Why can a person feel as if they are rotating in the opposite direction after suddenly stopping?

The sensation of rotating in the opposite direction after suddenly stopping is caused by the mechanics of the vestibular system within the inner ear, specifically the semicircular canals.12

These canals are filled with a fluid called endolymph. When you begin to rotate, the fluid’s inertia causes it to lag behind, which deflects a gelatinous structure called the cupula and stimulates the hair cells to signal movement to the brain.32

If you maintain a constant velocity, the fluid eventually catches up to the speed of the canal, and the cupula returns to its resting position, meaning the brain no longer receives a signal of rotation. When you suddenly stop, the fluid—due to its inertia—continues to move. This causes the cupula to be deflected in the opposite direction of the original rotation. The brain interprets this new deflection as movement, creating the false sensation that you are rotating in the opposite direction, often accompanied by dizziness and nystagmus.123