It's no laughing matter, but people look funny if they text and walk at the same time.
Dr Siobhan Schabrun says they look like robots.
She should know. She has spent many hours testing the ability of 26 people to type and read text messages while walking.
At best, they irritate other people on the footpath or have a minor fall.
At worst, people can end up in traffic, on a railway line or in the sea.
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Dr Schabrun gives an example of a Facebook-engrossed tourist who had to be rescued from the sea in December after walking off a Melbourne pier.
"People slow down and deviate from a straight line. They swerve more," says the University of Western Sydney physiotherapist, whose study is published in the journal PLOS ONE.
"Even if they think they are walking straight, they are probably not. That's an issue if you are near traffic or a train track."
It's more pronounced if people are typing, but also noticeable if they are reading.
"People walk like robots. They try to keep their head straight so their eyes can stay on the phone. They lock their arms, their trunk and their head together.
"The more rigid people are, the more likely they are to fall.
"You think that walking is such a simple skill until you put a phone in someone's hand."
Her advice to texters: "Move to one side and stop so you don't drive everybody around you mad. Don't try doing both at once. Especially if you are near traffic."
