Emerging technologies such as exoskeletons and electrical muscle stimulation can initiate movement within the human body, blurring the boundary between user and machine. While prior research has explored how such systems augment bodily action, most focus on movement execution rather than decision-making. In this work, we investigate what happens when a bodily-integrated system acts with its own logic and initiates bodily movement alongside users. We present three game scenarios where an exoskeleton controls one arm while the user controls the other, designed to evoke different relational framings: proxy, collaboration, and opposition. Through a qualitative study (N = 16), we examine how users interpret such interactions, and how shared bodily control shapes bodily experience and human-machine relationship. We further contribute a set of implications for designing bodily technologies that decide and move together with users, opening up design possibilities for systems that share bodily control, not merely actuate on users’ behalf.

Nature has long been valued for its restorative impact on emotion and well-being, motivating many HCI systems to incorporate nature as a calming design material. However, cultural traditions such as Taoism frame nature not as passive, but as an active, symbolic force for emotional transformation. We present Zenergy, a mobile application that uses a large language model to generate personalized guided meditations grounded in Taoist nature imagery. Based on users’ emotional and contextual input, Zenergy leads them through a symbolic journey using natural metaphors such as wind to release burdens, rivers to restore flow, and sunlight to renew strength. A mixed-method field study (N = 27) showed that Zenergy enhanced users’ self-efficacy, emotional clarity, and spiritual connection. We introduce transformative nature imagery as a design lens for everyday empowerment, and offer strategies for embedding culturally grounded symbolism into interactive well-being technologies.

Advances in emerging technologies, such as on-body mechanical actuators and electrical muscle stimulation, have allowed computers to take control over our bodies. This presents opportunities as well as challenges, raising fundamental questions about agency and the role of our bodies when interacting with technology. To advance this research field as a whole, we brought together expert perspectives in a week-long seminar to articulate the grand challenges that should be tackled when it comes to the design of computers’ control over our bodies. These grand challenges span technical, design, user, and ethical aspects. By articulating these grand challenges, we aim to begin initiating a research agenda that positions bodily control not only as a technical feature but as a central, experiential, and ethical concern for future human–computer interaction endeavors.

Nature plays a crucial role in human health and well-being, but little is known about how blind people experience and relate to it. We conducted a survey of nature relatedness with blind (N=20) and sighted (N=20) participants, along with in-depth interviews with 16 blind participants, to examine how blind people engage with nature and the factors shaping this engagement. Our survey results revealed lower levels of nature relatedness among blind participants compared to sighted peers. Our interview study further highlighted: 1) current practices and challenges of nature engagement, 2) attitudes and values that shape engagement, and 3) expectations for assistive technologies that support safe and meaningful engagement. We also provide design implications to guide future technologies that support nature engagement for blind people. Overall, our findings illustrate how blind people experience nature beyond vision and lay a foundation for technologies that support inclusive nature engagement.

Urbanization increasingly separates people from nature, negatively affecting well-being. While prior work has explored technological interventions to foster human-nature interaction (HNI), embedding nature engagement into daily urban life remains challenging. We present GreenCompass, a social mobile application that recommends nearby micro-opportunities for nature encounters through context-aware scheduling, gamification, and adaptive tasks. To evaluate its effectiveness, we conducted a four-week mixed-methods field study with 40 participants split into two conditions: GreenCompass and a reminder-based baseline. Results showed that GreenCompass better improved nature relatedness, outdoor activity levels, well-being, perceived stress, and social connectedness. Our analysis identified four design themes: embedding nature into micro-moment integration, collective nature engagement, cultivating intrinsic bonds with nature, and system challenges. We further provide design implications to support everyday urban nature engagement. This work demonstrates how everyday mobile technology can help bridge the urban-nature divide and promote well-being.

Urbanization has limited people’s daily exposure to nature, reducing nature connection and overall well-being. Although virtual reality (VR) offers an alternative access to nature-like environments, it often lacks authenticity and connection to physical experiences. We present NatureCapture, a multi-user system that bridges real-world and virtual nature engagement by allowing users to capture real-world natural elements and collaboratively integrate them as interactive 3D models into a shared VR nature space. A two-week within-subjects study indicated that NatureCapture promoted nature connectedness, emotional regulation, and social closeness. Interviews further revealed that NatureCapture supported immersive and extended interactions with nature, promoted reciprocal engagement in virtual and real environments, and strengthened nature interaction through socially mediated engagement. Our work highlights the potential of user-driven real-to-3D transformation to preserve physical encounters with nature, combining the spatial flexibility and interactivity of VR. Such cross-environment paradigm offers a novel approach for sustaining human-nature connection in technologically mediated life.

Spiritual engagement is increasingly mediated by digital platforms, yet little is known about how this shift unfolds in non-Western contexts. In mainland China, individuals are turning to online social platforms like Douyin, WeChat, and Xiaohongshu to access spiritual content that blends religious, cultural, and philosophical traditions. In this paper, we present a mixed-methods study that combines a survey (N = 207) with in-depth interviews (N = 16) to examine how users engage with online spiritual content. The survey outlines general usage patterns across platforms, content types, and motivations, while the interviews reveal four key themes: the pragmatic use of spirituality to navigate emotional and material challenges; the flexible spiritual engagement; a cultural reconnection with spiritual heritage; and concerns over trust, authenticity, and regulation in the digital spiritual landscape. Based on these findings, we offer design implications for creating culturally grounded online spiritual experiences and contribute to HCI literature by advancing understanding of how sociotechnical systems can support spiritually meaningful engagement in diverse cultural contexts.

Dementia, one of the leading causes of neurodegenerative mortality in older adults, remains widely misunderstood by the general public—not only stigmatized socially, but also subject to persistent misconceptions about its symptoms, progression, and lived experience. These misunderstandings hinder timely care, empathy, and social support. To address this, we introduce LetheVR, a first-person serious game designed to promote both empathic understanding of individuals living with dementia and cognitive awareness of the disease itself. Targeted at general audiences, the system adopts experiential methods embedded within a game-based structure. Unlike traditional media and static educational tools, LetheVR integrates immersive symptom simulation, narrative-driven gameplay, and guided pedagogical reflection to engage users in the lived experience of dementia. In a controlled study with 60 participants, LetheVR significantly outperformed conventional interventions in improving measured empathy levels and symptom understanding. These findings highlight the potential of Virtual Reality combining with serious games and experiential methods as effective public health interventions for reshaping attitudes and correcting public misunderstandings about dementia.

Older adults often struggle to meet their psychological needs due to retirement and living alone. Recent studies suggest that games featuring emotional challenge (EC) can help fulfill basic psychological needs such as autonomy, competence, and relatedness by facilitating emotional exploration. However, it remains unclear whether older adults can benefit from EC games, whether they find this genre enjoyable, and how these games should be designed to better meet their needs. This work explores older adults' experiences and perceptions of playing EC games through two studies. The first study involved playing Detroit: Become Human, revealing that older adults derived multifaceted psychological experiences from playing the game. The second study involved a custom-designed game scenario tailored to older adults, demonstrating that meaningful choices significantly influenced autonomy need satisfaction. Based on these findings, we offer five design guidelines for developing EC games that satisfy psychological needs of older adults.

Recent advancements in large language models (LLMs) have shown promise in generating psychotherapeutic dialogues, particularly in the context of motivational interviewing (MI). However, the inherent lack of transparency in LLM outputs presents significant challenges given the sensitive nature of psychotherapy. Applying MI strategies, a set of MI skills, to generate more controllable therapeutic-adherent conversations with explainability provides a possible solution. In this work, we explore the alignment of LLMs with MI strategies by first prompting the LLMs to predict the appropriate strategies as reasoning and then utilizing these strategies to guide the subsequent dialogue generation. We seek to investigate whether such alignment leads to more controllable and explainable generations. Multiple experiments including automatic and human evaluations are conducted to validate the effectiveness of MI strategies in aligning psychotherapy dialogue generation. Our findings demonstrate the potential of LLMs in producing strategically aligned dialogues and suggest directions for practical applications in psychotherapeutic settings.

Complementary label learning (CLL) is a weakly supervised learning paradigm that constructs a multi-class classifier only with complementary labels, specifying classes that the instance does not belong to. We reformulate CLL as an inverse problem that infers the full label information from the output space information. To be specific, we propose to split the inverse problem into two subtasks: positive label guessing (PLG) and negative label enhancement (NLE), collectively called PLNL. Specifically, we use well-designed criteria for evaluating the confidence of the model output, accordingly divide the training instances into three categories: highly-confident, moderately-confident and under-confident. For highly-confident instances, we perform PLG to assign them pseudo labels for supervised training. For moderately-confident and under-confident instances, we perform NLE by enhancing their complementary label set at different levels and train them with the augmented complementary labels iteratively. In addition, we unify PLG and NLE into a consistent framework, in which we can view all the pseudo-labeling-based methods from the perspective of negative label recovery. We prove that the error rates of both PLG and NLE are upper bounded, and based on that we can construct a classifier consistent with that learned by clean full labels. Extensive experiments demonstrate the superiority of PLNL over the state-of-the-art CLL methods, e.g., on STL-10, we increase the classification accuracy from 34.96\% to 55.25\%. The source code is available at https://github.com/yhli-ml/PLNL.

Generative AI technologies are reshaping everyday environments by enabling multimodal interaction. As their ubiquity and agentic capacities grow, there is a pressing need to understand how these systems reshape human–computer interaction in relational, social, and systemic terms. We introduce a scenario-based design pack for investigating Human–GenAI relations. Grounded in assemblage theory and structured around a three-stage process—Prepare, Make, Reflect—the pack supports the prototyping, analysis, and critical reflection of emergent sociotechnical configurations. We evaluated the pack across three deployments: an ACM workshop (n=22), a multidisciplinary design session (n=20), and a university HCI class (n=260). Participants generated scenarios that surfaced relational issues of power, agency, visibility, and care. We contribute the design pack alongside an exploratory framework to advance relational enquiry into multimodal Human–GenAI relations, support more inclusive and socially responsive GenAI practices, and complement FATE approaches by grounding fairness, accountability, and transparency in lived, multimodal configurations.

Locomotion is a fundamental interaction in Virtual Reality (VR). Current locomotion methods, such as redirected walking, walking-in-place, and teleportation, make use of limited physical space and interaction mapping. However, there remains significant potential for improvement, particularly in reducing equipment burden and enhancing immersion. To locate these limitations, we rethink the procedure of VR walking interaction through the Human Information Processing paradigm. Finding that the peripherals' requirements and potential conflict in artificially designed interaction mappings are the bottlenecks in bridging intention and action, we developed MyGO, an AI-assisted locomotion prediction method. MyGO predicts users' future trajectories from their subtle movements, collected only by a VR headset, using a multitask learning (MTL) model. The proposed model demonstrates competitive results in both dataset validation and real-time studies. The code is available at https://github.com/ZichengLiu-seu/basic-MyGO.

Virtual reality (VR), as an immersive interactive technology that offers visual and auditory experiences, creates a fertile ground for both art appreciation and creation. However, current VR art face challenges such as limited experiences, restricted interaction and inadequate engagement. Accordingly, this study explores the design of the emotional feedback mechanism in museum-based VR environments. We proposed a novel paradigm for art interaction, embedding emotional feedback into the artistic re-creation to enrich and personalize the experience of artwork. Through an empirical study$(\mathrm{N}=48)$with a between-subjects design, we demonstrates that this artistic recreation enhances user engagement and emotional states by emphasizing audiovisual quality, interactive flexibility, and narrative coherence with the physical museum. We also shed light on the future design of interaction between people and art that aim to facilitate deeper, more engaged experience.

Chatbots or conversational agents (CAs) are increasingly used to improve access to digital psychotherapy. Many current systems rely on rigid, rule-based designs, heavily dependent on expert-crafted dialogue scripts for guiding therapeutic conversations. Although advances in large language models (LLMs) offer potential for more flexible interactions, their lack of controllability and explanability poses challenges in high-stakes contexts like psychotherapy. To address this, we conducted two studies in this work to explore how aligning LLMs with expert-crafted scripts can enhance psychotherapeutic chatbot performance. In Study 1 (N=43), an online experiment with a within-subjects design, we compared rule-based, pure LLM, and LLMs aligned with expert-crafted scripts via fine-tuning and prompting. Results showed that aligned LLMs significantly outperformed the other types of chatbots in empathy, dialogue relevance, and adherence to therapeutic principles. Building on findings, we proposed ''Script-Strategy Aligned Generation (SSAG)'', a more flexible alignment approach that reduces reliance on fully scripted content while maintaining LLMs' therapeutic adherence and controllability. In a 10-day field Study 2 (N=21), SSAG achieved comparable therapeutic effectiveness to full-scripted LLMs while requiring less than 40% of expert-crafted dialogue content. Beyond these results, this work advances LLM applications in psychotherapy by providing a controllable and scalable solution, reducing reliance on expert effort. By enabling domain experts to align LLMs through high-level strategies rather than full scripts, SSAG supports more efficient co-development and expands access to a broader context of psychotherapy.

Despite the growing exploration of body games for social interaction, current approaches predominantly focus on physical mimicry while overlooking the critical emotional dimension of bodily expression. We address this gap by investigating emotion mimicry as a novel game mechanic for enhancing social presence and interpersonal connection. This paper introduces EmoEcho, a two-player 2D side-scrolling game that integrates emotion mimicry into its core mechanics. In EmoEcho, one player's facial expressions trigger game events while the second player must mimic these expressions to interact with game elements. Through a controlled comparative study (N=24, 12 pairs) contrasting emotion-based input against conventional keyboard controls, we demonstrate that emotion mimicry significantly enhanced social presence and overall game experience. Qualitative interviews further suggest that emotion mimicry enriched player experience via intriguing emotion-based embodied interaction, collaborative emotion co-creation, and development of shared emotional experiences. Our findings extend the understanding of social body games beyond physical mimicry to the emotional domain and provide actionable design implications for creating emotional social games. This work opens new space for game designers to leverage face-to-face emotional expressions as a powerful interface for creating meaningful social play experiences.

The deployment of Conversational User Interfaces (CUIs) with advanced Large Language Models (LLMs) has significantly transformed health information seeking and dissemination, facilitating immediate and interactive communication between users and digital health resources. However, while trust is crucial for adopting health advice, how the dissemination interface influences people's perceived trust in health information provided by LLMs remains unclear. To address this, we conducted a mixed-methods, within-subjects lab study (N=20) to investigate how different CUIs (i.e., a text-based, speech-based, and embodied interface) affect user-perceived trust levels when delivering health information from an identical LLM source. Our key findings showed that: (a) participants' trust levels in health information delivered were significantly variant across different interfaces; (b) there are significant correlations between trust in health-related information and trust in the delivered interface as well as the usability level of the interface; (c) the type of health questions did not affect participants' perceived trust. Besides, we identified key factors influencing trust in health information delivered through various CUIs and explored differences in how people trust health information from LLM and its dissemination. We highlight the potential of LLM-powered CUIs in supporting health-related information-seeking behaviors. This work contributes insights for ensuring effective and trustworthy personal health information-seeking in the era of LLM-powered CUIs and multi-modal information dissemination.

Virtual co-embodiment in virtual reality (VR) allows two users to share an avatar, enabling skill transfer from teachers to learners and influencing their Sense of Ownership (SoO) and Sense of Agency (SoA). However, mismatches between actual movements and displayed actions in VR can impair user experience, posing challenges to learning effectiveness. Although previous studies have addressed the influence of virtual bodies' visual factors on SoO and SoA, the impact of co-embodied hands' appearances remains underexplored. We conducted two user studies to examine the effects of virtual self-hands' existence and their visual factors (transparency and congruency) on SoO, SoA, and social presence. Study One showed significant improvements in SoO and SoA with the existence of virtual self-hands. In Study Two, we kept the self-hands and further focused on hand transparency and congruency. We found that identical appearances between self-hands and co-embodied hands significantly enhanced SoO. These findings stressed the importance of visual factors for virtual hands, offering valuable insights for VR co-embodiment design.

The pleasure that often comes with eating can be further enhanced with intelligent technology, as the field of human-food interaction suggests. However, knowledge on how to design such pleasure-supporting eating systems is limited. To begin filling this knowledge gap, we designed “GustosonicSense”, a novel gustosonic eating system that utilizes wireless earbuds for sensing different eating and drinking actions with a machine learning algorithm and trigger playful sounds as a way to facilitate pleasurable eating experiences. We present the findings from our design and a study that revealed how we can support the "stimulation", "hedonism", and "reflexivity" for playful human-food interactions. Ultimately, with our work, we aim to support interaction designers in facilitating playful experiences with food.

While Virtual Reality Perspective-Taking (VRPT) demonstrates its efficiency in inducing empathy, its application primarily focuses on vulnerable humans, not animals. Existing animal-related works mainly targets farm animals and wildlife. In this work, we focus on stray animals and introduce iStrayPaws, a VRPT system that simulates stray animals’ challenging lives. The system offers users an immersive first-person journey into the world of stray animals encountering different difficulties like inclement weather, hunger, and illnesses. Enriched with audio-visual and kinesthetic design, the system seeks to deepen users’ understanding of stray animals’ life and foster profound emotional connections. To evaluate the system, a user study was conducted, which showed that VRPT recipients exhibited significant improvement in both state and trait empathy compared to traditional method. Our research not only delivers a novel, accessible, and interactive animal empathy experience but also provides innovative solutions for addressing stray animal issues and advancing broader animal welfare work.

Depression is a severe mental illness that can lead to negative moods and activities. The traditional clinical approach for diagnosing depression is face-to-face consultation, which is limited by time and space. Virtual Reality (VR), as a novel technology with higher accessibility and lower cost, can serve as an effective digital approach to diagnosing psychological disorders. In VR systems, users are exposed to various experimental scenarios, gaining immersive and interactive experiences. Recent research has demonstrated a relationship between depression and low spatial memory navigation ability (SMNA). Based on these considerations, we propose a VR system to detect one’s depression level by measuring spatial memory navigation performances. The system consists of three virtual scenarios with different spatial scales and dimensions. To study the system’s effectiveness, a pilot study with eight participants was conducted. The results showed differences in the participants’ spatial memory navigation performances in the three scenarios and a correlation between depression level and their spatial memory navigation performances.

The mental health of older adults is a vital issue in the era of global aging. Empathy towards older adults constitutes a crucial component of social interaction, as it engenders awareness of the physical and mental obstacles encountered by this population. Empathy promotes individuals to be more friendly, considerate, and prosocial when interacting with older adults on various occasions, such as volunteering and professional caring. Various approaches have been used to promote people's empathy, but disadvantages like low participation enthusiasm, high cost, and time-consuming cannot be ignored and are not easy to deal with. Aimed at facilitating people's empathy towards older adults, we developed EmpathiaVR, a virtual reality older adults experience simulation system. It provides a multi-sensory mixed reality experience, including vision, hearing, and kinesthesis, from an older person's perspective, which is beneficial for provoking users' empathy towards older adults. To investigate the effectiveness of the system, an empirical study was conducted with 24 participants. The experiment employed a between-subjects design with two groups. The experiment results from both the subjective reports and behavioral variables indicated that the system enhanced people's empathy.

Ingestible sensors have become smaller and more powerful and allow us to envisage new human-computer interactions and bodily play experiences inside our bodies. Users can swallow ingestible sensors, which facilitate interior body sensing functions that provide data on which play experiences can be built. We call bodily play that uses ingestible sensors as play technologies “ingestible play”, and we have adopted a research-through-design (RtD) approach to investigate three prototypes. For each prototype, we conducted a field study to understand the player experiences. Based upon these results and practical design experiences, we have developed a design framework for ingestible play. We hope this work can guide the future design of ingestible play; inspire the design of play technologies inside the human body to expand the current bodily play design space; and ultimately extend our understanding of how to design for the human body by considering the bodily experience of one’s interior body.

Human–computer interaction (HCI) is increasingly interested in supporting exertion experiences so more people can benefit from physical activity. So far, most systems have focused on sensing and presenting information to the user via screens to support the exertion experience. Interestingly, emerging technology can also act on the exerting user's body based on sensed information, granting researchers the potential to develop technology that not only “presents” but also “acts” on information throughout an integrated exertion experience. As a result, design opportunities surrounding computing machinery as contextually aware exertion partners are now available. However, there are currently no frameworks to guide the design of human–computer integration in an exertion context. To contribute to closing this gap, we designed three eBike systems to investigate different forms of integration with the exerting user and we studied the resulting user experiences. Based on the results of these three case studies, we present the first framework, including associated design tactics, to offer guidance on how to design human–computer integration in an exertion context.

Interest in combining interactive play and the human body, using “bodily play” systems, is increasing. While these systems primarily prioritize a player's control over their bodily actions, we see intriguing possibilities in the pursuit of “limited control over the body” as an intriguing design resource for bodily play systems. In this paper, we use three of our bodily play systems to illustrate how designers can engage with limited control over the body by varying the player's degree of indirect control (for instance, via other bodily activity and external triggers). We also propose four strategies for employing limited control over the body: Exploration, Reflection, Learning and Embracement. We hope our own work and the strategies developed from it will assist designers to employ limited control over the body, ultimately helping people benefit from engaging their bodies through play.

Sexual consent has undergone a transformation toward an “enthusiastic” feminist model that emphasizes consent as an ongoing and voluntary process of negotiation and affirmation. This paper considers how such a model can advance understandings of consent in HCI research and design in relation to embodied interactions with emerging technologies that also occur outside of sexual interactions. We apply the popular “FRIES” model of sexual consent (Freely given, Reversible, Informed, Enthusiastic and Specific) to three areas of embodied interaction: 1) bodily-play interactions, 2) persuasive interactions with smart technologies, and 3) intimate interactions with anthropomorphized devices. Based on erotic play practices, we contribute a “TEASE” process guideline (Traffic lights, Establish ongoing dialogue, Aftercare, Safewords, and Explicate soft/hard limits) to advance consensual practice in HCI and develop implementation scenarios.

Imaging capsules are ingestible sensors that capture the video of one's gastrointestinal tract for medical diagnosis. We believe that the capsule's experiential perspective is often overlooked by associated medical applications. This work explores the design of this experiential perspective through combining imaging capsules with digital play. We designed a playful wearable system called "InsideOut", where users play with the real-time video of their gastrointestinal tract captured by an imaging capsule. Based on an in-the-wild study, we derived four themes articulating the play experiences and discussed key design implications to guide future playful designs using imaging capsules. Our research highlights the opportunity of using medical imaging technologies to enable intriguing bodily play experiences. Furthermore, such experiences can deepen the players' engagement with and understanding of their bodies, ultimately contributing to a more playful and humanized health care agenda.

Prior psychology studies have shown that eating ice cream increases happiness, while human-computer interaction work has shown that interactive technology can enrich the eating experience. We explore the opportunity to combine these two through WeScream!, a playful social gustosonic system we designed-social gustosonic referring to the link between the acts of eating and listening as part of a social multisensory experience. WeScream! consists of two interdependent ice-cream cones that allow users to interact with musical sounds generated through the act of eating ice cream together. We report on an in-the-wild study that highlights how our system facilitated a "hard fun" experience through eating together, increased participants' awareness of relatedness, and drew shared attention to the ice cream's taste via increased face-to-face interaction. Drawing on these study insights, we also present three design tactics to guide designers in designing future social gustosonic experiences. Ultimately, we aim to contribute to a playful future of social eating experiences, supporting people in enjoying eating together.

Human-Computer Integration (HInt) is an emerging paradigm in which computational and human systems are closely interwoven. Integrating computers with the human body is not new. however, we believe that with rapid technological advancements, increasing real-world deployments, and growing ethical and societal implications, it is critical to identify an agenda for future research. We present a set of challenges for HInt research, formulated over the course of a five-day workshop consisting of 29 experts who have designed, deployed and studied HInt systems. This agenda aims to guide researchers in a structured way towards a more coordinated and conscientious future of human-computer integration.

There is an increasing trend in utilizing interactive technology for bodily integrations, such as additional limbs and ingestibles. Prior work on bodily integrated systems mostly examined them from a productivity perspective. In this article, we suggest examining this trend also from an experiential, playful perspective, as we believe that these systems offer novel opportunities to engage the human body through play. Hence, we propose that there is an opportunity to design "bodily integrated play". By relating to our own and other's work, we present an initial set of design strategies for bodily integrated play, aiming to inform designers on how they can engage with such systems to facilitate playful experiences, so that ultimately, people will profit from bodily play's many physical and mental wellbeing benefits even in a future where machine and human converge.

Bodily play systems are becoming increasingly prevalent, with research aiming to understand the associated player experience. We argue that a more nuanced lexicon describing "bodily play experience" can be beneficial to drive the field forward. We provide game designers with two German words to communicate two different aspects of experience: "Erfahrung", referring to experience where one is actively engaged in and gains knowledge from; and "Erlebnis", referring to a tacit experience often translated as "lived experience". We use these words to articulate a suite of design strategies for bodily play experiences by referring to past design work. We conclude by discussing these two aspects of experience in conjunction with two previously established perspectives on the human body. We believe this more nuanced lexicon can provide a clearer understanding for designers about bodily play allowing them to guide players in gaining the many benefits from such experiences.

There is an increasing trend in HCI to combine eating and technology. We highlight the potential of interactive technology to support an experiential perspective on eating, in particular, how interactive technology can support experiencing eating as play. To understanding this, we reflect on four playful interactive eating systems we designed and two other works to articulate five strategies: make eating challenging, break cultural norms, design across eating stages, reduce eating autonomy, and playfully extend the social aspect. For each, we also include practical implementation options to provide designers with initial guidance on how they can begin to support experiencing eating as play. Ultimately, with our work, we aim to facilitate a future where eating is more playful.

Ingestible sensors are pill-like sensors that people swallow mainly for medical purposes. We propose that ingestible sensors also offer unique opportunities to facilitate intriguing bodily experiences in a playful manner. To explore this, we present "HeatCraft", a two-player system that translates the user's body temperature measured by an ingestible sensor to localized thermal stimuli delivered through a waist belt equipped with heating pads. We conducted a study with 16 participants. The study revealed three design themes (Integration of body and technology, Integration of internal body and outside world, and Integration of play and life) along with some open challenges. In summary, this work contributes knowledge to the future design of playful experiences with ingestible sensors.

Recent HCI work on digital games highlighted the advantage for designers to take on a 1st person perspective on the human body (referring to the phenomenological "lived" body) and a 3rd person perspective (the material "fleshy" body, similar to looking in the mirror). This is useful when designing bodily play, however, we note that there is not much game design discussion on the 2nd person social perspective that highlights the unique interplay between human bodies. To guide designers interested in supporting players to experience their bodies as play, we describe how game designers can engage with the 2nd person social perspective through a set of design tactics based on four of our own play systems. With our work, we hope we can aid designers in embracing this 2nd person perspective so that more people can benefit from engaging their bodies through games and play.