Penta-State Probabilistic Model (PSPM)

Probability representation has relied on binary probability or fuzzy extensions, yet such frameworks often fail to capture the suggested way humans evaluate partial belief. This paper introduces the Penta-State Probabilistic Model (PSPM), a five-valued probabilistic logic designed to model directional and biased probability. PSPM characterises probability with five understandable states: True, False, Partial-True, Partial-False, and Undecided. PSPM also provides a flexible, human-aligned representation of belief states, enabling more accurate system modelling for decision-making and neural-inspired reasoning.