Eye-Tracking Smartphones Have Arrived. What About the Privacy Implications?

Last March, I wrote in Slate about eye-tracking, which could allow computers and smartphones of the future to collect information not only about what we read, but how we read it.

It appears that the future has arrived. The Samsung Galaxy S IV, which is slated for introduction next week, will reportedly include an eye-tracking feature to make it easier to scroll pages without physically touching the screen. Some people will view this as an added convenience, and for people with certain types of disabilities, navigating by eye-movement can be a vitally important way to interact with objects on a screen.

But there’s also something a bit chilling about the prospect that our mobile devices might be watching us while we’re watching them. After all, there is information in what our eyes do when they scan a page. Where do they linger? What do they skip?

In a world where there is potential marketing and advertising value in every scrap of data about how we interact with our devices, it is hard to imagine that this rich new source of information will go untapped. It probably won’t be long before terms of service for some mobile apps get revised to allow collection and resale of eye-tracking data. Clicking “accept” when downloading a new app may mean agreeing to have your eye movements sent to the cloud, analyzed, aggregated with other data collected from your device, and then resold into the mobile marketing ecosystem.

For the traditionalists among us who—how quaint!—prefer to keep our eye movements to ourselves when reading, there will presumably be an option to turn the tracking function off. But will turning it off mean that the smartphone stops tracking our eye movements altogether? Or that it still tracks them, but just doesn’t use the resulting information to alter the display on the screen? And, if history is any guide, there will be some third-party apps that “accidentally” collect eye movement information anyway, even when users explicitly request otherwise.

As I wrote last March, in a world without eye-tracking, our thoughts when we read something are largely our own, and we should enjoy it while it lasts. It looks like the curtain on one more form of privacy may be coming down a lot sooner than most of us expected.

This piece originally appeared at