The concept of backward masking originated in

psychoacoustics Psychoacoustics is the branch of psychophysics involving the scientific study of the perception of sound by the human auditory system. It is the branch of science studying the psychological responses associated with sound including noise, speech, ...

, referring to temporal masking of quiet sounds that occur moments before a louder sound. In

cognitive psychology Cognitive psychology is the scientific study of human mental processes such as attention, language use, memory, perception, problem solving, creativity, and reasoning. Cognitive psychology originated in the 1960s in a break from behaviorism, whi ...

, visual backward masking involves presenting one visual stimulus (a "mask" or "masking stimulus") immediately after a brief (usually 30 ms) "target" visual stimulus resulting in a failure to consciously perceive the first stimulus.Breitmeyer, B.G. and Ogmen, H. (2007
''Visual masking''
Scholarpedia, 2(7):3330. It is widely used in

psychophysiological Psychophysiology (from Greek , ''psȳkhē'', "breath, life, soul"; , ''physis'', "nature, origin"; and , ''-logia'') is the branch of psychology that is concerned with the physiological bases of psychological processes. While psychophysiology w ...

studies on

fear Fear is an unpleasant emotion that arises in response to perception, perceived dangers or threats. Fear causes physiological and psychological changes. It may produce behavioral reactions such as mounting an aggressive response or fleeing the ...

and

phobia A phobia is an anxiety disorder, defined by an irrational, unrealistic, persistent and excessive fear of an object or situation. Phobias typically result in a rapid onset of fear and are usually present for more than six months. Those affected ...

s that investigate the preattentive nonconscious reactions to fear-relevant stimuli. It is unknown how a later stimulus is able to block an earlier one. However, one theory for this phenomenon, known as the ''dual channel interaction'' theory, proposes that a fast signal created by the second stimulus is able to catch up to and overcome a slower signal sent from the first impulse. A similar phenomenon can occur when a masking stimulus precedes a target stimulus rather than follows it: this is known as ''forward masking'', or visual forward masking when the stimulus is visual. While not consciously perceived, the masked stimulus can nevertheless still have an effect on

cognitive Cognition is the "mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...

processes such as

context In semiotics, linguistics, sociology and anthropology, context refers to those objects or entities which surround a ''focal event'', in these disciplines typically a communicative event, of some kind. Context is "a frame that surrounds the event ...

interpretation. It has been shown that visually masked stimuli can elicit motor responses in simple reaction-time tasks (e.g. response priming) independent of their conscious visibility.Vorberg, D., Mattler, U., Heinecke, A., Schmidt, T., & Schwarzbach, J.: ''Different time courses for visual perception and action priming.'' In: ''Proceedings of the National Academy of Sciences USA'', Nr. 100, 2003, p. 6275-6280. It is a widespread belief that masked stimuli can be used for

psychological manipulation In psychology, manipulation is defined as an action designed to influence or control another person, usually in an underhanded or subtle manner which facilitates one's personal aims. Methods someone may use to manipulate another person may includ ...

(see subliminal messages, psychorama). However, the empirical evidence for subliminal persuasion is limited.

References

Audiology Hearing Acoustics Psychoacoustics {{psychology-stub