This problem, as described by Bred, also arises in people who normally drive a car today and every day. But if they do not drive and, for example, they read (in the car on the train) they may feel sick. This is due to the perception of a different image and movement. If you drive, these perceptions are synchronized and not bad, but if you read or even if the children are playing in the car and not watching the landscape, two pieces of information get into their brains and the brain somehow "fooles" about it.