More than half of smartphone owners turn to their phone rather than have "downtime", and more than one in three check their phone when there is a lull in conversation, the report from the Internet Advertising Bureau (IAB) said.
The study draws on 700 hours of video footage from consumers wearing FishEye cameras, which took a picture every five seconds over a three-day period, revealing that those surveyed picked up or used a connected device such as a smartphone, laptop or tablet on average 34 times each day.
Those who took part in the study averaged a total of two hours and 12 minutes a day using a connected device, while for 46% of this time they were using at least two devices, and sometimes three, simultaneously.
More than half of smartphone users (52%) said they prefer to check their smartphone if they have any "downtime" rather than sit and think.
The figure rises to 62% among 18 to 30-year-olds.
More than one third (37%) said they check their smartphone if there is a lull in conversation with friends, while 44% said their smartphone makes their commute more enjoyable.
And one in six (17%) smartphone owners said their phone had played some role - either browsing, researching or buying - in a purchase made in the previous fortnight.
IAB director of research and strategy Tim Elkington said: "One thing that stood out in the study was how surprised respondents were when told how frequently they'd looked at their phone, tablet or computer.
"It reinforces how normal 'omni-screening' - being just an arm's length away from some device that gets us online - has become.
"We also saw a broad pattern in how people use their devices. The morning is about getting information such as weather and travel, the afternoon for undertaking specific tasks such as banking or paying bills, while the evening is focused on entertainment, including shopping."
Dr Simon Hampton, lecturer in psychology at the University of East Anglia, said: "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.
"Rather than do nothing we're compelled to turn to them for reassuring comfort. What's exciting for marketers is that, unlike most of the examples above, this mildly compulsive behaviour might be exploited to encourage purchasing, particularly as digital increasingly blurs the line between shopping and entertainment."
:: Firefish polled 1,376 UK adults in September.