Subliminal Messages

A subliminal message is a signal or message embedded in another object, designed to pass below the normal limits of perception. These messages are indiscernible to the conscious mind, but are perceivable to the subconscious or deeper mind: for example, an image transmitted so briefly that it is only perceived subconsciously, but not otherwise noticed. Subliminal techniques have occasionally been used in advertising and propaganda.

Subliminal messages gain influence or power from the fact that they circumvent the critical functions of the conscious mind, and therefore subliminal suggestions are potentially much more powerful than ordinary suggestions. This route to influence or persuasion would be akin to auto-suggestion or hypnosis, wherein the subject is encouraged to be relaxed so that suggestions are directed to deeper (more gullible) parts of the mind; experts have suggested that the unconscious mind is incapable of critical refusal of hypnotic or subliminal suggestions.

Vicary's claims were promoted in Vance Packard's book The Hidden Persuaders, and led to a public outcry, and to many conspiracy theories of governments and cults using the technique to their advantage. The practice of subliminal advertising was subsequently banned in the United Kingdom and Australia, and by American networks and the National Association of Broadcasters in 1958.

In 1973, commercials in the United States and Canada for the game Hūsker Dū? flashed the message "Get it". During the same year, Wilson Bryan Key's book Subliminal Seduction claimed that subliminal techniques were widely used in advertising. Public concern was sufficient to cause the FCC to hold hearings in 1974. The hearings resulted in an FCC policy statement stating that subliminal advertising was "contrary to the public interest". Subliminal advertising was also banned in Canada.

Certain types of subliminal perception (hypnosis, for example) are known to effect the perceiver without any conscious knowledge of the effect on his part.

Perception of subliminal messages is a type of subconscious cognition. Unlike unconscious tasks such as attending to one signal in a noisy environment while keeping track of other signals (e.g., listening to one voice out of many in a crowded room) and automatic tasks such as breathing, subliminal message cognition cannot be done consciously.