Privacy research in the field of HCI is predominantly based on theories that view privacy as an individual decision, interpersonal boundary regulation, or adherence to context-specific norms. While these approaches have provided valuable insights, they do not sufficiently take into account the structural and relational power asymmetries that shape the emergence and restriction of privacy. This paper proposes a relational power framework of privacy that reconceptualizes privacy as an outcome of power‑laden interactions among individuals, institutions, communities, and technological infrastructures. Drawing on critical theory and actor-network theory, we show how widespread privacy models obscure dominance by overemphasising users’ agency, assuming symmetrical relationships, and depoliticizing contextual conditions. We argue that privacy should be viewed as shaped by power, which requires consideration of structures such as institutional arrangements and infrastructural configurations. Our framework provides HCI researchers and designers with an analytical tool to uncover and address power asymmetries.

Fairness is a recurring challenge in grassroots digital infrastructures, where collective action depends on volunteer contributions. This paper presents a study of Foodsharing.de, a grassroots FOSS platform with 185,000 members rescuing and redistributing surplus food. Drawing on 25 interviews and long-term activist involvement, we analyze two justice-oriented features: the Cherry-Picking Rule (distributional fairness) and Commitment Statistics (contributional fairness). We show how these fairness features become deeply entangled in practice and how they operate as policy-in-code, inscribing fairness logics into software and redistributing not only food and labor but also authority within the community. Rather than settling questions of justice, these interventions trigger renewed negotiation across deliberative spaces and everyday coordination, as encoded rules are interpreted, contested, and adapted. Building on these dynamics, we outline governance directions for justice-oriented grassroots infrastructures, highlighting the need for contestability and accountable autonomy to sustain negotiation and align technical change with community legitimacy.

Abstract Peer-to-peer sharing platforms become increasingly important in the platform economy. From an HCI-perspective, this development is of high interest, as those platforms mediate between different users. Such mediation entails dealing with various social issues, e.g., building trust between peers online without any physical presence. Peer ratings have proven to be an important mechanism in this regard. At the same time, scoring via car telematics become more common for risk assessment by car insurances. Since user ratings face crucial problems such as fake or biased ratings, we conducted a design case study to determine whether algorithm-based scoring has the potential to improve trust-building in P2P-carsharing. We started with 16 problem-centered interviews to examine how people understand algorithm-based scoring, we co-designed an app with scored profiles, and finally evaluated it with 12 participants. Our findings show that scoring systems can support trust-building in P2P-carsharing and give insights how they should be designed.

On online platforms, algorithms help us build and manage our relationships. However, their invisible interventions might also pose harm to these connections. Dating platforms offer a prime example where, despite extensive research on human-inflicted harm, the potential harm from the algorithms themselves, and user strategies for mitigating them, remains largely unexplored. In our analysis of 7,043 reviews and interviews with 30 Tinder users, we unveiled how users perceive algorithmic harm as damaging self-esteem, sabotaging potential relationships, encouraging antisocial behavior, and misrepresenting or marginalizing certain identities. We introduce a new algorithmic folk theory, the "conflict of interest" theory, perceived to perpetuate these harms. This theory encapsulates users' sense of a contradiction between the dating platform's promise of finding the perfect partner (leading to discontinued use of Tinder) and its commercial interest in retaining users to increase revenue. Users suspected various algorithmic processes pursuant to this theory, such as (a) throttling profile visibility, (b) manipulating users' matches, and (c) recommending large quantities of profiles that will not lead to matches. They also described various strategies in resistance or defense of these suspected algorithmic processes, such as engaging in counter-intuitive behaviour to disrupt the unfavorable algorithmic processes or leveraging location based filtering for match variety and safety. We conclude by discussing how the perceived algorithmic harms can inform the development of new algorithmic implementations that balance both user and company interests.

AI-powered systems pose unknown challenges for designers, policymakers, and users, making it more difficult to assess potential harms and outcomes. Although understanding risks is a requirement for building trust in technology, users are often excluded from risk assessments and explanations in policy and design. To address this issue, we conducted three workshops with 18 participants and discussed the EU AI Act, which is the European proposal for a legal framework for AI regulation. Based on results of these workshops, we propose a user-centered conceptual model with five risk dimensions (Design and Development, Operational, Distributive, Individual, and Societal) that includes 17 key risks. We further identify six criteria for categorizing use cases. Our conceptual model (1) contributes to responsible design discourses by connecting the risk assessment theories with user-centered approaches, and (2) supports designers and policymakers in more strongly considering a user perspective that complements their own expert views.

Abstract Despite various attempts to prevent food waste and motivate conscious food handling, household members find it difficult to correctly assess the edibility of food. With the rise of ambient voice assistants, we did a design case study to support households’ in situ decision-making process in collaboration with our voice agent prototype, Fischer Fritz. Therefore, we conducted 15 contextual inquiries to understand food practices at home. Furthermore, we interviewed six fish experts to inform the design of our voice agent on how to guide consumers and teach food literacy. Finally, we created a prototype and discussed with 15 consumers its impact and capability to convey embodied knowledge to the human that is engaged as sensor. Our design research goes beyond current Human-Food Interaction automation approaches by emphasizing the human-food relationship in technology design and demonstrating future complementary human-agent collaboration with the aim to increase humans’ competence to sense, think, and act.

Intelligent Personal Assistants (IPA) are advertised as reliable companions in the everyday life to simplify household tasks. Due to speech-based usability issues, users struggle to deeply engage with current systems. The capabilities of newer generations of standalone devices are even extended by a display, also to address some weaknesses like memorizing auditive information. So far, it is unclear how the potential of a multimodal experience is realized by designers and appropriated by users. Therefore, we observed 20 participants in a controlled setting, planning a dinner with the help of an audio-visual-based IPA, namely Alexa Echo Show. Our study reveals ambiguous mental models of perceived and experienced device capabilities, leading to confusion. Meanwhile, the additional visual output channel could not counterbalance the weaknesses of voice interaction. Finally, we aim to illustrate users’ conceptual understandings of IPAs and provide implications to rethink audiovisual output for voice-first standalone devices.

Critical consumerism is complex as ethical values are difficult to negotiate, appropriate products are hard to find, and product information is overwhelming. Although recommender systems offer solutions to reduce such complexity, current designs are not appropriate for niche practices and use non-personalized intransparent ethics. To support critical consumption, we conducted a design case study on a personalized food recommender system. Therefore, we first conducted an empirical pre-study with 24 consumers to understand value negotiations and current practices, co-designed the recommender system, and finally evaluated it in a real-world trial with ten consumers. Our findings show how recommender systems can support the negotiation of ethical values within the context of consumption practices, reduce the complexity of finding products and stores, and strengthen consumers. In addition to providing implications for the design to support critical consumption practices, we critically reflect on the scope of such recommender systems and its appropriation.

Frequently the main purpose of domestic artifacts equipped with smart sensors is to hide technology, like previous examples of a Smart Mirror show. However, current Smart Homes often fail to provide meaningful IoT applications for all residents’ needs. To design beyond efficiency and productivity, we propose to realize the potential of the traditional artifact for calm and engaging experiences. Therefore, we followed a design case study approach with 22 participants in total. After an initial focus group, we conducted a diary study to examine home routines and developed a conceptual design. The evaluation of our mid-fidelity prototype shows, that we need to study carefully the practices of the residents to leverage the physical material of the artifact to fit the routines. Our Smart Mirror, enhanced by digital qualities, supports meaningful activities and makes the bathroom more appealing. Thereby, we discuss domestic technology design beyond automation.

With the debates on climate change and sustainability, a reduction of the share of cars in the modal split has become increasingly prevalent in both public and academic discourse. Besides some motivational approaches, there is a lack of ICT artifacts that successfully raise the ability of consumers to adopt sustainable mobility patterns. To further understand the requirements and the design of these artifacts within everyday mobility adopted a practice-lens. This lens is helpful to get a broader perspective on the use of ICT artifacts along consumers’ transformational journey towards sustainable mobility practices. Based on 12 retrospective interviews with car-free mobility consumers, we argue that artifacts should not be viewed as ’magic-bullet’ solutions but should accompany the complex transformation of practices in multifaceted ways. Moreover, we highlight in particular the difficulties of appropriating shared infrastructures and aligning own practices with them. This opens up a design space to provide more support for these kinds of material-interactions, to provide access to consumption infrastructures and make them usable, rather than leaving consumers alone with increased motivation.

Recent publications propose concepts of systems that integrate the various services and data sources of everyday food practices. However, this research does not go beyond the conceptualization of such systems. Therefore, there is a deficit in understanding how to combine different services and data sources and which design challenges arise from building integrated Household Information Systems. In this paper, we probed the design of an Integrated Household Information System with 13 participants. The results point towards more personalization, automatization of storage administration and enabling flexible artifact ecologies. Our paper contributes to understanding the design and usage of Integrated Household Information Systems, as a new class of information systems for HCI research.

For over a decade, researchers from the practice-centered computing community are taking social practices as a unit of design. While the first generation focused on a social practice in isolation, more recent work argues for the (inter-)connections of mutually influencing practices as the primary unit of design. We discuss these current approaches to motivate the notion of a network of practices. Utilizing the case of food practices, we construct and analyze a network populated by the answers of 60 participants. Based on this network we suggest how to identify central elements and clusters as well as points for intervention within the overall network, but also within and in-between clusters of practices. Based on this, our work critically discusses how an understanding of practices as a network could improve practice-based research and design.