Human Motion Simulation (HMS) predicts and visualizes how virtual agents move and behave in various scenarios, aiding decision-making. However, it does not communicate the experience behind agents' behavior. To address this, we present Embodied Spatial Simulation (ESS), a concept combining augmented reality(AR) and HMS to support in-situ decision-making. It enables an XR user to create "what-if" scenarios, simulate virtual agents' behavior in situ, and experience the scenarios from their perspectives through embodiment. To demonstrate ESS, we developed a proof-of-concept prototype featuring two scenarios (e.g., fire evacuation planning). From expert walkthroughs (N=4) and a survey (N=38) with different professions, we found that incorporating embodiment into simulations can change users' intentions to use simulation outcomes. Rather than directly obtaining solutions from the results, users showed more interest in understanding the experience behind simulated behavior and using this insight to shape decisions. We discuss the potential of ESS to support future human-centered design practices.

Research in Augmented Reality (AR) and Virtual Reality (VR) has mostly viewed them in isolation.Yet, when used together in practical settings, AR and VR each offer unique strengths, necessitating multiple transitions to harness their advantages.This paper investigates potential challenges in Cross-Reality (CR) transitions to inform future application design.We implemented a CR system featuring a 3D modeling task that requires users to switch between PC, AR, and VR.Using a talk-aloud study (n=12) and thematic analysis, we revealed that frictions primarily arose when transitions conflicted with users' Spatial Mental Model (SMM).Furthermore, we found five transition archetypes employed to enhance productivity once an SMM was established.Our findings uncover that transitions have to focus on establishing and upholding the SMM of users across realities, by communicating differences between them.

While body ownership is central to research in virtual reality (VR), it remains unclear how experiencing an avatar over time shapes a person’s summary judgment of it. Such a judgment could be a simple average of the bodily experience, or it could follow the peak-end rule, which suggests that people’s retrospective judgment correlates with the most intense and recent moments in their experiencing. We systematically manipulate body ownership over a three-minute avatar embodiment using visuomotor asynchrony. Asynchrony here serves to negatively influence body ownership. We conducted one lab study ( N = 28 ) and two online studies (pilot: N = 97 and formal: N = 128 ) to investigate the influence of visuomotor asynchrony given (1) order, meaning early or late, (2) duration and magnitude while controlling the order, and (3) the interaction between order and magnitude. Our results indicate a significant order effect—later visuomotor asynchrony decreased the rating of body-ownership judgments more—but no convergent evidence on magnitude. We discuss how body-ownership judgments may be formed sensorily or affectively. • Late asynchrony reduces body-ownership judgments more than early asynchrony. • The end effect shows potential designs for enhancing virtual body experiences. • The peak effect of body-ownership judgments is challenging to influence.

Virtual Reality (VR) technologies become ubiquitous, allowing people to employ immersive experiences in their homes. Since VR participants are visually disconnected from their real-world environment, commercial products propose safety boundaries to prevent colliding with their surroundings. However, there is a lack of empirical knowledge on how people perceive and interact with safety boundaries in everyday VR usage. This paper investigates this research gap with two mixed-method empirical studies. Study 1 reports an online survey (n=48) collecting data about attitudes towards safety boundaries, behavior while interacting with them, and reasons for breakout. Our analysis with open coding reveals that some VR participants ignored safety boundaries intentionally, even breaking out of them and continuing their actions. Study 2 investigates how and why VR participants intentionally break out when interacting close to safety boundaries and obstacles by replicating breakouts in a lab study (n=12). Our interview and breakout data discover three strategies, revealing VR participants sometimes break out of boundaries based on their real-world spatial information. Finally, we discuss improving future VR safety mechanisms by supporting participants’ real-world spatial mental models using landmarks.

Whole-body movements enhance the presence and enjoyment of Virtual Reality (VR) experiences. However, using large gestures is often uncomfortable and impossible in confined spaces (e.g., public transport). We introduce FingerMapper, mapping small-scale finger motions onto virtual arms and hands to enable whole-body virtual movements in VR. In a first target selection study (n=13) comparing FingerMapper to hand tracking and ray-casting, we found that FingerMapper can significantly reduce physical motions and fatigue while having a similar degree of precision. In a consecutive study (n=13), we compared FingerMapper to hand tracking inside a confined space (the front passenger seat of a car). The results showed participants had significantly higher perceived safety and fewer collisions with FingerMapper while preserving a similar degree of presence and enjoyment as hand tracking. Finally, we present three example applications demonstrating how FingerMapper could be applied for locomotion and interaction for VR in confined spaces.

Human memory has notable limitations (e.g., forgetting) which have necessitated a variety of memory aids (e.g., calendars). As we grow closer to mass adoption of everyday Extended Reality (XR), which is frequently leveraging perceptual limitations (e.g., redirected walking), it becomes pertinent to consider how XR could leverage memory limitations (forgetting, distorting, persistence) to induce memory manipulations. As memories highly impact our self-perception, social interactions, and behaviors, there is a pressing need to understand XR Memory Manipulations (XRMMs). We ran three speculative design workshops (n=12), with XR and memory researchers creating 48 XRMM scenarios. Through thematic analysis, we define XRMMs, present a framework of their core components and reveal three classes (at encoding, pre-retrieval, at retrieval). Each class differs in terms of technology (AR, VR) and impact on memory (influencing quality of memories, inducing forgetting, distorting memories). We raise ethical concerns and discuss opportunities of perceptual and memory manipulations in XR.

“Virtual-Physical Perceptual Manipulations” (VPPMs) such as redirected walking and haptics expand the user’s capacity to interact with Virtual Reality (VR) beyond what would ordinarily physically be possible. VPPMs leverage knowledge of the limits of human perception to effect changes in the user’s physical movements, becoming able to (perceptibly and imperceptibly) nudge their physical actions to enhance interactivity in VR. We explore the risks posed by the malicious use of VPPMs. First, we define, conceptualize and demonstrate the existence of VPPMs. Next, using speculative design workshops, we explore and characterize the threats/risks posed, proposing mitigations and preventative recommendations against the malicious use of VPPMs. Finally, we implement two sample applications to demonstrate how existing VPPMs could be trivially subverted to create the potential for physical harm. This paper aims to raise awareness that the current way we apply and publish VPPMs can lead to malicious exploits of our perceptual vulnerabilities.