Porto Covo beach. Portugal
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.
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.