Texting can make you drive like a drunk. Now a new study shows that texting can also make you walk like a robot.
Researchers found that healthy people who read or send texts while hoofing it show subtle but potentially hazardous changes to their gait. As pedestrians busily tap and flick, they swerve more, walk more slowly and move their heads, arms and torsos in a stiff, graceless fashion that makes them more prone to falling when confronted with an obstacle.
"Reading and texting on a phone influence your ability to walk, but the problems we see are much greater when you text than when you read," says the study's lead author, physical therapist Siobhan Schabrun of the University of Western Sydney in Australia. "It is hard not to (text while walking), but people have to be very careful. … We need to be aware."
Smartphone-wielding pedestrians have made the news and the upper ranks of YouTube by walking off piers, falling onto train tracks and blundering into fountains, but the accidents aren't always comic. In one high-profile incident, a 15-year-old girl in Maryland was hit by a car and killed in 2012 while looking at her phone, and a recent rise in U.S. pedestrian deaths in traffic accidents has been attributed partly to cellphone use.
Schabrun and her colleagues set out to explore exactly how twiddling with a phone affects a person's gait. They had 26 healthy young people walk through a room under the gaze of eight cameras that captured precise details of their motions. As they walked, the subjects either scrolled through a text message or typed the words, "The quick brown fox jumps over the lazy dog."
Even though all 26 subjects were seasoned texters, spending an average of 30 minutes a day texting, they still couldn't walk normally as they texted. They unwittingly swerved off a straight line. Their heads did not stay still as they should have, instead swiveling to keep their eyes trained on their touch screens. Their arms, head and torso, rather than moving freely and fluidly, moved stiffly.
"People walk more like a robot" when absorbed in their phones, Schabrun says. "They move everything in line with the phone."
The changes seen by the researchers can put pedestrians at risk. Walkers who drift away from their intended path can stray into traffic or down a steep drop. People who walk stiffly are at greater risk of falling if they hit an obstacle, because their limited movements make them less likely to catch themselves, Schabrun says. The results are reported in today's PLOS ONE, a scientific journal.
It's not entirely clear why the walk of a texting pedestrian is distorted. One possibility, the researchers say, is that the extra head motion feeds bad information to the vestibular system, the apparatus in the inner ear that sends signals to the brain about the body's position in space. That may make it harder for people to walk in a straight line. Or perhaps the multitasking of walking while attending to a text overwhelms the brain, which then prioritizes that cool app over keeping to the straight and narrow.
The study is "excellent," says Stony Brook University's Lisa Muratori, a behavioral neuroscientist who was not involved in the new research and who has also studied walking during cellphone use. She says it's certainly plausible to think that changes in head movement could cause trouble.
Abnormal head motion makes it "much harder for you to react. A very small delay in reaction can cause a trip or a slip," Muratori says. "In a healthy person it shouldn't cause a fall, necessarily, but a trip over a curb into a street is a big problem."
The increased head movement reported in the study "is a really bad thing for gait," says University of Pittsburgh bioengineer April Chambers, who was not involved in the research. The new findings "highlight the need to maybe put your phone down more than (just) when you're driving."