From The Art and Popular Culture Encyclopedia
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 by the conscious mind, but allegedly affect the subconscious or deeper mind. Subliminal techniques have occasionally been used in advertising and propaganda; the purpose, effectiveness and frequency of such techniques is debated.
Subliminal stimuli (literally "below threshold"), contrary to supraliminal stimuli or "above threshold", are any sensory stimuli below an individual's absolute threshold for conscious perception. Visual stimuli may be quickly flashed before an individual may process them, or flashed and then masked, thereby interrupting the processing. Audio stimuli may be played below audible volumes, similarly masked by other stimuli, or recorded backwards in a process called backmasking. One example of subliminal stimuli may be observed in the commercials for the product "head on." If one listens closely, a repetition of the product name, along with a command for the buyer to follow a specific instruction (namely, the application to the forehead) may be heard. Introduced in 1895, the concept became controversial as "subliminal messages" in 1957 when marketing practitioners claimed its potential use in persuasion. The near-consensus among research psychologists is that subliminal messages do not produce a powerful, enduring effect on behavior; and that laboratory research reveals little effect beyond a subtle, fleeting effect on thinking. Apart from their controversial use in marketing, subliminal stimuli are employed in scientific research on perception without awareness, or unconscious perception.