Due to the complexity of the human brain, it has various levels of consciousness: the state of dreaming, conscious-rational and lastly the subconscious level. This last level is one which is not able to function through logic or reasoning abilities, and is unable to differentiate between what is real and what is fictional.

Subliminal messages that are sent into the subconscious mind gives it the basis to change the message into reality. It is a method of thought-controlling, as there is a link of communication between the subconscious and the conscious mind, allowing it to affect each other. Hence, there has been much controversy surrounding the use of these subliminal messages, as hidden persuasive messages have been used to influence audiences. Such incidents are commonly found in commercials and advertising, and in rock music. There has been much criticism on the use of insidious subliminal messages to increase profits.

Subliminal messages used in advertising or subliminal advertising, are most of the time consisting of brief visual or audio messages that your mind does not consciously register what it has seen or heard. There is usually a less than 25% chance that the audio or visual message will be noticed by the conscious, and is used to provide stimulus for action.

Subliminal advertising does exist. In actual fact, very few marketing agencies endeavor to insert such messages due to the powerful impact that they can exert on the audience, which would result in overwhelming negative press that would be received if the subliminal message was detected. This puts off any potential benefit that the subliminal advertising may bring.

According to an April 2006 issue of the New Scientist, studies have shown that subliminal advertising messages do work, under the right conditions. The researchers also found that priming only works when the prime is goal-relevant. In plain English, this means you're potentially going to buy something that quenches your thirst only if you were already thirsty anyway. Subliminal messages are thus more useful in priming a target audience to choose one brand over another, rather than in recreating an real need for the product.

While it is has yet to be sufficiently proven that the brief subliminal messages can affect your behavior without you knowing, it is still arguable that subliminal advertising can be more effective than normal means of promotional communications which people are consciously aware of.