PhotoSmartphone users take note: you know that your apps sometimes share information with “third parties” – it's one of those fine-print phrases you see everywhere nowadays – but there's a high chance you'd be horrified if you knew just how much information those apps share: enough to make tracking your movements and whereabouts ridiculously easy.

That's the conclusion computer scientists from Carnegie Mellon reached in a peer-reviewed study they released this week. As Carnegie Mellon News announced: “An experiment at Carnegie Mellon University shows that when people learn exactly how many times these apps share that information they rapidly act to limit further sharing.”

That experiment was simplicity itself: 23 smartphone users in the study signed up to receive a daily message called a “privacy nudge” telling them how many times their apps shared their location, phone call logs, contact lists or other information.

Those numbers were considerably higher than any of the study participants expected. One smartphone user received this notable privacy nudge: “Did you know? Your location has been shared 5398 times with Facebook, Groupon, GO Launcher EX and seven other apps in the last 14 days.”

Study participants were not happy with the results. “4,182 [times] — are you kidding me?” one of them asked. “It felt like I’m being followed by my own phone. It was scary. That number is too high.”

Sometimes it's necessary

Of course, a certain amount of location-tracking is necessary for various location-specific apps: you can't get discount offers from your local neighborhood businesses unless the app can determine exactly where “your local neighborhood” actually is.

Problem is, many apps seem to check locations far more frequently than necessary to provide their services. For example, the Weather Channel's app doesn't merely request device locations when necessary to provide location-specific weather forecasts; the Wall Street Journal noted that the app requested locations an average of once every ten minutes during the study period.

Groupon's app, which offers discount deals to local businesses, requested one smartphone user's coordinated 1,062 times in two weeks. Tracking a device's location every 10 minutes, or even every 20, is enough to provide a pretty comprehensive overview of that device-holder's regular movements and whereabouts.

Norman Sadeh, one of the Carnegie Mellon professors who co-wrote the study, said: “Does Groupon really need to know where you are every 20 minutes? The person would have to be accessing Groupon in their sleep.” (Neither Groupon nor the Weather Channel have offered comment about the study.)

Further complicating the problem is the fact that, as Sadeh noted, “The vast majority of people have no clue about what’s going on.” Indeed, most smartphone users have no way of accessing the relevant data about their apps' behavior anyway — but the study shows that when smartphone users do manage to get this information, they quickly change their privacy settings.


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