Encouraging Breath: Increasing Out‑of‑Session DMHI Engagement using a Shape‑Changing Biofeedback Physicalization within a Longitudinal RCTOut-of-session or "homework'' engagement is a primary limiting factor in clinical mental health outcomes. Despite weekly practitioner contact, adherence to prescribed Digital Mental Health Interventions (DMHIs) typically drops by 96.1% within two weeks. We evaluate Ankor, a handheld shape-changing biofeedback physicalization, as an adjunct to standard audio-guided mindfulness. In a longitudinal randomized controlled study (N=69), participants were assigned to Ankor+audio or audio-only control across six weekly 15-minute laboratory sessions, with optional DMHI use between sessions. Relative to control, Ankor yielded a 351% increase in total DMHI practice initiations and, by week 2, maintained 29.4% active users versus 2.9% in control, indicating substantially higher out-of-session engagement and reduced early disengagement. These findings demonstrate the capacity of shape-changing biofeedback physicalizations to extend adherence to DMHIs, highlighting kinaesthetic interactions as a promising design pathway for sustaining engagement in mental health interventions.2026AFAlexz Farrall et al.ADA UniversityShape-Changing Interfaces & Soft Robotic MaterialsBehavior Change & Reflection TechnologyMental Health Apps & Online Support CommunitiesCHI
HydroHaptics: High-Fidelity Force-Feedback on Soft Deformable Interfaces using Hydrostatic TransmissionSoft deformable interfaces offer unique interaction potential through input flexibility and diverse forms. However, force feedback on these devices remains limited, with pneumatic approaches lacking responsiveness and precision, while microhydraulic solutions are constrained to small form factors with limited input. We present HydroHaptics, a novel platform that enables high-fidelity force feedback on deformable interfaces via hydrostatic transmission. Surpassing current state-of-the-art methods, our approach allows fine-grained force feedback on soft interfaces, achieving a 10 N force change in < 100 ms and accurate 1 N, 10 Hz oscillation rendering. We detail the system's design and implementation, highlighting its ability to maintain the inherent interaction benefits of soft interfaces. A user study (N = 18)evaluates the system's performance, showing high accuracy in rendering distinct haptic effects (82.6% accuracy) and classifying input gestures (89.1% accuracy). To showcase the platform’s versatility, we present four applications illustrating HydroHaptics' potential to enhance interaction with deformable devices and unlock novel user experiences.2025JNJames David Nash et al.Force Feedback & Pseudo-Haptic WeightShape-Changing Interfaces & Soft Robotic MaterialsUIST
It Sounds Squishy: Understanding Cross-Modal Correspondences of Deformable Shapes and Sounds Computing interfaces are becoming increasingly sophisticated, with systems that engage multiple sensory channels simultaneously. Deformable and shape-changing interfaces offer rich tactile experiences, but there is limited understanding of how they can be combined with other modes of sensory feedback. We systematically explored the audio, visual and tactile cross-modal correspondences of deformable shapes with a particular focus on auditory feedback. 50 participants were asked to associate deformable tactile stimuli, varying in stiffness and shape, with the sound qualities pitch, brightness, fade-in time and fade-out time, under visuo-tactile and tactile-only conditions. Our findings provide the first insights on how (1) shape, both its form and visibility, play a significant role in associations for pitch and brightness; (2) stiffness plays a dominant role in associations over a sound’s fade-in and fade-out times. These findings are distilled into the first design guidelines for integrating auditory feedback into physical interfaces.2025MPMaisie Palmer et al.In-Vehicle Haptic, Audio & Multimodal FeedbackMid-Air Haptics (Ultrasonic)Shape-Changing Interfaces & Soft Robotic MaterialsDIS
Investigating the Benefits of Physical Models for Anatomical Education in Augmented RealityHistorically, anatomical education has utilised physical models; researchers are now looking to Augmented Reality (AR) to deliver more engaging learning experiences. While there are clear educational advantages to AR, most systems lack the cognitive benefits afforded by physical models. Our work explores the potential of combining physical anatomical models and AR. We first present a design space exploring the interplay between the two. From this, we created a tangible AR system utilising a physical vertebrae model for learning spinal anatomy and axial spondyloarthritis progression. We conducted a study (n=39) to evaluate its benefits for knowledge improvement and retention, compared with a virtual AR and screen-based version. We found no difference in learning outcomes, however, the physical model improved participants' learning experience. We then conducted an expert evaluation with clinicians to explore opportunities for using tangible AR in clinical practice. Results highlight potential benefits for patient understanding, and challenges surrounding accessibility.2025MWMatthew Wragg et al.University of Bath, Department of Computer ScienceMixed Reality WorkspacesVR Medical Training & RehabilitationCHI
Beyond Vacuuming: How Can We Exploit Domestic Robots’ Idle Time?We are increasingly adopting domestic robots (e.g., Roomba) that provide relief from mundane household tasks. However, these robots usually only spend little time executing their specific task and remain idle for long periods. They typically possess advanced mobility and sensing capabilities, and therefore have significant potential applications beyond their designed use. Our work explores this untapped potential of domestic robots in ubiquitous computing, focusing on how they can improve and support modern lifestyles. We conducted two studies: an online survey (n=50) to understand current usage patterns of these robots within homes and an exploratory study (n=12) with HCI and HRI experts. Our thematic analysis revealed 12 key dimensions for developing interactions with domestic robots and outlined over 100 use cases, illustrating how these robots can offer proactive assistance and provide privacy. Finally, we implemented a proof-of-concept prototype to demonstrate the feasibility of reappropriating domestic robots for diverse ubiquitous computing applications.2025YSYoshiaki Shiokawa et al.University of Bath, Department of Computer ScienceContext-Aware ComputingDomestic RobotsCHI
Squishy, Yet Satisfying: Exploring Deformable Shapes' Cross-Modal Correspondences with Colours and EmotionsSurfaces with deformable and shape-changing properties seek to enhance and diversify tangible interactions with computing systems. However, we currently lack fundamental knowledge and user interface design principles that connect the inherent properties of deformable shapes with our human senses and cognitive associations. To address this knowledge gap, we systematically explored deformable shapes' cross-modal correspondences (CC) with colours and emotions. In our CC study, 52 participants were presented with deformable shape stimuli that varied in stiffness and angularity. They were asked to associate these stimuli with colours and emotions under (i) visuo-tactile and; (ii) tactile-only conditions. For the first time, our findings reveal (1) how stiffness level primarily influences the CC associations and; (2) that stiffness and angularity play a significant role in CC associations over the visibility of the shapes. The results were distilled into design guidelines for future deformable, shape-changing interfaces that engage specific human senses and responses.2024CSCameron Steer et al.University of BathMid-Air Haptics (Ultrasonic)Shape-Changing Interfaces & Soft Robotic MaterialsCHI
Exploring Co-located Interactions with a Shape-Changing Bar ChartData-physicalizations encode data and meaning through geometry or material properties, providing a non-planar view of data, offering novel opportunities for interrogation, discovery and presentation. This field has explored how single users interact with complex 3D data, but the challenges in the application of this technology to collaborative situations have not been addressed. We describe a study exploring interactions and preferences among co-located individuals using a dynamic data-physicalization in the form of a shape-changing bar chart, and compare this to previous work with single participants. Results suggest that co-located interactions with physical data prompt non-interactive hand gestures, a mirroring of physicalizations, and novel hand gestures in comparison to single participant studies. We also note that behavioural similarities in participants between interactive tabletop studies and data-physicalizations may be capitalised upon for further development of these dynamic representations. Finally, we consider the implications and challenges for the adoption of these types of platforms.2023MSMiriam Sturdee et al.Lancaster UniversityShape-Changing Interfaces & Soft Robotic MaterialsData PhysicalizationCollaborative Learning & Peer TeachingCHI
Feel the Force, See the Force: Exploring Visual-tactile Associations of Deformable Surfaces with Colours and ShapesDeformable interfaces provide unique interaction potential for force input, for example, when users physically push into a soft display surface. However, there remains limited understanding of which visual-tactile design elements signify the presence and stiffness of such deformable force-input components. In this paper, we explore how people correspond surface stiffness to colours, graphical shapes, and physical shapes. We conducted a cross-modal correspondence (CC) study, where 30 participants associated different surface stiffnesses with colours and shapes. Our findings evidence the CCs between stiffness levels for a subset of the 2D/3D shapes and colours used in the study. We distil our findings in three design recommendations: (1) lighter colours should be used to indicate soft surfaces, and darker colours should indicate stiff surfaces; (2) rounded shapes should be used to indicate soft surfaces, while less-curved shapes should be used to indicate stiffer surfaces, and; (3) longer 2D drop-shadows should be used to indicate softer surfaces, while shorter drop-shadows should be used to indicate stiffer surfaces.2023CSCameron Steer et al.University of BathForce Feedback & Pseudo-Haptic WeightShape-Changing Interfaces & Soft Robotic MaterialsCHI
Manifesting Breath: Empirical Evidence for the Integration of Shape-Changing Biofeedback-based Artefacts within Digital Mental Health InterventionsDigital interventions are often used to support people with mental health conditions, but low engagement frequently reduces their effectiveness. We investigate the use of a Physical Artefact for Well-being Support (PAWS) to improve engagement and effectiveness of an audio-only guided well-being intervention. Through our handheld shape-changing biofeedback-based PAWS, users can synchronously feel their breath via kinaesthetic haptic feedback. By evaluating our device in a randomised-controlled experimental paradigm (N=58), we demonstrate significant reductions in physiological and subjective (self-reported) anxiety compared to an audio-only control. Our findings conclude that synchronous interactions with one‘s own physiological data via the PAWS, improves engagement and effectiveness of an intervention.2023AFAlexz Farrall et al.University of BathShape-Changing Interfaces & Soft Robotic MaterialsMental Health Apps & Online Support CommunitiesSleep & Stress MonitoringCHI
How to Evaluate Object Selection and Manipulation in VR? Guidelines from 20 Years of StudiesThe VR community has introduced many object selection and manipulation techniques during the past two decades. Typically, they are empirically studied to establish their benefits over the state-of-the-art. However, the literature contains few guidelines on how to conduct such studies; standards developed for evaluating 2D interaction often do not apply. This lack of guidelines makes it hard to compare techniques across studies, to report evaluations consistently, and therefore to accumulate or replicate findings. To build such guidelines, we review 20 years of studies on VR object selection and manipulation. Based on the review, we propose recommendations for designing studies and a checklist for reporting them. We also identify research directions for improving evaluation methods and offer ideas for how to make studies more ecologically valid and rigorous.2021JBJoanna Bergström et al.University of CopenhagenImmersion & Presence ResearchPrototyping & User TestingCHI
Reconfiguration Strategies with Composite Data PhysicalizationsComposite data physicalizations allow for the physical reconfiguration of data points, creating new opportunities for interaction and engagement. However, there is a lack of understanding of people's strategies and behaviors when directly manipulating physical data objects. In this paper, we systematically characterize different reconfiguration strategies using six exemplar physicalizations. We asked 20 participants to reorganize these exemplars with two levels of restriction: changing a single data object versus changing multiple data objects. Our findings show that there were two main reconfiguration strategies used: changes in proximity and changes in atomic orientation. We further characterize these using concrete examples of participant actions in relation to the structure of the physicalizations. We contribute an overview of reconfiguration strategies, which informs the design of future manually reconfigurable and dynamic composite physicalizations.2021KSKim Sauvé et al.Lancaster UniversityData PhysicalizationCHI
Understanding the Design Space of Embodied Passwords based on Muscle MemoryPasswords have become a ubiquitous part of our everyday lives, needed for every web-service and system. However, it is challenging to create safe and diverse alphanumeric passwords, and to recall them, imposing a cognitive burden on the user. Through consecutive experiments, we explored the movement space, affordances and interaction, and memorability of a tangible, handheld, embodied password. In this context, we found that: (1) a movement space of 200 mm × 200 mm is preferred; (2) each context has a perceived level of safety, which—together with the affordances and link to familiarity—influences how the password is performed. Furthermore, the artefact’s dimensions should be balanced within the design itself, with the user, and the context, but there is a trade-off between the perceived safety and ergonomics; and (3) the designed embodied passwords can be recalled for at least a week, with participants creating unique passwords which were reproduced consistently.2021RKRosa van Koningsbruggen et al.Bauhaus-Universität WeimarForce Feedback & Pseudo-Haptic WeightPasswords & AuthenticationCHI