SealMates: Improving Communication in Video Conferencing using a Collective Behavior-Driven AvatarThe limited nonverbal cues and spatially distributed nature of remote communication make it challenging for unacquainted members to be expressive during social interactions over video conferencing. Though it enables seeing others’ facial expressions, the visual feedback can instead lead to unexpected self-focus, resulting in users missing cues for others to engage in the conversation equally. To support expressive communication and equal participation among unacquainted counterparts, we propose SealMates, a behavior-driven avatar in which the avatar infers the engagement level of the group based on collective gaze and speech patterns and then moves across interlocutors' windows in the video conferencing. By conducting a controlled experiment with 15 groups of triads, we found the avatar's movement encouraged people to experience more self-disclosure and made them perceive everyone was equally engaged in the conversation than when there was no behavior-driven avatar. We discuss how a behavior-driven avatar influences distributed members' perceptions and the implications of avatar-mediated communication for future platforms.2024MAMark Armstrong et al.Session 4f: Multiplayer Gaming and CommunicationCSCW
Verifying Finger-Fitts Models for Normalizing Subjective Speed-Accuracy BiasesPrevious studies on the Finger-Fitts law (FFitts law) are lacking in sufficient experiments to verify its inherent potential. Since the FFitts law is originally a modified version of the effective width method to normalize speed-accuracy biases, the model fit would improve if multiple biases were mixed together and the throughputs would be more stable than using the nominal target width. In this study, we conduct an experiment in which participants tap 1D-bar and 2D-circular targets under three subjective biases: balancing the speed and accuracy, emphasizing speed, and emphasizing accuracy when they perform the tasks. The results showed that applying the effective width to Ko et al.'s refined FFitts law, which represents the touch ambiguity with a free parameter, was the most successful in normalizing biases. Reanalyzing another dataset on ray-casting pointing also led to the same conclusion. We thus recommend using Ko et al.'s model with effective width when researchers compare several experimental conditions such as devices and user groups.2024SYShota Yamanaka et al.Prototyping & User TestingComputational Methods in HCIMobileHCI
Better Definition and Calculation of Throughput and Effective Parameters for Steering to Account for Subjective Speed-accuracy TradeoffsIn Fitts' law studies to investigate pointing, throughput is used to characterize the performance of input devices and users, which is claimed to be independent of task difficulty or the user's subjective speed-accuracy bias. While throughput has been recognized as a useful metric for target-pointing tasks, the corresponding formulation for path-steering tasks and its evaluation have not been thoroughly examined in the past. In this paper, we conducted three experiments using linear, circular, and sine-wave path shapes to propose and investigate a novel formulation for the effective parameters and the throughput of steering tasks. Our results show that the effective width substantially improves the fit to data with mixed speed-accuracy biases for all task shapes. Effective width also smoothed out the throughput across all biases, while the usefulness of the effective amplitude depended on the task shape. Our study thus advances the understanding of user performance in trajectory-based tasks.2024NKNobuhito Kasahara et al.Meiji UniversityUser Research Methods (Interviews, Surveys, Observation)CHI
Waiting Time Perceptions for Faster Count-downs/ups Are More Sensitive Than Slower Ones: Experimental Investigation and Its ApplicationCountdowns and count-ups are very useful displays that explicitly show how long users should wait and also show the current processing states of a given task. Most countdowns or count-ups decrease or increase their digit every one second exactly, and most users have an implicit assumption that the digit changes every one second exactly. However, there are no studies that investigate how users perceive wait times with these countdowns and count-ups and that consider changing users' perception of time passing as shorter than the actual passage of time by means of countdowns and count-ups while taking into account such user assumptions. To clarify these issues, we first investigated how users perceive countdowns "from 3/5/10 to 0" and count-ups "from 0 to 3/5/10" that have different lengths of intervals from 800 to 1200 msec (Experiment 1). Next, on the basis of the results of Experiment 1, we explored a novel method for presenting countdowns to make users perceive the wait time as being shorter than the actual wait time (Experiment 2) and investigated whether such countdowns can be used in realistic applications or not (Experiment 3). As a result, we found that countdowns and count-ups that were "from 250 msec shorter to 10% longer" than 3, 5, or 10 sec were perceived as 3, 5, or 10 sec, respectively, and those "from 5 to 0" (their lengths were 5 sec) that first displayed extremely shorter intervals were perceived as being shorter than their actual length (5 sec). Finally, we confirmed the applicability and effectiveness of such displays in a realistic application. Thus, we strongly argue that these findings could become indispensable knowledge for researchers in this research field to reduce users' cognitive load during wait times.2024TKTakanori Komatsu et al.Meiji UniversityVisualization Perception & CognitionNotification & Interruption ManagementCHI
Varying Subjective Speed-accuracy Biases to Evaluate the Generalizability of Experimental Findings on Pointing-facilitation TechniquesIn typical experiments to evaluate novel pointing-facilitation techniques, participants are asked to perform a task as rapidly and accurately as possible. However, the balance can differ among participants, and the techniques' effectiveness would change if the majority of participants give weight to either speed or accuracy. We investigated the effects of three subjective biases (emphasizing speed, neutral, and emphasizing accuracy) on the evaluation results of pointing-facilitation techniques, namely Bubble Cursor and Bayesian Touch Criterion (BTC). The results indicate that Bubble Cursor outperformed the baseline in terms of movement time and error rate under all bias conditions, while BTC underperformed a simpler target-prediction technique, which was an inconsistent outcome to the original study. Examining multiple biases enables researchers to discuss the (dis)advantages of novel or existing techniques more precisely, which can be beneficial to reach a more reliable conclusion.2023SYShota Yamanaka et al.Yahoo Japan CorporationVoice User Interface (VUI) DesignComputational Methods in HCICHI
Bivariate Effective Width Method to Improve the Normalization Capability for Subjective Speed-accuracy Biases in Rectangular-target PointingThe effective width method of Fitts' law can normalize speed-accuracy biases in 1D target pointing tasks. However, in graphical user interfaces, more meaningful target shapes are rectangular. To empirically determine the best way to normalize the subjective biases, we ran remote and crowdsourced user experiments with three speed-accuracy instructions. We propose to normalize the speed-accuracy biases by applying the effective sizes to existing Fitts' law formulations including width W and height H. We call this target-size adjustment the bivariate effective width method. We found that, overall, Accot and Zhai's weighted Euclidean model using the effective width and height independently showed the best fit to the data in which the three instruction conditions were mixed (i.e., the time data measured in all instructions were analyzed with a single regression expression). Our approach enables researchers to fairly compare two or more conditions (e.g., devices, input techniques, user groups) with the normalized throughputs.2022SYShota Yamanaka et al.Yahoo Japan CorporationPrototyping & User TestingComputational Methods in HCICHI
EscapeLoom: Fabricating New Affordances for Hand WeavingHand-weaving is a beloved craft in history, holding promise for many opportunities in making from flat sheet fabrics to smart textiles. To afford new weaving experiences, we explore how 3D printed custom weaving tools interplay with different materiality, augmenting the design space of weaving. We propose novel weaving techniques enabled by 3D printed custom tools: (1) water-soluble draft to synchronize design intention and practice, (2) flexible warps to guide complex patterns and to shape resulting object, and (3) rigid global geometry for woven artifacts in 3D. EscapeLoom as a computational design tool enables users to employ various parameters in their computational design, and showcases many creative possibilities that move away from the traditional definition of a loom to dive into what more it can be.2021HDHimani Deshpande et al.Texas A&M UniversityShape-Changing Materials & 4D PrintingMakerspace CultureCHI
Preserving Agency During Electrical Muscle Stimulation Training Speeds up Reaction Time Directly After Removing EMSForce feedback devices, such as motor-based exoskeletons or wearables based on electrical muscle stimulation (EMS), have the unique potential to accelerate users’ own reaction time (RT). However, this speedup has only been explored while the device is attached to the user. In fact, very little is known regarding whether this faster reaction time still occurs after the user removes the device from their bodies–this is precisely what we investigated by means of a simple reaction time (RT) experiment, in which participants were asked to tap as soon as they saw an LED flashing. Participants experienced this in three EMS conditions: (1) fast-EMS, the electrical impulses were synced with the LED; (2) agency-EMS, the electrical impulse was delivered 40ms faster than the participant’s own RT, which prior work has shown to preserve one’s sense of agency over this movement; and, (3) late-EMS: the impulse was delivered after the participant’s own RT. Our results revealed that the participants’ RT was significantly reduced by approximately 8ms(up to 20ms) only after training with the agency-EMS condition. This finding suggests that the prioritizing agency during EMS training is key to motor-adaptation, i.e., it enables a faster motor response even after the user has removed the EMS device from their body.2021SKShunichi Kasahara et al.Sony CSL, The University of TokyoVibrotactile Feedback & Skin StimulationElectrical Muscle Stimulation (EMS)CHI
Programmable Filament: Printed Filaments for Multi-material 3D PrintingFrom full-color objects to functional capacitive artifacts, 3D printing multi-materials became essential to broaden the application areas of digital fabrication. We present Programmable Filament, a novel technique that enables multi-material printing using a commodity FDM 3D printer, requiring no hardware upgrades. Our technique builds upon an existing printing technique in which multiple filament segments are printed and spliced into a single threaded filament. We propose an end-toend pipeline for 3D printing an object in multi-materials, with an introduction of the design systems for end-users. Optimized for low-cost, single-nozzle FDM 3D printers, the system is built upon our computational analysis and experiments to enhance its validity over various printers and materials to design and produce a programmable filament. Finally, we discuss application examples and speculate the future with its potential, such as custom filament manufacturing on-demand.2020HTHaruki Takahashi et al.Desktop 3D Printing & Personal FabricationCircuit Making & Hardware PrototypingUIST
Servo-Gaussian Model to Predict Success Rates in Manual Tracking: Path Steering and Pursuit of 1D Moving TargetWe propose a Servo-Gaussian model to predict success rates in continuous manual tracking tasks. Two tasks were conducted to validate this model: path steering and pursuit of a 1D moving target. We hypothesized that (1) hand movements follow the servo-mechanism model, (2) submovement endpoints form a bivariate Gaussian distribution, thus enabling us to predict the success rate at which a submovement endpoint falls inside the tolerance, and (3) the success rate for a whole trial can be predicted if the number of submovements is known. The cross-validation showed R^2 > 0.92 and MAE < 4.9% for steering and R^2 > 0.95 and MAE < 6.5% for pursuit tasks. These results demonstrate that our proposed model delivers high prediction accuracy even for unknown datasets.2020SYShota Yamanaka et al.Human Pose & Activity RecognitionComputational Methods in HCIUIST
Taste Display that Reproduces Tastes Measured by a Taste SensorAiming for the creation and development of taste media, a taste display was developed in this study that can reproduce tastes measured using taste sensors. By performing iontophoresis on five gels, which contain dissolved electrolytes that reproduce the five basic tastes, the quantity of ions that contact the tongue was controlled. A tasteless gel was added, so that the sum of the currents flowing in the six gels could be kept constant, ensuring a uniform amount of stimulation on the tongue. The measured tastes could be successfully reproduced through calibration, in which the indicated taste levels were matched with the taste-sensor measurements. Furthermore, video-editing software was adapted to edit taste information as well as recorded audio and video. In addition, effector and equalizer prototypes were built that can not only reproduce the recorded tastes in their original states but also adjust the tastes to match individual preferences.2020HMHomei MiyashitaHaptic WearablesFood Culture & Food InteractionUIST
Exploring Auditory Information to Change Users' Perception of Time Passing as ShorterAlthough the processing speed of computers has been drastically increasing year by year, users still have to wait for computers to complete tasks or to respond. To cope with this, several studies have proposed presenting certain visual information to users to change their perception of time passing as shorter, e.g., progress bars with animated ribbing or faster/slower virtual clocks. As speech interfaces such as smart speakers are becoming popular, a novel method is required to make users perceive the passing of time as shorter by presenting auditory stimuli. We thus prepared 20 pieces of auditory information as experimental stimuli; that is, 11 auditory stimuli that have the same 10.1-second duration but different numbers of 0.1-second sine-wave sounds and 9 other auditory stimuli that have the same 10.1-second duration and numbers of sounds but different interval patterns between the sounds. We conducted three experiments to figure out which kinds of auditory stimuli can change users' perception of time passing as shorter. We found that a 10.1-second auditory stimulus that has 0.1-second sine-wave sounds appearing 11 times with intervals between the sounds that narrow rapidly in a linear fashion was perceived as shortest at about 9.3 seconds, which was 7.6% shorter than the actual duration of the stimulus. We also found that different interval patterns of sounds in auditory information significantly affected users' perception of time passing as shorter, while different numbers of sounds did not.2020TKTakanori Komatsu et al.Meiji UniversityVoice User Interface (VUI) DesignVisualization Perception & CognitionCHI
A 3D Printer Head as a Robotic ManipulatorWe introduce new ways of using 3D printer head as a 3-axis robotic manipulator to support advanced fabrication such as breaking support materials, assembling separately printed parts and actuating printed objects on a build-plate. To achieve these advanced fabrication techniques, we develop specific printing methods and redesign a low-cost commodity fused deposition modeling (FDM) 3D printer to that can attach/detach printed end-effectors which change the function of the 3D printer head (e.g. hook, break, and rotate printed objects). By combining our explored printing methods and advanced fabrication techniques, a low-cost FDM 3D printer print out kinetic objects one-off such as bevel gears, springs and linkage mechanisms. In addition, this technique enables actuating printed functional objects on a build-plate that need a power source and actuators such as a coffee mill.2019SKShohei Katakura et al.Desktop 3D Printing & Personal FabricationUIST
3D Pen + 3D Printer: Exploring the Role of Humans and Fabrication Machines in Creative MakingThe emergence of a 3D pen brings 3D modeling from a screen-based computer-aided design (CAD) system and 3D printing to direct and rapid crafting by 3D doodling. However, 3D doodling remains challenging, requiring craft skills to rapidly express an idea, which is critical in creative making. We explore a new process of 3D modeling using 3D pen + 3D printer. Our pilot study shows that users need support to reduce the number of non-creative tasks to explore a wide design strategy. With the opportunity to invent a new 3D modeling process that needs to incorporate both a pen and printer, we propose techniques and a system that empower users to print while doodling to focus on creative exploration. Our user study shows that users can create diverse 3D models using a pen and printer. We discuss the roles of the human and fabrication machine for the future of fabrication.2019HTHaruki Takahashi et al.Meiji UniversityDesktop 3D Printing & Personal FabricationCustomizable & Personalized ObjectsCHI
3D Printed Fabric: Techniques for Design and 3D Weaving Programmable TextilesWe present a 3D printing technique for a soft and flexible textile fabrication using a consumer grade fused deposition modeling (FDM) printer. By controlling the movement of the print header, the FDM alternately weaves the stringing fibers across a row of pillars. Owing to the structure of the fibers, which support and strengthen the pillars from each side, a thin and flexible sheet of fabric can be printed upright while the fibers are being weaved. In addition, this technique enables users to employ two material colors to design a pattern and prototype an interactive object through a variety of off-the-shelf material properties such as conductive filament. We detail a technique for weaving a textile and introduce a list of parameters that enable users to design various textiles. We demonstrate examples to show the feasibility of our approach and numerous applications to integrate printed textiles in a custom object design.2019HTHaruki Takahashi et al.Electronic Textiles (E-textiles)Shape-Changing Materials & 4D PrintingUIST
Steering through Successive ObjectsWe investigate stroking motions through successive objects with styli. There are several promising models for stroking motions, such as crossing tasks, which require endpoint accuracy of a stroke, or steering tasks, which require continuous accuracy throughout the trajectory. However, a task requiring users to repeatedly steer through constrained path segments has never been studied, although such operations are needed in GUIs, e.g., for selecting icons or objects on illustration software through lassoing. We empirically confirmed that the interval, trajectory width, and obstacle size significantly affect the movement speed. Existing models can not accurately predict user performance in such tasks. We found several unexpected results such as that steering through denser objects sometimes required less times than expected. Speed profile analysis showed the reasons behind such behaviors, such as participants' anticipation strategies. We also discuss the applicability of exiting performance models and revisions.2018SYShota Yamanaka et al.Yahoo Japan CorporationPrototyping & User TestingCHI
Double-sided Printed Tactile Display with Electro Stimuli and Electrostatic Forces and its AssessmentHumans can perceive tactile sensation through multimodal stimuli. To demonstrate realistic pseudo tactile sensation for the users, a tactile display is needed that can provide multiple tactile stimuli. In this paper, we have explicated a novel printed tactile display that can provide both the electrical stimulus and the electrostatic force. The circuit patterns for each stimulus were fabricated by employing the technique of double-sided conductive ink printing. Requirements for the fabrication process were analyzed and the durability of the tactile display was evaluated. Users’ perceptions of a single tactile stimulus and multiple tactile stimuli were also investigated. The obtained experimental results indicate that the proposed tactile display is capable of exhibiting realistic tactile sensation and can be incorporated by various applications such as tactile sensation printing of pictorial illustrations and paintings. Furthermore, the proposed hybrid tactile display can contribute to accelerated prototyping and development of new tactile devices.2018KKKunihiro Kato et al.Meiji UniversityVibrotactile Feedback & Skin StimulationShape-Changing Interfaces & Soft Robotic MaterialsCHI
Asian CHI Symposium: Emerging HCI Research CollectionThis symposium showcases the latest work from Asia on interactive systems and user interfaces that address under-explored problems and demonstrate unique approaches. In addition to circulating ideas and sharing a vision of future research in human-computer interaction, this symposium aims to foster social networks among academics (researchers and students) and practitioners and create a fresh research community from Asian region.2018SSSaki Sakaguchi et al.The University of TokyoDeveloping Countries & HCI for Development (HCI4D)User Research Methods (Interviews, Surveys, Observation)CHI
Vibrational Artificial Subtle Expressions: Conveying System’s Confidence Level to Users by Means of Smartphone VibrationArtificial subtle expressions (ASEs) are machine-like expressions used to convey a system's confidence level to users intuitively. So far, auditory ASEs using beep sounds, visual ASEs using LEDs, and motion ASEs using robot movements have been implemented and shown to be effective. In this paper, we propose a novel type of ASE that uses vibration (vibrational ASEs). We implemented the vibrational ASEs on a smartphone and conducted experiments to confirm whether they can convey a system’s confidence level to users in the same way as the other types of ASEs. The results clearly showed that vibrational ASEs were able to accurately and intuitively convey the designed confidence level to participants, demonstrating that ASEs can be applied in a variety of applications in real environments.2018TKTakanori Komatsu et al.Meiji UniversityVibrotactile Feedback & Skin StimulationExplainable AI (XAI)CHI