Motion sickness
Cause
A specific form of terrestrial motion sickness, being carsick is quite common and evidenced by disorientation while reading a map, a book, or a small screen during travel. Carsickness results from the sensory conflict arising in the brain from differing sensory inputs. Motion sickness is caused by a conflict between signals arriving in the brain from the inner ear, which forms the base of the vestibular system, the sensory apparatus that deals with movement and balance, and which detects motion mechanically. If someone is looking at a stationary object within a vehicle, such as a magazine, their eyes will inform their brain that what they are viewing is not moving. Their inner ears, however, will contradict this by sensing the motion of the vehicle. Varying theories exist as to cause. The sensory conflict theory notes that the eyes view motion while riding in the moving vehicle while other body sensors sense stillness, creating conflict between the eyes and inner ear. Another suggests the eyes mostly see the interior of the car which is motionless while the vestibular system of the inner ear senses motion as the vehicle goes around corners or over hills and even small bumps. Therefore, the effect is worse when looking down but may be lessened by looking outside of the vehicle.
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