Thermal imaging plays a vital role in search and rescue, yet little is known about how color palette selection affects human recognition performance. While AI-based detection dominates current research, manual identification remains crucial in unpredictable or ethically sensitive conditions. This study evaluates three commonly used thermal palettes, White Hot, Ironbow, and Rainbow, using a recently available dataset of challenging aerial images. In an online user study with 75 participants, task time, hit accuracy, and not found responses were measured. Results show that White Hot enabled faster and more accurate performance, while Rainbow significantly hindered detection. These findings offer practical guidance for designing thermal interfaces and highlight the importance of perceptual optimization in augmented vision systems.

This study investigates the effects of dynamic and static visual manipulations, specifically darkening vignettes, on user experience and task performance in extended reality (XR) environments. By using heart rate (HR) as physiological feedback, the study explores how dynamic visual adaptations based on HR impact immersion, task focus, and user comfort. A user study (n = 16) found that while dynamic vignettes could increase immersion and encourage a more focused approach, they also induced discomfort, anxiety, and reduced task performance for some participants. The results reveal that although users may adapt to these visual effects over time, the variability in emotional and physical reactions suggests that such dynamic visual adaptations based on physiological signals should be carefully calibrated to balance enhanced immersion with user comfort. This research contributes to the understanding of adaptive XR environments and the role of physiological feedback in shaping user experience.

The emoji keyboard for collecting feedback in-the-wild

Numerous digital games and media with historical themes aim to educate or engage audiences with heritage. When developing a historical video game, some of the most critical design decisions are centered around finding the balance between an accurate presentation of historical facts and engaging gameplay. This paper examines the game developer's role in selecting and presenting historical content through a case study of a mobile game development process. The design choices and developers' positions related to using historical facts are examined through thematic analysis of interview data and game design documents. Recurring themes in the data reveal a constant interplay between game features and historical content, supported by historical knowledge and technology. In small teams, individual developers often make crucial design decisions while performing multiple roles. As key findings, we report that the resourcing and timing of historical research significantly impacts developers' decisions, and note varying degrees of interest in historical accuracy within the development team.

Emojis are increasingly used in tools to evaluate user opinions, typically through happy-to-sad rating scales. We extended this concept by developing an emoji-based User Experience Questionnaire (UEQ), a well-established UX evaluation tool. Our design process involved selecting emojis corresponding to UEQ adjectives and creating bipolar emoji scales. The final tool covered 11 scales but could not represent the novelty subscale due to limitations of the emoji language. A comparative user study showed statistically similar results for 7 out of 11 scales between the emoji-based and word-based UEQs. Although the word-based version was preferred, our findings suggest that emoji-based scales can be a viable alternative for UX evaluation. Our work provides new insights into the potential and limitations of using emojis in UX research. Supplementary materials include a ready-to-use UEQ-Emoji form and an analysis tool.

Artificial Intelligence (AI) solutions are becoming prevalent in almost all aspects of human life. However, their acceptance may be limited by a lack of transparency of how the AI works. Explainable AI (XAI) aims to provide the users of AI systems with an understanding of why decisions are made, increasing trust in the system. To date, research into XAI has focused on the use of graphical user interfaces, presenting numerical, textual or graphical explanations. However, AI is increasingly being used in systems that include physical devices, and hence the need for explainability in physical or tangible user interfaces (TUI) is also increasing. We present an initial conceptual framework for tangible explainable AI (TangXAI), which identifies the potential approaches of communicating XAI through physical artifacts, using the concepts of data physicalization and tangible interaction. The framework provides a basis into which ongoing research of tangible explainable AI can be mapped and related research gaps identified.

We investigate the user experience of taking a remote museum tour with 360 video technologies. We compare the experience of viewing a 360 video feed on a laptop screen vs. a 360 virtual reality (VR) video experienced through a head-mounted display (HMD). Our salient findings from a user study (n = 10) highlight that HMD VR provides a better immersion and sense of control for users. However, the HMD VR user experience suffers from the lack of personal contact, such as eye contact with the guide, discontinuities in the visual presentation, and missing multimodal contextual cues. The research contributes to the design of remote tourism services.

Online surveys present a quick and efficient method to collect user experience data. However, they are less effective at extracting qualitative data. Due to response fatigue when answering open-ended questions, the quality of responses may be poor, and participants can skip answering individual questions, or drop out from the survey entirely, potentially introducing bias. To address these challenges, we developed a prototype tool that enables a test moderator to initiate a chat intervention with a participant at any point during the completion of an online survey. Through this approach, participants can be prompted to return to complete unanswered questions or provide clarification to given answers. A functional prototype system has been implemented and, as future work, will be evaluated with a variety of content and question types.

Abstract This paper addresses graveyards as a context for designing interactive technology, especially pervasive displays and the presentation of information related to graves and the dead. We present our research containing three user studies: a focus group–based study on perceptions of different display technologies in the cemetery context, evaluation of a gravestone display prototype, and a user study with a graveyard navigator prototype. Whereas, HCI research surrounding death has so far largely focused on an individual’s digital remains, our focus is on the physical graveyard setting. We contribute to understanding the potential impacts and opportunities of interactive technology in this design context. Our salient findings highlight the cultural sensitivity and importance of dignity related to the context, unobtrusiveness of the technology, and concerns for privacy and social acceptability. Concepts taking into account these design aspects were of interest for those researching family histories, and visitors seeking improved navigation for the graveyard.

One mechanism for the spread of the COVID-19 virus is through contaminated surfaces, e.g. tables in cafes, trains or public libraries. This mechanism may be prevented by cleaning the table surface between each use. In practice, this can be optimized by directing arriving users to clean tables and highlighting to staff which surfaces require cleaning. One approach to achieve this is through making the table surface itself smart and indicate its clean or dirty status. In the CleanLeaf table we demonstrate two approaches to integrating indication in a table surface, LEDs under a thin wood veneer and electrochromic displays. Rather than explicit light emitting display based signage, the design demonstrates calm computing with the display forming an integral part of the surface design.

Workplace stress is a growing problem, which is often not identified by sufferers and those around them until it becomes chronic. Moreover, admitting to feel stressed is a highly private and therefore sensitive topic, particularly at work. Informed by the findings from six in-depth interviews, we designed the manually self-adjusted wearable BuSiNec: a Busyness Signifying Necklace. 18 participants wore it at their workplace and reported on their experiences and their usage behavior through a diary and in a focus group interview. Our findings indicate that BuSiNec supports self-reflection on stress and further stimulates valuable discussions among co-users which in turn increased mutual consideration. Participants were conscious of their their displayed busyness status towards others and used the display to encourage or discourage discussions and interruptions, or as a warning of upcoming hurry. From these findings, we derive recommendations for the integration of affective state information in wearable displays.

Medical images taken with mobile phones by patients, i.e. medical selfies, allow screening, monitoring and diagnosis of skin lesions. While mobile teledermatology can provide good diagnostic accuracy for skin tumours, there is little research about emotional and physical aspects when taking medical selfies of body parts. We conducted a survey with 100 participants and a qualitative study with twelve participants, in which they took images of eight body parts including intimate areas. Participants had difficulties taking medical selfies of their shoulder blades and buttocks. For the genitals, they prefer to visit a doctor rather than sending images. Taking the images triggered privacy concerns, memories of past experiences with body parts and raised awareness of the bodily medical state. We present recommendations for the design of mobile apps to address the usability and emotional impacts of taking medical selfies.

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.

We explore the possibilities of augmented and virtual reality (AR and VR) as co-design tools for service design. Four expert service designers, working in industry, tried out and discussed different VR and AR based tools: Head mounted display (HMD) based VR and AR, and projected environments. The findings emphasize that HMD techniques are not favored, as they isolate the wearer from the co-design situation and hinder the observation of emotions and expressions. Projection of the design context was positively commented, as supporting collaboration in co-design sessions.

Sliders are one of the most fundamental components used in touchscreen user interfaces (UIs). When entering data using a slider, errors occur due e.g. to visual perception, resulting in inputs not matching what is intended by the user. However, it is unclear if the errors occur uniformly across the full range of the slider or if there are systematic offsets. We conducted a study to assess the errors occurring when entering values with horizontal and vertical sliders as well as two common visual styles. Our results reveal significant effects of slider orientation and style on the precision of the entered values. Furthermore, we identify systematic offsets that depend on the visual style and the target value. As the errors are partially systematic, they can be compensated to improve users' precision. Our findings provide UI designers with data to optimize user experiences in the wide variety of application areas where slider based touchscreen input is used.

In this paper, we investigate the use of mobile technology in an underexplored context, the bed that couples share. Despite large amounts of research on the impact of pre-bedtime technology use on our sleep and mental state, scant research in the HCI field focuses on the physical bed as a negotiated site of technology use by couples. This paper explores (a) the meaning of the bed accessed by mobile technology and (b) the strategies of both individual and shared technology use in bed, in the context of couple's relationships. We investigate the effects of mobile technology to couples' bed-sharing practices through in-depth interviews (n = 12) and an online survey (n = 117). We report on creative and negotiated bodily practices of mobile technology use by couples in bed, and the perceived effects on couples' verbal and physical interaction and the intimacy of the bed.

We present the design and prototype of the Linn Dress, a transforming dress that allows its wearer to dynamically reveal and conceal areas of skin, as they feel comfortable and appropriate for different contexts. Electrochromic displays are employed as the elements enabling the garment's dynamic transparency. The Linn Dress is designed for office workers with a lively lifestyle, who shift directly from the work environment to social evening events. The dress presents professional working attire, and when transformed to reveal exciting open cuts and patterns, a cocktail dress.

VitaBoot is a footwear concept incorporating dynamic graphical patterns which indicate the wearer's activity level. Whilst shoes are an important element in fashion wear and a lot of research has focused on shoes as input devices, comparable few concepts have explored the potential for their use as an output space. We created a boot design that incorporates dynamic patterning through the use of electrochromic (EC) displays embedded in the surface material. The boot was designed and constructed from scratch, using a faux leather material, ensuring the overall aesthetic of the design, including the integration of the required control electronics and power source. The boot connects wirelessly to a chest-worn heart rate belt, and pattern changes indicate when the wearer's heart rate is above a predefined threshold. VitaBoot demonstrates the potential for dynamic shoe patterning for aesthetic or functional means, and the suitability of flexible, low-power EC display technology in this domain.

Focusing on pedestrian safety in the era of automated vehicles, we investigate the interaction between pedestrians and automated cars. In particular, we investigate the influence of external car displays (ECDs) on pedestrians' crossing behavior, and the time needed to make a crossing decision. We present a study in a high-immersion VR environment comparing three alternative car-situated visualizations: a smiling grille, a traffic light style indicator, and a gesturing robotic driver. Crossing at non-designated crossing points on a straight road and at a junction, where vehicles turn towards the pedestrian, are explored. We report that ECDs significantly reduce pedestrians' decision time, and argue that ECDs support comfort, trust and acceptance in automated vehicles. We believe ECDs might become a valuable addition for future vehicles.

The amount of status and notification information available to people is increasing beyond the capacity of the current primary delivery channel of smartphones. Ambient displays, e.g. embedded in the home or work environment present an alternative channel, suited to less critical information. We created an ambient display by manipulating the natural shadows cast by a house plant to carry information. To explore user perceptions of the shadow display we evaluated it in a focus group (n = 6). Whilst participants saw some potential in the approach, there were concerns about identifying the meaning of the display and the psychological effects of distorting reality. The work highlights the potential for designers to explore the use of functional shadows to carry non-critical information.

Virtual reality offers a potential solution to enable visiting inaccessible cultural heritage sites. We present the design, prototyping and evaluation (n = 6) of a virtual visit to a historic graveyard. The Salla World War II graveyard is located in an inaccessible border zone between Finland and Russia. Our virtual graveyard, accessed through a head mounted display, aimed to create an as accurate as possible simulation of the Salla graveyard, including its atmosphere. Users are enabled to navigate the virtual graveyard and place a candle on a grave. Although the simulation was considered immersive, participants wished for more authenticity and details, e.g. being able to light the virtual candle. The work opens discussion on the need for dignity in the design of virtual experiences for sensitive cultural heritage sites.

We investigate an unconventional user interface (UI) material, water, and how applying it to a finger-touch based input affects the user experience (UX). We compare the use of touchscreen, mechanical and liquid covered sliders, and three different approaches of how water is applied to the surface of the slider. The salient findings of our user study (n=25) show that liquid changes the perception of the slider control making it more hedonic and experiental. When interacting with water, users prefer larger and more free-form gestures, and factors such as depth and temperature of the liquid affect the experience. Our work provides information for interaction designers focusing on user experience, unconventional materials for interactive systems, aesthetics, and calm UIs.

We present the design and prototype of the Idle Stripes shirt, which is an aesthetic, clothing-integrated display, reflecting the wearer's physical activity in an ambient manner. The design is targeted to be smart business-wear for an office worker, which creates awareness of immobility periods during typical sitting-intensive office work. Long periods of such sitting are known to be health risks. The Idle Stripes shirt promotes healthy working, encouraging the wearer to break up their office desk work with walking breaks. The design prototype is constructed of a fabric with integrated optical fibers, which are illuminated based on the sitting time detected by an app running on the wearer's mobile phone.

This tutorial addresses the application of service design methods for Human Computer Interaction (HCI). The tutorial will cover methodological and practical aspects of service design, focusing on three key tools -- stakeholder maps, consumer journey and business model canvas. The service design methods are tried out with interactive exercises, where participants in groups apply the methods to a design case. Service design is an emerging field, which applies a holistic design approach to understand and design for human experience. With an increasing number of digital services, both in commercial and public frontiers, it is important to develop services that are easy to use, and where the consumer's journey through the service pathways is fluent and consistent.

In this paper, we consider graveyards as a design context, and present a prototype graveyard-navigator mobile application. The app enables search and navigation to particular graves and provides information on family connections between the buried. We evaluate the application, and chart general perceptions of technology use in graveyards through in situ interviews in a graveyard (n=12). Our findings reveal that navigating in a graveyard with the mobile application was found both useful and acceptable, whereas visualizing family trees was perceived with mixed feelings, due to privacy concerns. The perceptions of technology use in the graveyard emphasized the importance of unobtrusiveness and respect for the peace and privacy of other visitors, as well as for the context.

We present Connected Candles, a peripheral aesthetic display for creating awareness and connecting people in long distance relationships (LDRs). The system consists of a pair of candle stands, which each include two candles, one being a real candle and the other electronic. The candle stands are placed at different locations, and are connected over the Internet such that lighting the real candle illuminates the electronic candle at the distant location. We present the concept's design, prototype, and its evaluation in a focus group based user study. Our findings illustrate the potential for using candles as a peripheral user interface to mediate emotional communication between couples in long-distance relationships.

We present our prototype application of head mounted display (HMD) based augmented reality (AR) for use in in factory contexts. The prototype was evaluated in a focus group based user study held at an industrial production line. The prototype was implemented using a Microsoft HoloLens, and supported placing different AR notifications, such as machinery fault or maintenance messages, in the environment. The prototype was used as a stimulus in the focus group consisting of factory workers (n = 6) for exploring the potential use of HMD AR in the industrial production line context. As the main findings, we identified two themes where factory workers saw HMD AR as a potential technology: in task instruction, and in confirming correct functionality. The technology was seen as having potential for collaborative tasks, especially for receiving instructions. Hands-free usage and ability to interact whilst wearing gloves were highly appreciated.

We present a work in progress, enabling an audience to influence a painter, through electrical muscle stimulation (EMS) to co-create visual art works. Two sets of EMS pads are positioned on the painter's arm such that stimulation pulses, triggered on a collocated tablet interface by audience members, cause deviation in the ongoing brushstroke. LEDs co-located with the EMS pads provide additional visual feedback to the audience of stimulation delivery. In an initial trial, rather than focusing on co-creation, the audience amused themselves by mischievously diverting the painter from his work.

We present BreathScreen, a concept where clouds created by breathing are used as a projection surface for a picoprojector, creating an ephemeral user interface. In cold weather conditions the clouds are created naturally by warm breath condensing, but in other conditions an electric vaporizer may be used. We present an initial evaluation of the concept in a user study (n = 8), utilising a vaporizer-based BreathScreen prototype. The concept was positively received by study participants as a natural, hands-free interface and considered magical and aesthetically beautiful. Additionally, we provide guidance on the quantity of content that may be displayed on a BreathScreen, which is limited both by the length of a human breath and the contrast of the system.

The widespread popularity of Pokémon GO presents the first opportunity to observe the geographic effects of location-based gaming at scale. This paper reports the results of a mixed methods study of the geography of Pokémon GO that includes a five-country field survey of 375 Pokémon GO players and a large scale geostatistical analysis of game elements. Focusing on the key geographic themes of places and movement, we find that the design of Pokémon GO reinforces existing geographically-linked biases (e.g. the game advantages urban areas and neighborhoods with smaller minority populations), that Pokémon GO may have instigated a relatively rare large-scale shift in global human mobility patterns, and that Pokémon GO has geographically-linked safety risks, but not those typically emphasized by the media. Our results point to geographic design implications for future systems in this space such as a means through which the geographic biases present in Pokémon GO may be counteracted.

Being in nature is typically regarded to be calming, relaxing and purifying. When in nature, people often seek to be mobile through physical activity such as hiking. But also, nature provides an opportunity for meditative, mindful or inspiring experiences remote from urban everyday life. Mobile Technologies such as sports tracking technologies, electronic tourist guides, mobile phone integrated cameras and omnipresent social media access, have potential to both enhance and disrupt a user's interaction with and experience of nature. This MobileHCI workshop follows on from the first successful NatureCHI workshop by focusing on the challenges associated with the design of mobile technologies that support unobtrusive interaction in nature.

In this note, we study interaction with a finger worn ring, focusing on interaction enabled by the ring form factor. We report on 2 user studies, the first (n=13) investigating preferences for different interactions, whilst the second (n=7) explores usage contexts and applications. Twelve different ways of interacting with a ring were evaluated, including e.g. changing the placement of the ring on the fingers and moving the ring along or around a finger. Based the study results, the practical usability and concerns with each of the ring interactions is discussed. Whereas the concept was generally well received, the main concerns related to false positives, losing the ring e.g. when changing finger, and limitations from the rigid size of the form factor.

Flying drones have the potential to act as navigation guides for pedestrians, providing more direct guidance than the use of handheld devices. Rather than equipping a drone with a display or indicators, we explore the potential for the drone's movements to communicate the route to the walker. For example, should the drone maintain a constant distance a few meters in front of the pedestrian, or should it position itself further along the navigation route, acting as a beacon to walk towards? We created a set of flying drone gestures and evaluated them in an online survey (n = 100) and an in-the-wild user test (n = 10) where participants were guided on a walking route by a flying drone. As a result, we propose an initial set of drone gestures for pedestrian navigation and provide further design recommendations.

The future vision of commonplace, everyday wear of augmented reality glasses, brings potential to the fashion world, where physical and virtual aspects can be blended to create an overall aesthetic. An enabler for this is the integration of computer-readable visual markers as part of clothing design. We introduce a design space for the use of visual markers on garments, with aspects of visual style, tag size, content, content type, customizability, attachment technique, and reader application. Two prototypes of clothing-integrated visual marker solutions, viewed with a mobile augmented reality (AR) application, are presented and evaluated via a focus group study, an online survey and an in-the-wild study. Our findings highlight that when designing wearable computing garments, the visual design is very important for acceptability, and that a user's personal style largely dictates their preference for the concept and willingness to wear the garment. Wearable AR markers were considered as suitable for wear in social situations, such as parties or events, and as a tool for group cohesion or for showing campaign or ideological information.

Mobile devices are currently the most commonly used platform to experience Augmented Reality (AR). Nevertheless, they typically provide a less than ideal ergonomic experience, requiring the user to operate them with arms raised. In this paper we evaluate how to improve the ergonomics of AR experiences by modifying the angle between the mobile device's camera and its display. Whereas current mobile device cameras point out vertically from the back cover, we modify the camera angle to be 0, 45 and 90 degrees. In addition, we also investigate the use of the smartwatch as an AR browser form factor. Key findings are, that whilst the current approximately see-through configuration provides the fastest task completion times, a camera offset angle of 45° provides reduced task load and was preferred by users. When comparing different form factors and screen sizes, the smartwatch format was found to be unsuitable for AR browsing use.

We present an in-the-wild user study (n=27) investigating the combination of two mobile technologies - picoprojectors and marker based information browsing. We studied a tour, where the tour guide used combinations of fixed and projected elements to present information, and compare four cases: A) as a baseline, a traditional paper poster, B) a projected poster, C) a printed paper fiducial marker, viewed through a mobile device browser application, and D) a projected fiducial marker viewed through a mobile device browser application. As a contribution, we present a novel approach to ad hoc projection of markers, and the findings of the user study. Here, the salient findings suggest that the techniques using markers have the potential to enhance tour participants' experience, but face practical challenges due to lighting conditions and image stability.

This paper describes the use of a head mounted display as a design tool to gain better understanding of the issues faced by visually impaired people. The Oculus Rift Head Mounted Display (HMD) was used to navigate through a virtual 3D city model whilst conducting wayfinding and target location tasks. In addition to the baseline of normal vision, we simulated visual disabilities (macular degeneration. cataracts, glaucoma and myopia), such that the user experienced them in first person. We evaluated the system with 14 design students, who found the system useful and helpful in understanding the challenges faced by the visually impaired. The method can be applied to the early design phases of architectural and space design, where 3D models are increasingly commonly used.

Until today, mobile computing has been very much confined to conventional computing form factors, i.e. laptops, tablets and smartphones, which have achieved de facto design standards in outlook and shape. However, wearable devices are emerging, and especially glasses are an appealing form factor for future devices. Currently, although companies such as Google have productized a solution, little user research and design exploration has been published on either the user preferences or the technology. We set ourselves to explore the design directions for smart glasses with user research grounded use cases and design alternatives. We describe our user research utilizing a smart glasses design probe in an experience sampling method study (n=12), and present a focus group based study (n=14) providing results on perceptions on alternative industrial designs for smart glasses.

In this demo, we present a set-up that utilizes augmented reality (AR) in a display set-up combining a public and a private display for presenting health related information. Our installation includes a life-size poster of a human body, which is viewed through a mobile phone camera viewfinder that augments different body parts with health related data. We envision that this kind of set-up could be utilized in contexts where informative posters or similar are commonly used, and where people would benefit from accessing personal wellness or health information, such as a gym or medical doctor's waiting room.

We present an interactive cinema concept, where the audience can interact with the movie through an interactive pillow. We report on a background study (n=30) and a study evaluating a simulated tangible UI concept (n=10). Our findings indicate that tangible UIs have potential as a non-distractive interaction medium, e.g. as they don't create light pollution, can be used in different postures, and allow detection of spontaneous input actions such as squeezing. The results also show that people are interested in seeing records of not only their own performance, but also of the reactions and highlights experienced by their fellow spectators.

Mobile stereoscopic 3D (S3D) user experience (UX) design has not yet been widely studied. Stereoscopy in today's products is used for visual design purposes, whilst the potential for holistic interaction design and utilitarian aspects have been neglected. In this paper we introduce the design, implementation and evaluation of a mobile S3D phonebook application. In the application stereoscopy was used to augment the 2D user interface (UI) design to provide information related to the time when the last call with each phonebook contact was made. We describe the results of the pilot study charting the design directions, laboratory study of first impressions, and results of a field trial, where 21 participants used the application for a few days. The S3D UI design provoked first impressions related to entertainment and 2D UI to practical qualities, whereas the field study showed that our S3D phonebook design successfully demonstrated that utilitarian value can be incorporated to the design.

Mobile user interfaces (UIs) utilizing stereoscopic 3D have so far been driven predominantly by visual design, and when interaction design has been considered, the focus has been on single user use cases. In this paper, we introduce a novel way to utilize stereoscopy in a mobile user interface in a collaborative task. We define a shared space, appearing below the screen level, which is used in a collaborative task of sharing mobile phone photos. Two users are able to share content by moving items between the private layer, at zero parallax, and shared layer, at positive parallax. We developed the application through an iterative design process including two user studies (n=27, n=19). We report positive evaluation results especially in regard of the utilitarian aspects of the UI design.

Accidental triggering of unwanted interaction when using a handheld touch screen device is a problem for many users. Accidental touches on capacitive touch screen based mobile telephones were analyzed in a user test. Patterns that are characteristic of unintentional touches were identified. Layout guidelines to reduce the amount of unintentional touches are presented. Additionally, filtering criteria is defined that rejected 79.6% of unintentional touches whilst rejecting only 0.8% of intentional touches.

In this paper we describe a novel interaction method for interacting with mobile devices without the need to access a keypad or a display. A tap with a hand can be reliably detected e.g. through a pocket by means of an acceleration sensor. By carefully designing the user interface, the tap can be used to activate logically similar functionalities on the device, leading to a simple but useful interaction method. We present results of user tests aimed at studying the usability of various tap input based user interface applications.