ExtraRoom by Gunnar Green (in collaboration with Bernhard Hopfengaertner).
"The image above shows the 'food dispenser". The subject would suck nutrients from it: normal meals would indeed be too rich in stimuli (shape, textures, ordering on the plate, smell, etc.). Besides, their elimination would erase any sense of time. The rest of the room would be totally bland and white, with only a toilet. It is soundproof and features no window. The architecture of the room with its surfaces that are never horizontal nor vertical induces mental unrest.
It has been observed that deprivation rooms increase the receptivity to propaganda. After 36 hours spent in the room, the mind of its inhabitant would be ready to receive desirable messages through speakers. The input would be repeated several times until the appropriate psychological alteration has been reached. The door will then open. The person can now go back to their normal life."