The funny thing about motion sickness is no one's entirely sure what it is.

"Motion sickness is a natural response, in otherwise healthy people, to certain kinds of situations in which … and then things get fuzzy," says Dr. Thomas Stoffregen, who studies human movement at the University of Minnesota.

We do know, however, that when it comes to the car, the best way to avoid getting sick is to take the wheel. Which begs the question: What happens when autonomous cars arrive? Are we all gonna hurl?

It's a small-scale, almost silly concern, but one that's symptomatic of bigger questions about the coming age of self-driving cars. And it goes to the center of what may be the biggest obstacle to making us comfortable when robots rule the roads: Transferring control over to the car without totally freaking out.

Watching the Road

There's good reason drivers rarely get carsick, Stoffregen says: They know exactly what's coming and can prepare for it—avoiding the expectation gap and the unwanted physical movement that may cause queasiness. Don't undervalue how much work your muscles are doing in the car, even when riding shotgun: You're not just sitting there, you're controlling your necks, shoulders, hips, and more. "The stabilizing of the body for the driver is always anticipatory. They set the body up in advance to be ready," Stoffregen says.

That's why if you're prone to motion sickness, you're likely more comfortable up front: A better view gives you a better idea what's coming. It's not an ideal solution, though: Even if you know a turn is coming, you don't know how fast the driver will take it or at what angle, so you can't prepare perfectly. "The passenger's stabilization of the body is always compensatory. And it's less refined, less precisely keyed to what the motions of the car are," Stoffregen says.

In a self-driving car, no one's safe. There's no more driver. The entity deciding how to drive, the angle and speed of each turn, is a computer. So once cars go autonomous, will everyone be blowing chunks?

Fortunately, no. Just "6 to 10 percent of Americans adults riding in fully self-driving vehicles would be expected to often, usually, or always experience some level of motion sickness," Michael Sivak and Brandon Schoettle wrote in a study for the University of Michigan Transportation Research Institute. And all the things people do now to avoid feeling sick will work just fine: Face forward, don't read, close your eyes, and so on. After all, just because you can spin your seat to face the rear doesn't mean you have to.

Settling Our Stomachs

Plus, self-driving cars promise to settle our stomachs in some ways. Machines won't make abrupt maneuvers. The promise of cars that talk to on another will make stop and go traffic less common by ironing out the speed fluctuations that create the super annoying "accordion effect." Rubbernecking will be eliminated, and there will be fewer accidents to gawk at in the first place.

Since automakers are reinventing the car anyway, they've got a chance to include some new features to stop us vomiting behind the wheel.

Volvo says it's considered car sickness, and thinks its improved engine mapping and suspension systems will smooth the movement of the car. Connectivity may help here as well: "By foreseeing issues that could cause a start-stop action," a company rep says, "we can reduce the tendency for motion sickness." It wants to find out more about the issue when it starts testing autonomous driving with real customers in 2017.

Mercedes has a couple of ideas related to its futuristic F 015 autonomous concept. It could project various virtual landscapes on interior displays to make passengers feel better. The cooler thought is basically an optical illusion to trick your brain into feeling stable: Passengers who swivel their seats to face the back will see a monitor showing an artificial horizon, "with a pre-defined optical vanishing point and a symbolically reduced representation of the vehicle’s motion in the form of particle streams." (The horizon is a natural "visual stabilizer," Stoffregen says.)

Christie Hemm Klok/WIRED

Audi says the question of motion sickness isn't something it's paying a lot of attention right now. A company rep notes we're still a ways from fully autonomous driving, and the interim steps—like cars that can handle themselves only on the highway—will require human attention anyway. Google says this could be something it looks into, but it's got "nothing to share right now."

It's Actually About Control

Let's be real: This an infinitesimal problem in the long run. More than a million people are killed in traffic accidents every year, 30,000 of them in the US. Technology that can reduce that in any way is worth the occasional technicolor yawn. But addressing motion sickness ties into bigger questions about how we will interact with autonomous vehicles and what will change about our lives in the car once we're no longer needed behind the wheel.

This is a question about surrendering control. Letting go of the wheel will make some people queasy, but it will make a whole lot more of them nervous. That's as serious a challenge for automakers as perfecting the technology and convincing regulators this technology is a good idea.

The great design challenge for autonomous driving is not making the seats super cushy or finding new ways to use touchscreens. It's about letting people relax and feel safe. Consumers must be confident the car knows what's going on—that it sees that kid about to run into the street, the motorcyclist coming up from behind, and everything else—and will handle it safely. For humans, this is easy. Passengers can often deduce what a driver sees just by watching her gaze and body language.

There are a lot more nuanced ways to have interface with machines. Gadi Amit, founder of NewDealDesign

It's harder to read a computer's thinking. You could program the car to do things like glow red when it perceives a threat, or tell you, "Don't worry, I see that truck merging into our lane." Problem is, that can get annoying, too. You want to relax while riding, not be bombarded with constant updates about what's happening. To make things more complicated, different drivers will want different levels of reassurance, and that will likely change as they get more comfortable with their car driving itself.

"This is a big problem we have in technology in general," says Gadi Amit, founder of San Francisco-based NewDealDesign. It's called "alert fatigue." For example, many cars beep if you're about to back into something. Many of them do it with such intensity and at so little provocation that it's more distracting than helpful. Or, worse, desensitizing. People don't hear them anymore.

Amit doesn't have the answer for finding the right balance of keeping you informed and letting you concentrate on playing Star Fox. But he says it starts with more subtle forms of communication. "There are a lot more nuanced ways to have interface with machines" than shrill beeping, flashing icons, and alphanumeric displays.

Fortunately, some auto designers are keyed into Amit's thinking. When Audi's A7 concept car goes into piloted mode, its steering wheel retracts a few inches, just far enough to make it clear you are no longer in charge, but close enough to grab if things go bad. Jaguar has a concept that uses a haptic device to "tap" a driver on the shoulder to stop him from opening the door into the path of a cyclist. Those would have to be tweaked of course, but they're evidence of new ways of thinking.

In its F 015 concept, Mercedes uses ambient and blinking lights on displays that line the interior, so the car "communicates continually that everything is under control and lets the passenger know what happens next."

We have no idea if any of these ideas will work. But we do know we need this kind of experimentation to create vehicles that not only drive themselves, but keep us comfortable enough to let them do it.

But just to be safe, some easy-to-clean materials would be a good idea.