Embodiment can enhance conversational agents, such as increasing their perceived presence. This is typically achieved through visual representations of a virtual body; however, visual modalities are not always available, such as when users interact with agents using headphones or display-less glasses. In this work, we explore auditory embodiment. By introducing auditory cues of bodily presence - through spatially localized voice and situated Foley audio from environmental interactions - we investigate how audio alone can convey embodiment and influence perceptions of a conversational agent. We conducted a 2 (spatialization: monaural vs. spatialized) x 2 (Foley: none vs. Foley) within-subjects study, where participants (n=24) engaged in conversations with agents. Our results show that spatialization and Foley increase co-presence, but reduce users' perceptions of the agent's attention and other social attributes.

Remote VR teleoperation with supernumerary robotic limbs enables distant users to operate in another’s local space. While a shared first-person view aids hand-eye coordination, locking the guest’s camera to the host’s head can degrade comfort, embodiment, and coordination. Based on a formative study (N=10) using a virtual supernumerary robotic limbs configuration to stress-test coordination, we propose guest-driven perspective switching from a shared first-person baseline (Shared Embodied View) to two alternatives: (a) a stabilized view with guest-controlled rotation (Embedded Anchored View), and (b) a fully decoupled third-person view (Out-of-body View). We ran a user study with 24 pairs (N=48), who switched between the baseline and proposed views as task demands changed. We measured performance, embodiment, fatigue, physiological arousal, and switching behaviors. Our results reveal role-dependent trade-offs: Out-of-body View improves navigation efficiency and reduces errors, while Embedded Anchored View supports embodiment. We conclude with guidelines: use Embedded Anchored View for hand-centric adjustments, Out-of-body View for navigation and object placement, and ensure smooth transitions.

Augmented Reality (AR) is increasingly positioned as a tool for knowledge work, providing beneficial affordances such as a virtually limitless display space that integrates digital information with the user's physical surroundings. However, for AR to supplant traditional screen-based devices in knowledge work, it must support prolonged usage across diverse contexts. Until now, few studies have explored the effects, opportunities, and challenges of working in AR outside a controlled laboratory setting and for an extended duration. This gap in research limits our understanding of how users may adapt its affordances to their daily workflows and what barriers hinder its adoption. In this article, we present findings from a longitudinal diary study examining how participants incorporated an AR laptop - Sightful's Spacetop EA - into their daily work routines. 14 participants used the device for 40-minute daily sessions over two weeks, collectively completing 103 hours of AR-based work. Through survey responses, workspace photographs, and post-study interviews, we analyzed usage patterns, workspace configurations, and evolving user perceptions. Our findings reveal key factors influencing participants' usage of AR, including task demands, environmental constraints, social dynamics, and ergonomic considerations. We highlight how participants leveraged and configured AR's virtual display space, along with emergent hybrid workflows that involved physical screens and tasks. Based on our results, we discuss both overlaps with current literature and new considerations and challenges for the future design of AR systems for pervasive and productive use.

While Virtual Reality (VR) systems can present virtual elements such as notifications anywhere, designing them so they are not missed by or distracting to users is highly challenging for content creators. To address this challenge, we introduce a novel approach to predict the noticeability of virtual elements. It computes the visual saliency distribution of what users see, and analyzes the temporal changes of the distribution with respect to the dynamic virtual elements that are animated. The computed features serve as input for a long short-term memory (LSTM) model that predicts whether a virtual element will be noticed. Our approach is based on data collected from 24 users in different VR environments performing tasks such as watching a video or typing. We evaluate our approach (n = 12), and show that it can predict the timing of when users notice a change to a virtual element within 2.56 sec compared to a ground truth, and demonstrate the versatility of our approach with a set of applications. We believe that our predictive approach opens the path for computational design tools that assist VR content creators in creating interfaces that automatically adapt virtual elements based on noticeability.

Audio notifications provide users with an efficient way to access information beyond their current focus of attention. Current notification delivery methods, like phone ringtones, are primarily optimized for high noticeability, enhancing situational awareness in some scenarios but causing disruption and annoyance in others. In this work, we build on the observation that music listening is now a commonplace practice and present MARingBA, a novel approach that blends ringtones into background music to modulate their noticeability. We contribute a design space exploration of music-adaptive manipulation parameters, including beat matching, key matching, and timbre modifications, to tailor ringtones to different songs. Through two studies, we demonstrate that MARingBA supports content creators in authoring audio notifications that fit low, medium, and high levels of urgency and noticeability. Additionally, end users prefer music-adaptive audio notifications over conventional delivery methods, such as volume fading.

Virtual Reality (VR) allows users to flexibly choose the perspective through which they interact with a synthetic environment. Users can either adopt a first-person perspective, in which they see through the eyes of their virtual avatar, or a third-person perspective, in which their viewpoint is detached from the virtual avatar. Prior research has shown that the visual perspective affects different interactions and influences core experiential factors, such as the user’s sense of embodiment. However, there is limited understanding of how auditory perspective mediates user experience in immersive virtual environments. In this paper, we conducted a controlled experiment $(N=24)$ on the effect of the user’s auditory perspective on their performance in a sound localization task and their sense of embodiment. Our results showed that when viewing a virtual avatar from a third-person visual perspective, adopting the auditory perspective of the avatar may increase agency and self-avatar merging, even when controlling for variations in task difficulty caused by shifts in auditory perspective. Additionally, our findings suggest that differences in auditory perspective generally have a smaller effect than differences in visual perspective. We discuss the implications of our empirical investigation of audio perspective for designing embodied auditory experiences in VR.

In this work, we investigate three control strategies – joystick, laser, and tilt – for playing a platform game in mobile augmented reality. We analyze these strategies using both objective game metrics as well as self-reported measures of autonomy, competence, and intuitiveness. We found no significant differences in self-reported autonomy and competence between our three controllers, despite clear differences in duration needed to play, clear differences in the amount of movement of the character, and significant differences in intuitiveness ratings. All controllers were effective for playing the game. However, despite the joystick’s faster completion times and higher intuitiveness ratings, half of our players still chose our laser or tilt controller as their favorite. These results were consistent even with different difficulties of game level.

Current Virtual Reality systems are designed for interaction under visual control. Using built-in cameras, headsets track the user’s hands or hand-held controllers while they are inside the field of view. Current systems thus ignore the user’s interaction with off-screen content—virtual objects that the user could quickly access through proprioception without requiring laborious head motions to bring them into focus. In this paper, we present HOOV, a wrist-worn sensing method that allows VR users to interact with objects outside their field of view. Based on the signals of a single wrist-worn inertial sensor, HOOV continuously estimates the user’s hand position in 3-space to complement the headset’s tracking as the hands leave the tracking range. Our novel data-driven method predicts hand positions and trajectories from just the continuous estimation of hand orientation, which by itself is stable based solely on inertial observations. Our inertial sensing simultaneously detects finger pinching to register off-screen selection events, confirms them using a haptic actuator inside our wrist device, and thus allows users to select, grab, and drop virtual content. We compared HOOV’s performance with a camera-based optical motion capture system in two folds. In the first evaluation, participants interacted based on tracking information from the motion capture system to assess the accuracy of their proprioceptive input, whereas in the second, they interacted based on HOOV’s real-time estimations. We found that HOOV’s target-agnostic estimations had a mean tracking error of 7.7 cm, which allowed participants to reliably access virtual objects around their body without first bringing them into focus. We demonstrate several applications that leverage the larger input space HOOV opens up for quick proprioceptive interaction, and conclude by discussing the potential of our technique.

Virtual Reality (VR) has the potential to transform how we work: it enables flexible and personalized workspaces beyond what is possible in the physical world. However, while most VR applications are designed to operate in a single empty physical space, work environments are often populated with real-world objects and increasingly diverse due to the growing amount of work in mobile scenarios. In this paper, we present InteractionAdapt, an optimization-based method for adapting VR workspaces for situated use in varying everyday physical environments, allowing VR users to transition between real-world settings while retaining most of their personalized VR environment for efficient interaction to ensure temporal consistency and visibility. InteractionAdapt leverages physical affordances in the real world to optimize UI elements for the respectively most suitable input technique, including on-surface touch, mid-air touch and pinch, and cursor control. Our optimization term thereby models the trade-off across these interaction techniques based on experimental findings of 3D interaction in situated physical environments. Our two evaluations of InteractionAdapt in a selection task and a travel planning task established its capability of supporting efficient interaction, during which it produced adapted layouts that participants preferred to several baselines. We further showcase the versatility of our approach through applications that cover a wide range of use cases.

Virtual Reality (VR) systems have traditionally required users to operate the user interface with controllers in mid-air. More recent VR systems, however, integrate cameras to track the headset's position inside the environment as well as the user's hands when possible. This allows users to directly interact with virtual content in mid-air just by reaching out, thus discarding the need for hand-held physical controllers. However, it is unclear which of these two modalities-controller-based or free-hand interaction-is more suitable for efficient input, accurate interaction, and long-term use under reliable tracking conditions. While interacting with hand-held controllers introduces weight, it also requires less finger movement to invoke actions (e.g., pressing a button) and allows users to hold on to a physical object during virtual interaction. In this paper, we investigate the effect of VR input modality (controller vs. free-hand interaction) on physical exertion, agency, task performance, and motor behavior across two mid-air interaction techniques (touch, raycast) and tasks (selection, trajectory-tracing). Participants reported less physical exertion, felt more in control, and were faster and more accurate when using VR controllers compared to free-hand interaction in the raycast setting. Regarding personal preference, participants chose VR controllers for raycast but free-hand interaction for mid-air touch. Our correlation analysis revealed that participants' physical exertion increased with selection speed, quantity of arm motion, variation in motion speed, and bad postures, following ergonomics metrics such as consumed endurance and rapid upper limb assessment. We also found a negative correlation between physical exertion and the participant's sense of agency, and between physical exertion and task accuracy.

Diminished reality (DR) refers to the concept of removing content from a user’s visual environment. While its implementation is becoming feasible, it is still unclear how users perceive and interact in DR-enabled environments and what applications it benefits. To address this challenge, we first conduct a formative study to compare user perceptions of DR and mediated reality effects (e. g., changing the color or size of target elements) in four example scenarios. Participants preferred removing objects through opacity reduction (i. e., the standard DR implementation) and appreciated mechanisms for maintaining a contextual understanding of diminished items (e. g., outlining). In a second study, we explore the user experience of performing tasks within DR-enabled environments. Participants selected which objects to diminish and the magnitude of the effects when performing two separate tasks (video viewing, assembly). Participants were comfortable with decreased contextual understanding, particularly for less mobile tasks. Based on the results, we define guidelines for creating general DR-enabled environments.

Real-world work-spaces typically revolve around tables, which enable knowledge workers to comfortably perform tasks over an extended period of time during productivity tasks. Tables afford more ergonomic postures and provide opportunities for rest, which raises the question of whether they may also benefit prolonged interaction in Virtual Reality (VR). In this paper, we investigate the effects of tabletop surface presence in situated VR settings on task performance, behavior, and subjective experience. In an empirical study, 24 participants performed two tasks (selection, docking) on virtual interfaces placed at two distances and two orientations. Our results show that a physical tabletop inside VR improves comfort, agency, and task performance while decreasing physical exertion and strain of the neck, shoulder, elbow, and wrist, assessed through objective metrics and subjective reporting. Notably, we found that these benefits apply when the UI is placed on and aligned with the table itself as well as when it is positioned vertically in mid-air above it. Our experiment therefore provides empirical evidence for integrating physical table surfaces into VR scenarios to enable and support prolonged interaction. We conclude by discussing the effective usage of surfaces in situated VR experiences and provide initial guidelines.

Augmented Reality (AR) has the potential to leverage environmental information to better facilitate distributed collaboration, however, such applications are difficult to develop. We present XSpace, a toolkit for creating spatially-aware AR applications for distributed collaboration. Based on a review of existing applications and developer tools, we design XSpace to support three methods for creating shared virtual spaces, each emphasizing a different aspect: shared objects, user perspectives, and environmental meshes. XSpace implements these methods in a developer toolkit, and also provides a set of complimentary visual authoring tools to allow developers to preview a variety of configurations for a shared virtual space. We present five example applications to illustrate that XSpace can support the development of a rich set of collaborative AR experiences that are difficult to produce with current solutions. Through XSpace, we discuss implications for future application design, including user space customization and privacy and safety concerns when sharing users' environments.

Past research recognized that paper has many advantages over digital devices, such as affordability, tangibility, and flexibility. Paper, however, also lacks many of the functionalities available in digital technologies, such as access to online resources and the ability to display interactive content. Prior research therefore identified opportunities for fusing the two mediums into a combined interface. This work presents a literature review on this form of innovation - technologies that bridge the paper-digital gap. First, we synthesize an understanding of paper and its relationship with digital devices through the lens of past works. Then, we outline the state-of-the-art for paper-digital interfaces and highlight possible use cases and implementation approaches. Last, we discuss design considerations and future work for developing paper-digital interfaces. Our work may be beneficial for HCI researchers interested in the development of hybrid paper-digital interfaces, and more broadly in embedding digital functionalities in everyday objects.

There is increased interest in using virtual reality in education, but it often remains an isolated experience that is difficult to integrate into current instructional experiences. In this work, we adapt virtual production techniques from filmmaking to enable mixed reality capture of instructors so that they appear to be standing directly in the virtual scene. We also capitalize on the growing popularity of live streaming software for video conferencing and live production. With XRStudio, we develop a pipeline for giving lectures in VR, enabling live compositing using a variety of presets and real-time output to traditional video and more immersive formats. We present interviews with media designers experienced in film and MOOC production that informed our design. Through walkthrough demonstrations of XRStudio with instructors experienced with VR, we learn how it could be used in a variety of domains. In end-to-end evaluations with students, we analyze and compare differences of traditional video vs. more immersive lectures with XRStudio.

We present an optimization-based approach that automatically adapts Mixed Reality (MR) interfaces to different physical environments. Current MR layouts, including the position and scale of virtual interface elements, need to be manually adapted by users whenever they move between environments, and whenever they switch tasks. This process is tedious and time consuming, and arguably needs to be automated for MR systems to be beneficial for end users. We contribute an approach that formulates this challenge as a combinatorial optimization problem and automatically decides the placement of virtual interface elements in new environments. To achieve this, we exploit the semantic association between the virtual interface elements and physical objects in an environment. Our optimization furthermore considers the utility of elements for users’ current task, layout factors, and spatio-temporal consistency to previous layouts. All those factors are combined in a single linear program, which is used to adapt the layout of MR interfaces in real time. We demonstrate a set of application scenarios, showcasing the versatility and applicability of our approach. Finally, we show that compared to a naive adaptive baseline approach that does not take semantic associations into account, our approach decreased the number of manual interface adaptations by 33%.

Augmented reality (AR) gaming is becoming widely available thanks to improvements in hand-held devices such as phones and tablets. In this work, we describe our system for generating levels for the AR game, Q*bird. In Q*bird, the player must visit every cell in the level while avoiding bees and cannon balls, similarly to the 1982 arcade game, Q*bert. To create a new level, designers place game elements using virtual cards. The system then generates the remainder of the level, ensuring that it’s navigable. Designers can edit these levels by dragging and dropping the created geometry. To test, the designer can drop a character into the level and play it. This system aids playtesting and level design by allowing levels to be quickly specified and tested in the same environment in which the game is played. Furthermore, this system offers an example of how the design of AR levels can also be performed in AR.