A subliminal video instructional device comprises circuitry for receiving an underlying video signal and presenting this signal to horizontal and vertical synchronization detection circuits, circuitry for generating a subliminal video message synchronized to the underlying video signal, and circuitry...http://www.google.com/patents/US5644363?utm_source=gb-gplus-sharePatent US5644363 - Apparatus for superimposing visual subliminal instructional materials on a video signal
