This paper explores (1) the role of metaphors in physical data representations and (2) the concept of tacit data: implicitly known data which are hard to uncover. In a semester course with twenty-three students, five teams explored how to represent self-chosen ‘tacit data’ in a visualisation, haptification, and dynamic physicalisation. Throughout these phases, our notion of tacit data evolved, resulting in a proposed working definition. Moreover, we noticed that metaphors played an increasingly important role. Based on analysis of students’ work and interviews with them, we found that tacit data and physical data representations need metaphors. For haptifications and physicalisations, metaphors help to circumvent limitations, curate data, and communicate to the audience. As tacit data were seen as ‘soft’ and difficult to quantify, metaphors made the data workable. Furthermore, tacit data benefit from physical representations, which offer further dimensions to represent the feeling and intimate aspects of data.

Despite irreversibility being omnipresent in the lifeworld, research on interactions making use of irreversibility in computing systems is still in the early stages. User freedom – provided by the undo functionality – is considered to be a pillar of “usable” computer systems, overcoming irreversibility. Within this paper, we set up a thought experiment, challenging the “undo feature” and instead take advantage of irreversibility in the interaction with physical computing systems (tangibles, robots, etc). First, we present three material speculations, each inherently utilizing irreversibility. Second, we elaborate on the concept of irreversible interactions by contextualizing our work with critical HCI discourses and deducing three design strategies. Finally, we discuss irreversibility as a design element for self-reflection, meaningful acting, and a sustainable relationship with technology. While previously individual aspects of irreversibility have been explored, we contribute a comprehensive discussion of irreversible interactions in HCI presenting artifacts, a conceptualization, design strategies, and application purposes.

Communication is crucial for interpersonal connection, but sometimes we simply cannot find the right words. Some data, such as complex emotions, are either hard to quantify or are otherwise difficult to communicate. We have access to numerous personal statistics from quantified self devices, but hidden data are either untracked or require abstraction. In this paper, we explore physicalizations to communicate hidden data between couples. We recruited six couples (N=12 participants, 163 telegram responses) to participate in a two-week sensitization diary study followed by two participatory co-design sessions. We then hosted a one-day expert prototyping workshop (N=5) to create tangible artifacts based on the findings of the participatory phase. By iterating on the topic in three ways, we contribute (i) a design framework for understanding and tangibly representing hidden data, (ii) a discussion on the appropriateness of these methodologies, and (iii) open research questions to guide future research in the field.

Embedded interfaces support active indexing, the process of making sense of the experienced. While this supports the creation of meaningful relationships, findings are limited on how it could support sustaining the significance of historical places. We selected two historical places of daily use and developed two AR apps for each. The apps aimed at fostering participants’ indexing and meaningful connection to the places by presenting their history. One app offered passive, informative content. The other displayed an interactive, moral dilemma emphasizing the places’ social values. We tested the apps in two between-subjects studies with N=42 participants in total. We explored how participants ’ historical understanding can be improved by embedding our interfaces on five levels (spatially, physically, contextually, historically, and morally). We found that the morally embedded AR stories supported active indexing stronger than the passive ones and argued that they could foster meaningful relationships between users and historical places.

Concrete is a ubiquitous material in urban environments and increasingly used by industry and the maker movement. However, there is little research about its affordance and its potential for embedded User Interfaces (UI). In our ongoing work, we investigate different manufacturing processes and design strategies to change and adapt the affordances of concrete to make it appear interactive. We tested three interface elements, a button, a scroll wheel, and a slider, with 33 participants in a lab elicitation study. Each was created in two versions following two design strategies, one with a more natural look, the other more abstract. Five participants then bodystormed ideas with the prototypes in an outdoor environment. Based on our explorations, we discuss design considerations for creating concrete interfaces including the potential of both design strategies and present different application scenarios.

We present StringTouch, a user interface design exploration translating the expressive resource of string instruments to a new interface morphology. StringTouch transfers the string as a tactile element of interaction to the touch surface, resulting in a tactilely experienceable interface. In this paper we discuss our research through design centered approach, which focused on the exploration of musical string instruments and their translation to the UI context. To investigate this specific design space, we analyzed the systematic and handling of string instruments as well as common HCI principles to develop the interaction concept. The resulting experience prototype demonstrates the idea’s potential for haptic UI design and provides insights into the prototyping process. We present: (1) the investigation of string instruments as a resource for TUI design and (2) the transfer to a generic UI context to inform new hybrid interface morphologies that combine features of tangible, touch, and flexible interaction.

To give robots, which are black box systems for most users, feedback we have to implement interaction paradigms that users understand and accept, for example reward and punishment. In this paper we present the first HRI experience prototype which implements gradual destructive interaction, namely breaking a robot's leg as a punishment technique. We conducted an exploratory experiment (N=20) to investigate participants' behavior during the execution of three punishment techniques. Using a structured analysis of videos and interviews, we provide in-depth insights into participants' attitude towards these techniques. Participants preferred more abstract techniques and felt uncomfortable during human-like punishment interaction. Based on our findings, we raise questions how human-like technologies should be designed. A video documentation of the project can be found here: https://vimeo.com/348646727

Virtual Reality experiences and games present believable virtual environments based on graphical quality, spatial audio, and interactivity. The interaction with in-game characters, controlled by computers (agents) or humans (avatars), is an important part of VR experiences. Pre-captured motion sequences increase the visual humanoid resemblance. However, this still precludes realistic social interactions (eye contact, imitation of body language), particularly for agents. We aim to make social interaction more realistic via social touch. Social touch is non-verbal, conveys feelings and signals (coexistence, closure, intimacy). In our research, we created an artificial hand to apply social touch in a repeatable and controlled fashion to investigate its effect on the perceived human-likeness of avatars and agents. Our results show that social touch is effective to further blur the boundary between computer- and human-controlled virtual characters and contributes to experiences that closely resemble human-to-human interactions.

Traces of use in public environments show the behaviour patterns of the masses. Taking advantage of this quality, we want to use such traces as design tool to indicate possible interactions in e.g. newly built areas while keeping a natural and calm environment. Due to current lacking knowledge about such traces, this work aims at understanding the perception of traces of use in public places. Therefore we collected a total of 182 pictures of traces of use in urban environments. A focus group discussed and classified a preselected set of pictures. In an online picture viewing survey, 18 different pictures were reviewed for pattern identification (N= 32-52). Overlaps were visualized in heatmaps. We contribute an analysis of which public traces of use are easy to recognize with great agreement and which are not.

Tangible user interfaces create the possibility to provide users with an exploratory, expressive and flexible access to musical interaction. However, new technologies and metaphors can additionally open up further opportunities and mental models for the design of new interaction concepts. In the scope of my thesis I explore new metaphors by designing and building new interfaces which finally explore these ideas and concepts. In addition to the conceptual work, the development of new technologies, which are necessary for the implementation of these concepts, is a central part of the work. In this paper I present the prototypes COMB and StringTouch and discuss potential application areas for the implementation of core ideas regarding both concepts.

This paper introduces a tangible user interface (TUI) concept designed for child-oriented musical interaction and education by the name of COMB. The interaction concept of the interface is based upon the natural behavior and metaphors found in children's play during construction with building-blocks. This paradigm is used to increase the accessibility of the otherwise expert-focused digital and electronic music to children. We evaluated our prototype during two different study setups. We found preliminary indications that this concept fosters imitation during learning. Therefore, the usage of shape as a meaningful element of interaction could be a promising design strategy for interfaces addressing children. In this paper we present the theoretical foundation of the concept as well as technical details of the prototype. Furthermore, we discuss how this concept can be applied to increase accessibility of technology in various other domains.