Comic layouts are increasingly shaped by the interaction affordances of reading devices, such as scrollable smartphone comics. eXtended Reality (XR) headsets are emerging media consumption devices, offering spatial affordances for new comic layouts. We investigated how XR could enhance comic experiences through participatory design with comic creators, readers, and HCI experts. Participants used ComiXR, our novel XR comic platform, to adapt a print comic for XR while thinking aloud. Participants preferred spatially placed panels that use depth to separate characters from backgrounds. Ambient sound and haptics enhanced immersion, while eye-tracking addressed limitations, e.g. hiding spoilers. However, comic creators expressed potential difficulty in authoring these non-visual elements. Participants explained that XR comic layouts could change between stationary and public mobile settings, where social acceptability and situational awareness become prominent challenges. Our findings support the continued cultural and artistic significance of comics and identify new use cases for XR.

Automated vehicles (AVs) must communicate their yielding intentions to pedestrians at crossings. External Human-Machine Interfaces (eHMIs, on-vehicle displays) are promising solutions, but were primarily tested with walking pedestrians. Runners are a significant pedestrian group who move faster and face distinct bodily and perceptual demands, raising questions about how pedestrian activity influences eHMI use. We conducted an outdoor study using an augmented reality simulator. Participants navigated a virtual crossing while walking and running; an approaching AV displayed one of three eHMIs: red/green colour-changing lights, animated cyan lights, or no-eHMI. No-eHMI consistently underperformed. Walkers mostly stopped and validated eHMI signals with vehicle behaviour; they processed both eHMI animations and colour changes effectively. Runners experienced greater time pressure to cross, increasing reliance on the eHMI over vehicle behaviour. They preferred colour changes over animation for rapid decisions. These findings are crucial for promoting eHMI inclusivity and physical wellbeing as AVs join our roads.

User authentication on head-mounted displays (HMDs) relies on passwords, which are cumbersome to input and susceptible to shoulder-surfing attacks. Recent research has revealed that behavioral signals collected during common HMD tasks are highly distinctive between users. Building on these findings, this paper presents a knowledge-driven behavioral authentication system for HMDs. Our system leverages user-defined gestures as cues and trains an anomaly detector on hand joint motion signals for each user. To evaluate effectiveness, we conducted a comprehensive multi-session user study (n = 20) and an observation attack study (n = 10). The results show that gestures secured with joint motions are resilient to worst-case scenario video-based observation attacks (AUC = 0.97, EER = 3.58%) and maintain high recall performance over one week (AUC = 0.93, EER = 9.82%). These findings suggest that user-generated biometric hand gestures offer a promising approach to securing HMDs.

Tracking hand poses on wrist-wearables enables rich, expressive interactions, yet remains unavailable on commercial smartwatches, as prior implementations rely on external sensors or custom hardware, limiting their real-world applicability. To address this, we present WatchHand, the first continuous 3D hand pose tracking system implemented on off-the-shelf smartwatches using only their built-in speaker and microphone. WatchHand emits inaudible frequency-modulated continuous waves and captures their reflections from the hand. These acoustic signals are processed by a deep-learning model that estimates 3D hand poses for 20 finger joints. We evaluate WatchHand across diverse real-world conditions—multiple smartwatch models, wearing-hands, body postures, noise conditions, pose-variation protocols—and achieve a mean per-joint position error of 7.87 mm in cross-session tests with device remounting. Although performance drops for unseen users or gestures, the model adapts effectively with lightweight fine-tuning on small amounts of data. Overall, WatchHand lowers the barrier to smartwatch-based hand tracking by eliminating additional hardware while enabling robust, always-available interactions on millions of existing devices.

Zooming and panning are fundamental input actions for exploring complex 2D and 3D scenes and data such as images, maps, and designs. Multi-touch zoom/pan interactions have been proven effective on mobile devices, and have been directly ported to HMDs, where they are typically accomplished by analogous but relatively large-scale movements of both hands. We argue that such motions are inefficient and induce fatigue and explore how the eye-tracking features of HMDs can be leveraged to achieve improvements. We evaluated three interaction techniques that combine gaze with two-handed, one-handed, and head-based input in a study (N = 24) that contrasts them against a baseline two-handed technique. The results indicate that gaze-assisted two- and one-handed techniques outperform the baseline (17%-36% faster), while our head-based technique achieves similar performance to the Baseline but leaves the hands free for other tasks. We further developed a VR application demonstrating these techniques and validating their practical applicability.

Eye tracking offers new opportunities for interaction and data collection as users adopt head-mounted displays (HMDs). However, most HMDs either lack a built-in eye tracker or restrict access to gaze data, preventing researchers from realizing their full potential. Third-party eye trackers are a potential solution; however, existing methods for integrating them into HMDs are rarely evaluated and heavily depend on the specific software platform or device. Therefore, we present a validated open-source framework for cross-device eye tracking. We developed the framework on Pupil Labs Neon and assessed performance across three representative HMDs—the Apple Vision Pro, Meta Quest 3, and XREAL Air 2 Ultra. Results showed our framework significantly outperformed Pupil Lab’s implementation on the Quest 3 while maintaining consistent accuracy across other devices. By releasing the framework, this work establishes a validated foundation for cross-device gaze tracking, enabling accessible and reproducible eye tracking research in augmented and virtual reality environments.

Wireless earbuds are an appealing platform for wearable computing on-the-go. However, their small size and out-of-view location mean they support limited different inputs. We propose finger identification input on earbuds as a novel technique to resolve these problems. This technique involves associating touches by different fingers with different responses. To enable it on earbuds, we adapted prior work on smartwatches to develop a wireless earbud featuring a magnetometer that detects fields from a magnetic ring. A first study reveals participants achieve rapid, precise earbud touches with different fingers, even while mobile (time: 0.98s, errors: 5.6%). Furthermore, touching fingers can be accurately classified (96.9%). A second study shows strong performance with a more expressive technique involving multi-finger double-taps (inter-touch time: 0.39s, errors: 2.8%) while maintaining high accuracy (94.7%). We close by exploring and evaluating the design of earbud finger identification applications and demonstrating the feasibility of our system on low-resource devices.

Smartwatches offer powerful features, but their small touchscreens limit the expressiveness of the input that can be achieved. To address this issue, we present, and open-source, the first sonar-based around-device input on an unmodified consumer smartwatch. We achieve this using a fine-grained, one-dimensional sonar-based finger-tracking system. In addition, we use this system to investigate the fundamental issue of how to trigger selections during around-device smartwatch input through two studies. The first examines the methods of double-crossing, dwell, and finger tap in a binary task, while the second considers a subset of these designs in a multi-target task and in the presence and absence of haptic feedback. Results showed double-crossing was optimal for binary tasks, while dwell excelled in multi-target scenarios, and haptic feedback enhanced comfort but not performance. These findings offer design insights for future around-device smartwatch interfaces that can be directly deployed on today's consumer hardware.

The advancement of wearable intelligent systems presents a unique opportunity to transform how humans interact with digital content. This workshop explores the design of Interactive Multimodal Information Retrieval and Access systems specifically tailored for Heads-Up Computing environments. By leveraging multimodal inputs, such as voice, gaze, and gesture, these systems enable real-time, hands-free access to digital information, facilitating seamless and efficient interaction. The goal is to support tasks requiring rapid information access in dynamic environments while ensuring users remain "heads-up" and engaged with the real world. This half-day workshop will share research outcomes and best practices, foster community building, and facilitate discussions on key challenges. By bringing together researchers and practitioners, it aims to drive further advancements in both research and practical applications within this rapidly evolving field.

Wearable Augmented Reality headsets are inherently mobile: they enable hands-free and immersive interaction while on the go.Despite this, research into input methods that cater to mobility issues, such as the instabilities introduced by canonical tasks such as walking, remains in its infancy.This paper addresses this omission by presenting StabilizAR, a technique to enhance head cursor input while walking.It introduces a novel cursor velocity limit activated by the mutual alignment of head and eye vectors that enhances fine-grained targeting without compromising input speed during large-scale cursor motion.It integrates this with a target scoring system that reduces the precision required during selection by accruing proximity-based estimates of a user's intended target.Two studies show these combined techniques dramatically increase targeting performance-boosting success rates from 6% to 91% while mobile-and elevate measures of usability and user preference.They show StabilizAR's potential to enable genuinely mobile HMD use.

Group dance, a sub-genre characterized by intricate motions made by a cohort of performers in tight synchronization, has a longstanding and culturally significant history and, in modern forms such as cheerleading, a broad base of current adherents. However, despite its popularity, learning group dance routines remains challenging. Based on the prior success of interactive systems to support individual dance learning, this paper argues that group dance settings are fertile ground for augmentation by interactive aids. To better understand these design opportunities, this paper presents a sequence of user-centered studies of and with amateur cheerleading troupes, spanning from the formative (interviews, observations) through the generative (an ideation workshop) to concept validation (technology probes and speed dating). The outcomes are a nuanced understanding of the lived practice of group dance learning, a set of interactive concepts to support those practices, and design directions derived from validating the proposed concepts. Through this empirical work, we expand the design space of interactive dance practice systems from the established context of single-user practice (primarily focused on gesture recognition) to a multi-user, group-based scenario focused on feedback and communication.

This paper investigates the use of through-skull sound conduction to authenticate smartglass users. We mount a surface transducer on the right mastoid process to play cue signals and capture skull-transformed audio responses through contact microphones on various skull locations. We use the resultant bio-acoustic information as classification features. In an initial single-session study (N=25), we achieved mean Equal Error Rates (EERs) of 5.68% and 7.95% with microphones on the brow and left mastoid process. Combining the two signals substantially improves performance (to 2.35% EER). A subsequent multi-session study (N=30) demonstrates EERs are maintained over three recalls and, additionally, shows robustness to donning variations and background noise (achieving 2.72% EER). In a follow-up usability study over one week, participants report high levels of usability (as expressed by SUS scores) and that only modest workload is required to authenticate. Finally, a security analysis demonstrates the system’s robustness to spoofing and imitation attacks.

Virtual Reality (VR) technology facilitates effective, flexible, and safe industrial training for novice technicians when on-site training is not feasible. However, previous research has shown that training in VR may be less successful than traditional learning approaches in real-world settings, and haptic interaction may be the key to improving virtual training. In this study, we integrated pseudo-haptic feedback from motion delay with vibrotactile stimulation to enhance the sense of presence, enjoyment, and the perception of physical properties in VR, which may be crucial for achieving faithful simulations. The impact of combined haptic support was assessed in a complex industrial training procedure completing a variety of tasks such as component assembly and cleaning. The results indicate that vibrotactile cues are beneficial for presence and enjoyment, whereas pseudo-haptic illusions effectively enable kinesthetic sensations. Furthermore, multimodal haptic feedback that mixed the two yielded the most advantageous outcomes. Our findings highlight the potential of the pseudo-haptic and vibrotactile fusion in industrial training scenarios, presenting practical implications of the state-of-the-art haptic technologies for virtual learning.

Gestures drawn on touchscreens have been proposed as an authentication method to secure access to smartphones. They provide good usability and a theoretically large password space. However, recent work has demonstrated that users tend to select simple or similar gestures as their passwords, rendering them susceptible to dictionary based guessing attacks. To improve their security, this paper describes a novel gesture password strength meter that interactively provides security assessments and improvement suggestions based on a scoring algorithm that combines a probabilistic model, a gesture dictionary, and a set of novel stroke heuristics. We evaluate this system in both online and offline settings and show it supports creation of gestures that are significantly more resistant to guessing attacks (by up to 67%) while also maintaining performance on usability metrics such as recall success rate and time. We conclude that gesture password strength meters can help users select more secure gesture passwords.

Smartwatches support diverse applications but suffer from security issues due to their limited resources; their small size poorly supports the rich, accurate input required for screen lock authentication. Additionally, traditional approaches to unlocking smart devices, such as Personal identification number, are highly susceptible to attacks such as guessing and video observation. Therefore, we propose PushPIN, a novel scheme that combines knowledge-based and behavioral biometric approaches to increase security. Input symbols are composed of the selection of one of four different targets with one of five different pressure levels, for a total of 20 possibilities. We complement this passcode by capturing behavioral biometric features from screen touches and wrist motion during input. We present two studies to assess the performance of PushPIN. The first assesses both usability and security against a random guessing attack. It shows acceptable usability—recall times of approximately 8 s and no errors—and strong security: equal error rates of 0.51%. The second study examines the resistance of PushPIN against a video observation attack, ultimately revealing that 36.67% of PushPINs could be cracked, performance that represents a substantial improvement over prior work on pressure-based authentication input. We conclude that pressure-based input can increase the security, while maintaining reasonable usability, of smartwatch lock systems.

The diminutive size of wrist wearables has prompted the design of many novel input techniques to increase expressivity. Finger identification, or assigning different functionality to different fingers, has been frequently proposed. However, while the value of the technique seems clear, its implementation remains challenging, often relying on external devices (e.g., worn magnets) or explicit instructions. Addressing these limitations, this paper explores a novel approach to natural and unencumbered finger identification on an unmodified smartwatch: sonar. To do this, we adapt an existing finger tracking smartphone sonar implementation—rather than extract finger motion, we process raw sonar fingerprints representing the complete sonar scene recorded during a touch. We capture data from 16 participants operating a smartwatch and use their sonar fingerprints to train a deep learning recognizer that identifies taps by the thumb, index, and middle fingers with an accuracy of up to 93.7%, sufficient to support meaningful application development.

Social Network Services (SNSs) evoke diverse affective experiences. While most are positive, many authors have documented both the negative emotions that can result from browsing SNS and their impact: Facebook depression is a common term for the more severe results. However, while the importance of the emotions experienced on SNSs is clear, methods to catalog them, and systems to detect them, are less well developed. Accordingly, this paper reports on two studies using a novel contextually triggered Experience Sampling Method to log surveys immediately after using Instagram, a popular image-based SNS, thus minimizing recall biases. The first study improves our understanding of the emotions experienced while using SNSs. It suggests that common negative experiences relate to appearance comparison and envy. The second study captures smartphone sensor data during Instagram sessions to detect these two emotions, ultimately achieving peak accuracies of 95.78% (binary appearance comparison) and 93.95% (binary envy).

Head-Mounted Display based Virtual Reality is proliferating. However, Visually Induced Motion Sickness (VIMS), which prevents many from using VR without discomfort, bars widespread adoption. Prior work has shown that limiting the Field of View (FoV) can reduce VIMS at a cost of also reducing presence. Systems that dynamically adjust a user’s FoV may be able to balance these concerns. To explore this idea, we present a technique for standard 360° video that shrinks FoVs only during VIMS inducing scenes. It uses Visual Simultaneous Localization and Mapping and peripheral optical flow to compute camera movements and reduces FoV during rapid motion or optical flow. A user study (N=23) comparing 360° video with unrestricted-FoVs (90°), reduced fixed-FoVs (40°) and dynamic-FoVs (40°-90°) revealed that dynamic-FoVs mitigate VIMS while maintaining presence. We close by discussing the user experience of dynamic-FoVs and recommendations for how they can help make VR comfortable and immersive for all.

Typing on wearables while situationally impaired, such as while walking, is challenging. However, while HCI research on wearable typing is diverse, existing work focuses on stationary scenarios and fine-grained input that will likely perform poorly when users are on-the-go. To address this issue we explore single-handed wearable typing using intra-hand touches between the thumb and fingers, a modality we argue will be robust to the physical disturbances inherent to input while mobile. We first examine the impact of walking on performance of these touches, noting no significant differences in accuracy or speed, then feed our study data into a multi-objective optimization process in order to design keyboard layouts (for both five and ten keys) capable of supporting rapid, accurate, comfortable, and unambiguous typing. A final study tests these layouts against QWERTY baselines and reports performance improvements of up to 10.45% WPM and 39.44% WER when users type while walking.

Assembling circuits is a challenging and time consuming activity for novice makers, frequently resulting in incorrect placements of wires and components into breadboards. This results in errors that are difficult to identify and debug, and delays that hinder creating, exploring or reconfiguring circuit layouts. This paper presents VirtualWire, a tool that allows users to rapidly design and modify circuits in software and have these changes instantiated in real-time as electrical connections on a physical breadboard. To achieve this, VirtualWire dynamically translates circuit design files into physical connections inside a hardware switching matrix, which handles wiring across breadboard rows and to/from an embedded Arduino. The user can interactively test, tune, and share different circuit layouts for an Arduino shield, and once satisfied, can fabricate the circuit on a permanent substrate. Quantitative and qualitative user studies demonstrate that VirtualWire significantly reduces the time taken for (by 37%), and the number of errors made during (by 53%) circuit assembly, while also supporting users in creating readable, space-efficient and flexible layouts.

Individuals share a diversity of content on social media for a variety of reasons. Research has often described and explained disclosure via the application of a subjective cost–benefit analysis framed around reciprocity, suggesting that people communicate selfishly motivated by the expectation of receiving something in return. This paper investigates the moderating effects of tie strength and interpersonal trust on the relationship between expected reciprocity and intensity of communication between two social media connections. A Facebook application presented participants with a random set of their friends and asked them to rate their friendships in terms of these values. Overall, 90 participants rated 1728 friendships, while the application collected 11 activity variables depicting the actual communication that has taken place in each pair of connections. A principal component analysis was used to distinguish between text- and photograph-related communication, and two moderated multiple regressions were conducted to establish the moderating effects. The results show significant moderating effects of tie strength and trust on the communication around photographs, but not around text. This study contributes to communication research by explicating the ways that tie strength and trust affect patterns of communication on social media. Implications for social media researchers and designers are discussed.

Touches between the fingers of an unencumbered hand represent a ready-to-use, eyes-free and expressive input space suitable for interacting with wearable devices such as smart glasses or watches. While prior work has focused on touches to the inner surface of the hand, touches to the nails, a practical site for mounting sensing hardware, have been comparatively overlooked. We extend prior implementations of single touch sensing nails to a full set of five and explore their potential for wearable input. We present design ideas and an input space of 144 touches (taps, flicks and swipes) derived from an ideation workshop. We complement this with data from two studies characterizing the subjective comfort and objective characteristics (task time, accuracy) of each touch. We conclude by synthesizing this material into a set of 29 viable nail touches, assessing their performance in a final study and illustrating how they could be used by presenting, and qualitatively evaluating, two example applications.

Touchscreen gestures are attracting research attention as an authentication method. While studies have showcased their usability, it has proven more complex to determine, let alone enhance, their security. Problems stem both from the small scale of current data sets and the fact that gestures are matched imprecisely - by a distance metric. This makes it challenging to assess entropy with traditional algorithms. To address these problems, we captured a large set of gesture passwords (N=2594) from crowd workers, and developed a security assessment framework that can calculate partial guessing entropy estimates, and generate dictionaries that crack 23.13% or more gestures in online attacks (within 20 guesses). To improve the entropy of gesture passwords, we designed novel blacklist and lexical policies to, respectively, restrict and inspire gesture creation. We close by validating both our security assessment framework and policies in a new crowd-sourced study (N=4000). Our blacklists increase entropy and resistance to dictionary based guessing attacks.

Visually Induced Motion Sickness (VIMS), when the visual system detects motion that is not felt by the vestibular system, is a deterrent for first-time Virtual Reality (VR) users and can impact its adoption rate. Constricting the field-of-view (FoV) has been shown to reduce VIMS as it conceals optical flow in peripheral vision, which is more sensitive to motion. Additionally, several studies have suggested the inclusion of visual elements (e.g., grids) consistent with the real world as reference points. In this paper, we describe a novel technique dynamically controlled by a video’s precomputed optical flow and participants’ runtime head direction and evaluate it in a within-subjects study (N = 24) on a 360° video of a roller coaster. Furthermore, based on a detailed analysis of the video and participant’s experience, we provide insights on the effectiveness of the techniques in VIMS reduction and discuss the role of optical flow in the design and evaluation of the study.

Assembling circuits on breadboards using reference designs is a common activity among makers. While tools like Fritzing offer a simplified visualization of how components and wires are connected, such pictorial depictions of circuits are rare in formal educational materials and the vast bulk of online technical documentation. Electronic schematics are more common but are perceived as challenging and confusing by novice makers. To improve access to schematics, we propose SchemaBoard, a system for assisting makers in assembling and inspecting circuits on breadboards from schematic source materials. SchemaBoard uses an LED matrix integrated underneath a working breadboard to visualize via light patterns where and how components should be placed, or to highlight elements of circuit topology such as electrical nets and connected pins. This paper presents a formative study with 16 makers, the SchemaBoard system, and a summative evaluation with an additional 16 users. Results indicate that SchemaBoard is effective in reducing both the time and the number of errors associated with building a circuit based on a reference schematic, and for inspecting the circuit for correctness after its assembly.

We empirically explore fundamental requirements for achieving VR in-air typing by observing the unconstrained eyes-free in-air typing of touch typists. We show that unconstrained typing movements differ substantively from previously observed constrained in-air typing movements and introduce a novel binary categorization of typing strategies: typists who use finger movements alone (FINGER) and those who combine finger movement with gross hand movement (HAND). We examine properties of finger kinematics, correlated movement of fingers, interrelation in consecutive key-strokes, and 3D distribution of key-stroke movements. We report that, compared to constrained typing, unconstrained typing generates shorter (49 mm) and faster (764 mm/s) key-strokes with a high correlation of finger movement and that the HAND strategy group exhibits more dynamic key-strokes. We discuss how these findings can inform the design of future in-air typing systems.

In virtual environments, spatial discrepancies between visual and haptic scenes negatively impact user performance and experience. This paper shows how spatial discrepancies due to pose differences can occur in a haptic augmented virtuality system with an encountered-type haptic display. To mitigate this problem, we propose visual guidance, an algorithm that dynamically manipulates the visual scene to compensate for discrepancies. The effectiveness of this algorithm was verified in a pair of studies involving a button pressing task and spatial discrepancies between ±150 mm and ±40°. Experimental results show that discrepant trials using the technique yield error rates and a number of speed peaks (representing the number of targeting movements) that are comparable to those attained in trials with zero spatial discrepancy. This result was also achieved without requiring a dedicated adaptation or training process, ensuring the algorithm can be used immediately by users. A pair of follow-up studies also indicates the algorithm has little impact on subjective ratings of simulator sickness, suggesting that sporadic use of the algorithm will not negatively affect user's experience of a virtual environment. We believe that the visual guidance algorithm presented in this paper can be used to create more useful and compelling experiences in various haptic training applications incorporating encountered-type haptic displays.

Smartwatches support access to a wide range of private information but little is known about the security and usability of existing smartwatch screen lock mechanisms. Prior studies suggest that smartwatch authentication via standard techniques such as 4-digit PINs is challenging and error-prone. We conducted interviews to shed light on current practices, revealing that smartwatch users consider the ten-key keypad required for PIN entry to be hard to use due to its small button sizes. To address this issue, we propose the Personal Identification Chord (PIC), an authentication system based on a four-button chorded keypad that enables users to enter ten different inputs via taps to one or two larger buttons. Two studies assessing usability and security of our technique indicate PICs lead to increases in setup and (modestly) recall time, but can be entered accurately while maintaining high recall rates and may improve guessing entropy compared to PINs.

Haptic cues are a valuable feedback mechanism for smart glasses. Prior work has shown how they can support navigation, deliver notifications and cue targets. However, a focus on actuation technologies such as mechanical tactors or fans has restricted the scope of research to a small number of cues presented at fixed locations. To move beyond this limitation, we explore perception of in-air ultrasonic haptic cues on the face. We present two studies examining the fundamental properties of localization, duration and movement perception on three facial sites suitable for use with glasses: the cheek, the center of the forehead, and above the eyebrow. The center of the forehead led to optimal performance with a localization error of 3.77mm and accurate duration (80%) and movement perception (87%). We apply these findings in a study delivering eight different ultrasonic notifications and report mean recognition rates of up to 92.4% (peak: 98.6%). We close with design recommendations for ultrasonic haptic cues on the face.

Wearable head-mounted displays combine rich graphical output with an impoverished input space. Hand-to-face gestures have been proposed as a way to add input expressivity while keeping control movements unobtrusive. To better understand how to design such techniques, we describe an elicitation study conducted in a busy public space in which pairs of users were asked to generate unobtrusive, socially acceptable hand-to-face input actions. Based on the results, we describe five design strategies: miniaturizing, obfuscating, screening, camouflaging and re-purposing. We instantiate these strategies in two hand-to-face input prototypes, one based on touches to the ear and the other based on touches of the thumbnail to the chin or cheek. Performance assessments characterize time and error rates with these devices. The paper closes with a validation study in which pairs of users experience the prototypes in a public setting and we gather data on the social acceptability of the designs and reflect on the effectiveness of the different strategies.

The small screens of smartwatches provide limited space for input tasks. Finger identification is a promising technique to address this problem by associating different functions with different fingers. However, current technologies for finger identification are unavailable or unsuitable for smartwatches. To address this problem, this paper observes that normal smartwatch use takes places with a relatively static pose between the two hands. In this situation, we argue that the touch and angle profiles generated by different fingers on a standard smartwatch touch screen will differ sufficiently to support reliable identification. The viability of this idea is explored in two studies that capture touches in natural and exaggerated poses during tapping and swiping tasks. Machine learning models report accuracies of up to 93% and 98% respectively, figures that are sufficient for many common interaction tasks. Furthermore, the exaggerated poses show modest costs (in terms of time/errors) compared to the natural touches. We conclude by presenting examples and discussing how interaction designs using finger identification can be adapted to the smartwatch form factor.

SmoothMoves is an interaction technique for augmented reality (AR) based on smooth pursuits head movements. It works by computing correlations between the movements of on-screen targets and the user's head while tracking those targets. The paper presents three studies. The first suggests that head based input can act as an easier and more affordable surrogate for eye-based input in many smooth pursuits interface designs. A follow-up study grounds the technique in the domain of augmented reality, and captures the error rates and acquisition times on different types of AR devices: head-mounted (2.6%, 1965ms) and hand-held (4.9%, 2089ms). Finally, the paper presents an interactive lighting system prototype that demonstrates the benefits of using smooth pursuits head movements in interaction with AR interfaces. A final qualitative study reports on positive feedback regarding the technique's suitability for this scenario. Together, these results indicate show SmoothMoves is viable, efficient and immediately available for a wide range of wearable devices that feature embedded motion sensing.

Smartwatches are emerging device category that feature highly limited input and display surfaces. We explore how touch contact areas, such as lines generated by flat fingers, can be used to increase input expressivity in these diminutive systems in three ways. Firstly, we present four design themes that emerged from an ideation workshop in which five designers proposed concepts for smartwatch touch area interaction. Secondly, we describe a sensor unit and study that captured user performance with 31 area touches and contrasted this against standard targeting performance. Finally, we describe three demonstration applications that instantiate ideas from the workshop and deploy the most reliably and rapidly produced area touches. We report generally positive user reactions to these demonstrators: the area touch interactions were perceived as quick, convenient and easy to learn and remember. Together this work characterizes how designers can use area touches in watch UIs, which area touches are most appropriate and how users respond to this interaction style.

This paper explores how an Android application used in combination with a tangible appcessory can facilitate learning for visually impaired students of geometry. This paper presents the status of this ongoing project. It describes the application, the physical appcessory as well as early stage user studies. The application enables visually impaired users to explore simple geometric forms displayed on a tablet through sound and vibrotactile feedback. A deformable physical appcessory that can be manipulated to adopt these forms and its shape sensed by the tablet adds an additional tactile layer to the application and experience. Three user engagements with visually impaired serve as early validations of our project and ideas and provide feedback that directs design and development of future work. Current avenues for the future work will include additional interaction modes in the application, e.g. the ability to digitize real world forms, and improving the robustness of the tangible appcessory.

PassBYOP is a new graphical password scheme for public terminals that replaces the static digital images typically used in graphical password systems with personalized physical tokens, herein in the form of digital pictures displayed on a physical user-owned device such as a mobile phone. Users present these images to a system camera and then enter their password as a sequence of selections on live video of the token. Highly distinctive optical features are extracted from these selections and used as the password. We present three feasibility studies of PassBYOP examining its reliability, usability, and security against observation. The reliability study shows that image-feature based passwords are viable and suggests appropriate system thresholds - password items should contain a minimum of seven features, 40% of which must geometrically match originals stored on an authentication server in order to be judged equivalent. The usability study measures task completion times and error rates, revealing these to be 7.5 s and 9%, broadly comparable with prior graphical password systems that use static digital images. Finally, the security study highlights PassBYOP's resistance to observation attack - three attackers are unable to compromise a password using shoulder surfing, camera-based observation, or malware. These results indicate that PassBYOP shows promise for security while maintaining the usability of current graphical password schemes.

This paper presents a comprehensive study of the impact of visual-haptic spatial discrepancies on human performance in a targeting task conducted in a visual-haptic virtual and augmented environment. Moreover, it explores whether the impact of this effect varies with two additional variables: 1) haptic wall stiffness and 2) visual cursor diameter. Finally, we discuss the relative dominance of visual and haptic cues during a targeting task. The results indicate that while the spatial discrepancies studied exerted a small effect on the time required to perform targeting, they impacted the absolute errors considerably. Additionally, we report that haptic wall stiffness has a significant effect on absolute errors while the visual cursor diameter has a significant effect on movement time. Finally, we conclude that while both visual and haptic cues are important during targeting tasks, haptic cues played a more dominant role than visual cues. The results of this paper can be used to predict how human targeting performance will vary between systems, such as those using haptically enabled virtual reality or augmented reality technologies that feature visual-haptic spatial discrepancies.

Tablet computers and portable eReaders are gradually becoming the preferred platform for the consumption of textual materials. However, although these technologies are powerful, it is widely acknowledged that print documents better support the advanced active reading tasks necessary to gain a deep understanding of a text. While prior work to address this issue has aimed improve digital eReaders by either leveraging familiar physical affordances or by extending paper's capabilities with digital tools, in this paper we propose a juncture of these two approaches. We first present a formative study that captures the needs and requirements of users during active reading tasks with tablets. We instantiate the findings in the design of a simple physical aid to support active reading: a smart bookmark. We then define an interaction space for this device, describe a set of interfaces designed to facilitate active reading and close with a user study that assesses the potential of the bookmark device and interaction techniques.

Interacting with smartwatches poses new challenges. Although capable of displaying complex content, their extremely small screens poorly match many of the touchscreen interaction techniques dominant on larger mobile devices. Addressing this problem, this paper presents beating gestures, a novel form of input based on pairs of simultaneous or rapidly sequential and overlapping screen taps made by the index and middle finger of one hand. Distinguished simply by their temporal sequence and relative left/right position these gestures are designed explicitly for the very small screens (approx. 40mm square) of smartwatches and to operate without interfering with regular single touch input. This paper presents the design of beating gestures and a rigorous empirical study that characterizes how users perform them -- in a mean of 355ms and with an error rate of 5.5%. We also derive thresholds for reliably distinguishing between simultaneous (under 30ms) and sequential (under 400ms) pairs of screen touches or releases. We then present five interface designs and evaluate them in a qualitative study in which users report valuing the speed and ready availability of beating gestures.

Tangible systems present compelling interaction opportunities but are typically enabled by complex, bulky, awkward or expensive sensing infrastructures. This hinders their adoption in many application areas. In order to address this issue, this paper explores the use of simple active magnetic tokens that create carefully controlled patterns of varying magnetic flux as the building blocks of tangible systems. We describe the construction of these tokens and a software system capable of detecting their presence and inferring their location based on data sampled from a single triaxial magnetometer a standard component of most current mobile devices. The system can recognize token positions from a set of six pre-calibrated locations with an accuracy of 99%. We describe the hardware and software components of this system and five demonstration applications that illustrate its functionality.

In task performance, pragmatic actions refer to behaviors that make direct progress, while epistemic actions involve altering the world so that cognitive processes are faster, more reliable or less taxing. Epistemic actions are frequently presented as a beneficial consequence of interacting with tangible systems. However, we currently lack tools to measure epistemic behaviors, making substantiating such claims highly challenging. This paper addresses this problem by presenting ATB, a video-coding framework that enables the identification and measurement of different epistemic actions during problem-solving tasks. The framework was developed through a systematic literature review of 78 papers, and analyzed through a study involving a jigsaw puzzle -- a classical spatial problem -- involving 60 participants. In order to assess the framework's value as a metric, we analyze the study with respect to its reliability, validity and predictive power. The broadly supportive results lead us to conclude that the ATB framework enables the use of observed epistemic behaviors as a performance metric for tangible systems. We believe that the development of metrics focused explicitly on the properties of tangible interaction are currently required to gain insight into the genuine and unique benefits of tangible interaction. The ATB framework is a step towards this goal.

Avatars can be employed as a motivational tool, for example, allowing non-verbal communication that can be close to human communication. We describe two lab studies where we presented participants with avatars that communicated verbally via text and visually via expressions. In the first study, participants rated five different categories of captions and corresponding avatars. Results showed that the most persuasive, consistent and trustworthy verbal feedback was given in a humanized form. The second study was an exhaustive forced choice experiment where participants chose the happiest avatar from a pair displayed. Results showed participants found visual avatars more expressive and easier to understand than their verbal counterparts, and that users respond differently when presented with negative or positive emotions. This paper contributes to a better understanding of how to design feedback for expressive avatars.

The touch screen interaction paradigm, currently dominant in mobile devices, begins to fail when very small systems are considered. Specifically, "fat fingers", a term referring to the fact that users' extremities physically obstruct their view of screen content and feedback, become particularly problematic. This paper presents a novel solution for this issue based on sensing touches to the perpendicular edges of a device featuring a front-mounted screen. The use of such offset contact points ensures that both a user's fingers and the device screen remain clearly in view throughout a targeting operation. The configuration also supports a range of novel interaction scenarios based on the touch, grip and grasp patterns it affords. To explore the viability of this concept, this paper describes EdgeTouch, a small (6 cm) hardware prototype instantiating this multi-touch functionality. User studies characterizing targeting performance, typical user grasps and exploring input affordances are presented. The results show that targets of 7.5-22.5 degrees in angular size are acquired in 1.25-1.75 seconds and with accuracy rates of 3%-18%, promising results considering the small form factor of the device. Furthermore, grasps made with between two and five fingers are robustly identifiable. Finally, we characterize the types of input users envisage performing with EdgeTouch, and report occurrence rates for key interactions such as taps, holds, strokes and multi-touch and compound input. The paper concludes with a discussion of the interaction scenarios enabled by offset sensing.

Location prediction enables us to use a person's mobility history to realize various applications such as efficient temperature control, opportunistic meeting support, and automated receptionists. Indoor location prediction is a challenging problem, particularly due to a high density of possible locations and short transition distances between these locations. In this paper we present Indoor-ALPS, an Adaptive Indoor Location Prediction System that uses temporal-spatial features to create individual daily models for the prediction of when a user will leave their current location (transition time) and the next location she will transition to. We tested Indoor-ALPS on the Augsburg Indoor Location Tracking Benchmark and compared our approach to the best performing temporal-spatial mobility prediction algorithm, Prediction by Partial Match (PPM). Our results show that Indoor-ALPS improves the temporal-spatial prediction accuracy over PPM for look-aheads up to 90 minutes by 6.2%, and for up to 30 minute look-aheads by 10.7%. These results demonstrate that Indoor-ALPS can be used to support a wide variety of indoor mobility prediction-based applications.

Stereoscopic displays can simulate the perception of depth information, potentially increasing human distance perception in remote viewing scenarios such as those involved in robotic tele-operation. However, distance perception is a complex perceptual task that is not yet fully understood. Two current research issues are how different stereoscopic displays and viewing heights affect egocentric distance perception. This paper describes an experiment conducted to investigate these issues. It compared distance perception in a real environment with that in identical visual scenes observed through an HMD and 3D Stereo Display. Other parameters, notably field of view, were tightly controlled. Motivated by fact that many tele-operation scenarios involve near ground viewing positions (due to the fact that many robots are small), the study also explored the impact of viewing height (at 20 cm and 110 cm) on distance perception. Results indicated substantial under-estimation of distance across all conditions. Interesting, low eye-height led to a significant reduction in the level of underestimation in the HMD and 3D Stereo Display, a variation that may be due to changes in the perceived height of the horizon in the real world 20 cm viewing height condition, compared to the fixed height of the perceived horizon in the videos shown on the HMD and 3D Stereo Display.

This study explores the links between motives for using a social network service and numerical measures of that activity. Specifically, it identified motives for Facebook use by employing a Uses and Gratifications (U&G) approach and then investigated the extent to which these motives can be predicted through usage and network metrics collected automatically via the Facebook API. In total, 11 Facebook usage metrics and eight personal network metrics served as predictors. Results showed that all three variable types in this expanded U&G frame of analysis (covering social antecedents, usage metrics, and personal network metrics) effectively predicted motives and highlighted interesting behaviors. To further illustrate the power of this framework, the intricate nature of privacy in social media was explored and relationships drawn between privacy attitudes (and acts) and measures of use and network structure.

This paper explores uses and gratifications of a content community on a social network service - a music video sharing group on Facebook. In a two-stage study, 20 users first generated words or phrases to describe how they used the group, and what they enjoyed about their use. These phrases were coded into 34 questionnaire items that were then completed by 57 new participants. Factor analysis on this data revealed four gratifications: contribution; discovery; social interaction and entertainment. These factors are interpreted and discussed, leading to design implications and guidelines aimed at informing the design of future online services that combine media sharing with social interaction to create online systems based on a rich and meaningful object-centered sociality.

We introduce context-aware scalable authentication (CASA) as a way of balancing security and usability for authentication. Our core idea is to choose an appropriate form of active authentication (e.g., typing a PIN) based on the combination of multiple passive factors (e.g., a user's current location) for authentication. We provide a probabilistic framework for dynamically selecting an active authentication scheme that satisfies a specified security requirement given passive factors. We also present the results of three user studies evaluating the feasibility and users' receptiveness of our concept. Our results suggest that location data has good potential as a passive factor, and that users can reduce up to 68% of active authentications when using an implementation of CASA, compared to always using fixed active authentication. Furthermore, our participants, including those who do not using any security mechanisms on their phones, were very positive about CASA and amenable to using it on their phones.

Tangible interaction allows the control of digital information through physical artifacts - virtual data is tied to real-world objects. Sensing and display technologies that enable this kind of functionality are typically complex. This represents a barrier to entry for researchers and also restricts where these interaction techniques can be deployed. Addressing these limitations, recent work has explored how the touch screens on mobile devices can be used as sensing and display platforms for tangible interfaces. This paper extends this work by exploring how magnets can be employed to achieve similar ends. To achieve this, it describes the design and construction of eight magnetic appcessories. These are cheap, robust physical interfaces that leverage magnets (and the magnetic sensing built into mobile devices) to support reliable and expressive tangible interactions with digital content.

This paper explores how different interfaces to a problem-solving task affect how users perform it. Specifically, it focuses on a customized version of the game of Four-in-a-row and compares play on a physical, tangible game board with that conducted in mouse and touch-screen driven virtual versions. This is achieved through a repeated measures study involving a total of 36 participants and which explicitly assesses aspects of cognitive work through measures of time task, subjective workload, the projection of mental constructs onto external structures and the occurrence of explanatory epistemic actions. The results highlight the relevance of projection and epistemic action to this problem-solving task and suggest that the different interface forms afford instantiation of these activities in different ways. The tangible version of the system supports the most rapid execution of these actions and future work on this topic should explore the unique advantages of tangible interfaces in supporting epistemic actions.

This paper argues that inherent support for offline activities -- activities that are not sensed by the system -- is one of strongest benefits of tangible interaction over more traditional interface paradigms. By conducting two studies with single and paired users on a simple tangible tabletop scheduling application, this paper explores how tabletop interfaces could be designed to better support such offline activities. To focus its exploration, it looks at offline activities in terms of how they support cognitive work, such as aiding exploration of problem spaces or lowering task complexity. This paper concludes with insights relating to the form, size, and location for spaces that afford offline actions, and also the design of tangible tokens themselves.

Studio participants will design and prototype tangible board-games for NIKVision: a tabletop computer for young children. The goal of this studio is to give designers and developers hands-on experience of developing a functional prototype of a tangible tabletop application without the intrinsic difficulties of managing electronic sensors, actuators and machine vision algorithms. During the studio attendees will complete a simple but conceptually complete tangible board-game prototype during the workshop day by abstracting the technologies and keeping focus firmly on the application behaviours and the interactions between users, objects and the system. This will be achieved through using the ToyVision toolkit, a set of software tools that lowers the threshold of prototyping both the "bits" and "atoms" of interactive tabletop games.

Tangible interaction links digital data with physical forms to support embodied use. Puzzle pieces, which their inherent physical syntax of connectable elements, provide a powerful and expressive metaphor on which to construct such tangible systems. Prior work has explored this potential in the domain of edutainment systems for children aimed at tasks such as learning logic, programming or organizational skills. Although this work is promising, it has largely focused on relatively advanced concepts and children of ages 7-12 years. The work presented in this paper adopts the same perspective but focuses on young children (5 and under) and a simpler range of concepts relating to the clustering and manipulation of data. To achieve this it presents the design (including results from a series of six formative field studies) and implementation of the Digital Dream Lab tabletop puzzle block system. This system, intended for installation in a museum, engages young children (aged 4-5) to explore simple programmatic concepts and the link between the physical and virtual world. The paper closes with design recommendations of future work targeting this goal, setting and age group.

The aviation industry is fundamental to today's connected global economies, rapidly and effectively linking people, places and cultures. However, aviation struggles to provide a high quality of service; air travelers typically report dissatisfaction and frustration with their experiences. This paper describes fieldwork in the form of 63 interviews that aims to understand the needs of air travelers in order to improve user experiences during and around air travel. Three themes from this traveler-centered user research process are presented and the design of FlyTalk, a mobile phone application inspired by this data and tailored to the needs of air travelers is described. FlyTalk collates existing information about airports and their procedures, presents this to users in a location and context aware interface and seamlessly integrates social media features connecting travelers with both their service providers and each other. This paper argues air travel is an important but overlooked domain for HCI practitioners and that mobile applications that meet user needs in this scenario have the potential to reduce travel costs while improving traveler satisfaction.

Draw-a-Secret password schemes, like the Google Android Pattern Lock, entail stroking out a shape on a touch screen. This paper explores techniques for expanding the richness of this input modality (multitouch input, off-target interaction) in order to increase password entropy and resistance to observation. A formative user study highlights user perceptions and usability issues relating to this design space and suggests directions for future development of this concept.

Haptic and audio cues now appear commonly in computer interfaces, partially due to inherent advantages such as their support for eyes-free interaction. Their invisible, unobservable nature also makes them ideal candidates for security interfaces in which users have to enter secret information such as passwords. In particular, researchers have explored this idea through the design of PIN entry authentication systems based on multi-modal combinations of visual and non-visual content or on the recognition of small sets of unimodal haptic or audio stimuli. This paper highlights the benefits and performance limitations of these approaches and introduces an alternative based on unimodal audio or haptic temporal numerosity - the ability to accurately and rapidly determine the number of cues presented in rapid temporal succession. In essence, in a numerosity interface, rather than recognizing distinct cues, users must count the number of times that a single cue occurs. In an iterative process of design and evaluation, three prototypes implementing this concept are presented and studies of their use reported. The results show the fastest PIN entry times and lowest error rates to be 8 s and 2%, figures that improve substantially on previous research. These results are attained while maintaining low levels of workload and substantial resistance to observation attack (as determined via camera attack security studies). In sum, this paper argues that unimodal audio and haptic numerosity is a valuable and relatively unexplored metaphor for non-visual input and demonstrates the validity of this claim in the demanding task of unobservable authentication systems.

Tangible user interfaces are portals to digital information. In the future, securing access to such material will be an important concern. This paper describes the design, implementation and evaluation of a PIN entry system based on audio or haptic cues that is suitable for integration into such physical systems. The current implementation links movements on a mobile phone touch screen with the display of non-visual cues; selection of a sequence of these cues composes a password. Studies reveal the validity of this approach in terms of task times and error rates that improve over prior art. In sum, this paper demonstrates the potential of non-visual PINs as a mechanism for securing access to a range of systems, ultimately incorporating mobile, ubiquitous or tangible interfaces.

Research on tangible interaction and digital haptics has rarely intertwined, despite the natural relationship between physicality and touch. This paper addresses this relatively unexplored domain by presenting the Haptic Wheel, a freestanding single-axis rotational controller incorporating vibro-tactile cues. In addition to describing the hardware and implementation, the paper discusses the potential application of the system for eyes-free interaction, password entry and as an active puck on a tabletop system. The paper suggests that systems with active haptic feedback have unexploited potential as tools for tangible interaction.

The TEI Work-in-Progress workshop invited submissions about designing, making, studying, exploring and experiencing of projects on tangible, embedded and embodied interaction. The workshop aimed to provoke, intrigue, and inspire the TEI community by sharing work-in-progress practice, late breaking innovation, cutting-edge research, and controversial and compelling work. It provided a venue for eliciting feedback and fostering discussions and collaborations among TEI colleagues. The TEI Work-in-Progress workshop provided an opportunity for members of the TEI community with common and diverse interests to meet in the context of a focused and interactive discussion and a showcase for exciting new work that is still at an early stage.

Authentication in public spaces poses significant security risks. Most significantly, passwords can be stolen, potentially leading to fraud. A common method to steal a PIN is through an observation attack, either using a camera or through direct observation (e.g. shoulder-surfing). This paper addresses this problem by presenting the design and implementation of a novel input keypad which uses tactile cues as means to compose a password. In this system, passwords are encoded as a sequence of randomized vibration patterns, making it visually impossible for an observer to detect which items are selected. An evaluation of this system shows it outperforms previous interfaces which have used tactile feedback to obfuscate passwords.

This paper presents a multi-pronged study of users' location-sharing practices in the context of online social networks. The contribution of this study is two-fold: first it presents a series of insights relating to location-sharing practices, and second it highlights the use of third-person scenarios as a useful method for eliciting privacy concerns and potentially educating users.

This paper examines a visual design element unique to situated, hot-spot style, services: locativeness. This is the extent to which the media representing a service relates to its immediate physical environment. This paper explores the effect of locativeness on trust with two studies assessing user attitudes in depth. The first is an implicit, or preconscious, test and the second an explicit test based on voiced value judgments. To provide a richer context, the second study contrasts locativeness with other traditional aspects of design: branding and quality. The results indicate users have a strong implicit association between locative images and trust, and that this is partially reflected in their explicit choices. This is an important interface aspect that designers should consider in order to create trustworthy situated services.

Research on vibrotactile displays for mobile devices has developed and evaluated complex multi-dimensional tactile stimuli with promising results. However, the possibility that user distraction, an inevitable component of mobile interaction, may mask (or obscure) vibrotactile perception has not been thoroughly considered. This omission is addressed here with three studies comparing recognition performance on nine tactile icons between control and distracter conditions. The icons were two dimensional (three body sites against three roughness values) and displayed to the wrist. The distracter tasks were everyday activities: Transcription, mouse-based Data-entry and Walking. The results indicated performance significantly dropped in the distracter condition (by between 5% and 20%) in all studies. Variations in the results suggest different tasks may exert different masking effects. This work indicates that distraction should be considered in the design of vibrotactile cues and that the results reported in lab based studies are unlikely to represent real world performance.

Haptic devices are now commercially available and thus touch has become a potentially realistic solution to a variety of interaction design challenges. We report on an investigation of the use of touch as a way of reducing visual overload in the conventional desktop. In a two-phase study, we investigated the use of the PHANToM haptic device as a means of interacting with a conventional graphical user interface. The first experiment compared the effects of four different haptic augmentations on usability in a simple targeting task. The second experiment involved a more ecologically-oriented searching and scrolling task. Results indicated that the haptic effects did not improve users performance in terms of task completion time. However, the number of errors made was significantly reduced. Subjective workload measures showed that participants perceived many aspects of workload as significantly less with haptics. The results are described and the implications for the use of haptics in user interface design are discussed.