Market researcher James Vicary became well-known for a 1957 study attesting to the efficacy of subliminal advertising. His description of his experiment involved movie-theatre customers being shown very brief (0.03-second-long) advertisements for popcorn and soft-drinks, then purchasing substantially more of these than attendees who were not shown the advertisements.
The only problem was that Vicary’s results proved to be hard to replicate, and Vicary himself claimed that too many of the details of his experiment were confidential and could not be shared with other researchers. Suspicion grew, and Vicary admitted on television in 1962 that the study had been a “gimmick” with only a very small amount of data. A 1992 study by another researcher went farther and concluded that Vicary had not performed an experiment at all.
In spite of this, the idea persists that advertising below the level of consciousness is powerfully persuasive.