You see them every day, everywhere. Glued to their devices, these pedestrians are busy texting, watching videos or playing mobile games on their mobile phones.
So caught up in their own world, they seem oblivious to what is around them - stairs, other pedestrians or, worse, oncoming traffic.
Motorists are not the only ones who are distracted by their phones. Pedestrians are equally guilty of texting while using the roads and putting their lives at risk.
Dr Philip Koh, 49, a general practitioner who is also the chairman of the medical board at Healthway Medical Group, recalls treating a patient in his 30s who twisted his ankle badly two years ago when he fell into a drain near Upper Peirce Reservoir as he was replying to an SMS.
Dr Koh says: "The bad sprain left him unable to stand or walk for a week."
Dr Lee Kwok Keong, 40, a family physician at Avenue K Clinic @ Punggol, saw a similar case earlier this year in which a woman in her 50s suffered a sprain after she tripped while walking and playing a game on her mobile phone.
"She did not see a pothole in the pavement. Her whole foot went into it and she twisted her ankle."
He says he used to see about two or three such cases a year and this figure has grown slightly to three or four cases in the last year.
General practitioners in Britain have also seen more mobile phone-related injuries in the last year, reported The Daily Mail last Tuesday.
Of the 22 general practitioners surveyed, 14 saw a rise in such injuries, which include bumps to the forehead after hitting posts or walls, and grazed knees after falling.
In the Chinese city of Chongqing, a special "mobile-phone sidewalk" has been set up for pedestrians who insist on using their mobile phones.
Dr Leong Choon Kit, 47, a family physician at Mission Medical Clinic, is sceptical that one can tackle two different tasks simultaneously.
"Even if you don't get into an accident, you can walk into lamp posts or other passengers, board the wrong bus or get honked at by drivers," he says.
Summing up the dangers facing distracted road users, Dr Adrian Wang, 48, a psychiatrist at Dr Adrian Wang Psychiatric & Counselling Care, says: "On the road, a fraction of a second can make a difference, and focusing on your phone delays the body's reaction time."
"Looking at your phone also reduces your field of vision and makes you less aware of things happening around you. As a result, you may not see oncoming danger, such as a car or pothole."
However, those who walk and text say they are confident of their ability to multitask.
Says undergraduate Nur Zahirah Ismail: "I know it is dangerous, but I still do it because I haven't had an accident so far."
The 21-year-old checks her e-mail and social media network every day while walking to class or home. She also replies to messages and listens to music.
She say: "I still know what's going on around me even though I'm looking at my phone. I also remind myself while walking to be aware of my surroundings."
Credit control executive Victor Lim uses mobile apps such as Facebook, Instagram, WhatsApp and Telegram a few times every day while walking on roads and pavements.