A Chinese tourist, fixated on her mobile phone, made headlines late last year when she strolled straight off the end of Melbourne’s St Kilda Pier and nearly drowned in Port Philip Bay.

Accidents caused by mobile devices are becoming so common that the Pedestrian Council of Australia ran a television campaign to get people to tune out when they walked the pavements.

“Everybody knows that cigarettes cause cancer and we’ve got warnings on the packs,” council head Harold Scruby said. “Why shouldn’t there be a warning on the pack of any mobile phone or iPod or whatever saying ‘Do not use these devices while crossing the road’.”

Siobhan Schabrun, a neuroscientist at the University of Western Sydney, published a paper in PLOS ONE journal recently showing how it is that pedestrians too wrapped up in mobile devices become a danger to themselves and to others.

She videoed people walking normally, walking while they read text on a mobile phone and when they were keying in text. Their biomechanics showed that those walking without a phone did not deviate from a straight line, those reading text did and those actually texting were way off line.

“It’s not unexpected that people would do that,” she said. “It makes sense that if you are distracted and you’re looking at a phone then you can’t walk in a straight path.”

Less obviously, the research found that volunteers were walking not naturally, but like robots.

“They hold their phone and everything moves in line with the phone because they have to keep it steady so their eyes can focus on it,” she said. “We’re moving to this strange robot-like walk which compromises your balance because you don’t have enough freedom to move.”

Schabrun was not surprised by her findings, especially that texters were greater wanderers than readers.

“It’s less cognitively demanding to read than it is to text. You’re much more engaged in the task,” she said.

It was not so much the lack of peripheral vision that induced in pedestrians a failure to hold their line. It was that concentrating on the screen knocked them off balance.

Schabrun defended her research from those who might say it was a statement of the obvious.

“We still need the research to show what we think we see,” she said. “There are lots of examples of people deviating and falling onto a train track. But it's not clear under what circumstances they do so. It’s not clear that your balance might be compromised.

“It’s difficult to educate people or make appropriate guidelines because it’s all hearsay until somebody shows that it happens.”

- dpa