Co-constructed Emotion: A Collective Predictive Coding Theory of Interoception and Social Symbol Sharing

Emotion is both a psychological phenomenon rooted in physiological fluctuations and a socially constructed phenomenon shaped by language and culture. However, traditional psychological constructivism has remained confined to individual brain processes, while social constructivism has lacked a bottom-up computational mechanism explaining how language and culture emerge from bodily emotional substrates and dynamically evolve. To bridge this theoretical gap, this paper proposes the Theory of Co-constructed Emotion (TCoE) via Collective Predictive Coding (CPC), a framework coupling physiological regulation with social symbol sharing within a single active inference formulation. We extend the conventional CPC model by explicitly incorporating interoception---which is indispensable for modeling emotion from a physiological perspective---into each agent's generative model, alongside exteroception and internal and external representations. In TCoE, the co-construction of emotion is described as a dual inference process: an internal loop of allostasis regulating individual bodily states, and a social loop of communication sharing emotional concepts with others. These loops mutually minimize prediction errors mediated by shared symbols (emotion words). We argue that this theoretical framework 1) aligns with psychological findings on emotional contagion and concept formation, 2) enables constructive verification in multi-agent robotic systems, and 3) provides a computational redefinition of psychiatric conditions such as alexithymia as a disconnection between interoception and social symbols. Thus, we offer a novel computational foundation for emotion research that unifies individual embodiment and social symbol systems.