Why Can’t We Walk And Wear Google Glass At The Same Time?

New research explains why such a seemingly simple task is so hard to do.


The era of distracted walking is certainly upon us. Dividing attention between cell phone and sidewalk leaves an estimated 1,500 people a year in the hospital with an embarrassing story to tell. Controlled experiments have found that pedestrians using a phone recall less about their surroundings than other walkers do–with some people so zoned out that they fail to spot a unicycling clown.


Lately any discussion of distracted walking has centered on whether Google Glass will help or hurt the situation. On one hand, the device’s very design was supposed to free our eyes to look forward. On the other hand, looking isn’t seeing, and some cognitive scientists worry that our inability to see a device and the world around us at the same time could have “potentially dangerous consequences.”

Most of the evidence framing this debate has been based on cell phone use. Psychologists have shown quite clearly that people have a hard time concentrating on other tasks, such as driving, while they’re on their cell phones. But that comparison is problematic. People will interact with Glass in a much more visual way than they do with their phones. What we need is a study of people walking and considering their visual displays at the same time.

Image: Thomas La Mela via Shutterstock

You don’t need Google Glass to see where this one’s going. A research team led by behavioral scientist Terhi Mustonen of the University of Helsinki, in Finland, recently designed a study that examines walking and head-mounted displays–the technical name for Glass-type technology. The work was published online earlier this month in the Journal of Experimental Psychology: Applied.

Mustonen and collaborators recruited two dozen participants to partake in the study. The researchers equipped them with a head-mounted display called the Shimadzu Data Glass 2. It may have lacked the alliterative ring of Google Glass, but the apparatus had similar technological perks.

The participants used the head display to perform two types of tasks. One was a memory task that asked test participants to detect when a repeat number appeared in a series. The other was a visual task that had them detect the appearance of a rectangle in a series of squares. Participants performed these while sitting down and again while walking a taped path in a hallway. (The hall was closed off, for safety’s sake.)

Sitting down, the tasks weren’t too tough. The trouble began when participants started walking. Once ambulatory, the participants did a little worse on the memory task and much worse on the visual task–missing 20% more rectangles and triggering 10% more false alarms.

Image: Flickr user Aaron Anderer

Walking itself became rather hard. Participants slowed down and strayed from the taped hallway path while using the head display to do the simple memory task (spotting a back-to-back repeat in the series). During an advanced memory task (spotting a repeat number from two back) as well as the visual task, their walking speed and performance suffered even more.

“It is extremely difficult to process information from these two sources–the environment and the display–at the same time,” Mustonen tells Co.Design.

So why is it so difficult to walk and Glass at the same time? Part of the answer may be that walking requires some actual brainpower despite how automatic it feels. If that were the whole answer, though, we would expect people to do poorly at any display task while walking. In fact, participants did much worse at the visual one than the memory one.

For that reason, the researchers suspect that the brain of someone using Glass might be competing with itself for certain cognitive resources. During the visual task of spotting rectangles, for instance, attention might have been split between seeing where to walk and watching the series of squares change shape. Using our limited visual capacity for two simultaneous visual tasks may, in effect, make us worse at each.

“When concentrating on the [head-mounted display], walking gets more difficult,” says Mustonen. “When guiding the gait, performance in the HMD task suffers.”

The experiment has some limitations. The most obvious is that people don’t typically follow a taped path when they’re walking. Then again, one could argue that navigating a crowded sidewalk is equally difficult–so maybe call that a wash. It’s also worth wondering whether these experimental games are comparable to the real tasks people will use Glass to perform.


Still, the research suggests the rise of inattentive walking has only begun. Designers, lawmakers, and manners mavens can use this type of work to improve, regulate, and critique the technology (Mustonen, for one, cautions Glass-wearing walkers to be very careful in crowded places). It’s not at all reasonable to outlaw Glass, as some have suggested, but appreciating its peculiar brand of distraction is the responsible thing to do–if not for ourselves, then at least for the legion of unicycling clowns.

About the author

Eric Jaffe is an editor at CityLab, where he writes about transportation, history, and behavioral science, among other topics, through the lens of urban life. He's also the author of The King's Best Highway (2010) and A Curious Madness (2014)