The Ψ Model: A Five-Dimensional Active-Inference State Space for Mental-State Dynamics

This paper introduces the Ψ model, a five-dimensional state-space representation of mental states grounded in active inference. In this formulation, an individual’s psychological state is represented by a vector Ψ = (Ω, E, Π, Σ, Λ), corresponding to Order, Energy, Precision, Social Coupling, and Learning. The model is proposed as a clinically interpretable coordinate system for representing both ordinary psychological variation and psychopathology within a continuous dynamical space. By linking these dimensions to key constructs in active inference and predictive processing, the Ψ model aims to bridge phenomenological psychiatric description and computational accounts of mental-state organization and change. This conceptual framework provides a foundation for longitudinal modeling, comparative psychopathology, and computational psychiatry.