Is GPS Making Us Lost and Confused?

The turn-by-turn instructions of GPS-based navigation systems, ingeniously designed though they may be, can't always save us from ourselves.

Consider the experience of a man from San Diego who flew to the East Coast and picked up a GPS-equipped rental car at the airport. After 20 minutes, he sensed he was headed in the wrong direction. Then he realized that he had unthinkingly entered his California address as his destination.

“The navigation system had dutifully set a route back to his home in San Diego, 3,000 miles away,” said Barry Brown, co-director of the Mobile Life Center, based in Stockholm, which does research on mobile communication. The incident happened to a friend of his.

Mr. Brown is co-author of a recent paper titled “The Normal Natural Troubles of Driving With GPS.” The paper illuminates a drawback of GPS technology: that it is designed for docile drivers whose navigational skills have atrophied.

The field work for the study was done last year. Dr. Brown, who was then teaching at the , and a student assistant, Allison Primack, installed two video cameras in cars to record students and their parents as they drove with personal navigation systems of various kinds. The videotapes captured the turn-by-turn instructions, the drivers' responses, and, when things went badly and passengers were present, the in-car conversations about what to do - expletives included.

After analyzing the videotapes of their subjects' trips, the researchers constructed a typology of navigation “troubles,” including destination, route, sensing of the car's location and timing of a given turn instruction.

Human error, as it turns out, was responsible for many of the problems that occurred. When a driver exited the highway to pick up cupcakes while en route to another destination and wanted to return to the highway, her passenger entered the wrong highway junction for the device to use in recalculating the route, so the turn-by-turn directions were wrong.

This was not the fault of the software developers or a map deficiency, but the driver nonetheless placed the blame on the object that was most handy: “These GPS things - it's really confusing.” (“Ahh, shut up,” the passenger said.)

According to TomTom, a leading manufacturer of navigation devices, about 25 percent of all cars in the United States and Europe now have the devices. Turn-by-turn instructions are available as smartphone apps as well, and they are being built right into phones' operating systems, so the challenge of reducing navigation problems through better design is gaining more urgency.

IT'S important to remember that humans can take in only so much information at one time. Today's systems provide drivers with copious information in visual form, in addition to audible instructions. But research suggests that voice instructions without the screen may actually be safer.

A group of researchers led by Andrew L. Kun, associate professor of electrical and computer engineering at the , placed test subjects in immersive driving simulators and tracked the frequency and duration of their glances at a navigation screen, when their eyes left the road. They found that in a majority of instances, these glances lasted for more than 200 milliseconds, long enough to empirically affect driving.

In the experiment, the display was large and easy to see, mounted atop the dashboard. “You did not have to change your gaze angle much to see it,” Dr. Kun said. Consulting a smartphone's navigation app, on a much smaller screen and held lower, makes it more likely that a driver's eyes will leave the road for longer stretches.

“Voice-only instructions delivered subjects to their destinations, and you could argue that they drove better because they looked at the road more,” Dr. Kun said of his test subjects. “Yet a majority preferred having a navigation screen - they felt anxious without it.”

I asked Walter Hermsen, vice president for product management at TomTom, about the prospect of affordable navigation systems that project visual instructions onto the windshield. This augmented-reality technology has begun to appear as a factory-installed option in some luxury cars.

Mr. Hermsen said I was asking for too much. “The size of the contraption you would need to project a high-quality image in bright daylight would be quite large,” he said. “It's not practical as an aftermarket accessory.”

Still, his company's products have capabilities that the devices used in the academic studies lacked, like Internet connections and detailed, real-time traffic information that covers surface roads, not just highways. The company has also devised optimal routes that draw on a large database of actual road speeds, built with data collected anonymously from TomTom customers.

But no technology, however sophisticated, will ever completely eradicate the Normal Natural Troubles of Driving With Humans.