Shane Walker hops into his Toyota Prius hybrid and puts on his Google Glass. It's a lightweight glasses frame with a tiny computer built into the lens.

Google is at the forefront of a movement in wearable technology, gadgets we put on our bodies to connect us to the Internet, and perhaps nothing embodies that more than Glass. But the eyewear is raising eyebrows outside the high-tech industry. Before Glass even hits stores, lawmakers in several states want to ban it on the roads.

Walker, an independent developer living in San Francisco, turns on the GPS app and starts driving. Instead of talking out loud, like an app on a smartphone might, it shows him his route as a thin blue line and a triangle on the upper right corner of the lens.

"Google did a good job of making it nonintrusive, so it's not directly in your line of sight," he says.

But Walker's favorite feature is the camera. Say you're on a road trip. With a tap of the side, you can record the entire thing in decent resolution and then, with another tap, share it with your friends. Or you can wink and take a picture.

At a stop sign, Walker strokes the Glass frame with his right index finger. He's flipping through stored photos. The movement is so discreet — no bending his neck down like you would with a smartphone — and I have to ask him: "Is it something you would do if there was a police officer right in front of you?"

"I mean, it's debatable," he replies. "It is hands-free, so I do feel like in my legal right, it's OK for me to interact with stuff that doesn't require my hands, like winking, taking pictures."

Legislative Battle Over Public Safety

Ira Silverstein, a Democratic state senator from Illinois, disagrees. "Yeah, it's hands-free, but it can affect your vision," he says.

He's written a bill that says using Glass distracts drivers. "The first offense would be a misdemeanor. The second offense if, God forbid causes death, could be a felony."

Leading car insurance companies have not yet taken a position on Glass, but at least eight states have proposed legislation banning the use of Google Glass on the road. In West Virginia, Republican state Delegate Gary Howell says lawmakers need to act before Glass gets out of hand.

Glass is the ultimate multitasking machine. It streams incoming emails and scans the human eyelid for commands. But Howell says its high-tech creators aren't seeing a basic fact about the real world.

"Have they driven on mountain roads in West Virginia, where you've got one 15-mile-an-hour turn after another one, where you really need to be concentrating on what you're doing?" he says. "You could be wearing it, not looking at your driving but watching a video screen."

Google is responding to this roadblock by sending lobbyists around the country to dispel concerns. Spokesman Chris Dale says Glass can help drivers.

"It's actually not distracting, and it allows you — rather than looking down at your phone, you're looking up and you're engaging with the world around you," Dale says. "It was specifically designed to do that: to get you the technology you need, just when you need it, but then to get out of your way."

Not Texting, But Text

Back in Walker's car, Glass does something that a smartphone can't do. We turn a corner past a golden fire hydrant, and obscure facts suddenly start streaming in front of Walker's iris.

"When San Francisco burst into flames in the days following the disastrous 1906 earthquake, much of the city's network of fire hydrants failed," Walker reads. "Miraculously, this fire hydrant, nicknamed 'The Little Giant,' is said to have been the only functional ..." He goes on reading like this for about half a minute.

"Are you reading all of that from the upper right-hand corner of your eye?" I ask.

"Yeah," he says. "It's pretty cool. It's like text just floating in air."

Walker has a theory about why the text is not distracting him: "The layer is transparent, so your eye does a good job of seeing through it while also staring at it."

Earl Miller, a professor of neuroscience at MIT who specializes in multitasking, says this sounds like wishful thinking.

"You think you're monitoring the road at the same time, when actually what you're doing [is] you're relying on your brain's prediction that nothing was there before, half a second ago — that nothing is there now," he says. "But that's an illusion. It can often lead to disastrous results."

In other words, the brain fills in the gaps in what you see with memories of what you saw a half-second ago. Among scientists, that statement is not controversial. The politics of Google Glass — and where it's worn — clearly is.

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