The Double-Slit Experiment Is Already Happening in the Brain

The double-slit experiment, a cornerstone of quantum mechanics, is traditionally viewed as a paradoxical demonstration of wave-particle duality. This article posits that its core dynamic—superposition, interference, and environment-driven localization—is not a unique quantum phenomenon but a fundamental computational principle implemented by the brain. We introduce the Ze framework, arguing that the brain operates as a biological interferometer. Cognitive systems maintain multiple generative hypotheses in a state of active interference (superposition), analogous to the quantum wavefunction passing through both slits. "Which-path" information, supplied by sensory data, action, and social context, forces cognitive decoherence, localizing perception and decision into a single narrative. Sleep is recast as an intrinsic quantum eraser, periodically degrading which-path information to restore cognitive flexibility and prevent pathological hyper-localization. The framework structurally links quantum decoherence, Bayesian active inference, and the neurobiology of sleep and wake cycles. It provides a transdiagnostic model for psychopathology, where disorders like psychosis and PTSD are seen as dysregulations of this interference-localization cycle. We conclude that the brain does not observe quantum reality; it actively instantiates its core logic, making the double-slit experiment a continuous, lived process of resolving ambiguity to survive and understand the world.