Light Up Fireflies: Exploring the Design of Interpersonal Bodily Intertwinement in Social Body Games

Research Background and Issues

• Issues or Challenges
  Current game designs involving bodily interaction can partially achieve the sharing of bodily perception but are often limited to localized or segmented physical interactions (e.g., arm movements or action fragments). These approaches primarily focus on how one user's actions influence another user's physical experience rather than fostering deeper shared bodily experiences. There is relatively little research on in-depth "bodily fusion," and the experience of "sharing one body" has not been thoroughly explored in terms of how it can lead to deeper resonance and connection. This lack of deep fusion may limit the potential for immersive sensory enjoyment and interaction between players.

• Significance of the Research
  Understanding and designing "bodily fusion" can bring deeper interactive experiences in games and play a significant role in enhancing emotional connections and bodily awareness between players. Furthermore, this research could inspire applications in other fields, such as sports training, rehabilitation therapy, and social interaction design.

• Research Motivation and Related Work
  Inspired by the concept of Virtual Co-Embodiment, this study aims to explore in-depth "bodily fusion" through the design of a game. Here, "bodily fusion" is not limited to action coordination but involves players truly sharing one body in a virtual space, closely collaborating in terms of kinesthetic movement, perception, and intention, thereby forming a deeper experience of bodily resonance.

Solution

• Method or Approach
  The authors designed "Light Up Fireflies," a two-player VR social game where players jointly control a virtual avatar and share its left and right body parts. The game challenges players' interaction and coordination through cooperative tasks (lighting up fireflies) and maintaining balance.

• Innovations

  1. Introduced a "Body-part-segmented Virtual Co-Embodiment" model, where each player controls a specific part of the shared virtual avatar (e.g., left or right half of the body). This approach differs from traditional global weighted control methods by emphasizing individual contributions and the significance of collaboration.
  2. Game tasks emphasize coordination and bodily balance. This dynamic interaction design uniquely showcases mutual adaptation and fusion between bodies.
  3. The use of a first-person perspective to present the shared bodily experience significantly enhances immersion while addressing issues such as motion sickness caused by high interactivity.

• Implementation Steps and Technologies

  1. Virtual Setup and Implementation
     The game was developed using the Unity 3D platform, HTC VIVE Pro2 head-mounted displays, and Azure Kinect DK for motion capture, integrating multi-player data to achieve avatar control.
  2. Dynamic Balance Mechanism
     A virtual balance system based on the Center of Mass (CoM) and Base of Support (BoS) mechanics model was introduced and optimized. This system detects the dynamic stability of the virtual avatar in real-time and provides visual feedback (e.g., red screen flashes) to players.
  3. Immersion Optimization
     Adjustments were made to the first-person perspective, with each player maintaining independent head-tracking visuals to alleviate motion sickness and enhance immersion.
  4. Simplified Task Design
     The game objectives were simplified to walking and hand interactions, reducing the complexity of actions to minimize coordination errors and frustration from repeated failures, allowing players to focus more on the "fusion experience" itself.

Research Outcomes

• Specific Findings

  1. The game successfully designed a novel "virtual co-embodiment" experience, deeply embedding bodily actions and experiences into interactive design.
  2. Through experiments and interviews, the study revealed phenomena of deep fusion interaction experienced by players, including three experiential dimensions: bodily unfamiliarity, fused bodily sensations, and enhanced intersubjective bodily understanding.

• Advantages over Existing Solutions

  1. Traditional game designs are often limited to action-to-action control and fail to fully achieve the co-existence of dual bodily awareness. This study breaks through the single-subject and competitive frameworks of traditional bodily game design through virtual co-embodiment.
  2. The combined immersion of the first-person perspective and the real-time coordination system for evaluating collaborative tasks deepens players' bodily adaptation and psychological connection.

• Experimental or Evaluation Results

  • In a qualitative study involving 16 participants (8 pairs of players), participants reported novel experiences of bodily fusion, such as a dual sense of "separation and unity" and a significant improvement in understanding each other's intentions through bodily interaction.
  • The game's tasks helped players build trust through challenges and cooperation, increasing bodily rapport and familiarity.
  • The optimization of the balance mechanism and simplified task design effectively reduced platform-induced motion sickness and bodily coordination issues during gameplay. However, some players still experienced brief disorientation under high sensory load.

• Limitations and Future Directions

  1. Lack of Long-term Interaction Analysis: The study focused only on short-term player experiences, and future research should explore changes in long-term adaptation and fusion relationships.
  2. Simplicity of Action Design: The current task design is relatively simple. Future work could explore more complex interactive scenarios that reflect a wider variety of collaborative dynamics.
  3. Expansion to Multi-player Studies: The research focused on two-player interactions. Future studies could extend to multi-player co-embodiment to explore higher-dimensional collaboration and balance design.
  4. Diverse User Groups: The participants were all young adults. Future research should include children, older adults, or participants from diverse cultural backgrounds to gain a comprehensive understanding of user experiences.
  5. Translation of Virtual Bodily Connection to Real-life: Further exploration is needed to understand whether virtual "intimacy" can effectively transfer to real-life, including its potential impact on the psychology of intimacy and social behavior.

Conclusion

"Light Up Fireflies" pioneers a new paradigm of shared-body gaming through virtual co-embodiment. It not only challenges players' coordination and collaboration skills but also inspires a rethinking of bodily boundaries and co-existence awareness through immersive gaming scenarios. This research provides innovative insights for virtual reality interaction design and lays the groundwork for applications in cooperative training, rehabilitation therapy, and even social interaction in real-world contexts.