Buildings, which people encounter continuously in their day-to-day life, are a compelling target for augmented reality (AR), being fixed, static structures often with plain, flat surfaces to use as potential canvases for AR content. We present a user study (n=15) where participants described how they would augment a Brutalist building they see/use often with AR content. Our results show a willingness to augment the building aesthetically and functionally We identify preliminary insights on where augmentations on buildings are preferred to be made, i.e. targeting flat, empty surfaces and the roof, avoiding windows and entrances.

Extended Reality (XR) interactions often rely on spatial hand or controller inputs - necessitating dexterous wrist, hand and finger movements including pressing virtual buttons, pinching to select, and performing hand gestures. However, there are scenarios where such dependencies may render XR devices and apps inaccessible to users - from situational/temporary impairments such as encumbrance, to physical motor impairments. In this paper, we contribute to a growing literature considering facial input as an alternative. In a user study (N=20) we systematically evaluate the usability of 53 Facial Action Units in VR, deriving a set of optimal (comfort, effort, performance) FAUs for interaction. We then use these facial inputs to drive and evaluate (N=10) two demonstrator apps: VR locomotion, and AR web browsing, showcasing how close facial interaction can get to existing baselines, and demonstrating that FAUs offer a viable, generalizable input modality for XR devices.

Rotational gain has been studied largely under active self-motion, where users control their own movement. In multiple VR scenarios, the user is under passive self-motion: their body is moved by a training simulator, a motorised chair, or a vehicle-based VR application. Users may be less sensitive to manipulation under passive motion - especially when engaged in a secondary task - meaning motion experiences could be expanded by high gains and even opposed virtual-physical motion. We identified both the perceptible and maximum comfortable thresholds of rotational gain when passively turned in a motorised chair, with and without a task, for the first time. We then applied those thresholds to an ’unbounded’ in-car VR game where the user experiences an entirely different route to their physical movement. We provide the first guidelines for creating enhanced passive motion experiences and open the design space to new applications not restricted by physical motion.

AR/VR use in-transit is increasing due to the advantages it provides over more limited mobile and seatback displays for work and play. However, despite the now common support for “travel mode” in consumer XR headsets such as the Meta Quest 3 and Apple Vision Pro, little is known about how this emergent technology has been used in-practice by passengers - from why and how they use it, to what real-world challenges they face during usage in these very public, shared contexts. To address this gap, we contribute a novel large scale analysis of Reddit posts discussing first-hand use of VR/AR in-transit. We captured 11,150 posts, producing 437 user accounts which were synthesized into themes in relation to: in-the-wild use of immersive devices, users' positive/negative sentiment about usage, challenges they faced, and social interactions and impediments that occurred. Our snapshot of the current reality of passenger XR provides real-world insight evidencing the need for more passenger-centric designs of spatial interfaces, interaction techniques, and reality awareness.

Jumping is an engaging physical activity bounded by individual physical capabilities. However in Virtual Reality (VR) we can apply perceptual manipulations like translational gain to real jumps, amplifying the user's apparent capabilities - jumping higher and further than is possible in reality. Prior work has focused on imperceptible gains, but this greatly limits the range of available experiences users can engage in, and designers can create. Research outside of jumping has shown that higher, clearly noticeable gains can still be comfortable, engaging and usable in VR. Therefore, in this paper, we evaluate ($\mathrm{N}=18$) the maximal comfortable gain applied to three jump types: forward, vertical, and sideways. We found, for the majority of participants, high gains ($>100 \mathrm{x}$) are not only comfortable but made users feel enhanced whilst retaining jump ownership, deriving guidelines on the extent to which we can amplify real jumps to feel superhuman in virtuality.

Augmented Reality Television (ARTV) affords new ways to experience media – from displaying auxiliary information to increasing immersion with additional 3D models. Many people consume video content when travelling or commuting; accordingly, the benefits of ARTV in this context merit investigation. We conducted a study (N=20) exploring the effects of using ARTV Ornamentations when watching Game of Thrones on a train. We used Virtual Reality to simulate use of AR in a train carriage and evaluated four different levels of ARTV Ornamentation, from a simple floating panel through to themed models and interior textures that change to match the on-screen visuals. Results showed that Ornamentations matching the show’s genre were sufficient to provide an engaging and immersive experience, but Ornamentations themed to the show which changed based on the scene further elevated the experience. This means it is possible for passengers to have an immersive experience while commuting without significantly reducing their awareness of their environment. We also reflect on the implications of our work for an existing ARTV framework and propose the inclusion of several new aspects to encourage designers to consider the unique challenges and affordances of ARTV Ornamentations.

AV-cyclist interaction research has focused on individual interfaces, e.g., eHMIs or AR glasses. However, cyclists using multiple independent interfaces could receive redundant or contradictory messages, causing unsafe encounters. We introduce the Holistic AV-Cyclist Interface: multiple displays facilitating communication together to ensure safe road sharing. We used participatory design with cyclists and HCI researchers (N = 12) to develop holistic interfaces around an actual vehicle equipped with an eHMI. Participants created holistic interfaces communicating blindspot warnings and AV intent and accommodating two-way communication, e.g. through on-bike directional indicators. They mostly placed interfaces on the bicycle handlebars and cycling accessories, e.g. helmet. Holistic interfaces could overcome design challenges: they can be multimodal, facilitate communication between AVs and multiple cyclists, and work in varying weather/visibility conditions. We categorised participant designs into a taxonomy and developed a novel holistic interface based on our findings. Our results are important for the safe integration of AVs into traffic.

The social cues drivers exchange with cyclists to negotiate space-sharing will disappear as autonomous vehicles (AVs) join our roads, leading to safety concerns. External Human-Machine Interfaces (eHMIs) on vehicles can replace driver social signals, but how these should be designed to communicate with cyclists is unknown. We evaluated three eHMIs across multiple traffic scenarios in two stages. First, we compared eHMI versatility, acceptability and usability in a VR cycling simulator. Cyclists preferred colour-coded signals communicating AV intent, easily seen through quick glances. Second, we refined the interfaces based on our findings and compared them outdoors. Participants cycled around a moving car with real eHMIs. They preferred eHMIs using large surfaces on the vehicle and animations reinforcing colour changes. We conclude with novel design guidelines for versatile eHMIs based on first-hand interaction feedback. Our findings establish the factors that enable AVs to operate safely around cyclists across different traffic scenarios.

To prevent motion sickness, Virtual Reality (VR) experiences for vehicle passengers typically present “matched motion”: real vehicle movements are replicated 1:1 by movements in VR. This significantly limits virtual applications. We provide foundations for in-car VR experiences that break this constraint by manipulating the passenger’s visual perception of linear velocity through amplifying and reducing the virtual speed. In two on-the-road studies, we examined the application of Vehicular Translational Gain (1.5-9.5x) and Attenuation (0.66-0.14x) to real car speeds (~50km/h) across two VR tasks (reading and gaming), exploring journey perception, impact on motion sickness, travel experience and tasks. We found that vehicular gain/attenuation can be applied without significantly increasing motion sickness. Gain was more noticeable and affected perceived speed, distance, safety, relaxation and excitement, being well-suited to gaming, while attenuation was more suitable for productivity. Our work unlocks new ways that VR applications can enhance and alter the passenger experience through novel perceptual manipulations of vehicle velocity.

Extended Reality (XR) offers the potential to transform the passenger experience by allowing users to inhabit varied virtual spaces for entertainment, work or social interaction, whilst escaping the constrained transit environment. XR allows remote collaborators to feel like they are together and enables them to perform complex 3D tasks. However, the social and physical constraints of the passenger space pose unique challenges to productive and socially acceptable collaboration. Using a collaborative VR puzzle task, we examined the effects of five different f-formations of collaborator placement and orientation in an interactive workspace on social presence, task workload, and implications for social acceptability. Our quantitative and qualitative results showed that face-to-face formations were preferred for tasks with a high need for verbal communication but may lead to social collisions, such as inadvertently staring at a neighbouring passenger, or physical intrusions, such as gesturing in another passenger’s personal space. More restrictive f-formations, however, were preferred for passenger use as they caused fewer intrusions on other passengers’ visual and physical space.

Cybersickness remains a major drawback of Virtual Reality (VR) headsets, as a breadth of stationary experiences with visual self-motion can result in visually-induced motion sickness. However, not everybody experiences the same intensity or type of adverse symptoms. Here we propose that prior experience with virtual environments can predict ones degree of cybersickness. Video gaming can enhance visuospatial abilities, which in-turn relate negatively to cybersickness - meaning that consistently engaging in virtual environments can result in protective habituation effects. In a controlled stationary VR experiment, we found that 'VR-naive' video gamers experienced significantly less cybersickness in a virtual tunnel-travel task and outperformed 'VR-naive' non-video gamers on a visual attention task. These findings strongly motivate the use of non-VR games for training VR cybersickness resilience, with future research needed to further understand the mechanism(s) by which gamers become cybersickness resilient - potentially expanding access to VR for even the most susceptible participants.

Autonomous vehicles (AVs) must communicate their intentions to nearby road users and may use external Human-Machine Interfaces (eHMIs). Most eHMIs have focused on interaction with pedestrians at crossings. However, these may not work for cyclists, who can be anywhere around vehicles and encounter them in diverse traffic scenarios. We used participatory design with cyclists and AutoUI researchers (N = 12) collaborating in a real-world setting to design eHMIs around an actual vehicle. Participants preferred eHMIs that co-exist with traditional vehicle signals and use a single design language across traffic scenarios to communicate awareness and intent quickly without distracting their attention from the road. We used our findings to develop a taxonomy of eHMI features for cyclists, allowing us to synthesise the designs and contribute versatile eHMI concepts catered to cyclists’ needs. This is important to ensure AVs can safely navigate and interact with cyclists in all road scenarios.

Extended Reality (XR) technology brings exciting possibilities for aeroplane passengers, allowing them to escape their limited cabin space. Using nearby physical surfaces enables a connection with the real world while improving the XR experience through touch. However, available surfaces may be located in awkward positions, reducing comfort and input performance and thus limiting their long-term use. We explore the usability of passive haptic surfaces in different orientations, assessing their effects on input performance, user experience and comfort. We then overcome ergonomic issues caused by the confined space by using perceptual manipulation techniques that remap the position and rotation of physical surfaces and user movements, assessing their effects on task workload, comfort and presence. Our results show that the challenges posed by constrained seating environments can be overcome by a combination of passive haptics and remapping the workspace with moderate translation and rotation manipulations. These manipulations allow for good input performance, low workload and comfortable interaction, opening up XR use while in transit.

Standalone Virtual Reality (VR) headsets can be used when travelling in cars, trains and planes. However, the constrained spaces around transport seating can leave users with little physical space in which to interact using their hands or controllers, and can increase the risk of invading other passengers' personal space or hitting nearby objects and surfaces. This hinders transport VR users from using most commercial VR applications, which are designed for unobstructed 1-2m 360° home spaces. In this paper, we investigated whether three at-a-distance interaction techniques from the literature could be adapted to support common commercial VR movement inputs and so equalise the interaction capabilities of at-home and on-transport users: Linear Gain, Gaze-Supported Remote Hand, and AlphaCursor. First, we analysed commercial VR experiences to identify the most common movement inputs so that we could create gamified tasks based on them. We then investigated how well each technique could support these inputs from a constrained $50\mathrm{x}50\text{cm}$ space (representative of an economy plane seat) through a user study $(\mathrm{N}=16)$, where participants played all three games with each technique. We measured task performance, unsafe movements (play boundary violations, total arm movement) and subjective experience and compared results to a control 'at-home' condition (with unconstrained movement) to determine how similar performance and experience were. Results showed that Linear Gain was the best technique, with similar performance and user experience to the 'at-home' condition, albeit at the expense of a high number of boundary violations and large arm movements. In contrast, AlphaCursor kept users within bounds and minimised arm movement, but suffered from poorer performance and experience. Based on the results, we provide eight guidelines for the use of, and research into, at-a-distance techniques and constrained spaces.

We present PassengXR, an open-source toolkit for creating passenger eXtended Reality (XR) experiences in Unity. XR allows travellers to move beyond the physical limitations of in-vehicle displays, rendering immersive virtual content based on - or ignoring - vehicle motion. There are considerable technical challenges to using headsets in moving environments: maintaining the forward bearing of IMU-based headsets; conflicts between optical and inertial tracking of inside-out headsets; obtaining vehicle telemetry; and the high cost of design given the necessity of testing in-car. As a consequence, existing vehicular XR research typically relies on controlled, simple routes to compensate. PassengXR is a cost-effective open-source in-car passenger XR solution. We provide a reference set of COTS hardware that enables the broadcasting of vehicle telemetry to multiple headsets. Our software toolkit then provides support to correct vehicle-headset alignment, and then create a variety of passenger XR experiences, including: vehicle-locked content; motion- and location-based content; and co-located multi-passenger applications. PassengXR also supports the recording and playback of vehicle telemetry, assisting offline design without resorting to costly in-car testing. Through an evaluation-by-demonstration, we show how our platform can assist practitioners in producing novel, multi-user passenger XR experiences.

Ultrasound haptic patterns can be rendered by continuously moving an ultrasonic focal point. It is not known how this focal point motion affects haptic perception. We present two psychophysical experiments investigating the perception of an ultrasound haptic focal point moving along a circular path. Our first experiment finds that a sensation of motion is perceived at speeds up to 17 revs–1, similar to the ‘flutter’ sensation. Our second experiment found a linear relationship between movement speed and perceived intensity up to this speed. Our findings give new insight into ultrasound haptic perception and give designers empirical evidence to inform contactless haptic feedback design.

Auditory headsets capable of actively or passively intermixing both real and virtual sounds are in-part acoustically transparent. This paper explores the consequences of acoustic transparency, both on the perception of virtual audio content, given the presence of a real-world auditory backdrop, and more broadly in facilitating a wearable, personal, private, always-available soundspace. We experimentally compare passive acoustically transparent, and active noise cancelling, orientation-tracked auditory headsets across a range of content types, both indoors and outdoors for validity. Our results show differences in terms of presence, realness and externalization for select content types. Via interviews and a survey, we discuss attitudes toward acoustic transparency (e.g. being perceived as safer), the potential shifts in audio usage that might be precipitated by adoption, and reflect on how such headsets and experiences fit within the area of Mixed Reality.

Room-scale Virtual Reality (VR) has become an affordable consumer reality, with applications ranging from entertainment to productivity. However, the limited physical space available for room-scale VR in the typical home or office environment poses a significant problem. To solve this, physical spaces can be extended by amplifying the mapping of physical to virtual movement (translational gain). Although amplified movement has been used since the earliest days of VR, little is known about how it influences reach-based interactions with virtual objects, now a standard feature of consumer VR. Consequently, this paper explores the picking and placing of virtual objects in VR for the first time, with translational gains of between 1x (a one-to-one mapping of a 3.5m*3.5m virtual space to the same sized physical space) and 3x (10.5m*10.5m virtual mapped to 3.5m*3.5m physical). Results show that reaching accuracy is maintained for up to 2x gain, however going beyond this diminishes accuracy and increases simulator sickness and perceived workload. We suggest gain levels of 1.5x to 1.75x can be utilized without compromising the usability of a VR task, significantly expanding the bounds of interactive room-scale VR.

Young children with visual impairments tend to engage less with their surroundings, limiting the benefits from activities at school. We investigated novel ways of using sound from a bracelet, such as speech or familiar noises, to tell children about nearby people, places and activities, to encourage them to engage more during play and help them move independently. We present a series of studies, the first two involving visual impairment educators, that give insight into challenges faced by visually impaired children at school and how sound might help them. We then present a focus group with visually impaired children that gives further insight into the effective use of sound. Our findings reveal novel ways of combining sounds from wearables with sounds from the environment, motivating audible beacons, devices for audio output and proximity estimation. We present scenarios, findings and a design space that show the novel ways such devices could be used alongside wearables to help visually impaired children at school.

This paper explores the combination of multiple concurrent modalities for conveying emotional information in HCI: temperature, vibration and abstract visual displays. Each modality has been studied individually, but can only convey a limited range of emotions within two-dimensional valence-arousal space. This paper is the first to systematically combine multiple modalities to expand the available affective range. Three studies were conducted: Study 1 measured the emotionality of vibrotactile feedback by itself; Study 2 measured the perceived emotional content of three bimodal combinations: vibrotactile + thermal, vibrotactile + visual and visual + thermal. Study 3 then combined all three modalities. Results show that combining modalities increases the available range of emotional states, particularly in the problematic top-right and bottom-left quadrants of the dimensional model. We also provide a novel lookup resource for designers to identify stimuli to convey a range of emotions

We demonstrate a technique for rendering textured haptic surfaces in mid-air, using an ultrasound haptic display. Our technique renders tessellated 3D `haptic' shapes with different waveform properties, creating surfaces with distinct perceptions.

Blind children engage with their immediate environment much less than sighted children, particularly through self-initiated movement or exploration. Research has suggested that providing dynamic feedback about the environment and the child's actions within/against it may help to encourage reaching activity and support spatial cognitive learning. This paper investigated whether the accuracy of peripersonal reaching (space within arm's reach) can be improved by the use of dynamic sound from both the objects to reach for and the reaching hand itself (via a worn speaker). We ran two studies that tested the efficacy of static and dynamic audio feedback designs with blind and visually impaired young people, to identify optimal feedback designs. Study 1 was with young adults aged 18 to 22 and Study 2 involved children aged 12 to 17. The results showed that dynamic audio feedback helps to build spatial connections between the objects and the reaching hand and participants were able to reach more accurately, compared to unchanging feedback.

There are inherent associations between temperature and emotion in language, cognition and subjective experience [22,42]. However, there exists no systematic mapping of thermal feedback to models of emotion that could be used by designers and users to convey a range of emotions in HCI. A common way of classifying emotions and quantifying emotional experience is through ratings along valence and arousal dimensions, originating from Russell's circumplex model [32]. Therefore, the research in this paper mapped subjective ratings of a range of thermal stimuli to the circumplex model to understand the range of emotions that might be conveyed through thermal feedback. However, as the suitability of the model varies depending on the type of emotional stimuli [31], we also compared the goodness of fit of ratings between the circumplex and vector [8,31] models of emotion. The results showed that thermal feedback was interpreted as representing a limited range of emotions concentrated in just two quadrants or categories of the circumplex: high valence, low arousal and low valence, high arousal. Warm stimuli were perceived as more pleasant/positive than cool stimuli and altering either the rate or extent of temperature change affected both valence and arousal axes simultaneously. The results showed a significantly better fit to a vector model than to the circumplex.

Visually impaired children often have difficulty with everyday activities like locating items, e.g. favourite toys, and moving safely around the home. It is important to assist them during activities like these because it can promote independence from adults and helps to develop skills. Our demonstration shows our work towards a multimodal sensing and output system that adapts the lighting conditions at home to help visually impaired children with such tasks.

In this paper we describe a demonstration of our multimodal affective feedback designs, used in research to expand the emotional expressivity of interfaces. The feedback leverages inherent associations and reactions to thermal, vibrotactile, auditory and abstract visual designs to convey a range of affective states without any need for learning feedback encoding. All combinations of the different feedback channels can be utilised, depending on which combination best conveys a given state. All the signals are generated from a mobile phone augmented with thermal and vibrotactile stimulators, which will be available to conference visitors to see, touch, hear and, importantly, feel.

Blind children engage with their immediate environment much less than sighted children, particularly through self-initiated movement or exploration. Research has suggested that providing dynamic feedback about the environment and the child--s actions within/against it may help to encourage reaching activity and support spatial cognitive learning. This paper presents an initial study suggesting the accuracy of peripersonal reaching can be improved by the use of dynamic sound from both the objects to reach for and the reaching hand itself (via a worn speaker) that changes based on the proximity of the hand to the object. The demonstration will let attendees try the interaction and feedback designs

Research has shown that thermal feedback can be an engaging and convincing means of conveying experimenter-predefined meanings, e.g., material properties or message types. However, thermal perception is subjective and its meaning in interaction can be ambiguous. Interface designers may not be sure how users could naïvely interpret thermal feedback during interaction. Little is also known about how users would choose thermal cues to convey their own meanings. The research in this paper tested subjective interpretations of thermal stimuli in three different scenarios: social media activity, a colleague's presence and the extent of use of digital content. Participants were also asked to assign their own thermal stimuli to personal experiences, to help us understand what kinds of stimuli people associate with different meanings. The results showed strong agreement among participants concerning what warmth (presence, activity, quality) and cool mean (absence, poor quality). Guidelines for the design of thermal feedback are presented to help others create effective thermal interfaces.

Ultrasonic haptic feedback is a promising means of providing tactile sensations in mid-air without encumbering the user with an actuator. However, controlled and rigorous HCI research is needed to understand the basic characteristics of perception of this new feedback medium, and so how best to utilise ultrasonic haptics in an interface. This paper describes two experiments conducted into two fundamental aspects of ultrasonic haptic perception: 1) localisation of a static point and 2) the perception of motion. Understanding these would provide insight into 1) the spatial resolution of an ultrasonic interface and 2) what forms of feedback give the most convincing illusion of movement. Results show an average localisation error of 8.5mm, with higher error along the longitudinal axis. Convincing sensations of motion were produced when travelling longer distances, using longer stimulus durations and stimulating multiple points along the trajectory. Guidelines for feedback design are given.

Thermal feedback is a new area of research in HCI and, as such, there has been very little investigation of the impact of environmental factors on its use for interaction. To address this shortcoming we conducted an experiment to investigate how ambient temperature and humidity could affect the usability of thermal feedback. If environmental conditions affect perception significantly, then it may not be suitable for mobile interactions. Evaluations were conducted outdoors in varying environmental conditions over a period of 5 months. Results showed that the ambient temperature has a significant impact on people's ability to detect stimuli and also their perception of these stimuli. Humidity has a negligible effect for most humidity values. Despite this, previous thermal feedback design recommendations still hold in varying temperatures and humidities showing that thermal feedback is a useful tool for mobile interaction.

There has been little discussion on how the materials used to create deformable devices, and the subsequent interactions, might influence user performance and preference. In this paper we evaluated how the stiffness and required deformation extent (bending up and down bimanually) of mobile phone-shaped deformable devices influenced how precisely participants were able to move to and maintain target extents of deformation (bend). Given the inherent haptic feedback available from deforming devices (over rigid devices), we also compared performance with, and without, external visual feedback. User perception and preference regarding the different devices were also elicited. Results show that, while device stiffness did not significantly affect task performance, user comfort and preferences were strongly in favour of softer materials (0.45 N·m/rad) and moderate amounts of deformation. Removing external visual feedback led to less precise user input, but inaccuracy remained low enough to suggest non-visual interaction with deformable devices is feasible.

This paper expands the repertoire of non-visual feedback for mobile interaction, established through Earcons and Tactons, by designing structured thermal cues for conveying information. Research into the use of thermal feedback for HCI has not looked beyond basic 'yes-no' detection of stimuli to the unique identification of those stimuli. We first designed thermal icons that varied along two parameters to convey two pieces of information. We also designed intramodal tactile icons, combining one thermal and one vibrotactile parameter, to test perception of different tactile cues and so evaluate the possibility of augmenting vibrotactile displays with thermal feedback. Thermal icons were identified with 82.8% accuracy, while intramodal icons had 96.9% accuracy, suggesting thermal icons are a viable means of conveying information in mobile HCI, for when audio and/or vibrotactile feedback is not suitable or desired.

Thermal stimulation is a rich, emotive and salient feedback channel that is well suited to HCI, but one that is yet to be fully investigated. Thermal feedback may be suited to environments that are too loud for audio or too bumpy for vibrotactile feedback. This paper presents two studies into how well users could detect hot and cold stimuli presented to the fingertips, the palm, the dorsal surface of the forearm and the dorsal surface of the upper arm. Evaluations were carried out in static and mobile settings. Results showed that the palm is most sensitive, cold is more perceivable and comfortable than warm and that stronger and faster-changing stimuli are more detectable but less comfortable. Guidelines for the design of thermal feedback are outlined, with attention paid to perceptual and hedonic factors.

Thermal feedback is a new area of research in HCI. To date, studies investigating thermal feedback for interaction have focused on virtual reality, abstract uses of thermal output or on use in highly controlled lab settings. This paper is one of the first to look at how environmental factors, in our case clothing, might affect user perception of thermal feedback and therefore usability of thermal feedback. We present a study into how well users perceive hot and cold stimuli on the hand, thigh and waist. Evaluations were carried out with cotton and nylon between the thermal stimulators and the skin. Results showed that the presence of clothing requires higher intensity thermal changes for detection but that these changes are more comfortable than direct stimulation on skin.

This paper presents a study looking into the effects of walking and the use of visual and audio feedback on the application of pressure for linear targeting. Positional and Rate-based control methods are compared in order to determine which allows for more stable and accurate selections, both while sitting and mobile. Results suggest that Rate-based control is superior for both mobile (walking) and static (sitting) linear targeting, and that mobility significantly increases errors, selection time and subjective workload. The use of only audio feedback significantly increased errors and task time for Positional control and static Rate-based control, but not mobile Rate-based control. Despite this, the results still suggest that audio control of pressure interaction while walking is highly accurate and usable.

Despite many successes in desktop applications, little work has looked at the use of pressure input on mobile devices and the different issues associated with mobile interactions e.g. non-visual feedback. This study examined pressure input on a mobile device using a single Force Sensing Resistor (FSR) with linearised output as a means of target selection within a menu, where target menu items varied in size and location along the z-axis. Comparing visual and audio feedback, results showed that, overall, eyes-free pressure interaction reached a mean level of 74% accuracy. With visual feedback mean accuracy reached 85%. Participants could accurately distinguish up to 10 pressure levels when given adequate feedback indicating a high level of control.