The way users hold a smartphone depends on the interaction task, yet little is known about the fingers’ engagement with the device’s surfaces beyond the touchscreen. Such an understanding not only opens up opportunities for novel on- and off-screen interactions, but also the device’s possible physical affordances. We present a study (N=23) that examines the hands’ physical engagement with the smartphone beyond the touchscreen across nine mobile interactions. Grasps were annotated from photographs, and contact regions were captured using residual heat traces from grasping the device. Our findings show that fingers and palms adopt a variety of support roles and postures when engaging with the smartphone’s back and side edges. The hand-contact maps reveal distinct patterns, differing in contact frequency and placement. This work contributes an empirical characterisation of hands’ back and edge engagement, highlighting design opportunities for future smartphone usage extending beyond the touchscreen.

Haptic sensations in pen-based surface interactions within virtual reality (VR) rely on specialised haptic devices like pens or tablets. However, as VR becomes more mobile, reducing the need for external hardware is crucial, shifting the focus to head-mounted displays (HMDs) for haptic feedback. In this work, we explore head-mounted relocation of multisensory feedback, combining vibrations and audio, to simulate varying levels of surface roughness during pen-based surface interaction in VR. In a within-subject user study (N=18), we evaluated the influence of the combined technique compared to the vibration-only and audio-only techniques on the perceived surface roughness. Our results indicate that all relocation techniques allowed participants to distinguish at least three out of five roughness levels through their haptic and/or auditory senses. Moreover, while the combination of vibration and audio feedback produced the highest perceived levels of surface roughness for rougher simulated surfaces, the vibration-only approach enabled the perception of more distinguishable roughness levels in the lower range of simulated surfaces. Our findings provide early evidence that haptic surface sensations can be relocated via head-mounted simulation during pen-based interactions, offering initial insights for future HMDs that integrate multisensory feedback.

Regulations for privacy protection aim to protect individuals from the unauthorized storage, processing, and transfer of their personal data but oftentimes fail in providing helpful support for understanding these regulations. To better communicate privacy policies for smartwatches, we need an in-depth understanding of their concepts and provide better ways to enable developers to integrate them when engineering systems. Up to now, no conceptual model exists covering privacy statements from different smartwatch manufacturers that is reusable for developers. This paper introduces such a conceptual model for privacy policies of smartwatches and shows its use in a model-driven software engineering approach to create a platform for data visualization of wearable privacy policies from different smartwatch manufacturers. We have analyzed the privacy policies of various manufacturers and extracted the relevant concepts. Moreover, we have checked the model with lawyers for its correctness, instantiated it with concrete data, and used it in a model-driven software engineering approach to create a platform for data visualization. This reusable privacy policy model can enable developers to easily represent privacy policies in their systems. This provides a foundation for more structured and understandable privacy policies which, in the long run, can increase the data sovereignty of application users.

Dedicated handheld controllers facilitate haptic experiences of virtual objects in mixed reality (MR). However, as mobile MR becomes more prevalent, we observe the emergence of controller-free MR interactions. To retain immersive haptic experiences, we explore the use of mobile devices as a substitute for specialised MR controller. In an exploratory gesture elicitation study (n = 18), we examined users’ (1) intuitive hand gestures performed with prospective mobile devices and (2) preferences for real-time haptic feedback when exploring haptic object properties. Our results reveal three haptic exploration modes for the mobile device, as an object, hand substitute, or as an additional tool, and emphasise the benefits of incorporating the device’s unique physical features into the object interaction. This work expands the design possibilities using mobile devices for tangible object interaction, guiding the future design of mobile devices for haptic MR experiences.

Virtual reality (VR) objects react dynamically to users’ touch interactions in real-time. However, experiencing changes in weight through the haptic sense remains challenging with consumer VR controllers due to their limited vibrotactile feedback. While prior works successfully applied pseudo-haptics to perceive absolute weight by manipulating the control-display (C/D) ratio, we continuously adjusted the C/D ratio to mimic weight changes. Vibrotactile feedback additionally emphasises the modulation in the virtual object’s physicality. In a study (N=18), we compared our multimodal technique with pseudo-haptics alone and a baseline condition to assess participants’ experiences of weight changes. Our findings demonstrate that participants perceived varying degrees of weight change when the C/D ratio was adjusted, validating its effectiveness for simulating dynamic weight in VR. However, the additional vibrotactile feedback did not improve weight change perception. This work extends the understanding of designing haptic experiences for lightweight VR systems by leveraging perceptual mechanisms.

Handheld virtual reality (VR) controllers enable users to manipulate virtual objects in VR but do not convey a virtual object's weight. This hinders users from effectively experiencing lighter and heavier objects. While previous work explored either hardware-based interfaces or software-based pseudo-haptics, in this paper, we combine two techniques to improve the virtual weight perception in VR. By adapting the trigger resistance of the VR controller when grasping a virtual object and manipulating the control-display (C/D) ratio during lifting, we create a continuous weight sensation. In a psychophysical study (N=29), we compared our combined approach against the individual rendering techniques. Our results show that participants were significantly more sensitive towards smaller weight differences in the combined weight simulations compared to the individual methods. Additionally, participants were also able to determine weight differences significantly faster with both cues present compared to the single pseudo-haptic technique. While all three techniques were generally valued to be effective, the combined approach was favoured the most. Our findings demonstrate the meaningful benefit of combining physical and virtual techniques for virtual weight rendering over previously proposed methods.

Privacy Policies inform users about how their personal data is managed while fulfilling the obligatory requirements. Past studies have shown that users often do not read privacy policies, cannot comprehend the long and complex policy documents, and resort to providing their consent without knowledge. To enable users to make an informed decision, we explored serious games as a new medium to improve their understanding of privacy policies. In a mobile escape room game, users engage with the data collection and processing by solving different puzzles. We validated the game concept in a user study by comparing it to a conventional textual policy. Our findings show that the game promoted greater information recall in users. However, a trade-off seems to exist between frustration, duration and understanding. We show strategies for turning a privacy policy into game elements for a mobile escape room game and incorporating privacy information into different puzzles. We recommend that the choice of a privacy policy format should vary in a case-by-case scenario and should accommodate different target audiences.

With the rise of COVID-19 cases globally, many countries released digital tools to mitigate the effects of the pandemic. In Germany the Robert Koch Institute (RKI) published the Corona-Data-Donation-App, a virtual citizen science (VCS) project, to establish an early warning system for the prediction of potential COVID-19 hotspots using data from wearable devices. While work on motivation for VCS projects in HCI often presents egoistic motives as prevailing, there is little research on such motives in crises situations. In this paper, we explore the socio-psychological processes and motivations to share personal data during a pandemic. Our findings indicate that collective motives dominated among app reviews (n=464) and in in-depth interviews (n=10). We contribute implications for future VCS tools in times of crises that highlight the importance of communication, transparency and responsibility.

Mobile navigation apps are among the most used mobile applications and are often used as a baseline to evaluate new mobile navigation technologies in field studies. As field studies often introduce external factors that are hard to control for, we investigate how pedestrian navigation methods can be evaluated in virtual reality (VR). We present a study comparing navigation methods in real life (RL) and VR to evaluate if VR environments are a viable alternative to RL environments when it comes to testing these. In a series of studies, participants navigated a real and a virtual environment using a paper map and a navigation app on a smartphone. We measured the differences in navigation performance, task load and spatial knowledge acquisition between RL and VR. From these we formulate guidelines for the improvement of pedestrian navigation systems in VR like improved legibility for small screen devices. We furthermore discuss appropriate low-cost and low-space VR-locomotion techniques and discuss more controllable locomotion techniques.