Researchers at the University of Michigan Transportation Research Institute predicted that more people will experience motion sickness once self-driving cars get on the road.

The study involved more than 3,200 adults from different countries including the United States, India, China, Japan, Great Britain and Australia. The researchers asked them what activities that they are most likely to do while inside a self-driving car.

The responses showed that the majority of the participants are most likely to do activities that can trigger motion sickness such as reading, texting, watching movies or television, playing games or working.

Up to 12 percent of the participants, regardless of where they came from, are expected to experience moderate to severe motion sickness. Other activities cited by the participants, although they won't trigger motion sickness, included watching the road, talking on the phone or sleeping while riding.

"Motion sickness is expected to be more of an issue in self-driving vehicles than in conventional vehicles," Michael Sivak, study author of the U-M Transportation Research Institute, said in a news release. "The reason is that the three main factors contributing to motion sickness-conflict between vestibular (balance) and visual inputs, inability to anticipate the direction of motion and lack of control over the direction of motion-are elevated in self-driving vehicles.

"However, the frequency and severity of motion sickness is influenced by the activity that one would be involved in instead of driving."

The findings of the study provide insight to self-driving car manufacturers for them to improve their vehicle designs to lessen motion sickness such as using large, transparent windows and videos and seats that can be fully reclined to restrict head motion.

Some of the car manufacturers that are testing their self-driving cars include Google, Audi, Mercedes-Benz, Tesla, Nissan, Honda and Volvo. Analysts predicted that these vehicles could hit the road as soon as five years from now depending on the federal approval.