http://en.wikipedia.org/wiki/Panopticon

The Panopticon is a type of institutional building designed by the English philosopher and social theorist Jeremy Bentham in the late 18th century. The concept of the design is to allow a single watchman to observe (-opticon) all (pan-) inmates of an institution without the inmates being able to tell whether or not they are being watched. Although it is physically impossible for the single watchman to observe all cells at once, the fact that the inmates cannot know when they are being watched means that all inmates must act as though they are watched at all times, effectively controlling their own behaviour constantly