the direction of various objects they had been tasked to locate. Significantly more error was observed when pointing at objects in overlapping spaces as compared to the non-overlapping layout. Further analysis suggests that participants pointed towards where objects would be located in the non-overlapping layout, regardless of how much overlap was present. This suggests that, when participants are not aware that any manipulation is present, they automatically adapt their representation of the spaces based on judgments of relative size and visible constraints on the size of the whole system.

Most commercial virtual reality applications with self avatars provide users with a “one-size fits all” avatar. While the height of this body may be scaled to the user's height, other body proportions, such as limb length and hand size, are rarely customized to fit an individual user. Prior research has shown that mismatches between users' avatars and their actual bodies can affect size perception and feelings of body ownership. In this paper, we consider how concepts related to the virtual hand illusion, user experience, and task efficiency are influenced by variations between the size of a user's actual hand and their avatar's hand. We also consider how using a tracked controller or tracked gestures affect these concepts. We conducted a 2×3 within-subjects study (n=20), with two levels of input modality: using tracked finger motion vs. a hand-held controller (Glove vs. Controller), and three levels of hand scaling (Small, Fit, and Large). Participants completed 2 block-assembly trials for each condition (for a total of 12 trials). Time, mistakes, and a user experience survey were recorded for each trial. Participants experienced stronger feelings of ownership and realism in the Glove condition. Efficiency was higher in the Controller condition and supported by play data of more time spent, blocks grabbed, and blocks dropped in the Glove condition. We did not find enough evidence for a change in agency and the intensity of the virtual hand illusion depending on hand size. Over half of the participants indicated preferring the Glove condition over the Controller condition, mentioning fun and efficiency as factors in their choices. Preferences on hand scaling were mixed but often attributed to efficiency. Participants liked the appearance of their virtual hand more while using the Fit instead of Large hands. Several interaction effects were observed between input modality and hand scaling, for example, for smaller hands, tracked hands evoked stronger feelings of ownership compared to using a controller. Our results show that the virtual hand illusion is stronger when participants are able to control a hand directly rather than with a hand-held device, and that the virtual reality task must first be considered to determine which modality and hand size are the most applicable.

In this paper, we present an initial study to investigate the effects stereotypical settings and avatar appearance of embodied avatars on a user's implicit racial bias. Literature demonstrates the effects embodied avatars can have on a users biases, both implicit and explicit. These shifts in bias and behavior could be caused by the avatars appearance or the stereotypical environment. Few studies have investigated the presence of stereotypical triggers and avatar representation in a learning, game-like environment. With virtual reality entertainment and training simulations becoming popular it is necessary to better understand the effects avatars can have on our behavior, perception, and biases. This study will investigate the potential effects of embodied avatars reinforcing a user's implicit racial biases.

Many questions still remain of the uses both positive and negative of virtual avatars. With virtual avatars primed for consumer entertainment, the effects they can elicit must be further investigated before mainstream adoption. In this paper we present an overview of the potential risks posed by virtual avatars. Followed by a study designed to investigate these risks, and finally ethical research considerations for researchers interested in conducting research with virtual avatars.

The commercialization of Virtual Reality (VR) devices has made it easier for everyday users to experience VR from the comfort of their living rooms. This recent uptake in VR has also increased reported incidents of cybersickness. Cybersickness refers to the discomfort experienced by an individual while experiencing virtual environments. The symptoms are similar to those of motion sickness but are more disorienting in nature resulting in dizziness, blurred vision, etc. Cybersickness is currently one of the biggest hurdles to the widespread adoption of VR, and it is therefore critical to explore the factors that influence its onset. Towards this end, we present a proof of concept simulation to study cybersickness in highly realistic immersive virtual environments.

Research has shown that self-avatars (life-size representations of the user in Virtual Reality (VR)) can affect how people perceive virtual environments. In this paper, we investigated whether the visual fidelity of a self-avatar affects reach boundary perception, as assessed through two variables: 1) action taken (or verbal response) and 2) correct judgment. Participants were randomly assigned to one of four conditions: i) high-fidelity self-avatar, ii) low-fidelity self-avatar, iii) no avatar (end-effector), and iv) real-world as reference task group. Results indicate that all three VR viewing conditions were significantly different from real world in regards to correctly judging the reachability of the target. However, based on verbal responses, only the "no avatar" condition had a non-trivial difference with real world condition. Taken together with reachability data, participants in "no avatar" condition were less likely to correctly reach to the reachable targets. Overall, participant performance improved after completing a calibration phase with feedback, such that correct judgments increased and participants reached to fewer unreachable targets.

Every task we perform in our day-to-day lives requires us to make judgements about size, distance, depth, etc. The same is true for tasks in an immersive virtual environments (IVE). Increasingly, Virtual Reality (VR) applications are being developed for training and entertainment, many of which require the user to determining whether s/he can pass through an opening. Typically, people determine their ability to pass through an aperture by comparing the width of their shoulders to the width of the opening. Thus, judgments of size and distance in an IVE are necessary for accurate judgments of passability. In this experiment, we empirically evaluate how passability judgments in an IVE, viewed through a Head-Mounted Display (HMD), compare to judgments made in the real world. An exact to scale virtual replica of the room and apparatus was used for the VR condition. Results indicate that the accuracy of passability judgments seem to be comparable to the real world.

Immersive Virtual Environments (IVEs) are becoming more accessible and more widely utilized for training. Previous research has shown that the matching of visual and proprioceptive information is important for calibration. While research has demonstrated that self-avatars can enhance ones' sense of presence and improve distance perception, the effects of self-avatar fidelity on near field distance estimations has yet to be investigated. This study tested the effect of avatar fidelity on the accuracy of distance estimations in the near-field. Performance with a virtual avatar was also compared to real-world performance. Three levels of fidelity were tested; 1) an immersive self-avatar with realistic limbs, 2) a low-fidelity self-avatar showing only joint locations, and 3) end-effector only. The results suggest that reach estimations become more accurate as the visual fidelity of the avatar increases, with accuracy for high fidelity avatars approaching real-world performance as compared to low-fidelity and end-effector conditions. In all conditions reach estimations became more accurate after receiving feedback during a calibration phase.

We describe a system for experiment standardization and distributing medication in medical trials using a virtual human. In our system, we employed a virtual experimenter that explains the experiment, medication, procedure and risks involved through a large screen display. The participant is able to interact with and ask questions of the virtual experimenter through a touch screen interface on an additional monitor display. During the interaction, the virtual experimenter will present the participant with a pill. The pill is physically distributed by a custom-made Arduino based dispenser. We conducted an initial user evaluation of the system using a placebo response protocol and a perceived pain scale. In the study, participants submerged their hand in a hot water bath before and after interacting with the system and reported their perceived pain response. The system was either a virtual human or text interface that either disseminated a pill stating that it was an analgesic or did not provide a medication. Through this system, we propose the potential use of virtual humans as a method to provide a consistent and standardized interaction between a participant and experimenter, while maintaining the benefits of social interaction in medication trials.

Creating realistic animations of virtual humans remains comparatively complex and expensive. This research explores the degree to which animation fidelity affects users' gaze behavior when interacting in virtual reality training simulations that include virtual humans. Participants were randomly assigned to one of three conditions, wherein the virtual patient either: 1) was not animated; 2) played idle animations; or 3) played idle animations, looked at the participant when speaking, and lip-synced speech and facial gestures when conversing with the participant. Each participant's gaze was recorded in an inter-personal interactive patient surveillance simulation. Results suggest that conversational and passive animations elicited visual attention in a similar manner, as compared to the no animation condition. Results also suggest that when participants face critical situations in inter-personal medical simulations, visual attention towards the virtual human decreases while gaze towards goal directed activities increases.

In a group setting, it is possible for attributes of one group member to indirectly affect how other group members are perceived. In this paper, we explore whether one group member's agency (e.g. if they are real or virtual) can indirectly affect behavior with other group members. We also consider whether variations in the agency of a group member directly affects behavior with that group member. To do so, we examined gaze behavior during a team training exercise, in which sixty-nine nurses worked with a surgeon and an anesthesiologist to prepare a simulated patient for surgery. The agency of the surgeon and the anesthesiologist were varied between conditions. Nurses' gaze behavior was coded using videos of their interactions. Agency was observed to directly affect behavior, such that participants spent more time gazing at virtual teammates than human teammates. However, participants continued to obey polite gaze norms with virtual teammates. In contrast, agency was not observed to indirectly affect gaze behavior. The presence of a second human did not affect participants' gaze behavior with virtual teammates.

In this paper we present a study exploring whether the physical presence of another human changes how people perceive and behave with virtual teammates. We conducted a study (n = 69) in which nurses worked with a simulated health care team to prepare a patient for surgery. The agency of participants' teammates was varied between conditions; participants either worked with a virtual surgeon and a virtual anesthesiologist, a human confederate playing a surgeon and a virtual anesthesiologist, or a virtual surgeon and a human confederate playing an anesthesiologist. While participants perceived the human confederates to have more social presence (p <; 0.01), participants did not preferentially agree with their human team members. We also observed an interaction effect between agency and behavioral realism. Participants experienced less social presence from the virtual anesthesiologist, whose behavior was less in line with participants' expectations, when a human surgeon was present.

In this paper, we present the preliminary results of an ongoing study exploring how mixed-agency teams influence feelings of social presence. Participants worked with a team composed of either two virtual humans or a team composed of one virtual human and one real human. We found that while the presence of a human teammate did not affect overall feelings of social presence, the presence of a human teammate did appear to strengthen participants' perceptions that their virtual teammates were not real.

Stressful interpersonal experiences can be difficult to prepare for. Virtual humans may be leveraged to allow learners to safely gain exposure to stressful interpersonal experiences. In this paper we present a between-subjects study exploring how the presence of a virtual human affected learners while practicing a stressful interpersonal experience. Twenty-six fourth-year medical students practiced performing a prostate exam on a prostate exam simulator. Participants in the experimental condition examined a simulator augmented with a virtual human. Other participants examined a standard unaugmented simulator. Participants reactions were assessed using self-reported, behavioral, and physiological metrics. Participants who examined the virtual human experienced significantly more stress, measured via skin conductance. Participants stress was correlated with previous experience performing real prostate exams; participants who had performed more real prostate exams were more likely to experience stress while examining the virtual human. Participants who examined the virtual human showed signs of greater engagement; non-stressed participants performed better prostate exams while stressed participants treated the virtual human more realistically. Results indicated that stress evoked by virtual humans is linked to similar previous real-world stressful experiences, implying that learners real-world experience must be taken into account when using virtual humans to prepare them for stressful interpersonal experiences.

The concepts of immersion and presence focus on the environment in a virtual environment. We instead focus on embodied conversational agents (ECAs). ECAs occupy the virtual environment as interactive partners. We propose that the ECA analogues of immersion and presence are physicality and social presence. We performed a study to determine the effect of an ECA's physicality on social presence and eliciting realistic behavior from the user. The results showed that increasing physicality can elicit realistic behavior and increase social presence but there was also an interaction effect with plausibility.