According to a new study released by the Transportation Research Institute of the University of Michigan, riding in a self-driving car may lead to motion sickness for passengers.

This is because the things that will allow passengers to do while riding in driverless cars such as texting, reading, working and watching videos, for example, are activities that increase the risk of individuals from acquiring motion sickness. Gazing down to do these things adds to the increased chance of motion sickness.

While riding in a moving car, it is the driver with the best seats because he or she has the optimal field of vision. In addition, because the driver is constantly looking at the road and can expect the vehicle's movements, the driver's vestibular system, the parts of the brain and inner ear which are controlling eye movements and balance, are working in unison. This leads to a much lower risk of nausea.

"By switching from driver to passenger, by definition, one gives up control over the direction of motion, and there are no remedies for this," wrote Michael Sivak and Brandon Schoettle in their research.

Adults have a higher chance of acquiring motion sickness compared to children, with the worst symptoms including vomiting and vertigo.

The study analyzed the motion sickness frequency among passengers and the things that the subjects said that they would do if they did not have to drive, as with riding in a self-driving vehicle.

According to the results of the study, 6 percent to 10 percent of adult Americans in driverless vehicles will be expected to always or often acquire motion sickness.

The authors of the study wrote, however, that changes in the design of such cars will reduce the risk of passengers acquiring motion sickness. Such changes include the expansion of the field of views of passengers through large windows, optimization of the gaze direction of passengers through the proper orientation of video displays and placing heads-up displays on the car's windows.

In addition, the physical form of passengers while riding driverless cars could also decrease the risk of motion sickness, such as with seats that can fully recline to allow passengers to lie down flat on their back. Swivel seats should be avoided, according to the authors.

The study added that the calculations for acquiring motion sickness were based on assumptions that self-driving vehicles will have cabins similar to the traditional cars of today. If driverless cars will use windows that reduce the visibility to the outside, the chance for motion sickness would worsen.

However, if driverless cars will lead to smoother riding experiences compared to traditional cars, then motion sickness could be less frequent and severe.