Backward masking
Encyclopedia
Backward masking has several meanings:
- The original meaning of the term, in psychoacousticsPsychoacousticsPsychoacoustics is the scientific study of sound perception. More specifically, it is the branch of science studying the psychological and physiological responses associated with sound...
, refers to temporal maskingTemporal maskingTemporal masking or "non-simultaneous masking" occurs when a sudden stimulus sound makes inaudible other sounds which are present immediately preceding or following the stimulus...
of quiet sounds that occur moments before a louder sound. - A similar meaning, in use in cognitive psychologyCognitive psychologyCognitive psychology is a subdiscipline of psychology exploring internal mental processes.It is the study of how people perceive, remember, think, speak, and solve problems.Cognitive psychology differs from previous psychological approaches in two key ways....
, refers to a phenomenon wherein presenting one visual stimulusStimulus (physiology)In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....
(a "mask" or "masking stimulus") immediately after another brief (≤ 50 ms) "target" visual stimulus leads to a failure to consciously perceive the first stimulus. A similar phenomenon can occur when a masking stimulus precedes a target stimulus rather than following it: this is known as forward masking. While not consciously perceived, the masked stimulus can nevertheless still have an effect on cognitive processes such as contextContext (language use)Context is a notion used in the language sciences in two different ways, namely as* verbal context* social context- Verbal context :...
interpretation. It has been shown that visually masked stimuli can elicit motor responses in simple reaction-time tasks (e.g., Response PrimingResponse primingIn the psychology of perception and motor control, the term response priming denotes a special form of Priming. Generally, priming effects take place whenever a response to a target stimulus is influenced by a prime stimulus presented at an earlier time...
) independent of their conscious visibility. It is a widespread belief that masked stimuli can be used for psychological manipulationPsychological manipulationPsychological manipulation is a type of social influence that aims to change the perception or behavior of others through underhanded, deceptive, or even abusive tactics. By advancing the interests of the manipulator, often at the other's expense, such methods could be considered exploitative,...
(see subliminal messages, psychoramaPsychoramaPsychorama is the act of communicating subliminal information through film by flashing images on the screen so quickly that they cannot be perceived by the conscious mind.-Popular culture:...
). However, the empirical evidence for subliminal persuasionSubliminal stimuliSubliminal stimuli , contrary to supraliminal stimuli or "above threshold", are any sensory stimuli below an individual's threshold for conscious perception. The large majority of research has found that subliminal messages do not produce strong or lasting changes in behavior...
is limited. - In popular music, "backward masking" incorrectly refers to backmaskingBackmaskingBackmasking is a recording technique in which a sound or message is recorded backward on to a track that is meant to be played forward...
, or hiding messages in sound recordings that are audible when played backward.