Subliminal stimuli

Subliminal stimuli is any sensory stimuli below an individual's absolute threshold for conscious perception. Visual stimuli may be quickly flashed before an individual may process them, or flashed and then masked, thereby interrupting the processing. One application of subliminal stimuli is brainwashing. Brainwashing is a process in which a group or individual "systematically uses unethically manipulative methods to persuade others to conform to the wishes of the manipulator(s), often to the detriment of the person being manipulated". The term has been applied to any tactic, psychological or otherwise, which can be seen as subverting an individual's sense of control over their own thinking, behavior, emotions or decision making.

Doctor Who

 * "Rise of the Cybermen": Scientist Doctor John Lumic, uses electrical transmitters and receivers in order to brainwash entire population centers on a city-wide scale, ultimately transforming his mindless drones into Cybermen.
 * "The Age of Steel": Brainwashed citizens of Europe, turned into robotic Cybermen, fight up against members of a human resistance in an alternate timeline.

Hart to Hart

 * "Hart of Diamonds: A woman named Lily Von Borg finds a way to brainwash Jennifer Hart into a stealing a cache of very valuable diamonds.