Subliminal stimuli are those that fall below the absolute threshold for conscious awareness. They are detected by the sensory system yet are too weak or too brief to be reported.

Laboratory studies show that subliminal presentation can produce priming effects: a briefly flashed word or image can influence subsequent judgments or reaction times even when participants deny having seen it. The effects are typically small and short-lived. Claims that subliminal messages in advertising or self-help recordings can powerfully alter consumer behavior or personal habits have not been supported by rigorous evidence.

The existence of subliminal perception demonstrates that sensory processing and even some forms of learning can occur without conscious awareness. It does not imply that the unconscious is easily programmed by hidden messages. Thresholds vary with attention, expectation, and individual sensitivity, so a stimulus that is subliminal for one person or occasion may be detectable for another.

What the senses register but awareness does not yet acknowledge is subliminal.