|Some dare call it|
Subliminal messages are images, sounds or pieces of text which are worked into various media and, in theory, are picked up by the subconscious mind of the viewer or listener but not their conscious mind. They can come in several forms: images or text which flash up briefly on a film or TV broadcast, too quickly to be registered consciously; symbols worked into images; backward masking, and so forth. Donate to RationalWiki
Early research into the phenomenon was performed by James Vicary, who claimed to have inserted examples of subliminal advertising (a term he coined) into a film called Picnic. Messages telling audiences to buy Coca-Cola and popcorn flashed up onscreen every five seconds, each lasting only 1/3000 of a second and so unnoticed by the conscious minds of the audiences.
According to Vicary, Coca-Cola sales went up by 18.1% as a result of this, while popcorn sales went up by 57.8%. However, he was subsequently challenged to repeat the experiment; he did so and there was no such increase in sales. He eventually admitted to falsifying the data first time round.
More recent research They all must die has actually shown that there is a (very) tiny grain of truth in ideas about subliminal messages. The use of a technique called "flash suppression" can unconsciously prime an image in subjects. However, the effect is very temporary and does not bear any resemblance to the claimed effects of Satanic messages on Led Zeppelin albums.