One who identifies as a scientist and conducts scientific research regularly is usually associated with an institution of higher learning or a research center devoted to specific types of issues. Such a person may hold a doctorate or masters degree from a university whose goal, in part, has been to teach how to conduct sound, replicable research with clearly defined independent and dependent variables and with minimal interference from confounding extraneous variables. A graduate from a research program presumably has learned to value the scientific process. Association with a reputable institution helps to ensure that researchers conduct and publish work that meets the scientific standards of that institution. Scientists usually do not make money from their research findings. They may earn prestige among other scientists and may receive benefits for writing successful grants. A scientist typically does not have the time, knowledge, or motivation to engage in the marketing of a finished product for mass consumption.

“Pseudoscientists” usually do not assign this label to themselves. Rarely does one say “Hello, I’m a pseudoscientist from Brand X Institute [or, I am just freelancing]. Please make that distinction. I’m a pseudoscientist, not a scientist.” The problem arises when a person promotes unscientific findings as scientific and attempts to get others to behave in accord with the findings as though they had been obtained in a scientific manner. To lend credence to their findings, some pseudoscientists may establish a prestigious-sounding organizational name to which benefactors can make donations. Those who mislead people by labeling unscientific research findings as scientific tend to incite scientists to call them “pseudoscientists” and to call those they deceive “gullible believers in nonsense.”

The name-calling and arguments typically take the form of attack and ridicule. But what is the forum for these interchanges? Given that scientists and pseudoscientists travel in different circles, the scientific viewpoint needs to be presented in the arena where pseudoscience finds its believers, that is, in everyday forms of information dissemination. A letter to the editor may not be published, or if published it may not be read. Asking a newspaper to cover the scientific position of a sensationalized pseudoscientific finding may be helpful if reports of both positions are published at the same time, which assumes you have advance notice of such stories. Countering paid advertising by pseudoscientists with paid advertisements for the validity and superiority of the scientific method is possible, but not probable, since pseudoscientists run advertisements to make money and scientists would be paying for an ad to keep people from wasting money. However, a common means of communicating information is through day-to-day conversation. Personal testimonials are a powerful form of persuasion.

But why would believers in commercial pseudoscientific products want to hear what we have to say? They wouldn’t, unless we as scientists can offer something of more value and utility than the pseudoscientists do. We suggest that if scientists were to adopt the role of consumer watchdogs and consumer educators, more people would be likely to listen.

Among the most widely marketed pseudoscience products today are “subliminal” tapes. These tapes, which their manufacturers claim will provide quick, effortless solutions for many personal problems, can be found virtually anywhere. They are even advertised in publications devoted to promoting science, such as Discover magazine. Although such tapes are ubiquitous, there is a lack of empirical evidence for any effectiveness beyond that of a “placebo” effect (Grover 1979; Dutto and Galli 1982; Treimer and Simonson 1986). Psychology, the scientific discipline supposedly devoted to the explanation of human behavior, has had little success in disputing the viability of such products (Anastasi 1964; Dudley 1987; Goldiamond 1966; Moore 1982, 1985; Saegert 1987; Schulman 1981). Part of psychology’s lack of success in countering the claims for these products may be attributed to points made earlier concerning communication problems and the motivation of the proponents.

As is well known, subliminal tapes typically have an audible side, on which the message is clearly present. On the opposite side, however, all one typically hears is subdued music intended to “lull the listener into relaxation wherein the subliminal messages can work.” Of course one can’t hear the message, only the music. It is at this point that a scientist may suggest that it is impossible for a weak stimulus to compete successfully against more powerful stimuli (Dixon 1971) for either selective attention or control of behavior. Unfortunately, while this logic may be perfectly obvious to us, many subliminal subscribers would now stop listening to the scientist.

How to continue the conversation at this point depends upon your time and patience as well as your motivation to educate or irritate. You may decide to assume the message is there and ask the proponent or salesperson why we can’t hear it. Predictably, the answer will be that the message only interacts with the unconscious mind without our awareness. Now you counter that whether the message works with the unconscious or the conscious mind, such a message still needs to impinge on the nervous system through auditory receptors. So why can’t our ears hear the message?

Most often, the proponent will say either that the message has been increased to such a high frequency that it is beyond our range of perception or that it is at too low a frequency or volume, but that it certainly is there. Such a reply acknowledges that the message is beyond the range of human auditory perception! If you then raise that point, ironically the subliminal proponent will agree. You might now ask if a dog or a bat could hear the message. We have, in fact, received affirmative answers to this question from clerks intent on sales. Our next question has been, of course: Can these tapes help my dog lose weight, or help my bat to develop a more positive self-esteem? At this point, we have been asked to leave the store, had the phone suddenly disconnected, or found fellow customers laughing as the ludicrous nature of subliminal tapes became apparent. But such an approach does little to teach people to engage in scientific thinking or to become discriminating, thoughtful shoppers.

Actually, the messages on subliminal tapes can’t be heard because they are in fact not there. Merikle (1988) conducted a spectrographic analysis of several subliminal audiotapes and found no evidence for the presence of any identifiable speech sounds. If you were to present this data to the subliminal subscribers, they would stop listening, because they prefer to believe individual testimonials. They choose to believe something, anything, that will offer them even the hope of relief from their problems.

Instead of a direct confrontation, one might ask them if they can think of alternative hypotheses to account for any beneficial effects of such tapes. Remember, the intended message is audible on one side. Presumably people will listen to the audible side at least once so they will know what it is they are supposed to hear on the subliminal side. After hearing the message, when they subsequently listen to the inaudible side they may rehearse to themselves what they are supposed to be hearing. Even if they do not listen to the audible side, the label on the tape will prompt them to think about what it is they want changed and how they might achieve those changes. Your providing plausible reasons for the positive results from the testimonials may help demystify the operation of such tapes. In addition, it may be helpful to point out that 30 testimonials from 30 people would be vastly different from 30 testimonials from among 500 people. In other words, how many negative or neutral outcomes were there?

You may also question the high cost of the tapes and explain that paying a lot for a product makes one more likely to persist in believing that there are qualities for success residing in the product’s use. You may question the bottom-line motivation and qualifications of the seller and the product researcher. You may inquire about the consumer’s knowledge of the scientific method and offer to fill in missing facts. You should use commonly understood examples of consumer safety and the rigorous testing most products must pass depending upon the category of the product. For example, why must a tire for a car meet higher testing standards than a pressurized tire for a toy? If a product can be marketed without passing rigorous tests, how effective can it be, and what kind of product can it be? There is a big difference between testing that proves a product does not cause harm and testing that proves that a product actually has a beneficial effect.

In addition to all of the above depending on your ability to be personable and patient, you need to be able to offer people alternatives for solving their problems other than buying subliminal tapes, resorting to drugs, or joining the latest New Age fringe group. What do you have to offer them in the way of incorporating scientific thinking and principles into their lives to help better solve their problems? First, one might try to convince them that there are no quick and painless solutions for maladaptive behaviors or thought patterns that have developed over many years. Part of this involves warning them about charlatans who in order to make a quick profit encourage the belief that there are quick cures. Effective and lasting behavior-changing of any kind actually involves concentrated effort, also called work, and adherence to certain data-based prescriptive guidelines. Second, people need reassurance that they can solve their problems by resorting to the use of professional, legitimate, and scientifically supported materials and personal commitment. Low-cost self-help groups based on scientific principles are always a viable option. Third, you need to try to convince them that learning some basic, logical, scientific principles, and how to define problems objectively, will help them solve future problems or avoid them altogether.

Finally, as a result of these actions, you will demonstrate that scientists are concerned about their fellow human beings and that they want to share scientific knowledge where the impact is greatest. If a scientist only applies the scientific method in his or her research and is not able or willing to share the applicability of this method for solving everyday human problems, then there is little ground to argue with the pseudoscientists, who are more than happy to fill the void.

References

• Anastasi, A. 1964. “Subliminal Perception.” In Fields of Applied Psychology, edited by A. Anastasi. New York: McGraw-Hill.
• Dixon, N. F. 1971. Subliminal Perception: The Nature of a Controversy. London: McGraw-Hill.
• Dudley, S. 1987. Subliminal advertising: What is the controversy about? Akron Business and Economic Review, 18:6-18.
• Dutto, F. N., and N. Galli. 1982. The effects of noxious subliminal suggestion upon smoking atttitudes and behavior. EDRS, Document #ED 217 359.
• Glover, E. D. 1979. Decreasing smoking behavior through subliminal stimulation treatments. Journal of Drug Education, 9:273-283.
• Goldiamond, 1.1966. “Statement on Subliminal Advertising.” In Control of Human Beharior, vol. 1, edited by R. Ulrich, T. Stachnik, and J. Mabry. Glenview, 111.: Scott Foresman.
• Kurtz, P. 1988. Skeptic’s burnout: Hard weeks on the astrology battle line. SKEPTICAL INQUIRER, 13:4-6.
• Merikle, D. M. 1988. Subliminal auditory messages: An evaluation. Psychology Marketing, 5:355-372.
• Moore, T. E. 1982. Subliminal advertising: What you see is what you get. Journal of Marketing, 46:38-47.
• —-.1985. Subliminal delusion. Psychology Today, May, pp. 9-10.
• Sagan, C. 1987. The burden of skepticism. SKEPTICAL INQUIRER, 12:38-46.
• Saegert, J. 1987. Why marketing should quit giving subliminal advertising the benefit of the doubt. Psychology Marketing, 4:107-120.
• Schulman, M. 1981. The great conspiracy. [Review of “The Clam Plate Orgy."] Journal of Communication, 31:209
• Treimer, M., and M. R. Simonson. 1986. “Old Wine in New Bottles: Subliminal Messages in Instructional Media.” Paper presented at the Annual Convention of the Association for Educational Communications Technology, Las Vegas, Nev.

A short time later you hear that you and your friend weren't the only ones desiring popcorn and Coke at the theater that day. According to reports in newspapers and magazines, James Vicary, an advertising expert, had secretly flashed, at a third of a millisecond, the words “Eat Popcorn” and “Drink Coke” onto the movie screen. His studies, lasting six weeks, involved thousands of moviegoing subjects who received a subliminal message every five seconds during the film. Vicary claimed an increase in Coke sales of 18 percent and a rise in popcorn sales of almost 58 percent. Upon reading their newspapers, most people were outraged and frightened by a technique so devilish that it could bypass their conscious intellect and beam subliminal commands directly to their subconscious.

In an article titled “Smudging the Subconscious,” Norman Cousins (1957) captured similar feelings as he pondered the true meaning of such a device. As he put it, “if the device is successful for putting over popcorn, why not politicians or anything else?” He wondered about the character of people who would dream up a machine to “break into the deepest and most private parts of the human mind and leave all sorts of scratchmarks.” Cousins concluded that the best course of action would be “to take this invention and everything connected to it and attach it to the center of the next nuclear explosive scheduled for testing.”

Cousins’s warnings were taken to heart. The Federal Communications Commission immediately investigated the Vicary study and ruled that the use of subliminal messages could result in the loss of a broadcast license. The National Association of Broadcasters prohibited the use of subliminal advertising by its members. Australia and Britain banned subliminal advertising. A Nevada judge ruled that subliminal communications are not protected as free speech.

The Vicary study also left an enduring smudge on Americans’ consciousness-if not their subconscious. As a teacher of social psychology and a persuasion researcher, one of the questions I am most frequently asked is, “Do you know about the ‘Eat Popcorn/Drink Coke’ study that they did?” At cocktail parties, I am often pulled aside and, in hushed tones, told about the “Eat Popcorn/Drink Coke” study. Indeed, my original interest in subliminal persuasion was motivated by an attempt to know how to respond to such questions.

Three public opinion polls indicate that the American public shares my students’ fascination with subliminal influence (Haber 1959; Synodinos 1988; Zanot, Pincus, and Lamp 1983). By 1958, just nine months after the Vicary subliminal story first broke, 41 percent of survey respondents had heard of subliminal advertising. This figure climbed to 81 percent in the early 1980s, with more than 68 percent of those aware of the term believing that it was effective in selling products. Most striking, the surveys also revealed that many people learn about subliminal influence through the mass media and through courses in high school and college.

But there is a seamier side to the “Eat Popcorn/Drink Coke” study-one that is rarely brought to public attention. In a 1962 interview with Advertising Age, James Vicary announced that the original study was a fabrication intended to increase customers for his failing marketing business. The circumstantial evidence suggests that this time Vicary was telling the truth. Let me explain by recounting the story of the “Eat Popcorn/Drink Coke” study as best I can, based on various accounts published in academic journals and trade magazines (see Advertising Research Foundation 1958; “ARF Checks” 1958; Danzig 1962; McConnell, Cutler, and McNeil 1958; “Subliminal Ad” 1958; “Subliminal Has” 1958; Weir 1984).

Advertisers, the FCC, and research psychologists doubted Vicary’s claims from the beginning and demanded proof. To meet these demands, Vicary set up demonstrations of his machine. Sometimes there were technical difficulties in getting the machine to work. When the machine did work, the audience felt little compulsion to comply with subliminal commands, prompting an FCC commissioner to state, “I refuse to get excited about it-I don’t think it works” ("Subliminal Has” 1958).

In 1958, the Advertising Research Foundation pressed Vicary to release his data and a detailed description of his procedures. They argued that it had been more than a year since the results were made public and yet there had been no formal write-up of the experiment, which was necessary to evaluate the claims. To this day, there has been no primary published account of the study, and scientists interested in replicating the results must rely on accounts published in such magazines as the Senior Scholastic ("Invisible Advertising” 1957), which, although intended for junior-high students, presents one of the most detailed accounts of the original study.

Pressures for a replication accumulated. Henry Link, president of Psychological Corporation, challenged Vicary to a test under controlled conditions and supervised by an independent research firm. No change occurred in the purchase of either Coke or popcorn (Weir 1984). In one of the more interesting attempted replications, the Canadian Broadcast Corporation, in 1958, subliminally flashed the message “Phone Now” 352 times during a popular Sunday night television show called Close-up ("Phone Now” 1958). Telephone usage did not go up during that period. Nobody called the station. When asked to guess the message, viewers sent close to five hundred letters, but not one contained the correct answer. However, almost half of the respondents claimed to be hungry or thirsty during the show. Apparently, they guessed (incorrectly) that the message was aimed at getting them to eat or drink.

Finally, in 1962 James Vicary lamented that he had handled the subliminal affair poorly. As he stated, “Worse than the timing, though, was the fact that we hadn’t done any research, except what was needed for filing for a patent. I had only a minor interest in the company and a small amount of data-too small to be meaningful. And what we had shouldn’t have been used promotionally” (Danzig 1962). This is not exactly an affirmation of a study that supposedly ran for six weeks and involved thousands of subjects.

My point in presenting the details of the Vicary study is twofold. First, the “Eat Popcorn/Drink Coke” affair is not an isolated incident. The topic of subliminal persuasion has attracted the interest of Americans on at least four separate occasions: at the turn of the century, in the 1950s, in the 1970s, and now in the late 1980s and early 1990s. Each of these four flourishings of subliminal persuasion show a similar course of events. First, someone claims to find an effect; next, others attempt to replicate that effect and fail; the original finding is then criticized on methodological grounds; nevertheless the original claim is publicized and gains acceptance in lay audiences and the popular imagination. Today we have reached a point where one false effect from a previous era is used to validate a false claim from another. For example, I recently had the occasion to ask a manufacturer of subliminal self-help audiotapes for evidence of his claim that his tapes had therapeutic value. His reply: “You are a psychologist. Don't you know about the study they did where they flashed ‘Eat Popcorn and Drink Coke’ on the movie screen?”

During the past few years, I have been collecting published articles on subliminal processes-research that goes back over a hundred years (Suslowa 1863) and includes more than a hundred articles from the mass media and more than two hundred academic papers on the topic (Pratkanis and Greenwald 1988). In none of these papers is there clear evidence in support of the proposition that subliminal messages influence behavior. Many of the studies fail to find an effect, and those that do either cannot be reproduced or are fatally flawed on one or more methodological grounds, including: the failure to control for subject expectancy and experimenter bias effects, selective reporting of positive over negative findings, lack of appropriate control treatments, internally inconsistent results, unreliable dependent measures, presentation of stimuli in a manner that is not truly subliminal, and multiple experimental confounds specific to each study. As Moore points out, there is considerable evidence for subliminal perception or the detection of information outside of self-reports of awareness. However, subliminal perception should not be confused with subliminal persuasion or influence-motivating or changing behavior-for which there is little good evidence (see McConnell, Cutler, and McNeil 1958; Moore 1982 and 1988). My second reason for describing the Vicary study in detail is that it seems to me that our fascination with subliminal persuasion is yet another example of what Richard Feynman (1985) called “cargo-cult science.” For Feynman, a cargo-cult science is one that has all the trappings of science-the illusion of objectivity, the appearance of careful study, and the motions of an experiment-but lacks one important ingredient: skepticism, or a leaning over backward to see if one might be mistaken. The essence of science is to doubt your own interpretations and theories so that you may improve upon them. This skepticism is often missing in the interpretation of studies claiming to find subliminal influence. Our theories and wishes for what we would like to think the human mind is capable of doing interferes with our ability to see what it actually does.

The cargo-cult nature of subliminal research can be seen in some of the first studies on the topic done at the turn of the century. In 1900, Dunlap reported a subliminal Muller-Lyer illusion-a well-known illusion in which a line is made to appear shorter or longer depending on the direction of angles placed at its ends. Dunlap flashed an “imperceptible shadow” or line to subliminally create this illusion. He claimed that his subjects’ judgment of length was influenced by the imperceptible shadows. However, Dunlap’s results could not be immediately replicated by either Titchener and Pyle (1907) or by Manro and Washburn (1908). Nevertheless, this inconsistency of findings did not stop Hollingworth (1913) from discussing the subliminal Muller-Lyer illusion in his advertising textbook or from drawing the conclusion that subliminal influence is a powerful tool available to the advertiser.

I contend that it was no accident that subliminal influence was first investigated in America at the turn of the century. The goal of demonstrating the power of the subliminal mind became an important one for many people at that time. It was a time of great religious interest, as illustrated by academic books on the topic, religious fervor among the populace, and the further development of a uniquely American phenomenon-the spiritual self-help group. One such movement, popular in intellectual circles, was called “New Thought,” which counted William James among its followers. The doctrine of New Thought stated that the mind possesses an unlimited but hidden power that could be tapped-if one knew how-to bring about a wonderful happy life and to exact physical cures. Given the rise of industrialization and the anonymity of newly formed city life, one can see how a doctrine of the hidden power of the individual in the face of realistic powerlessness would be well received in some circles.

The historian Robert Fuller (1982; 1986) traces the origins of New Thought and similar movements to early American interest in the teachings of Franz Anton Mesmer. Fuller’s point is that the powerful unconscious became a replacement for religion’s “soul.” Mesmer’s doctrines contended that each person possessed a hidden, though strong, physical force, which he termed animal magnetism. This force could be controlled by the careful alignment of magnets to effect personality changes and physical cures. On one level, mesmerism can be viewed as a secularization of the metaphor of spiritual humans that underlies witchcraft. Animal magnetism replaced the soul, and good and bad magnets replaced angels and devils that could invade the body and affect their will. Mesmerism was introduced to America at the beginning of the nineteenth century and, characteristic of Yankee ingenuity, self-help movements soon sprang up with the goal of improving on Mesmer’s original magnet therapy; they did so by developing the techniques of hypnotism, seances, the healing practices of Christian Science, positive thinking, and the speaking cure.

With the distance of a century, we overlook the fact that many journals of the nineteenth century were devoted to archiving the progress of mesmerism and with documenting the influence of the unconscious on the conscious. As Dunlap (1900) said in the introduction to his article on the subliminal Muller-Lyer illusion, “If such an effect is produced, then we have evidence for the belief that under certain conditions things of which we are not and can not become conscious have their immediate effects upon consciousness.” In other words, we would have one of the first scientific demonstrations that the unconscious can powerfully influence the conscious. A simple step perhaps, but who knows what wonderful powers of the human mind wait to be unleashed.

As a postscript to the subliminal Muller-Lyer affair, I should point out that 30 years later Joseph Bressler- a student of Hollingworth-was able to reconcile the empirical differences between Dunlap and his opponents. Bressler (1931) found that as the subliminal angles increased in intensity-that is, as they approached the threshold of awareness-the illusion was more likely to be seen. This finding, along with many others, served as the basis for concluding that there is no absolute threshold of awareness-it can vary as a function of individual and situational factors-and led to the hypothesis that, on some trials, subjects could see enough of the stimulus to improve their guessing at what might be there. (See also Holender 1986 and Cheesman and Merikle’s 1985 distinction between objective and subjective thresholds.)

Other manifestations of “subliminal-mania” illustrate additional aspects of a cargo-cult science. In the early 1970s, during the third wave of popular interest in subliminal persuasion, the best-selling author Wilson Bryan Key (1973; 1976; 1980; 1989) advanced the cargo-cult science of subliminal seduction in two ways. (See also Creed 1987.) First, Key argued that subliminal techniques were not just limited to television and movies. Cleverly hidden messages aimed at inducing sexual arousal are claimed to be embedded in the photographs of print advertisements. Key found the word sex printed on everything from Ritz crackers to the ice cubes in a Gilbey Gin ad. Second, Key was successful in linking the concept of subliminal persuasion to the issues of his day. The 1970s were a period of distrust by Americans of their government, businesses, and institutions. Key claimed that big advertisers and big government are in a conspiracy to control our minds using subliminal implants.

The legacy of Key’s cargo-cult science is yet with us. I often ask my students at the University of California, Santa Cruz, if they have heard of the term subliminal persuasion and, if so, where. Almost all have heard of the term and about half report finding out about it in high school. Many received an assignment from their teachers to go to the library and look through magazine ads for subliminal implants.

These teachers miss an opportunity to teach science instead of cargo-cult science. Key (1973) reports a study where more than a thousand subjects were shown the Gilbey Gin ad that supposedly contained the word sex embedded in ice cubes. Sixty-two percent of the subjects reported feeling “aroused,” “romantic,” “sensuous.” Instead of assuming that Key was right and sending students out to find subliminals, a science educator would encourage a student to ask, “But where is the control group in the Gilbey Gin ad study? Perhaps an even higher percentage would report feeling sexy if the subliminal “sex” was removed-perhaps the same, perhaps less. One just doesn't know.

Now in the late 1980s and early 1990s, we see a fourth wave of interest in subliminal influence. Entrepreneurs have created a $50-million plus industry offering subliminal self help audio- and video tapes designed to improve everything from selfesteem to memory, to employee and customer relations, to sexual responsiveness, and-perhaps most controversial-to overcoming the effects of family and sexual abuse (Natale 1988). The tapes work, according to one manufacturer, because “subliminal messages bypass the conscious mind, and imprint directly on the subconscious mind, where they create the basis for the kind of life you want.” Part of the popularity of such tapes no doubt springs from the tenets of New Age. Like its predecessor New Thought, New Age also postulates a powerful hidden force in the human personality that can be controlled for the good, not by magnets, but by crystals, and can be redirected with subliminal commands.

Accusations concerning the sinister use of subliminal persuasion continue as well. In the summer of 1990, the rock band Judas Priest was placed on trial for allegedly recording, in one of their songs, the subliminal implant ”Do it.” This message supposedly caused the suicide deaths of Ray Belknap and James Vance.

What is the evidence that subliminal influence, despite not working in the 1900s, 1950s, and 1970s, is now effective in the 1990s? Tape company representatives are likely to provide you with a rather lengthy list of “studies” demonstrating their claims. Don't be fooled. The studies on these lists fall into two camps-those done by the tape companies and for which full writeups are often not available, and those that have titles that sound as if they apply to subliminal influence, but really don’t. For example, one company lists many subliminal perception studies to support its claims. It is a leap of faith to see how a lexical priming study provides evidence that a subliminal self-help tape will cure insomnia or help overcome the trauma of being raped. Sadly, the trick of claiming that something that has nothing to do with subliminal influence really does prove the effectiveness of subliminal influence goes back to the turn of the century. In the first footnote to their article describing a failure to replicate Dunlap’s subliminal Muller-Lyer effect, Titchener and Pyle (1907) state: “Dunlap finds a parallel to his own results in the experiments of Pierce and Jastrow on small difference of sensations. There is, however, no resemblance whatever between the two investigations.” In a cargo-cult science, any evidence-even irrelevant facts-is of use and considered valuable.

Recently, there have been a number of studies that directly tested the effectiveness of subliminal self-help tapes. I conducted one such study in Santa Cruz with my colleagues Jay Eskenazi and Anthony Greenwald (Pratkanis, Eskenazi, and Greenwald 1990). We used massmarketed audiotapes with subliminal messages designed to improve either self esteem or memory abilities. Both types of tapes contained the same supraliminal content-various pieces of classical music. However, they differed in their subliminal content. According to the manufacturer, the self-esteem tapes contained subliminal messages like “l have high self-worth and high self-esteem.” The memory tape contained subliminal messages like “My ability to remember and recall is increasing daily.”

Using public posters and ads placed in local newspapers, we recruited volunteers who appeared most interested in the value and potential of subliminal self-help therapies (and who were probably similar to those likely to buy such tapes). On the first day of the study, we asked our volunteers to complete three different self-esteem and three different memory measures. Next they randomly received their subliminal tape, but with an interesting twist. Half of the tapes were mislabeled so that some of the subjects received a memory tape, but thought it was intended to improve self-esteem, whereas others received a self-esteem tape that had been mislabeled as memory improvement. (Of course half the subjects received correctly labeled tapes.)

The volunteers took their tapes home and listened to them every day for five weeks (the period suggested by the manufacturer for maximum effectiveness). During the listening phase, we attempted to contact each subject about once a week to encourage their daily listening. Only a handful of subjects were unable to complete the study, suggesting a high level of motivation and interest in subliminal therapy. After five weeks of daily listening, they returned to the laboratory and once again completed self-esteem and memory tests and were also asked to indicate if they believed the tapes to be effective.

The results: the subliminal tapes produced no effect (improvement or decrement) on either selfe steem or memory. But our volunteers did not believe this to be the case. Subjects who thought they had listened to a self-esteem tape (regardless of whether they actually did or not) were more likely to be convinced that their self-esteem had improved, and those who thought they had listened to a memory tape were more likely to believe that their memory had improved as a result of listening to the tape. We called this an illusory placebo effect-placebo, because it was based on expectations; illusory, because it wasn’t real. In sum, the subliminal tapes did nothing to improve self-esteem or memory abilities but, to some of our subjects, they appeared to have an effect. As we put it in the title of our report of this study, “What you expect is what you believe, but not necessarily what you get.”

Our results are not a fluke. We have since repeated our original study twice using different tapes and have yet to find an effect of subliminal messages upon behavior as claimed by the manufacturer (Greenwald, Spangenberg, Pratkanis, and Eskenazi 1991). By combining our data from all three studies, we gain the statistical power to detect quite small effects. Still, there is no evidence of a subliminal effect consistent with the manufacturers’ claims.

Other researchers are also finding that subliminal self-help tapes are of no benefit to the user. In a series of three experiments, Auday, Mellett, and Williams (1991) tested the effectiveness of bogus and real subliminal tapes designed either to improve memory, reduce stress and anxiety, or increase self-confidence. The subliminal tapes proved ineffective on all three fronts. Russell, Rowe, and Smouse (1991) tested subliminal tapes designed to improve academic achievement and found the tapes improved neither grade point average nor final examination scores. Lenz (1989) had 270 Los Angeles police recruits listen for 24 weeks to music with and without subliminal implants designed to improve either knowledge of the law or marksmanship. The tapes did not improve either. In a recent test, Merikle and Skanes (1991) found that overweight subjects who listened to subliminal weight-loss tapes for five weeks showed no more weight loss than did control subjects. In sum, independent researchers have conducted 9 studies to evaluate the effectiveness of subliminal self-help tapes. All 9 studies failed to find an effect consistent with the manufacturers’ claims. (See also Eich and Hyman 1991.)

It appears that, despite the claims in books and newspapers and on the backs of subliminal self help tapes, subliminal-influence tactics have not been demonstrated to be effective. Of course, as with anything scientific, it may be that someday, somehow, someone will develop a subliminal technique that may work, just as someday a chemist may find a way to transmute lead to gold. I am personally not purchasing lead futures on this hope however.

The history of the subliminal controversy teaches us much about persuasion-but not the subliminal kind. If there is so little scientific evidence of the effectiveness of subliminal influence, why then do so many Americans believe it’ works? In a nutshell, I must conclude, with Feynman, that despite enjoying the fruits of science, we are not a scientific culture, but one of ill-directed faith as defined in Hebrews 11:1 (KJV): “Now faith is the substance of things hoped for, the evidence of things not seen.”

We can see the workings of this faulty faith, not science, in the more than a hundred popular press articles on the topic of subliminal persuasion. Many of the articles (36 percent) deal with ethical and regulatory concerns of subliminal practices-assuming them to be effective. Only 18 percent of the articles declare flatly that subliminal influence is ineffective, with the remaining either claiming that it works or suggesting a big “maybe” to prompt readers’ concern.

In general, popular press articles fail to rely on scientific evidence and method to critically evaluate subliminal findings. Positive findings are emphasized and null results rarely reported. Problems with positive subliminal findings, such as lack of control groups, expectancy effects, setting subliminal thresholds, and so on, are rarely mentioned. If negative information is given, it is often presented at the end of the article, giving the reader the impression that, at best, the claims for subliminal effectiveness are somewhat controversial. Recent coverage of subliminal self-help tapes, however, have been less supportive of subliminal claims-but this may reflect more of an attack on big business than an embrace of science.

Instead of the scientific method, those accused of subliminal persuasion (mostly advertisers) are subjected to what can be termed the “witch test.” During the Middle Ages, one common test of witchcraft was to tie and bind the accused and throw her into a pond. If she floats, she is a witch. If she drowns, then her innocence is affirmed. Protestations by the accused were taken as further signs of guilt.

How do we know that subliminals work and that advertisers use them? As Key notes, advertisers spend a considerable amount of money on communications that contain subliminal messages. Why would they spend such vast sums if subliminal persuasion is ineffective? The fact that these subliminal messages cannot be readily identified or seen and that the advertisers deny their use further demonstrates the craftiness of the advertiser. After all, witches are a wiley lot, carefully covering their tracks. It appears that the only way that advertisers can prove their innocence, by the logic of the witch test, is to go out of business at the bottom of the pond, thereby showing that they do not possess the arts of subliminal sorcery. In contrast, just as the motives of the Inquisition for power and fortune went unquestioned, so too the motives of the proponents of subliminal seduction, who frequently profit by the sale of more newspapers, books, or audiotapes, are rarely (or have only recently been) questioned.

The proponents of subliminal persuasion make use of our most sacred expectations, hopes, and fears. Each manifestation of interest in subliminal influence has been linked to the important philosophies and thinking of the day-New Thought in the 1900s, brainwashing in the 1950s, the corruption of big governments in the 1970s, and New Age philosophy today.

But the belief in subliminal persuasion provides much more for the individual. We live in an age of propaganda; the average American will see approximately seven million advertisements in a lifetime. We provide our citizens with very little education concerning the nature of these persuasive processes. The result is that many may feel confused and bewildered by basic social processes (see Pratkanis and Aronson 1992). The negative side of subliminal persuasion is presented as an irrational force outside the control of the message recipient. As such, it takes on a supernatural” devil made me do it” quality capable of justifying and explaining why Americans are often persuaded and can seemingly engage in irrational behavior. Why then did I buy this worthless product at such a high price? Subliminal sorcery. On the positive side, a belief in subliminal persuasion imbues the human spirit at least with the possibility of overcoming the limitations of being human and of living a mundane existence. We can be like the gods-healing ourselves, finding enjoyment in everything we do, working for the benefit of humankind by tapping our own self potentials. Perhaps our theories of what should be or what we would like to be have caused us to be a little less critical of the claims for the power of subliminal influence.

But belief in subliminal persuasion is not without its cost. Perhaps the saddest aspect of the subliminal affair is that it distracts our attention from more substantive issues. By looking for subliminal influences, we may ignore more powerful, blatant influence tactics employed by advertisers and sales agents. We may ignore other, more successful ways-such as science-for reaching our human potentials.

Consider the tragic suicide deaths of teenagers Ray Belknap and James Vance that were brought to light in the recent trial of Judas Priest. They lived troubled lives-lives of drug and alcohol abuse, run-ins with the law, learning disabilities, family violence, and chronic unemployment. What issues did the trial and the subsequent mass-media coverage emphasize? Certainly not the need for drug treatment centers; there was no evaluation of the pros and cons of America’s juvenile justice system, no investigation of the schools, no inquiry into how to prevent family violence, no discussion of the effects of unemployment on a family. Instead, our attention was mesmerized by an attempt to count the number of subliminal demons that can dance on the end of a record needle.

In this trial, Judge Jerry Carr Whitehead (Vance & Belknap v. Judas Priest & CBS Records 1990) ruled in favor of Judas Priest, stating: “The scientific research presented does not establish that subliminal stimuli, even if perceived, may precipitate conduct of this magnitude. There exist other factors which explain the conduct of the deceased independent of the subliminal stimuli.” Perhaps now is the time to lay the myth of subliminal sorcery to rest and direct our attention to other, more scientifically documented ways of understanding the causes of human behavior and improving our condition.

Acknowledgments

I thank Elliot Aronson, Timothy E. Moore, Marlene E. Turner, and Rick Stoltz for helpful comments. Portions of this paper were presented at the American Psychological Association meetings on August 12, 1990, in Boston, Massachusetts, and the CSICOP Conference on May 3, 1991, in Berkeley/Oakland, California.

References

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What is subliminal perception? Should we be worried (or perhaps enthused) about covert manipulation of thoughts, attitudes, and behaviors? My reviews (Moore 1982;1988) have dealt primarily with the validity of the more dramatic claims made on behalf of subliminal techniques and devices. Such an appraisal requires a working definition of “subliminal perception.” Then we need to determine whether the conditions under which it occurs and the means by which it is achieved are reflected in the products on the market.

How should “awareness” be defined? One way is simply to ask observers whether or not they are “aware” of a stimulus. If the observer denies any awareness, then the stimulus, is, by definition, below an awareness threshold. Using this approach, unconscious perception consists of demonstrating that observers can be affected by stimuli whose presence they do not report. Another way to define "awareness” involves requiring observers to distinguish between two or more stimuli that are presented successively. With fast exposure durations, observers may be unable to distinguish between stimuli, or between a stimulus’s presence or absence. This method was advocated by Eriksen (1960) and defines consciousness as the observer’s ability to discriminate between two or more alternative stimuli in a forced-choice task. In this context, unconscious perception consists of a demonstration that observers are affected by stimuli whose presence they cannot detect. The approaches are different and involve different sorts of evidence. In the former case the stimuli are not reported; in the latter instance the stimuli cannot be detected.

These two methods of defining consciousness have been referred to as “subjective” and “objective,” respectively, by Merikle and his coworkers (Cheesman and Merikle 1986; Merikle and Cheesman 1986). Higher levels of visibility are typically associated with subjective thresholds. The disadvantage of a subjective definition is that a failure to report a stimulus’s presence may result from response bias (i.e., the observer is ambivalent about the stimulus’s presence and elects to report its absence). As Merikle (1984) has argued, the use of subjective thresholds implies that each participant provides his or her own idiosyncratic definition of “awareness.” Consequently, awareness thresholds could (and would) vary greatly from subject to subject.

Some recent studies (e.g., Cheesman and Merikle 1986) have looked at performance when both subjective and objective thresholds have been assessed. Such studies indicate that subliminal perception is most appropriately viewed as perception in the absence of concurrent phenomenal experience. We sometimes receive information when subjectively we feel that nothing useful has been"seen.” Investigators can establish that perception has occurred in the face of disavowals from participants by forcing them to guess. Respondents may object that they have no basis for making a decision, but by using a forced-choice task we can see that their guesses are more accurate than they would be if they were guessing at random. Clearly, some information is being utilized.

When respondents’ guesses are at chance in a detection task, there is no well-established evidence for perception. Thus, subliminal perception is not perception in the absence of a detectable signal. Rather, it occurs under conditions where subjects can detect a signal on at least some proportion of trials. Subjects may claim to be guessing without realizing that their guesses are better than chance. According to Merikle, the dissociation between these two indicators of perception (signal detection vs. introspective reports) defines the necessary empirical conditions for demonstrating subliminal perception. There is an inconsistency between what observers know and what “they know they know.”

Recent reviews of research findings in subliminal perception have provided very little evidence that stimuli below observers’ subjective thresholds influence motives, attitudes, beliefs, or choices (Moore 1988; 1991b; Pratkanis and Greenwald 1988; Greenwald, in press). In most studies, the stimuli do not consist of directives, commands, or imperatives, and there is no reliable evidence that subliminal stimuli have any pragmatic impact or effects on intentions. Studies that do purport to find such effects are either unreplicated or methodologically flawed in one or more ways. There is very little evidence for any perceptual processing at all (let alone any pragmatic consequences) when perceptual awareness is equated with an objective threshold.

How do the dramatic claims regarding undetectable stimuli stack up against the preceding review? What are these claims and what is their status? I shall confine my comment to claims involving advertising applications and self-help auditory tapes.

Advertising

Many people believe that most advertisements contain hidden sexual images or words that affect our susceptibility to the ads. This belief is widespread even though there is no evidence for such practices, let alone evidence for such effects. “Embedded” stimuli are difficult to characterize in terms of signal-detection theory Or threshold-determination procedure because most of them remain unidentifiable even when focal attention is directed to them. Nevertheless, the use of the term subliminal is a fait accompli, and belief in such an influence is primarily the consequence of the writings and lectures of just one person-Wilson Bryan Key (1973, 1976; 1980; 1990). Key offers no scientific evidence to support the existence of subliminal images; nor does he provide any empirical documentation of their imputed effects (Creed 1987: see also Vokey and Read).

In a review of Key’s most recent book, John O'Toole, president of the American Association of Advertising Agencies wondered: “Why is there a market for yet another re-run of this troubled man’s paranoid nightmares?” (O'Toole 1989: 26). Part of the reason that Key’s books sell so well may be that they are not what they appear to be. The information is not presented as the subjective fantasies of one person. Instead, it is presented as scientific, empirical fact. Science is respectable. Consequently, if claims are cloaked in scientific jargon, and if propositions are asserted to be scientifically valid, people can be fooled. Key knows this and uses it to his advantage. His intent is to persuade; and if he can do so by misrepresenting scientific data and findings, he is apparently prepared to do so.

Key provided pretrial testimony at the Judas Priest trial in Reno, Nevada, in the summer of 1990. Two teenagers had committed suicide. Their parents sued Judas Priest and CBS Records Inc., alleging that subliminal messages in Judas Priest’s music contributed to the suicides. Key was testifying on behalf of the plaintiffs, and at the trial he responded to a question about scientific methodology by saying: “Science is pretty much what you can get away [with] at any particular point in history and you can get away with a great deal” (Vance/Roberson v. CBS/ Judas Priest, 1990: 60). This unabashed disdain for anything approaching scientific integrity has not endeared him to the scientific community.

Attempting to apply scientific criteria to propositions for which there is no pretense at scientific foundation is a relatively futile exercise. Key’s only interest in science seems to be in the persuasive power of adopting a scientific posture or style. The use of scientific jargon does not necessarily reflect scientific attitudes or methods. Under these circumstances, even to apply the term pseudoscience seems unwarranted.

Extravagant claims notwithstanding, advertising may affect us in subtle and indirect ways. While there is no scientific evidence for the existence of “embedded” figures or words, let alone effects from them, the images and themes contained in advertisements may well influence viewers’ attitudes and values without their awareness. In other words, the viewer may be well aware of the stimulus, but not necessarily aware of the connection between the stimulus and responses or reactions to it. For example, there was a television commercial a few years ago for skin cream in which a mother and daughter were portrayed. The viewer was challenged to distinguish mother from daughter. According to Postman (1988), the unstated message is that in our culture it is desirable that a mother not look older than her daughter. A number of social scientists believe that advertising may play a role in the development of personal identity and social values (Leiss, Klein, and Jhally 1986; Schudson 1984; Wachtel 1983). It is difficult, however, to isolate advertising’s role from the many other social forces at work. Moreover, most research on advertising effects consists of content analyses of the ads themselves. Such studies leave many unanswered questions about the impact of that content on the viewing public.

Subliminal Auditory Self-help Tapes

When claims about covert advertising were raised in September 1957, the New Yorker lamented that “minds had been broken and entered” (Moore 1982). More than three decades later, claims of covert subliminal manipulation persist. Television commercials, magazine ads, and bookstores promote subliminal tapes that promise to induce dramatic improvements in mental and psychological health. These devices are ostensibly capable of producing many desirable effects, including weight loss, breast enlargement, improvement of sexual function, and relief from constipation.

Subliminal tapes represent a change in modality from visual to auditory, and now subliminal stimulation is supposedly being harnessed for a more noble purpose-psychotherapy, clearly a less crass objective than that of covert advertising. However, the scientific grounds for substantiating the utility of today’s self-help tapes is as poor as was the documentation for advertising effects 30 years ago. Proponents seem to have assumed that for obtaining subliminal effects one modality is as good as another. Claims about the utility of subliminal tapes are essentially claims about the subliminal perception of speech-a phenomenon for which there is very little evidence (Moore 1988). The basic problem is that the few studies that purport to have demonstrated effects of subliminal speech used such crude methods for defining subliminality that the findings are quite uninteresting (e.g., Henley 1975; Borgeat et al. 1985).

It is not obvious what the analogue to visual masking is for a speech signal. Masking, in the visual domain, is procedurally defined with relative precision. The mask does not mutilate or change the target stimulus-it simply limits the time available for perceiving the preceding target. In the absence of the mask, the target is easily perceived. In the auditory domain, the target signal is reduced in volume and further attenuated by the superimposition of other supraliminal material. Often the subliminal “message” is accelerated or compressed to such a degree that the message is unintelligible, even when supraliminal. It is an extraordinary claim that an undetectable speech signal engages our nervous system and is perceived-consciously or not. Signal detection is an implicit sine qua non of most theories of speech perception (Massaro 1987). To assert that “subliminal speech” is unconsciously perceived appears to call into question some very fundamental principles of sensory physiology. What is the nature of the signal that arrives at the basilar membrane? If the critical signal is washed out or drowned out by other sounds, then on what basis are we to suppose that the weaker of the two signals becomes disentangled, and comprehensible? The tapes also have a dubious conceptual rationale in their assumed therapeutic impact. Even if the message could achieve semantic representation, how or why should it affect motivation? Answering the question “How?” is important, because it provides the theoretical justification for the practice.

There are subliminally embedded messages at work. You won’t be able to hear them consciously. But your subconscious will. And it will obey [Zygon].

To gain control, it is necessary speak to the subconscious mind in a language that it comprehends-we have to speak to it subliminally. [Mind Communications Inc.]

Is there a pipeline to the id? Can we sneak directives into the unconscious through the back door? There may be a fundamental misconception at work here, consisting of equating unconscious perceptual processes with the psychodynamic unconscious (Eagle 1987; Marcel 1988). Cognitive psychologists use the term unconscious to refer to perceptual processes and effects of which we have no phenomenal awareness. Induced movement is an example of an unconscious perceptual process. Tacit knowledge of and conformity to grammatical rules is another example of unconscious processing. No one would want to argue, however, that either of these domains of activity have anything to do with the psychodynamic unconscious. Psychodynamic theorists use the term unconscious as a noun with a capital U, to refer to, for lack of a better term, the id-"a cauldron full of seething excitations,” as Freud expressed it. Because semantic activation without conscious awareness can be demonstrated, some observers have jumped to the conclusion that subliminal stimulation provides relatively direct access to the id. This assumption has neither theoretical nor empirical support.

While tape distributors often claim that their products have been scientifically validated, there is no evidence of therapeutic effectiveness (e.g., Auday et al. 1991; Greenwald et al. 1991; Merikle and Skanes, in press; Russell et al. 1991). In addition, both Merikle (1988) and Moore (1991a) have conducted studies that showed that many tapes do not appear to contain the sort of signal that could, in principle, allow subliminal perception to occur.

Quite apart from the lack of empirical support, there is little or no theoretical motivation for expecting therapeutic effects from such stimuli. The “explanation” consists of attributing to the systemic unconscious whatever mechanisms or processes would be logically necessary in order for the effects to occur. Because there is no independent evidence for such “unconscious” perceptual processes, it is not surprising that there is no evidence for the imputed effects (see Eich and Hyman 1991; Moore 199lb). Furthermore, Greenwald (1992) has recently queried the conventional psychoanalytic conception of a sophisticated unconscious processor, arguing that it is neither theoretically necessary nor empirically substantiated.

The burden of proof of the viability of these materials is on those who are promoting their use. There is no such proof, and therefore the possibility of health fraud could be raised. These tapes sometimes sell for as much as $400 a set. Of even greater concern is the fact that legitimate forms of therapy may go untried in the quest for a fast, cheap “cure.”

According to William Jarvis, president of the National Coalition Against Health Fraud, a quack is “anyone who promotes, for financial gain, a remedy known to be false, unsafe, or unproven” (Jarvis 1989: 4). Fraud, on the other hand, implies intentional deception. Consequently, not all quackery is fraud, nor is fraud synonymous with quackery. As Jarvis has pointed out, in some ways quacks may be worse than frauds. “The most dangerous quacks are the zealots who will take the poison themselves in their enthusiasm for their nostrums. Sincerity may make quacks more socially tolerable, but it goes far in enhancing their danger to the public” (Jarvis 1989: 4).

Scientists, the Media, and the Popularization of Science

The popularity and interest in the topic of subliminal influences-both inside and outside academic circles-can be attributed, in part, to media coverage (c.f., Pratkanis 1992). Conspiracy theories make good copy, and in subliminal advertising we have a large-scale technological conspiracy to control people’s minds with invisible stimuli. With subliminal tapes you can allegedly change your behavior and your personality in profound and important ways-effortlessly and painlessly. The quick fix of psychotherapy is an intriguing notion. It is therefore small wonder that it continues to be a popular topic for writers. Carl Sagan (1987) has suggested that pseudoscience flourishes because the scientific community does a poor job of communicating its findings. To propose that we can be influenced in dramatic ways by undetectable stimuli is a remarkable claim with little scientific support, but blaming journalists for promulgating the claim absolves the scientific community from any responsibility in the educational process. Relations between scientists and the press could be improved if scientists communicated more clearly. Researchers take such great pains to avoid making absolute pronouncements that they often err in the opposite direction. We sometimes speak with a tentativeness that belies the facts, understating our confidence that some propositions are true and that others are false (Rothman 1989). When we talk to the press, we need to speak plainly. For example, Phil Merikle recently observed that “there’s unanimous opinion that subliminal tapes are a complete sham and a fraud” (Rae 1991). Merikle is correct, but such candor is relatively rare. Who will distinguish science from pseudoscience if not the scientists?

Paradoxically, while negative scientific evidence continues to accumulate, the subliminal-tape industry-fueled by aggressive advertising campaigns-thrives. As Burnham (1987) has noted, advertising’s authority often derives from the use of scientific regalia. Advertising’s purpose is, however, antithetical to that of science: “Advertisers [are] engaged in remystifying the world, not demystifying it” (Burnham 1987: 247). Extraordinary claims, if they are repeated often enough, can perpetuate extraordinary beliefs. When nonsense masquerades as science and magic is disguised as therapy, the result is not always laughable. Consider the self-help tape for survivors of sexual abuse; the user is informed that lasting relief from the trauma of abuse is contingent upon the victim’s acknowledgment of their own role in causing the abuse in the first place (Moore l99lb).

Conclusion

Subliminal advertising and psychotherapeutic effects from subliminal tapes are ideas whose scientific status appears to be on a par with wearing copper bracelets to cure arthritis. Not even the most liberal speculations regarding the use of subliminal techniques for “practical” purposes impute any potential utility to these practices (Bornstein 1989). The interesting question to ask is not “Do subliminal advertising techniques or subliminal auditory tapes work?” but, rather, “How did these implausible ideas ever acquire such an undeserved mantle of scientific respectability?” The answer involves a complex interplay of public attitudes toward science, how social science is popularized in the mass media, and how the scientific community communicates to those outside the scientific community. Carl Sagan may be right-pseudoscience will flourish if scientists don’t take more responsibility for the accurate dissemination of scientific information.

According to Burnham (1987), superstition has triumphed over rationalism and skepticism partly because scientists no longer engage in the popularization of science-summarizing, simplifying, and translating scientific findings for lay audiences. The function of popularizing science and health is now carried out by journalists and educators. Consequently, many topics, including this one, receive coverage that is, at best, deficient in background information and meaningful context, and at worst, fragmented and misleading. Further confusion is caused by the tendency among journalists to manufacture controversies where none exists by juxtaposing the pronouncements of “authorities” who contradict one another. If all authorities (including those with financial stakes in their positions) are equally admissible, controversies abound.

Note

I am grateful to Phil Merikle and Anthony Pratkanis for comments on an earlier draft of this paper, portions of which were presented to the American Speech and Hearing Association’s annual convention in St. Louis, November 18, 1989, to the American Psychological Association’s annual convention in Boston, August 12,1990, and to the annual convention of the Committee for the Scientific Investigation of Claims of the Paranormal, Berkeley, Calif., May 2, 1991. Inquiries should be directed to Timothy E. Moore, Department of Psychology, Glendon College, York University, 2275 Bayview Ave., Toronto, Ont. M4N 3M6. E-mail: GL2500020@YUVENUS.

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Recent research in subliminal perception has provided very riffle evidence that stimuli below observers’ subjective thresholds influence motives, attitudes, beliefs or choices.

“Subliminal advertising and psychotherapeutic effects from subliminal saves are ideas whose scientific status appear to be on a par with wearing copper bracelets to cure arthritis.”

“Quite apart from the lack of empirical substantiation, there is little or no theoretical motivation for expecting therapeutic effects from such stimuli.”