Otolith Illusion: Gravity–Acceleration Ambiguity

The utricle and saccule — the otolith organs of the inner ear — don't measure gravity directly; they measure specific force, the vector sum of gravity and linear acceleration acting on a bed of dense otoconia crystals. Because those two contributions are physically indistinguishable at the sensor, a level head undergoing forward acceleration produces the exact same hair-bundle shear as a stationary head tilted backward. This simulator renders a 3D utricle macula whose otoconia layer visibly shifts and whose stereocilia visibly bend under a first-order viscous-gel response to your chosen tilt and acceleration, while a live "sensed down" arrow tilts away from true gravity to show the somatogravic illusion in real time — the same misperception that has caused real accidents when pilots trusted their inner ear over their instruments during acceleration.