Stubby fingers may be the reason many consumers end up checking out ads on smartphones and tablets.

Facebook FB, +1.93% , Google GOOG, +0.32% and other tech companies have puzzled over how to make advertising work on mobile devices. But it turns out that tablet and smartphone users, when reading news sites, are more likely to click on ads than those using computers, a new survey suggests.

Consumers don’t appear to be turned off by mobile ads, according to a survey of nearly 10,000 people by Pew Research Center and The Economist Group. Half of tablet and smartphone users notice ads when they’re getting news on their mobile device. Of that amount, roughly 15% click on ads. “People notice ads on mobile devices and may be even more likely to click on them than they are to click on other digital ads,” the report states. A recent Ad Age study, in stark contrast, found that less than 1% of people click on digital ads regardless of the viewing platform.

But tech pros say the result may be less a measure of the quality of the ads than the size of users’ thumbs.“False positives, namely clumsy digits, are the real culprits here,” says Jonathan Rick, a digital communications consultant based in Washington, D.C. This will become less of a problem for frustrated smartphone owners as screen sizes continue to get bigger, he says. Others say the digital ad world doesn’t make it easy to avoid ads either. Mark Spoonauer, editor-in-chief at LaptopMag.com, says many mobile ads are designed so that the window-shuttering “X” button is so small, it makes the ad more difficult to vanquish. “I’ve seen many people accidentally click on ads in an effort to get rid of them,” he says.

Plus, the line between mobile marketing and entertainment is becoming blurred, experts say. “It’s difficult for users to tell the difference between ads and content on small devices,” says technology analyst Jeff Kagan. Facebook and Twitter both have personalized “sponsored” stories, which are effectively advertising by another name. Zynga, which makes apps like Angry Birds and Words with Friends, also has sponsored stories. Mobile advertising is expected to reach hit $20 billion by 2015 from $2 billion currently, says Kleiner Perkins Caufield & Byers, a venture capital firm, making up 40% of all online ads.

That said, people happily browse ads on their tablets and smartphones during their leisure time, according to one co-author of the Pew study. “Desktops are more search, find and run,” says Amy Mitchell, deputy director at Pew Research Center’s Project for Excellence in Journalism. People spend more time reading on tablets and read longer articles, as the screen is visually more appealing than a standard computer’s, she says. In fact, some 90% of Pew respondents say their tablet reading is personal. “It gives people more opportunity to notice everything on the page and think, ‘Maybe I’ll check this ad out too,’” she says. Of those who did click on ads, she says, 7% made a purchase.