Motion sickness occurs due to an imbalance between visual images and which part of the body that senses motion?

Motion sickness arises from a conflict between the sensory inputs that the body receives regarding motion. Specifically, the middle ear plays a crucial role in this process. Inside the middle ear are structures known as the vestibular system, which includes the semicircular canals and otolith organs. These components are responsible for detecting changes in motion and position relative to gravity.

When you are in a moving vehicle but your visual perception does not align with that motion—such as when reading a book while in a car—your eyes see something stationary, while your inner ear senses movement. This disparity can lead to confusion in the brain, which ultimately results in symptoms such as dizziness, nausea, and discomfort, characteristic of motion sickness.

In contrast, while the brain does process all the sensory information, it is the middle ear's vestibular system that directly senses motion and contributes most significantly to the issue of motion sickness when communication with visual input is disrupted.