There is an even more fascinating and diabolical element to what can be done with location information. New research suggests that by cross-referencing your geographical data with that of your friends, it’s possible to predict your future whereabouts with a much higher degree of accuracy.

This is what’s known as predictive modeling, and it requires nothing more than your cellphone data.

If we are naïve to think of them as phones, what should we call them? Eben Moglen, a law professor at Columbia University, argues that they are robots for which we — the proud owners — are merely the hands and feet. “They see everything, they’re aware of our position, our relationship to other human beings and other robots, they mediate an information stream around us,” he has said. Over time, we’ve used these devices less for their original purpose. A recent survey by O2, a British cell carrier, showed that making calls is the fifth-most-popular activity for smartphones; more popular uses are Web browsing, checking social networks, playing games and listening to music. Smartphones are taking over the functions that laptops, cameras, credit cards and watches once performed for us.

If you want to avoid some surveillance, the best option is to use cash for prepaid cellphones that do not require identification. The phones transmit location information to the cell carrier and keep track of the numbers you call, but they are not connected to you by name. Destroy the phone or just drop it into a trash bin, and its data cannot be tied to you. These cellphones, known as burners, are the threads that connect privacy activists, Burmese dissidents and coke dealers.

Prepaids are a hassle, though. What can the rest of us do? Leaving your smartphone at home will help, but then what’s the point of having it? Turning it off when you’re not using it will also help, because it will cease pinging your location to the cell company, but are you really going to do that? Shutting it down does not even guarantee it’s off — malware can keep it on without your realizing it. The only way to be sure is to take out the battery. Guess what? If you have an iPhone, you will need a tiny screwdriver to remove the back cover. Doing that will void your warranty.

Matt Blaze, a professor of computer and information science at the University of Pennsylvania, has written extensively about these issues and believes we are confronted with two choices: “Don’t have a cellphone or just accept that you’re living in the Panopticon.”

There is another option. People could call them trackers. It’s a neutral term, because it covers positive activities — monitoring appointments, bank balances, friends — and problematic ones, like the government and advertisers watching us.

We can love or hate these devices — or love and hate them — but it would make sense to call them what they are so we can fully understand what they do.