We have all seen them: lurching along city streets, only breaking their gaze from their object of desire when they either bump into another person or building – or a beeping car swerves to avoid them.
The age of the "nomophobic" -- those who are afraid of being without their mobile phone -- is upon us, according to a U.K. academic.
"People's inability to leave their phones alone is the newest addition to common 'displacement' behaviours such as smoking, doodling, fiddling with objects and picking at food. It's also an extension of 'nomophobia' – the fear of being without your mobile," according to Dr Simon Hampton, psychology lecturer at the University of East Anglia.
"Rather than do nothing, we're compelled to turn to them for reassuring comfort."
Smartphones now dominate the handset market in the developed world, and are used by more than half the mobile phone users in the U.S., South Korea, the U.K., Norway, Sweden and Australia, according to eMarketer.
Yet concerns have been raised about their prevalence. The US National Highway Traffic Safety Administration blamed a 8 percent rise in the number of American pedestrians killed in road accidents between 2009-11 on "distracted walking" – walking while texting, reading or listening to music.
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Psychologists have also warned that it may have the effect of isolating young people in particular and inhibiting their communication skills.
The average web-connected user in the U.K. uses a smartphone, tablet or laptop for a total of two hours, 12 minutes a day, and for nearly half this time they're using at least two devices, sometimes three, according to data collected by the Internet Advertising Bureau from close to 1,400 smartphone users.
Smartphone usage changes throughout the day, with users focused on getting information like weather, travel and news in the morning, doing tasks like banking in the afternoon, and using their devices for entertainment and shopping in the evening, according to the IAB.
This is even having an impact on etiquette, with more than a third of users regularly looking at their phone while talking to friends.
And quiet periods of reflection are increasingly being swapped for fiddling with your phone. Over half of the phone users surveyed by IAB prefer to check their smartphone if they have "downtime" rather than just sit and think, and this rises to 62 percent among the 18-30 year olds surveyed.
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This new addiction reinforces the importance of digital media as a way of targeting consumers, for retailers in particular.
"This mildly compulsive behaviour might be exploited to encourage purchasing, particularly as digital increasingly blurs the line between shopping and entertainment," Hampton said.
"There's no doubt that connected devices have changed the shopping process but even how people regard it. Shopping, particularly browsing for aspirational products such as holidays or higher-value items, has become part of the evening's leisure time," Tim Elkington, director of Research & Strategy at the Internet Advertising Bureau, said.