Virtual reality (VR) multiplayer games increasingly use asymmetry (e.g., differences in a person’s capability or the user interface) and resulting interdependence between players to create engagement even when one player has no access to a head-mounted display (HMD). Previous work shows this enhances player experience (PX). Until now, it remains unclear whether and how an asymmetric game design with interdependences creates comparably enjoyable PX for both an HMD and a non-HMD player. In this work, we designed and implemented an asymmetric VR game (different in its user interface) with two types of interdependence: strategic (difference in game information/player capability) and biometric (difference in player’s biometric influence). Our mixed-methods user study (N=30) shows that asymmetries positively impact PX for both player roles, that interdependence strongly affects players’ perception of agency, and that biometric feedback—while subjective—is a valuable game mechanic.

Virtual and augmented reality head-mounted displays (HMDs) are currently heavily relying on spatially tracked input devices (STID) for interaction. These STIDs are all prone to the phenomenon that a discrete input (e.g. button press) will disturb the position of the tracker, resulting in a different selection point during ray-cast interaction (Heisenberg Effect of Spatial Interaction). Besides the knowledge of its existence, there is currently a lack of a deeper understanding of its severity, structure and impact on throughput and angular error during a selection task. In this work, we present a formal evaluation of the Heisenberg effect and the impact of body posture, arm position and STID degrees of freedom on its severity. In a Fitt's Law inspired user study (N=16), we found that the Heisenberg effect is responsible for 30.45% of the overall errors occurring during a pointing task, but can be reduced by 25.4% using a correction function.

One of the great benefits of virtual reality (VR) is the implementation of features that go beyond realism. Common "unrealistic" locomotion techniques (like teleportation) can avoid spatial limitation of tracking, but minimize potential benefits of more realistic techniques (e.g. walking). As an alternative that combines realistic physical movement with hyper-realistic virtual outcome, we present JumpVR, a jump-based locomotion augmentation technique that virtually scales users' physical jumps. In a user study (N=28), we show that jumping in VR (regardless of scaling) can significantly increase presence, motivation and immersion compared to teleportation, while largely not increasing simulator sickness. Further, participants reported higher immersion and motivation for most scaled jumping variants than forward-jumping. Our work shows the feasibility and benefits of jumping in VR and explores suitable parameters for its hyper-realistic scaling. We discuss design implications for VR experiences and research.

The design of graphical augmented reality (AR) markers requires compromise between the aesthetic appearance and tracking reliability. To investigate the topic, we created a virtual reality (VR) pipeline to evaluate marker performance, and validated it against real-world performance for a set of graphical AR markers. We report that, with the well known Vuforia framework and typical smartphone hardware, well designed 20 × 20 cm markers can be tracked at distances of up to 68 cm. We note that the number of feature points is particularly important to a marker’s angular performance.

Cognitive impairment such as memory loss, an impaired executive function and decreasing motivation can gradually undermine instrumental activities of daily living (IADL). With an older growing population, previous works have explored assistive technologies (ATs) to automate repetitive components of therapy and thereby increase patients' autonomy and reduce dependence on carers. While most ATs were built around screens and projection-based augmented reality (AR), the potential of head-mounted displays (HMDs) for therapeutic assistance is still under-explored. As a contribution to this effort we present cARe, an HMD-based AR framework that uses in-situ instructions and a guidance mechanism to assist patients with manual tasks. In a case study with six geriatric patients, we investigated the prototype's feasibility during a cooking task in comparison to a regular paper-based recipe. Qualitative and quantitative results indicate that cARe has potential to offer assistance to older individuals with declining cognitive function in their day-to-day tasks and increase their independence in an enjoyable way.

Cognitive impairment such as memory loss, an impaired executive function and decreasing motivation can gradually undermine instrumental activities of daily living (IADL). With an older growing population, previous works have explored assistive technologies (ATs) to automate repetitive components of therapy and thereby increase patients' autonomy and reduce dependence on carers. While most ATs were built around screens and projection-based augmented reality (AR), the potential of head-mounted displays (HMDs) for therapeutic assistance is still under-explored. In this interactive demonstration, we present cARe, an HMD-based AR framework that uses in-situ instructions and a guidance mechanism to assist patients with manual tasks. In a case study with six geriatric patients, we investigated the prototype's feasibility during a cooking task in comparison to a regular paper-based recipe. Qualitative and quantitative results indicate that cARe has potential to offer assistance to older individuals with declining cognitive function in their day-to-day tasks and increase their independence in an enjoyable way.

While the real world provides humans with a huge variety of sensory stimuli, virtual worlds most of all communicate their properties by visual and auditory feedback due to the design of current head mounted displays (HMDs). Since HMDs offer sufficient contact area to integrate additional actuators, prior works utilised a limited amount of haptic actuators to integrate respective information about the virtual world. With the Face/On prototype complex feedback patterns are introduced that combine a high number of vibration motors with additional thermal sources to transport multi-modal and spatial information. A pre-study determining the boundaries of the feedbacks' intensities as well as a user study showing a significant increase of presence and enjoyment validate Face/On's approach.

The scarcity of established input methods for augmented reality (AR) head-mounted displays (HMD) motivates us to investigate the performance envelopes of two easily realisable solutions: indirect cursor control via a smartwatch and direct control by in-air touch. Indirect cursor control via a smartwatch has not been previously investigated for AR HMDs. We evaluate these two techniques for carrying out three fundamental user interface actions: target acquisition, goal crossing, and circular steering. We find that in-air is faster than smartwatch (p <; 0.001) for target acquisition and circular steering. We observe, however, that in-air selection can lead to discomfort after extended use and suggest that smartwatch control offers a complementary alternative.

We present SwiVRChair, a motorized swivel chair to nudge users' orientation in 360 degree storytelling scenarios. Since rotating a scene in virtual reality (VR) leads to simulator sickness, storytellers currently have no way of controlling users' attention. SwiVRChair allows creators of 360 degree VR movie content to be able to rotate or block users' movement to either show certain content or prevent users from seeing something. To enable this functionality, we modified a regular swivel chair using a 24V DC motor and an electromagnetic clutch. We developed two demo scenarios using both mechanisms (rotate and block) for the Samsung GearVR and conducted a user study (n=16) evaluating the presence, enjoyment and simulator sickness for participants using SwiVRChair compared to self control (Foot Control). Users rated the experience using SwiVRChair to be significantly more immersive and enjoyable whilst having a decrease in simulator sickness.

We present GyroVR, head worn flywheels designed to render inertia in Virtual Reality (VR. Motions such as flying, diving or floating in outer space generate kinesthetic forces onto our body which impede movement and are currently not represented in VR. We simulate those kinesthetic forces by attaching flywheels to the users head, leveraging the gyroscopic effect of resistance when changing the spinning axis of rotation. GyroVR is an ungrounded, wireless and self contained device allowing the user to freely move inside the virtual environment. The generic shape allows to attach it to different positions on the users body. We evaluated the impact of GyroVR onto different mounting positions on the head (back and front) in terms of immersion, enjoyment and simulator sickness. Our results show, that attaching GyroVR onto the users head (front of the Head Mounted Display (HMD)) resulted in the highest level of immersion and enjoyment and therefore can be built into future VR HMDs, enabling kinesthetic forces in VR.

In this paper we present ColorSnakes, a PIN-based authentication mechanism for smartphones which uses fake paths on a grid of numbers to disguise user input. In a lab study (n=24),we evaluated variations of ColorSnakes in terms of usability and security. In comparison to direct input, indirect input significantly reduced the risk of shoulder surfing (10.5%) without increasing the input time. In a follow up real-world study (n=12), we compared ColorSnakes with PIN entry and Android's Pattern Unlock over the course of three weeks. Although authentication time for ColorSnakes was higher than for the other two mechanisms, participants valued the security benefit over its slightly higher error rate and increased authentication time. We argue that ColorSnakes could be used as an additional authentication mechanism alongside current mechanisms, thus providing the user with the choice of changing to ColorSnakes for certain applications or when there is an observer.