With mobile internet usage skyrocketing, and more and more publishers investing in developing mobile experiences, it’s no surprise that expectations for mobile advertising are high.

That doesn’t mean, however, that challenges don’t exist. One of the biggest: fat fingers, which are producing clicks that consumers never intended but advertisers have to pay for

Recognizing this problem, one of the largest purveyors of mobile ads, Google, had previously added a confirmation feature to text ads displayed on mobile phones which asks a user who clicks on an ad in a certain fashion to verify that the click was intended.

Yesterday, Google announced that it is expanding this confirmation feature to its image-based formats designed to be served in-app. On the Google Mobile Ads Blog, the search giant explained:

By expanding confirmed clicks to in-app image ad banners, we’re now making this improved user experience consistent across the vast majority of the ads that we serve in mobile apps. In our initial tests, we found that confirmed clicks notably improve mobile conversion rates, with a slight decrease in clickthrough as accidental clicks are avoided.

It’s interesting to note Google’s reference to a “slight” decrease in CTRs. Some studies have suggested that nearly half of mobile ad clicks are accidental, but Google’s comment seems to indicate that the introduction of a confirmation is not causing a significant reduction in clicks.

Does this mean that concerns over fat fingers have been overblown? Perhaps, but it’s too early to tell. Google only asks for click confirmation when a click takes place on the “outer border of the ad” because it says it determined that clicks in these regions were far more likely to be accidental. That, of course, doesn’t mean thataccidental clicks aren’t produced elsewhere.

At the end of the day, it’s clear that, for most display and text ads, there is no perfect solution to the fat finger problem. Confirmations can help, but advertisers should probably count on some percentage of clicks being accidental, just as they count on some percentage of AdWords clicks being fraudulent.

Ultimately, the success of mobile ad campaigns will be based not on how well Google and others filter out accidental clicks but how well advertisers convert real clicks and how much they pay for them.