US Patent 9405918 Viewer-based device control

A computing device can monitor the gaze direction of people around the device to determine whether any unintended viewers are viewing content displayed on the device. A user can activate a privacy mode of the device, such that when an unintended viewer is detected the device can take an appropriate action. In some cases the device can notify the primary user of the device using audible, visual, or tactile alerts. In other cases, the device can modify the display of content such that the unintended viewer is unable to decipher or view the content, or is otherwise notified of the detection.