"Backward masking has several meanings.The original meaning of the term, in psychoacoustics, refers to temporal masking of quiet sounds that occur moments before a louder sound.A similar meaning, in use in cognitive psychology, refers to a phenomenon wherein presenting one visual stimulus (a \"mask\" or \"masking stimulus\") immediately after another brief (\u2264 50 ms) \"target\" visual stimulus leads to a failure to consciously perceive the first stimulus."@en .