A recent study conducted by the University of Michigan's Transportation Research Institute predicts that passengers in self-driving cars will be more likely to experience motion sickness than in traditional automobiles.
Specifically, the study estimates that anywhere between 6% and 10% of passengers would experience some level of motion sickness "often, usually, or always," while as many as 12% would feel moderate or severe motion sickness "at some time."
The researchers looked at the factors that contribute to motion sickness – "conflict between vestibular and visual inputs, inability to anticipate the direction of motion, and lack of control over the direction of motion" – and estimated how much more likely passengers would be to experience them while traveling in self-driving cars. They concluded that these factors "are elevated in self-driving vehicles."
In self-driving cars, passengers lose control of the vehicle, and therefore they are less able to anticipate when it might be moving. This might sound no different than riding as a passenger with a friend or a cab driver, but consider that when a driver is planning to switch lanes, he or she usually glances somewhere else, grips the wheel differently, or gives some other abstract hint that the car is about to move. Whether passengers consciously register this or not, they may be preparing for some kind of motion. An increase in other activities while traveling – like reading or watching videos, which more than a third of Americans say they are likely to do, according to the study – isn't likely to help with the issue.
An article at Fast Co.Exist pointed out that self-driving car manufacturers could develop solutions to this problem, and that's important to point out. The market is still very young, and cars that present these issues aren't likely to make it to the market if 10% of focus groups end up getting sick.
Either way, just add motion sickness to the long list of obstacles that the self-driving car will have to overcome in order to make it to the roads.