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Subliminal stimuli (pronounced /sʌbˈlɪmɨnəl/, literally "below threshold"), contrary to supraliminal stimuli or above threshold, are any sensory stimulation 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 1897, the concept became controversial as subliminal messages in 1957 when marketing practitioners claimed its potential use in persuasion. Subsequent scientific research, however, has been unable to replicate most of these marketing claims beyond a mere placebo effect.




Used in advertising to create familiarity with new products, subliminal messages make familiarity into a preference for the new products. Johan Karremans suggests that subliminal messages have an effect when the messages are goal-relevant.[1] Karremans did a study assessing whether subliminal priming of a brand name of a drink would affect a person’s choice of drink, and whether this effect is caused by the individual’s feelings of being thirsty.

His study sought to ascertain whether or not subliminally priming or preparing the participant with text or an image without being aware of it would make the partaker more familiar with the product. Half of his participants were subliminally primed with Lipton Ice ("Lipton Ice" was repeatedly flashed on a computer screen for 24 milliseconds), while the other half was primed with a control that did not consist of a brand. In his study he found that subliminally priming a brand name of a drink (Lipton Ice) made those who were thirsty want the Lipton Ice. Those who were not thirsty, however, were not influenced by the subliminal message since their goal was not to quench their thirst.[1]

Subconscious stimulus by single words is well known to be modestly effective in changing human behavior or emotions. This is evident by a pictorial advertisement that portrays four different types of rum. The phrase "U Buy" was embedded somewhere, backwards in the picture. A study was done to test the effectiveness of the alcohol ad. Before the study, participants were able to try to identify any hidden message in the ad, none found any. In the end, the study showed 80% of the subjects unconsciously perceived the backward message, meaning they showed a preference for that particular rum.[2]

Though many things can be perceived from subliminal messages, only a couple words or a single image of unconscious signals can be internalized. As only a word or image can be effectively perceived, the simpler features of that image or word will cause a change in behavior (i.e., beef is related to hunger). This was demonstrated by Byrne in 1959. The word "beef" was flashed for several, five millisecond intervals during a sixteen-minute movie to experimental subjects, while nothing was flashed to controlled subjects. Neither the experimental nor controlled subjects reported for a higher preference for beef sandwiches when given a list of five different foods, but the experimental subjects did rate themselves as hungrier than the controlled subjects when given a survey. If the subjects were flashed a whole sentence, the words would not be perceived and no effect would be expected.[3]

In 1983, in five studies with 52 undergraduate and graduate students, found that although subliminally flashing and the masking the words affects the availability of conscious processing, it however has little effect on visual processing itself. This suggests that perceptual processing is an unconscious activity that proceeds to all levels of available and redescription analysis. For example if flashed the word "butter" the individual would be quicker to identify the word "bread" than an unrelated word such as "bottle."[4]


In 1991, Baldwin and others in two studies questioned whether priming individuals with images flashed for an instant may affect experiences of self. In the first study flashed images of the scowling face of their faculty adviser or an approving face of another before graduate students evaluated their own research ideas. In the second study, participants who were Catholic were asked to evaluate themselves after being flashed a disapproving face of the Pope or another unfamiliar face. In both studies the self-ratings were lower after the presentation of a disapproving face with personal significance, however in the second study there was no effect if the disapproving face were unfamiliar.[5]

In 1992, Krosnick and others in two studies with 162 undergraduates demonstrated that attitudes can develop without being aware of its antecedents. Individuals viewed nine slides of people performing familiar daily activities after being exposed to either an emotionally positive scene, such as a romantic couple or kittens, or an emotionally negative scene, such as a werewolf or a dead body between each slide. After exposure from which the individuals consciously perceived as a flash of light, the participants gave more positive personality traits to those people whose slides were associated with a emotionally positive scene and vice-versa. Despite the statistical difference, the subliminal messages had less of an impact on judgment than the slide's inherent level of physical attractiveness.[6] In order to determine whether these images affect an individual's evaluation of novel stimuli, unfamiliar Chinese characters, a study was conducted in 1993 which produced in similar results.[7]

In 1998, Bar and Biederman questioned whether an image flashed briefly would prime an individual's response. An image was flashed for 47 milliseconds and then a mask would interrupt the processing. Following the first presentation only one in seven individuals could identify the image, while after the second presentation fifteen and twenty minutes later one in three could identify the image.[8]

In 2004, in two studies 13 white individuals were exposed to either white or black faces, flashed either subliminally for 30 milliseconds or supraliminally for over half a second. Individuals showed greater fusiform gyrus and amygdala response to black faces than white, suggesting that the great amount of facial processing may be associated with a greater emotional response.[9]

In a 2005 study, individuals were exposed to subliminal image flashed 16.7 milliseconds that could signal a potential threat and again with a supraliminal image flashed for half a second. Individuals showed greater amygdala activity, although right amygdala showed greater response to subliminal fear and the left amygdala showed greater response to supraliminal fear. Furthermore supraliminal fear showed more sustained cortical activity, suggesting that subliminal fear may not entail conscious surveillance while supraliminal fear entails higher-order processing.[10]

In 2007, it was shown that subliminal exposure to the Israeli flag had a moderating effect on the political opinions and voting behaviors of Israeli volunteers. This effect was not present when a jumbled picture of the flag was subliminally shown.[11]


The manpage for the popular sound program SoX. The description of the "reverse" option says "Included for finding satanic subliminals."

Backmasking is a recording technique in which a sound or message is recorded backward onto a track that is meant to be played forward. During the 1970s, media reports raised a series of concerns of its impact on listeners,[12] stating that satanic messages were calling its listeners to commit suicide, murder, abuse drugs, or engage in sex—which were all rising at the time.[13][14]

In a series of scientific studies, individuals listening to messages played backwards with no accompanying music could discern: the gender of the speaker; whether the message was in English, French, or German; whether the sentence was declarative or a question; and occasionally a word or meaning of a sentence. However when comparing sentence pairs, individuals were more likely to be incorrect than if their response were by pure chance: if the message were spoken by different speakers; whether two sentences were semantically related; and label beyond pure chance whether a message was positive or negative in nature—suggesting that individual expectations influenced their response. Across a variety of tasks, the study were unable to find evidence that such messages affected an individual's behavior, and reasoned that if the individual could not discern the meaning of the message, then the presence of these messages would be more likely due to the listener's expectations than the existence of these messages in themselves.[12]

Some businesses claim improving an individual's memory or self-esteem while offering subliminal self-help tapes. These tapes did not produce an effect beyond a placebo, or an individual's expectation of their effectiveness.[15]


The effectiveness of subliminal messaging have been demonstrated to prime individual responses and stimulate mild emotional activity.[6][8] Applications, however, often base themselves on the persuasiveness of the message. The near-consensus among research psychologists is that subliminal messages do not produce a powerful, enduring effect on behavior;[16] and that laboratory research reveals little effect beyond a subtle, fleeting effect on thinking. For example, priming thirsty people with a subliminal word may, for a brief period of time, make a thirst-quenching beverage advertisement more persuasive.[17] Research upon those claims of a lasting effects such as weight loss, smoking cessation, how music in popular culture may corrupt their listeners, how it may facilitate unconscious wishes in psychotherapy, and how market practitioners may exploit their customers—conclude that there is no effect beyond a placebo.[18] In a 1994 study comparing television commercials with the message either supraliminal or subliminal, individuals produced higher ratings with those that were supraliminal. Unexpectedly, individuals somehow were less likely to remember the subliminal message than if there were no message.[19]



The director of Yale Psychology laboratory Ph.D. E. W. Scripture published The New Psychology in 1897 (The Walter Scott Ltd, London), which described the basic principles of subliminal messages.[20]

In 1900, Knight Dunlap, an American professor of psychology, flashed an "imperceptible shadow" to subjects while showing them a Müller-Lyer illusion containing two lines with pointed arrows at both ends which create an illusion of different lengths. Dunlap claimed that the shadow influenced his subjects subliminally in their judgment of the lengths of the lines.

Although these results were not verified in a scientific study, American psychologist Harry Levi Hollingworth reported in an advertising textbook that such subliminal messages could be used by advertisers.[21]

During World War II, the tachistoscope, an instrument which projects pictures for an extremely brief period, was used to train soldiers to recognize enemy airplanes.[20] Today the tachistoscope is used to increase reading speed or to test sight.[22]


In 1957, market researcher James Vicary claimed that quickly flashing messages on a movie screen, in Fort Lee, New Jersey, had influenced people to purchase more food and drinks. Vicary coined the term subliminal advertising and formed the Subliminal Projection Company based on a six-week test. Vicary claimed that during the presentation of the movie Picnic he used a tachistoscope to project the words "Drink Coca-Cola" and "Hungry? Eat popcorn" for 1/3000 of a second at five-second intervals. Vicary asserted that during the test, sales of popcorn and Coke in that New Jersey theater increased 57.8 percent and 18.1 percent respectively.[20][23]

However, in 1962 Vicary admitted to lying about the experiment and falsifying the results, the story itself being a marketing ploy.[24][25] An identical experiment conducted by Dr. Henry Link showed no increase in cola or popcorn sales.[23] A trip to Fort Lee, where the first experiment was alleged to have taken place, would have shown straight away that the small cinema there couldn't possibly have had 45,699 visitors through its doors in the space of 6 weeks. This has led people to believe that Vicary actually did not conduct his experiment at all.[23]

However, before Vicary's confession, his claims were promoted in Vance Packard's book The Hidden Persuaders,[26] and led to a public outcry, and to many conspiracy theories of governments and cults using the technique to their advantage.[27] The practice of subliminal advertising was subsequently banned in the United Kingdom and Australia,[21] and by American networks and the National Association of Broadcasters in 1958.[23]

But in 1958, Vicary conducted a television test in which he flashed the message "telephone now" hundreds of times during a Canadian Broadcasting Corporation program, and found no noticeable increase in telephone calls.[20]


In 1973, commercials in the United States and Canada for the game Hūsker Dū? flashed the message "Get it".[26] During the same year, Wilson Bryan Key's book Subliminal Seduction claimed that subliminal techniques were widely used in advertising.[23] Public concern was sufficient to cause the FCC to hold hearings in 1974. The hearings resulted in an FCC policy statement stating that subliminal advertising was "contrary to the public interest" and "intended to be deceptive".[23] Subliminal advertising was also banned in Canada following the broadcasting of Hūsker Dū? ads there.[20]

The December 16, 1973 episode of Columbo titled "Double Exposure", is based on subliminal messaging: it is used by the murderer, Dr. Bart Keppler, a motivational research specialist, played by Robert Culp, to lure his victim out of his seat during the viewing of a promotional film and by Lt. Columbo to bring Keppler back to the crime scene and incriminate him. Lt. Columbo is shown how subliminal cuts work in a scene mirroring James Vicary's experiment.[28][29]

In 1978, Wichita, Kansas TV station KAKE-TV received special permission from the police to place a subliminal message in a report on the BTK Killer (Bind, Torture, Kill) in an effort to get him to turn himself in. The subliminal message included the text "Now call the chief," as well as a pair of glasses. The glasses were included because when BTK murdered Nancy Fox, there was a pair of glasses lying upside down on her dresser; police felt that seeing the glasses might stir up remorse in the killer. The attempt was unsuccessful, and police reported no increased volume of calls afterward.[30]

A study conducted by the United Nations concluded that "the cultural implications of subliminal indoctrination is a major threat to human rights throughout the world."[31]

Campaigners have suggested subliminal messages appear in music. In 1985, two young men, James Vance and Raymond Belknap, attempted suicide. At the time of the shootings, Belknap died instantly. Vance was severely injured and survived. Their families were convinced it was because of a British rock band, Judas Priest. The families claimed subliminal messages told listeners to "do it" in the song "Better by You, Better Than Me". The case was taken to court and the families sought more than US$6 million in damages. The judge, Jerry Carr Whitehead said that freedom of speech protections would not apply to subliminal messages. He said he was not convinced the hidden messages actually existed on the album, but left the argument to attorneys.[32] The suit was eventually dismissed. In turn, he ruled it probably would not have been perceived without the "power of suggestion" or the young men would not have done it unless they really intended to.[33]

In 1985, Dr. Joe Stuessy testified to the United States Senate at the Parents Music Resource Center hearings that:

The message of a piece of heavy metal music may also be covert or subliminal. Sometimes subaudible tracks are mixed in underneath other, louder tracks. These are heard by the subconscious but not the conscious mind. Sometimes the messages are audible but are backwards, called backmasking. There is disagreement among experts regarding the effectiveness of subliminals. We need more research on that.[34]

Stuessy's written testimony stated that:

Some messages are presented to the listener backwards. While listening to a normal forward message (usually nonsensical), one is simultaneously being treated to a back-wards message. Some experts believe that while the conscious mind is trying to absorb the forward lyric, the subconscious is working overtime to decipher the backwards message.[35]

A few months after Judas Priest's acquittal, Michael Waller, the son of a Georgia minister, shot himself in the head while supposedly listening to Ozzy Osbourne's song Suicide Solution (despite the fact that the song Suicide Solution was not on the record [Ozzy Osbourne's Speak Of The Devil] found playing in his room when his suicide was discovered). His parents claimed that subliminal messages may have influenced his actions. The judge in that trial granted the summary judgment because the plaintiffs could not show that there was any subliminal material on the record. He noted, however, that if the plaintiffs had shown that subliminal content was present, the messages would not have received protection under the First Amendment because subliminal messages are, in principle, false, misleading or extremely limited in their social value (Waller v. Osbourne 1991). Justice Whitehead's ruling in the Judas Priest trial was cited to support his position.[36]


During the 2000 U.S. presidential campaign, a television ad campaigning for Republican candidate George W. Bush showed words (and parts thereof) scaling from the foreground to the background on a television screen. When the word BUREAUCRATS flashed on the screen, one frame showed only the last part, RATS.[37][38] The FCC looked into the matter,[39] but no penalties were ever assessed in the case.[citation needed]

A McDonald's logo appeared for one frame during the Food Network's Iron Chef America series on 2007-01-27, leading to claims that this was an instance of subliminal advertising. The Food Network replied that it was simply a glitch.[40]

On November 7, 2007, Network Ten Australia's broadcast of the ARIA Awards was called out for using subliminal advertising in an exposé by the Media Watch program on the ABC (Australian Broadcasting Corporation).[41]

In February 2007, it was discovered that 87 Konami slot machines in Ontario (OLG) casinos displayed a brief winning hand image before the game would begin. Government officials worried that the image subliminally persuaded gamblers to continue gambling; the company claimed that the image was a coding error. The machines were removed pending a fix by Konami.[42]

In 2007, to mark the 50th anniversary of James Vicary's original experiment, it was recreated at the International Brand Marketing Conference MARKA 2007. As part of the "Hypnosis, subconscious triggers and branding" presentation 1,400 delegates watched part the opening credits of the film PICNIC that was used in the original experiment. They were exposed to 30 subliminal cuts over a 90 second period. When asked to choose one of two fictional brands, Delta and Theta, 81% of the delegates picked the brand suggested by the subliminal cuts, Delta.[43]


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  29. ^ Re: [AMIA-L] Reply: "Sherlock Jr."
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  41. ^ Subliminal advertising. - ninemsn Video
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Further reading

  • Boese, Alex (2006), Hippo Eats Dwarf: A Field Guide to Hoaxes and Other B.S., Orlando: Harcourt, pp. 193–195, ISBN 0156030837 
  • Dixon, Norman F. (1971), Subliminal Perception: The nature of a controversy, New York: McGraw-Hill, ISBN 0070941475 
  • Greenwald, A. G. (1992). "New Look 3: Unconscious cognition reclaimed". American Psychologist 47 (6): 766–779. doi:10.1037/0003-066X.47.6.766. PMID 1616174.  edit
  • Holender, D. (1986), "Semantic activation without conscious identification in dichotic listening, parafoveal vision, and visual masking: A survey and appraisal", Behavioral and Brain Sciences 9 (1): 1–23 
  • Merikle, P. M.; Daneman, M. (1998), "Psychological Investigations of Unconscious Perception", Journal of Consciousness Studies 5 (1): 5–18 
  • Watanabe, T.; N, J.; Sasaki, Y. (2001). "Perceptual learning without perception". Nature 413 (6858): 844. doi:10.1038/35101601. PMID 11677607.  edit
  • Seitz, A. R.; Watanabe, T. (2003). "Psychophysics: is subliminal learning really passive?". Nature 422 (6927): 36. doi:10.1038/422036a. PMID 12621425.  edit
  • United States Senate, Ninety-ninth Congress, First Session on Contents of Music and the Lyrics of Records (September 19, 1985), Record Labeling: Hearing before the Committee on Commerce, Science, and Transportation, Washington, DC: U.S. Government Printing Office, 

External links

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