Peer Reviewed

Adaptive training of motor-skills, where the difficulty level of the training task is adapted optimally based on the learner’s skill levels, has been shown to enable higher learning gains compared to non-adaptive training. However, prior approaches rely on adapting physical tools that are tedious to design and build. This work investigates using augmented reality (AR) to achieve a similar objective of maintaining functional task difficulty – the difficulty experienced by the learner – at an optimal challenge point during adaptive training. A study prototype of an AR adaptive basketball training system was developed, wherein the learners train to throw a physical ball into a virtual AR hoop seen through a head-mounted device. Results from the study (N=16) aimed to measure the learning gains showed higher learning gains after adaptive AR training compared to non-adaptive AR training. An analysis of participant feedback, however, highlighted challenges with AR-based adaptive training, pointing to the need for a different design approach compared to the physical adaptive tools. Collectively, this exploratory study investigates the use of AR for adaptive motor-skill learning and lays the foundation for future research directions for the AR-tool design.

We explore the use of multimodal input to predict the landing position of a ray pointer while selecting targets in a virtual reality (VR) environment. We first extend a prior 2D Kinematic Template Matching technique to include head movements. This new technique, Head-Coupled Kinematic Template Matching, was found to improve upon the existing 2D approach, with an angular error of 10.0° when a user was 40% of the way through their movement. We then investigate two additional models that incorporated eye gaze, which were both found to further improve the predicted landing positions. The first model, Gaze-Coupled Kinematic Template Matching resulted in angular error of 6.8° for reciprocal target layouts and 9.1° for random target layouts, when a user was 40% of the way through their movement. The second model, Hybrid Kinematic Template Matching, resulted in angular error of 5.2° for reciprocal target layouts and 7.2° for random target layouts when a user was 40% of the way through their movement. We also found that using just the current gaze location resulted in sufficient predictions in many conditions. We reflect on our results by discussing the broader implications of utilizing multimodal input to inform selection predictions in VR.

The rapid growth of AR platforms, combined with the rising predictive power of intelligent systems, will fundamentally change interactive computing. Interaction will increasingly happen on the go, causing I/O to become constrained, ultimately leading to reliance on user intent prediction for aid. In this pictorial, we argue that to support the development of such systems, new predictive UI toolkits are required. We place the reader in the shoes of an App designer and outline the challenges that will be faced. We then describe a new predictive toolkit, leveraging Fuzzy Widgets, or “Fidgets” as the main UI building block. Fidgets extend Responsive Design into the realm of intelligent systems, to adapt not only to spatial constraints, but to system predictions as well. We then describe a working implementation of a predictive music application, built using our described framework, showcasing its benefits and range of adaptive abilities.

This work seeks to design and evaluate haptic feedback for sequential gestural inputs, where mid-air hand gestures are used to express system commands. Nine haptic patterns are first designed leveraging metaphors. To pursue efficient interaction, we examine the trade-off between pattern duration and recognition accuracy and find that durations as short as 0.3s-0.5s achieve roughly 80%-90% accuracy. We then examine the haptic design for sequential inputs, where we vary when the feedback for each gesture is provided, along with pattern duration, gesture sequence length, and age. Results show that providing haptic patterns right after detected hand gestures leads to significantly more efficient interaction compared with concatenating all haptic patterns after the gesture sequence. Moreover, the number of gestures had little impact on performance, but age is a significant predictor. Our results suggest that immediate feedback with 0.3s and 0.5s pattern duration would be recommended for younger and older users respectively.

Input false-positive errors, where a system recognizes an input action that the user did not perform, have been shown to be particularly costly for user experience. Recent work has suggested that eye-gaze behavior immediately following an input event can be used to detect whether the input was intended by a user or was the result of a false-positive error. The ability to detect these errors could enable systems that assist the user with error recovery, but little is currently known about how such error mediation techniques might be designed, or the benefits they could provide. This paper presents an initial investigation of the design of error mediation techniques, and an evaluation of their potential benefits. A controlled study demonstrated that error mediation techniques can save time when recovering from errors by helping users to notice and resolve these errors quickly when they occur.

Mixed reality (MR) provides users with novel affordances that allow them to overlay and experience reality in various visual manifestations. However, existing works mainly focused on using MR to augment a user’s present, which does not exhaust the full potential of contextual MR. In this paper, we empirically explore MR-Driven Near-Future Realities, a future multimodal MR experience that can overlay semantically-related augmentations within a user’s everyday life to allow them to preview, manipulate, and reflect on a near-future reality. We investigated this concept during a VR-based empirical study to understand users’ perceptions and opinions about MR-Driven Near-Future Realities. The results showed that users were positive about the concept of MR-Driven Near-Future Realities and were capable of eliciting near-future realities in various simulated real-world manifestations, but more demanding scenarios negatively affected their experience and task completion performance. Our goal is to spark meaningful and critical discussions about the use of MR-Driven Near-Future Realities to preview possible near-future realities in everyday life.

Text entry is a critical capability for any modern computing experience, with lightweight augmented reality (AR) glasses being no exception. Designed for all-day wearability, a limitation of lightweight AR glass is the restriction to the inclusion of multiple cameras for extensive field of view in hand tracking. This constraint underscores the need for an additional input device. We propose a system to address this gap: a ring-based mid-air gesture typing technique, RingGesture, utilizing electrodes to mark the start and end of gesture trajectories and inertial measurement units (IMU) sensors for hand tracking. This method offers an intuitive experience similar to raycast-based mid-air gesture typing found in VR headsets, allowing for a seamless translation of hand movements into cursor navigation. To enhance both accuracy and input speed, we propose a novel deep-learning word prediction framework, Score Fusion, comprised of three key components: a) a word-gesture decoding model, b) a spatial spelling correction model, and c) a lightweight contextual language model. In contrast, this framework fuses the scores from the three models to predict the most likely words with higher precision. We conduct comparative and longitudinal studies to demonstrate two key findings: firstly, the overall effectiveness of RingGesture, which achieves an average text entry speed of 27.3 words per minute (WPM) and a peak performance of 47.9 WPM. Secondly, we highlight the superior performance of the Score Fusion framework, which offers a 28.2% improvement in uncorrected Character Error Rate over a conventional word prediction framework, Naive Correction, leading to a 55.2% improvement in text entry speed for RingGesture. Additionally, RingGesture received a System Usability Score of 83 signifying its excellent usability.

Although mid-air hand gestures have been widely adopted by VR/AR products (e.g., Quest 2 and HoloLens), some drawbacks remain due to their lack of tangibility and tactile feedback. Opportunistic Tangible User Interfaces could address these shortcomings by repurposing existing objects in one's physical environment. However, there has yet to be a systematic investigation of the gestures that would be desirable when using opportunistic objects or how such gestures would be impacted by such objects. In this work, we conducted an elicitation study to investigate the desirability of object and gesture combinations across a variety of interactions. The results contribute (1) an opportunistic tangible UI gesture set for spatial interfaces, and (2) an Affordance-Based Object Selector Scheme that identifies ideal objects for tangible input given a desired input gesture, based on that object's physical affordances. Arising from these findings is the vision of the Adaptive Tangible User Interface, which supports the on-the-fly composition of tangible interfaces based on the affordances found in the physical environment and a user's input task.

Many XR devices use bare-hand gestures to reduce the need for handheld controllers. Such gestures, however, lead to false positive and false negative recognition errors, which detract from the user experience. While mediation techniques enable users to overcome recognition errors by clarifying their intentions via UI elements, little research has explored how mediation techniques should be designed in XR and how a user’s task and context may impact their design preferences. This research presents empirical studies about the impact of user perceived error costs on users’ preferences for three mediation technique designs, under different simulated scenarios that were inspired by real-life tasks. Based on a large-scale crowd-sourced survey and an immersive VR-based user study, our results suggest that the varying contexts within each task type can impact users’ perceived error costs, leading to different preferred mediation techniques. We further discuss the study implications of these results on future XR interaction design.

Microgestures can enable auxiliary input when the hands are occupied. Although prior work has evaluated the comfort of microgestures performed by the index finger and thumb, these gestures cannot be performed while the fingers are constrained by specific hand locations or postures. As the hand can be freely positioned with no primary posture, partially constrained while forming a pose, or highly constrained while grasping an object at a specific location, we leverage the middle, ring, and pinky fingers to provide additional opportunities for auxiliary input across varying levels of hand constraints. A design space and applications demonstrate how such microgestures can transfer across hand location and posture constraints. An online study evaluated their comfort and effort and a lab study evaluated their use for task-specific microinteractions. The results revealed that many middle finger microgestures were comfortable, and microgestures performed while forming a pose were preferred over baseline techniques.

While text entry is an essential and frequent task in Augmented Reality (AR) applications, devising an efficient and easy-to-use text entry method for AR remains an open challenge. This research presents STAR, a smartphone-analogous AR text entry technique that leverages a user’s familiarity with smartphone two-thumb typing. With STAR, a user performs thumb typing on a virtual QWERTY keyboard that is overlain on the skin of their hands. During an evaluation study of STAR, participants achieved a mean typing speed of 21.9 WPM (i.e., 56% of their smartphone typing speed), and a mean error rate of 0.3% after 30 minutes of practice. We further analyze the major factors implicated in the performance gap between STAR and smartphone typing, and discuss ways this gap could be narrowed.

In cinematic VR, viewers can only see a limited portion of the scene at any time. As a result, they may miss important events outside their field of view. While there are many techniques which offer spatial guidance (where to look), there has been little work on temporal guidance (when to look). Temporal guidance offers viewers a look-ahead time and allows viewers to plan their head motion for important events. This paper introduces spatiotemporal visual guidance and presents a new widget, RadarVR, which shows both spatial and temporal information of regions of interest (ROIs) in a video. Using RadarVR, we conducted a study to investigate the impact of temporal guidance and explore trade-offs between spatiotemporal and spatial-only visual guidance. Results show spatiotemporal feedback allows users to see a greater percentage of ROIs, with 81% more seen from their initial onset. We discuss design implications for future work in this space.

Gestural interaction has evolved from a set of novel interaction techniques developed in research labs, to a dominant interaction modality used by millions of users everyday. Despite its widespread adoption, the design of appropriate gesture vocabularies remains a challenging task for developers and designers. Existing research has largely used Expert-Led, User-Led, or Computationally-Based methodologies to design gesture vocabularies. These methodologies leverage the expertise, experience, and capabilities of experts, users, and systems to fulfill different requirements. In practice, however, none of these methodologies provide designers with a complete, multi-faceted perspective of the many factors that influence the design of gesture vocabularies, largely because a singular set of factors has yet to be established. Additionally, these methodologies do not identify or emphasize the subset of factors that are crucial to consider when designing for a given use case. Therefore, this work reports on the findings from an exhaustive literature review that identified 13 factors crucial to gesture vocabulary design and examines the evaluation methods and interaction techniques commonly associated with each factor. The identified factors also enable a holistic examination of existing gesture design methodologies from a factor-oriented viewpoint and highlighting the strengths and weaknesses of each methodology. This work closes with proposals of future research directions of developing an iterative user-centered and factor-centric gesture design approach as well as establishing an evolving ecosystem of factors that are crucial to gesture design.

Gaze-based interaction is a fast and ergonomic type of hands-free interaction that is often used with augmented and virtual reality when pointing at targets. Such interaction, however, can be cumbersome whenever user, tracking, or environmental factors cause eye tracking errors. Recent research has suggested that fallback modalities could be leveraged to ensure stable interaction irrespective of the current level of eye tracking error. This work thus presents Weighted Pointer interaction, a collection of error-aware pointing techniques that determine whether pointing should be performed by gaze, a fallback modality, or a combination of the two, depending on the level of eye tracking error that is present. These techniques enable users to accurately point at targets when eye tracking is accurate and inaccurate. A virtual reality target selection study demonstrated that Weighted Pointer techniques were more performant and preferred over techniques that required the use of manual modality switching.

In virtual reality (VR) environments, asymmetric bimanual interaction techniques can increase users’ input bandwidth by complementing their perceptual and motor systems (e.g., using the dominant hand to select 3D UI controls anchored around the non-dominant arm). However, it is unclear how to optimize the layout of such 3D UI controls for near-body and mid-air interactions. We evaluate the performance and limitations of non-dominant arm-anchored 3D UIs in VR environments through a bimanual pointing study. Results demonstrated that targets appearing closer to the skin, located around the wrist, or placed on the medial side of the forearm could be selected more quickly than targets farther away from the skin, located around the elbow, or on the lateral side of the forearm. Based on these results, we developed Armstrong guidelines, demonstrated through a Unity plugin to enable designers to create performance-optimized arm-anchored 3D UI layouts.

Existing approaches to trading off false positive versus false negative errors in input recognition are based on imprecise ideas of how these errors affect user experience that are unlikely to hold for all situations. To inform dynamic approaches to setting such a tradeoff, two user studies were conducted on how relative preference for false positive versus false negative errors is influenced by differences in the temporal cost of error recovery, and high-level task factors (time pressure, multi-tasking). Participants completed a tile selection task in which false positive and false negative errors were injected at a fixed rate, and the temporal cost to recover from each of the two types of error was varied, and then indicated a preference for one error type or the other, and a frustration rating for the task. Responses indicate that the temporal costs of error recovery can drive both frustration and relative error type preference, and that participants exhibit a bias against false positive errors, equivalent to ∼1.5 seconds or more of added temporal recovery time. Several explanations for this bias were revealed, including that false positive errors impose a greater attentional demand on the user, and that recovering from false positive errors imposes a task switching cost.

This paper presents Dream Lens, an interactive visual analysis tool for exploring and visualizing large-scale generative design datasets. Unlike traditional computer aided design, where users create a single model, with generative design, users specify high-level goals and constraints, and the system automatically generates hundreds or thousands of candidates all meeting the design criteria. Once a large collection of design variations is created, the designer is left with the task of finding the design, or set of designs, which best meets their requirements. This is a complicated task which could require analyzing the structural characteristics and visual aesthetics of the designs. Two studies are conducted which demonstrate the usability and usefulness of the Dream Lens system, and a generatively designed dataset of 16,800 designs for a sample design problem is described and publicly released to encourage advancement in this area.

PhenoLines is a visual analysis tool for the interpretation of disease subtypes, derived from the application of topic models to clinical data. Topic models enable one to mine cross-sectional patient comorbidity data (e.g., electronic health records) and construct disease subtypes-each with its own temporally evolving prevalence and co-occurrence of phenotypes-without requiring aligned longitudinal phenotype data for all patients. However, the dimensionality of topic models makes interpretation challenging, and de facto analyses provide little intuition regarding phenotype relevance or phenotype interrelationships. PhenoLines enables one to compare phenotype prevalence within and across disease subtype topics, thus supporting subtype characterization, a task that involves identifying a proposed subtype's dominant phenotypes, ages of effect, and clinical validity. We contribute a data transformation workflow that employs the Human Phenotype Ontology to hierarchically organize phenotypes and aggregate the evolving probabilities produced by topic models. We introduce a novel measure of phenotype relevance that can be used to simplify the resulting topology. The design of PhenoLines was motivated by formative interviews with machine learning and clinical experts. We describe the collaborative design process, distill high-level tasks, and report on initial evaluations with machine learning experts and a medical domain expert. These results suggest that PhenoLines demonstrates promising approaches to support the characterization and optimization of topic models.

During asynchronous collaborative analysis, handoff of partial findings is challenging because externalizations produced by analysts may not adequately communicate their investigative process. To address this challenge, we developed techniques to automatically capture and help encode tacit aspects of the investigative process based on an analyst's interactions, and streamline explicit authoring of handoff annotations. We designed our techniques to mediate awareness of analysis coverage, support explicit communication of progress and uncertainty with annotation, and implicit communication through playback of investigation histories. To evaluate our techniques, we developed an interactive visual analysis system, KTGraph, that supports an asynchronous investigative document analysis task. We conducted a two-phase user study to characterize a set of handoff strategies and to compare investigative performance with and without our techniques. The results suggest that our techniques promote the use of more effective handoff strategies, help increase an awareness of prior investigative process and insights, as well as improve final investigative outcomes.

Cross-sectional phenotype studies are used by genetics researchers to better understand how phenotypes vary across patients with genetic diseases, both within and between cohorts. Analyses within cohorts identify patterns between phenotypes and patients (e.g., co-occurrence) and isolate special cases (e.g., potential outliers). Comparing the variation of phenotypes between two cohorts can help distinguish how different factors affect disease manifestation (e.g., causal genes, age of onset, etc.). PhenoStacks is a novel visual analytics tool that supports the exploration of phenotype variation within and between cross-sectional patient cohorts. By leveraging the semantic hierarchy of the Human Phenotype Ontology, phenotypes are presented in context, can be grouped and clustered, and are summarized via overviews to support the exploration of phenotype distributions. The design of PhenoStacks was motivated by formative interviews with genetics researchers: we distil high-level tasks, present an algorithm for simplifying ontology topologies for visualization, and report the results of a deployment evaluation with four expert genetics researchers. The results suggest that PhenoStacks can help identify phenotype patterns, investigate data quality issues, and inform data collection design.

User-authored annotations of data can support analysts in the activity of hypothesis generation and sensemaking, where it is not only critical to document key observations, but also to communicate insights between analysts. We present annotation graphs, a dynamic graph visualization that enables meta-analysis of data based on user-authored annotations. The annotation graph topology encodes annotation semantics, which describe the content of and relations between data selections, comments, and tags. We present a mixed-initiative approach to graph layout that integrates an analyst's manual manipulations with an automatic method based on similarity inferred from the annotation semantics. Various visual graph layout styles reveal different perspectives on the annotation semantics. Annotation graphs are implemented within C8, a system that supports authoring annotations during exploratory analysis of a dataset. We apply principles of Exploratory Sequential Data Analysis (ESDA) in designing C8, and further link these to an existing task typology in the visualization literature. We develop and evaluate the system through an iterative user-centered design process with three experts, situated in the domain of analyzing HCI experiment data. The results suggest that annotation graphs are effective as a method of visually extending user-authored annotations to data meta-analysis for discovery and organization of ideas.

Sliders and Visual Analogue Scales (VASs) are input mechanisms which allow users to specify a value within a predefined range. At a minimum, sliders and VASs typically consist of a line with the extreme values labeled. Additional decorations such as labels and tick marks can be added to give information about the gradations along the scale and allow for more precise and repeatable selections. There is a rich history of research about the effect of labelling in discrete scales (i.e., Likert scales), however the effect of decorations on continuous scales has not been rigorously explored. In this paper we perform a 2,000 user, 250,000 trial online experiment to study the effects of slider appearance, and find that decorations along the slider considerably bias the distribution of responses received. Using two separate experimental tasks, the trade-offs between bias, accuracy, and speed-of-use are explored and design recommendations for optimal slider implementations are proposed.

The egocentric analysis of dynamic networks focuses on discovering the temporal patterns of a subnetwork around a specific central actor (i.e., an ego-network). These types of analyses are useful in many application domains, such as social science and business intelligence, providing insights about how the central actor interacts with the outside world. We present EgoLines, an interactive visualization to support the egocentric analysis of dynamic networks. Using a "subway map" metaphor, a user can trace an individual actor over the evolution of the ego-network. The design of EgoLines is grounded in a set of key analytical questions pertinent to egocentric analysis, derived from our interviews with three domain experts and general network analysis tasks. We demonstrate the effectiveness of EgoLines in egocentric analysis tasks through a controlled experiment with 18 participants and a use-case developed with a domain expert.

The differential diagnosis of hereditary disorders is a challenging task for clinicians due to the heterogeneity of phenotypes that can be observed in patients. Existing clinical tools are often text-based and do not emphasize consistency, completeness, or granularity of phenotype reporting. This can impede clinical diagnosis and limit their utility to genetics researchers. Herein, we present PhenoBlocks, a novel visual analytics tool that supports the comparison of phenotypes between patients, or between a patient and the hallmark features of a disorder. An informal evaluation of PhenoBlocks with expert clinicians suggested that the visualization effectively guides the process of differential diagnosis and could reinforce the importance of complete, granular phenotypic reporting.

We introduce Splash, a framework reducing development overhead for both data curators and visualization developers of client-server visualization systems. Splash streamlines the process of creating a multiple level-of-detail version of the data and facilitates progressive data download, thereby enabling real-time, on-demand navigation with existing visualization toolkits. As a result, system responsiveness is increased and the user experience is improved. We demonstrate the benefit of progressive loading for user interaction on slower networks. Additionally, case study evaluations of Splash with real-world data curators suggest that Splash supports iterative refinement of visualizations and promotes the use of exploratory data analysis.

Recently, research in 3D computer graphics and interaction has started to move beyond the narrow domain of single object authoring and inspection, and has begun to consider complex multiscale objects and environments. This generalization of problem scope calls for more general solutions, which are more akin to information visualization techniques than traditional computer graphics approaches.

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We present a comprehensive system for multiscale navigation of 3-dimensional scenes, and demonstrate our approach on multiscale datasets such as the Earth. Our system incorporates a novel image-based environment representation which we refer to as the cubemap. Our cubemap allows consistent navigation at various scales, as well as real-time collision detection without pre-computation or prior knowledge of geometric structure. The cubemap is used to improve upon previous work on proximal object inspection (HoverCam), and we present an additional interaction technique for navigation which we call look-and-fly. We believe that our approach to the navigation of multiscale 3D environments offers greater flexibility and ease of use than mainstream applications such as Google Earth and Microsoft Virtual Earth, and we demonstrate our results with this system.

We describe a new type of graphical user interface widget called the "PieCursor." The PieCursor is based on the Tracking Menu technique and consists of a radial cluster of command wedges, is roughly the size of a cursor, and replaces the traditional cursor. The PieCursor technique merges the normal cursor function of pointing with command selection into a single action. A controlled experiment was conducted to compare the performance of rapid command and target selection using the PieCursor against larger versions of Tracking Menus and a status quo Toolbar configuration. Results indicate that for small clusters of tools (4 and 8 command wedges) the PieCursor can outperform the toolbar by 20.8% for coarse pointing. For fine pointing, the performance of the PieCursor degrades approximately to the performance found for the Toolbar condition.