Knowing what collaborators attend to is essential. Previous studies demonstrated that shared gaze enhances coordination and social connectedness in remote settings. In collocated settings, gaze can be both naturally observable and technologically augmented. AR enables gaze cues to be rendered explicitly in the environment. To investigate if and how such cues are beneficial in collocated AR collaboration, we examined both qualitative and quantitative effects across three task types (puzzle, negotiation, search) and two spatial setups (plane, room), focusing on task completion time and the collaborative experience. In our user study with 24 dyads (n=48), we varied gaze visibility and measured task performance, user preference, social connectedness, and shared attention. Our results show that sharing gaze in collocated collaborative AR can increase shared attention, is perceived as helpful, and improves the user experience, similar to remote collaboration, but has a limited impact on the actual task completion time across the chosen tasks.

Humans excel at understanding social cues in communication, but robots struggle. Social cues are crucial for humans to interpret the intentions of their communication partners. Research indicates that we typically interpret the actions of anthropomorphic robots analogously to their human counterparts, paving a clear path to the design of appropriate social cues. For non-anthropomorphic robots, however, it is an open question how humans interpret social cues with different output modalities and in different contexts. Our study investigates whether social cues signaled by typical non-anthropomorphic modalities such as lights, sounds, and gestures are consistently interpreted across people and contexts. We, therefore, conducted a contextual investigation in a hospital, derived scenarios from co-design workshop, and tested 103 cues collected from the literature in a large online survey (N = 1545). Our results demonstrate that most human interpretations vary by context, highlighting the need to design dynamic and adaptive social cues for interactive robotic systems.

Acquiring tacit knowledge and practical skills often depends on direct observation and in situ training. AR offers an alternative by overlaying first-person step-by-step instructions that guide users through tasks such as assembly and repair. Previous work demonstrates the effectiveness of AR instruction for specific applications. In our experimental work, we systematically explore aspects of the broader design space. We conducted a controlled experiment (n = 40) to investigate three key factors identified in learning theory and XR embodiment research: imitation timing (parallel vs. sequential), limb visualization (hand vs. full arm), and limb visibility (opaque vs. semi-transparent). Across all conditions, participants followed AR instructions and afterward repeated the tasks from memory. We assessed performance, user experience, and retention. Our results show that parallel imitation is faster and increases embodiment, whereas sequential imitation enhances memory retention and comfort. Our findings provide guidance for the temporal and visual design of first-person AR tutorials.

Remote research facilities such as mountain observatories offer unique scientific and educational value, yet their physical inaccessibility limits participation for many audiences. This paper presents a location-independent, mobile Extended Reality (XR) application that extends the experiential reach of a mountain-based observatory beyond its geographic constraints. The application allows users to virtually explore a research telescope and interactively learn about the observatory’s scientific work, instrumentation, and operational principles. Following interviews with on-site visitors to identify access barriers and learning needs, we developed an XR experience and evaluated it in an in-the-wild study with three school classes (N = 35). We deployed the application across three contexts (remote location, intermediate plateau, mountain summit) and assessed factors such as mental load, presence, motivation, perceived access, and quiz results. Our findings indicate that context-dependent physical proximity influences all factors except the quiz outcome, highlighting the importance of proximity-aware design for future XR systems.

With the increasing spread of AR head-mounted displays suitable for everyday use, interaction with information becomes ubiquitous, even while walking. However, this requires constant shifts of our attention between walking and interacting with virtual information to fulfill both tasks adequately. Accordingly, we as a community need a thorough understanding of the mutual influences of walking and interacting with digital information to design safe yet effective interactions. Thus, we systematically investigate the effects of different AR anchors (hand, head, torso) and task difficulties on user experience and performance. We engage participants (n=26) in a dual-task paradigm involving a visual working memory task while walking. We assess the impact of dual-tasking on both virtual and walking performance, and subjective evaluations of mental and physical load. Our results show that head-anchored AR content least affected walking while allowing for fast and accurate virtual task interaction, while hand-anchored content increased reaction times and workload.

Our sense of touch plays a crucial role in physical collaboration, yet rendering realistic haptic feedback in collaborative extended reality (XR) remains a challenge. Co-located XR systems predominantly rely on prefabricated passive props that provide high-fidelity interaction but offer limited adaptability. Haptic Illusions (HIs), which leverage multisensory integration, have proven effective in expanding haptic experiences in single-user contexts. However, their role in XR collaboration has not been explored. To examine the applicability of HIs in multi-user scenarios, we conducted an experimental user study (N=30) investigating their effect on a collaborative object handover task in virtual reality. We manipulated visual shape and size individually and analyzed their impact on users' performance, experience, and behavior. Results show that while participants adapted to the illusions by shifting sensory reliance and employing specific sensorimotor strategies, visuo-haptic mismatches reduced both performance and experience. Moreover, mismatched visualizations in asymmetric user roles negatively impacted performance. Drawing from these findings, we provide practical guidelines for incorporating HIs into collaborative XR, marking a first step toward richer haptic interactions in shared virtual spaces.

Extended Reality (XR) technologies present innovative ways to augment sensory experiences, including taste perception. In this study, we investigated how augmented reality (AR) visual filters and synchronized audio cues affect gustation through a controlled experiment with 18 participants. Our findings revealed unexpected crossmodal interactions: while pink visual filter typically associated with sweetness reduced perceived bitterness in isolation, it paradoxically enhanced bitterness perception when combined with sweet-associated audio cue. Furthermore, we observed an inverse correlation between participant confidence levels and their perception of taste intensities across multiple dimensions, highlighting confidence as an overlooked factor in sensory experience design. These findings inform the design of nuanced multisensory experiences in immersive media, where subtle crossmodal interactions significantly influence user perception.

Generative AI in Virtual Reality offers the potential for collaborative object-building, yet challenges remain in aligning AI contributions with user expectations. In particular, users often struggle to understand and collaborate with AI when its actions are not transparently represented. This paper thus explores the co-creative object-building process through a Wizard-of-Oz study, focusing on how AI can effectively convey its intent to users during object customization in Virtual Reality. Inspired by human-to-human collaboration, we focus on three representation modes: the presence of an embodied avatar, whether the AI’s contributions are visualized immediately or incrementally, and whether the areas modified are highlighted in advance. The findings provide insights into how these factors affect user perception and interaction with object-generating AI tools in Virtual Reality as well as satisfaction and ownership of the created objects. The results offer design implications for co-creative world-building systems, aiming to foster more effective and satisfying collaborations between humans and AI in Virtual Reality.

Desktop screens are effective for supporting comparison tasks, but as the scale increases to room-sized or larger structures, context is lost. Users are forced to focus on isolated details through panning, zooming, and scrolling, making it difficult to maintain an overview while exploring finer details. Virtual Reality (VR) potentially offers a solution to this problem by immersing users in 3D spaces and enabling more intuitive comparisons. While related work has proposed many solutions for visualizing and interacting for comparison tasks in desktop environments, knowledge regarding the efficacy of supporting such tasks in VR environments is still lacking. We investigated varying visualization and interaction techniques in a controlled experiment with 24 participants. Our findings provide valuable insights for designing VR systems that improve usability, reduce workload, and enhance performance in comparison tasks.

Providing users with realistic sensations of object stiffness in virtual environments remains challenging due to the intricacies of our haptic sense. We investigate the use of a visuo-haptic illusion to alter the perceived stiffness of hand-held objects in virtual reality. We manipulate the Control-to-Display ratio of the index finger and thumb movements during pinching to make virtual objects feel softer or harder. We evaluated this approach on a variety of haptic representations and visualizations we selected through a pre-study survey (N=24). Results of our user study (N=20) demonstrate that this method effectively and reliably modifies stiffness perception, bridging gaps of 50% in physical stiffness without adversely affecting the visuo-haptic experience. Our findings offer insights into how different visual and haptic presentations impact stiffness perception, contributing to more effective and adaptable future haptic feedback systems.

Virtual Reality (VR) locomotion methods are mainly ground-based, room-scale, or discrete, making them ill-suited for flying experiences. Although leaning- and controller-based techniques are promising for flying in VR, we lack empirical evidence of their advantages. We compared combinations of leaning- and controller-based methods for steering and velocity in a user study (N = 24) using a broom metaphor to integrate these methods into an understandable locomotion reference. The steering methods were: 1) controller-pointing (CP) and 2) headset-leaning (HL); and for velocity control: 1) controller linear displacement (CLD) and 2) headset linear displacement (HLD). Results indicate that HL increase presence compared to CP. However, combining HL with CLD worsens coin collection rate, completion time, mental load, control factor ratings, and enjoyment. In contrast, HLD worked well when paired with either steering method. CP-CLD led to the highest coin collection rate and lowest mental load. All methods had comparable feelings of flying.

Seamless transition between public dialogue and private talks is essential in everyday conversations. Social Virtual Reality (VR) has revolutionized interpersonal communication by creating a sense of closeness over distance through virtual avatars. However, existing social VR platforms are not successful in providing safety and supporting private conversations, thereby hindering self-disclosure and limiting the potential for meaningful experiences. We approach this problem by exploring the factors affecting private conversations in social VR applications, including the usability of different interaction methods and the awareness with respect to the virtual world. We conduct both expert interviews and a controlled experiment with a social VR prototype we realized. We then leverage the outcomes of the two studies to establish a design space that considers diverse dimensions (including privacy levels, social awareness, and modalities), laying the groundwork for more intuitive and meaningful experiences of private conversation in social VR.

Fear of falling limits climbers' performance and progression, particularly for beginners who must develop trust in their safety equipment and falling techniques. Traditional methods of overcoming this fear through repeated practice are time-consuming and stressful. In this paper, we explore the potential of using Virtual Reality (VR) to assist climbers' training. We conducted an exploratory experiment in which 20 climbers performed multiple falls from a height of 5 meters both with and without a VR headset, experiencing 1-2 meters of free fall. We collected qualitative data through interviews conducted before, after, and following each fall. Our findings suggest that VR is a promising tool for reducing the fear of falling, though the exact mechanisms and effectiveness require further investigation through longitudinal studies. This study opens new possibilities for using VR as a training tool in climbing education, potentially accelerating the process of overcoming the fear of falling.

Augmented Reality (AR) is transforming the way we interact with virtual information in the physical world. By overlaying digital content in real-world environments, AR enables new forms of immersive and engaging experiences. However, existing AR systems often struggle to effectively manage the many interactive possibilities that AR presents. This vision paper speculates on AI-driven approaches for adaptive AR content placement, dynamically adjusting to user movement and environmental changes. By leveraging machine learning methods, such a system would intelligently manage content distribution between AR projections integrated into the external environment and fixed static content, enabling seamless UI layout and potentially reducing users' cognitive load. By exploring the possibilities of AI-driven dynamic AR content placement, we aim to envision new opportunities for innovation and improvement in various industries, from urban navigation and workplace productivity to immersive learning and beyond. This paper outlines a vision for the development of more intuitive, engaging, and effective AI-powered AR experiences.

Transferring knowledge across generations is fundamental to human civilization, yet the challenge of passing on complex practical skills persists. Methods without a physically present instructor, such as videos, often fail to explain complex manual tasks, where spatial and social factors are critical. Technologies such as eXtended Reality and Artificial Intelligence hold the potential to retain expert knowledge and facilitate the creation of tailored, contextualized, and asynchronous explanations regardless of time and place. In contrast to videos, the learner's perspective can be different from the recorded perspective in XR. This paper investigates the impact of asynchronous first- and third-person perspectives and gaze visualizations on efficiency, feeling of embodiment, and connectedness during manual tasks. The empirical results of our study (N=36) show that the first-person perspective is better in quantitative measures and preferred by users. We identify best practices for presenting preserved knowledge and provide guidelines for designing future systems.

Over the past decade, a noticeable increase in literature can be seen in wearable foot interfaces, which have evolved from activity tracking to enhancing human capabilities. Our legs, being the largest body limbs, play an essential role in various functions such as locomotion, maintaining balance, supporting proper posture and providing ground-contact using our feet. Hence, foot augmentations offer the opportunity to augment our entire body. However, most prior research focuses on specific application areas, thus affording a research agenda to further understand the full potential of feet in designing augmentations and to contextualize it in the broader human augmentation space. To achieve this, in this workshop, we invite researchers, designers, and practitioners, novice and expert, interested in designing human and foot augmentations. We will discuss how early foot interfaces helped in augmenting humans, and based on current work and trends in foot augmentation, we will formulate strategies for the next steps and discuss the applicability of such strategies in the broader space of human augmentation.

Interactive technology has a complicated relationship with recreation in nature. Many people have praised, and many have lamented the impact of interactive technology on recreation in nature. Because nature recreation has important wellness benefits and interactive technology is likely to remain a part of nature recreation, there is a need to design interactive technology for nature recreation. Unfortunately, little generalized knowledge exists on how to design such technology. We create new intermediate design knowledge for interactive technology in nature recreation by drawing from others' work, our prior work, and specifically Borgmann and Verbeek's philosophies of technology. Our contribution is a framework based on a decomposition of engagement into nine facets related to engagement with place, time, and community. Four examples demonstrate the descriptive and generative power of the framework. This framework may enable the creation of interactive systems that complement rather than compete with nature recreation and may better preserve the wellness benefits of nature recreation.

There is an increasing interest in combining interactive technology with food, leading to a new research area called human-food interaction. While food experiences are increasingly benefiting from interactive technology, for example in the form of food tracking apps, 3D-printed food and projections on dining tables, a more systematic advancement of the field is hindered because, so far, there is no comprehensive articulation of the grand challenges the field is facing. To further and consolidate conversations around this topic, we invited 21 HFI experts to a 5-day seminar. The goal was to review our own and prior work to identify the grand challenges in human-food interaction. The result is an articulation of 10 grand challenges in human-food interaction across 4 categories (technology, users, design and ethics). By presenting these grand challenges, we aim to help researchers move the human-food interaction research field forward.