Editing Motion sickness (section)

===Motion felt but not seen===
In these cases, motion is sensed by the [[vestibular system]] and hence the motion is felt, but no motion or little motion is detected by the [[visual system]], as in terrestrial motion sickness.{{citation needed|date=August 2021}}

====Carsickness====
{{more citations needed|section|date=February 2018}}
A specific form of [[wikt:terrestrial|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.<ref name="economist2018"/>

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.

In the early 20th century, Austro-Hungarian scientist [[Róbert Bárány]] observed the back and forth movement of the eyes of railroad passengers as they looked out the side windows at the scenery whipping by. He called this "railway [[nystagmus]]", also known as "optokinetic nystagmus". His findings were published in the journal ''Laeger'', 83:1516, Nov.17, 1921.

====Airsickness====
{{Main|Airsickness}}
Air sickness is a kind of terrestrial motion sickness induced by certain sensations of air travel.<ref name="Benson 2002" /> It is a specific form of motion sickness and is considered a normal response in healthy individuals. It is essentially the same as carsickness but occurs in an airplane. An airplane may bank and tilt sharply, and unless passengers are sitting by a window, they are likely to see only the stationary interior of the plane due to the small window sizes and during flights at night. Another factor is that while in flight, the view out of windows may be blocked by clouds, preventing passengers from seeing the moving ground or passing clouds.{{citation needed|date=July 2021}}

====Seasickness====
Seasickness is a form of terrestrial motion sickness characterized by a feeling of [[nausea]] and, in extreme cases, [[vertigo]] experienced after spending time on a boat.<ref name="Benson 2002"/>  It is essentially the same as carsickness, though the motion of a watercraft tends to be more regular. It is typically brought on by the rocking motion of the craft<ref name="Gahlinger 2000" /><ref name="Sharma1992" /> or movement while the craft is immersed in water.<ref name="Norfleet et al 1992" /> As with airsickness, it can be difficult to visually detect motion even if one looks outside the boat since water does not offer fixed points with which to visually judge motion. Poor visibility conditions, such as fog, may worsen seasickness. The greatest contributor to seasickness is the tendency for people being affected by the rolling or surging motions of the craft to seek refuge below decks, where they are unable to relate themselves to the boat's surroundings and consequent motion. Some people with carsickness are resistant to seasickness and vice versa.{{citation needed|date=February 2017}} Adjusting to the craft's motion at sea is called "gaining one's sea legs"; it can take a significant portion of the time spent at sea after disembarking to regain a sense of stability "post-sea legs".

====Centrifuge motion sickness====
Rotating devices such as [[Centrifuge#Aeronautics and astronautics|centrifuges]] used in astronaut training and amusement park rides such as the [[Rotor (ride)|Rotor]], [[Mission: Space]] and the [[Gravitron]] can cause motion sickness in many people.  While the interior of the centrifuge does not appear to move, one will experience a sense of motion.{{dubious|reason= this language confounds both forms of motion and sensations of motion; see talk-page section "confoundings"|date=March 2018}} In addition, [[centrifugal force]] can cause the vestibular system to give one the sense that downward is in the direction away from the center of the centrifuge rather than the true downward direction.<ref>{{Cite journal |last1=Bertolini |first1=Giovanni |last2=Straumann |first2=Dominik |date=2016 |title=Moving in a Moving World: A Review on Vestibular Motion Sickness |journal=Frontiers in Neurology |volume=7 |page=14 |doi=10.3389/fneur.2016.00014 |issn=1664-2295 |pmc=4753518 |pmid=26913019|doi-access=free }}</ref>

====Dizziness due to spinning====
When one spins and stops suddenly, fluid in the inner ear continues to rotate causing a sense of continued spinning while one's visual system no longer detects motion.{{citation needed|date=July 2021}}

====Virtual reality====
{{Main|Virtual reality sickness}}
Usually, VR programs would detect the motion of the user's head and adjust the rotation of vision to avoid dizziness. However, some cases such as system lagging or software crashing could cause lags in the screen updates. In such cases, even some small head motions could trigger the motion sickness by the [[Defence mechanism|defense mechanism]] mentioned below: the [[inner ear]] transmits to the brain that it senses motion, but the eyes tell the brain that everything is still.