After being told about hemianopsia (visual neglect) in an answer to another question, I started wondering if I could apply the same idea to artificial applications, such as securing information or hiding things.
Information has always been something we as humans have tried to control. Governments and companies are in an arms race with other governments and companies and third parties to develop better defenses. Is there some manner of artificial construct, or set of constructs, that would enable an entity to control what objects or information is physically seen by an arbitrary individual?
For example, Franklin has been cleared by the government to enter the Blue Room. He can enter the building with the Blue Room, go to the hall with the Blue Room, stand in the hall with the door to the Blue Room, use his id to unlock the door, and enter the Blue Room without any problem. The spy behind him, Clemont, who isn't cleared to enter the Blue Room, can follow Franklin into the building and to the hall, but he's too far behind Franklin to see where he went and doesn't see the door to the Blue Room.
For another example, Franklin is cleared by a company to watch streaming data on a certain computer screen. When he looks at the screen, from anywhere the screen is visible, he can see all the data streaming at that time. Clemont, however, who isn't cleared for this either, could press his face against the screen and see only his reflection on what appears to be a disabled device.
My first idea to support this would be a device that indiscriminately applies its effect out to a certain distance and an implant that neutralizes it. Thus, no one notices anything out of place, at least until an uncleared person watches a cleared person walk through a wall or simply vanish.