Learning Gravity: An Innately Constrained Bayesian Model of Human Vestibular Development

The vestibular apparatus is substantially organized before birth, whereas human equilibrium emerges only gradually through head control, sitting, standing, and independent walking. We propose an Innately Constrained Bayesian Model of Vestibular Development in which a phylogenetically shaped architecture constrains an initial model space; prenatal and postnatal experience calibrate internal models of self-motion and gravity; and developmentally gated plasticity modulates the rate of updating. We explicitly distinguish established evidence from interpretations and model-derived hypotheses. Recent human and nonhuman primate work on internal models, active self-motion, and multisensory recalibration is integrated with developmental and clinical evidence. The framework is then tested conceptually across congenital and acquired vestibular loss, altered gravity, and aging. Its proposed novelty lies not in Bayesian inference or internal models themselves, but in combining phylogenetic constraints, prenatal calibration, a qualitative transition at birth, time-dependent plasticity, and life-span context switching within a single developmental account. Finally, we operationalize the model through measurable predictions involving VOR adaptation, sensory-weighting coefficients, anticipatory postural responses, context-specific readaptation, and postural stability. The framework is intended as a falsifiable perspective rather than a definitive mechanistic account.