Texting on the hoof leads people to change the way they walk, new research has revealed. While researchers have previously looked at the impact of phone use while on a level surface, they have now explored how pedestrians cope while using their phones and negotiating that common trip-hazard: step.
Injuries from falling over or bumping into things while using a mobile phone are on the rise: in the US at least 1,500 pedestrians were reported to have visited hospital in 2010 alone as a result of such accidents.
"Part of it evolved from walking down the road in the middle of the day," said co-author of the research Matthew Timmis of Anglia Ruskin University in Chelmsford, Essex. "The person in front of me was walking very slowly and weaving, and I thought: it's quite early in the day: is this person intoxicated already?"
When he walked past, Timmis found the person was using their phone.
To explore the impact of phone engagement on walking, the team kitted out 21 participants with a head-mounted eye tracker and motion-analysis sensors, and asked them to walk 5.6 metres, negotiating an obstacle made of fibreboard and a step made of a box on the way.
Participants were asked to go around the course three times without a phone, and repeat while writing a text message, reading a text message or making a call three times, making a total of 12 turns each.
The results, published in the journal Plos One by researchers at Anglia Ruskin and the University of Essex, revealed that fiddling with a phone increased how long people took to complete the task, decreased how often people looked at the step and changed how they walked.
Participants adopted "an increasingly cautious stepping strategy" when using the phone and deviated from a straight path more often. While the effects were seen to various degrees for all three phone-use tasks, it was most pronounced when participants were asked to write a text message while walking.
They took 118% longer to complete the course when tapping out a text than when no phone was used. Participants were also found to fixate on the step 60% more and 91% longer, and fixate on the travel path 51% more, when phone-free.
Those simply talking with the phone to their ear were also found to show some odd behaviour. "We expect when we walk in an environment you are going to look on the ground, you are going to look at the obstacle or the hazard that is coming, and look ahead to check you are wandering in the right direction," said Timmis. "But when these guys were talking on the phone, they began to look at a bunch of other stuff that didn't matter."
While no one stumbled on the step in the tasks, the team found that the gait of participants was different when texting, talking or reading on the phone compared with when no phone was used -- a result, says Timmis, of phone users spending less time looking at their environment, meaning they were relying on less-detailed peripheral vision.
Approaching the step, both the participants' leading and trailing foot was closer to the front edge of the step, while the stride length for both feet while walking was 38% shorter when texting than for when no phone was used. On tackling the step, those texting were also found to lift their lead foot 18% higher, and step more slowly.
"That is very much the hallmark of what we term a 'safety strategy,'" said Timmis. The strategy, he added, reduced the cognitive burden on the working memory, freeing up resources for engaging with a phone -- with more resources needing for texting than making a call.
Timmis said that while the research showed phone-users had adopted a cautious walk, he warned that fiddling with a device could still result in accidents.
"The big risk here is suddenly-appearing hazards [like] a pedestrian suddenly walking in front of you," he said. "You are not going to be able to respond to that as efficiently, which increases the risk of injury."
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