Abstract: Despite apparent use of subliminal techniques in different media, there is as we have seen simply no evidence for effective subliminal persuasion in film or video, advertising, self-help audiotapes, or rock music, and there is certainly no theoretical basis to expect it. Perhaps the next time somebody tells you in whispered tones about the infamous “Popcorn and Coke” study as support for how some subliminal audiotape taught “this man” calculus while he was sleeping, you can set them straight.

From Wikipedia:

In 1985, University of Lethbridge psychologists John Vokey and J. Don Read conducted a study using Psalm 23 from the Bible, Queen’s “Another One Bites the Dust”, and other sound passages made up for the experiment. Vokey and Read concluded that if backmasking does exist, it is ineffective. Participants had trouble noticing backmasked phrases when the samples were played forwards, were unable to judge the types of messages (Christian, Satanic, or commercial), and were not led to behave in a certain way as a result of being exposed to the backmasked phrases. Vokey concluded that “we could find no effect of the meaning of engineered, backward messages on listeners’ behaviour, either consciously or unconsciously.”