Ladies & Gentlemen:

It is a pleasure to attend the 30th birthday of CSICOP and share a few stories about how critical thinking has impacted my life work.

I had the good fortune to grow up in Windsor, Colorado and become a childhood friend of Ken Frazier. We both dreamed of the future and were sure that science would improve that future. We spent countless hours discussing the latest science fiction ideas and comparing those ideas with what we were learning in science classes. Post university, our paths diverged but I continued to stay in contact with Ken, often through his work as editor of the National Academy of Sciences journal, then Science News, and for nearly thirty years through the pages of the Skeptical Inquirer.

I shed many of my metaphysical beliefs. Dousing to find water did not survive the article on Randi’s tests. PSI capabilities, so common to science fiction, did not stand up to CSICOP fellows work — people like Ray Hyman, Jim Alcock.

This exposure to critical thinking has played into my work and life view, and I hope it will be interesting to you to learn about how skeptical thinking has impacted a couple of these views.

First point: I observe that the world always forms mind-sets, or what Thomas Kuhn calls paradigms. The audience is of course familiar with how conventional wisdom, or indeed beliefs, clings to existing paradigms, often in the face of compelling evidence to the contrary. What excites me about the history of science is the phenomenal progress that has often followed a fundamental paradigm shift. Unraveling the mysteries of the universe began in earnest once we shed the earth-centric view. But these changes are slow and hard fraught. I have come to believe that obsolete mind-sets impose a great cost on society.

Second point: Mind-sets create advantages for certain groups. Sometimes these mind-sets confer status and respectability on their priests. Often the claims confer monetary advantages. Those claiming aliens visited Roswell created quite a business of books and tours. The folks claiming advantages for homeopathy make a great deal of money selling pure water.

Third point: Those who benefit from specific mind-sets often seek to improve those advantages by causing governance to enact rule-sets that make it illegal for citizens or businesses to behave in ways against the mind-sets. The Taliban made Islamic Sharia the law of Afghanistan, with significant personal benefit. School boards seek to block out those messy evolutionary facts that challenge their view of the bible as literal revealed truth. There will always be folks seeking rule-sets that confirm their beliefs or mind-sets.

Fourth point: These mind-sets develop in the commercial world as well as in science and religion. And, although this may surprise some of my academic colleagues, some people are even more interested in money than in academic status. They lobby government to enact rule-sets that benefit their firms.

The Old AT&T;, after I am sure much deep study, concluded that it was in the national interest for government to continue to enforce AT&T; absolute monopoly over voice communication. The Chairman of AT&T; told Congress in the early 70’s that if the laws allowed connection to the network of communication equipment made by any firm but AT&T;, there could be a nationwide communications failure. Happily, Congress did not buy AT&T;’s self-serving logic, and the communications revolution picked up speed.

What you may not be aware of is that the same AT&T; testified before a congressional committee chaired by Congressman Al Gore and argued that the internet could not possibly develop without monopoly control — Gore’s committee rejected this request for a limiting rule-set, and may have truly fathered the internet.

Which lends me to energy. Energy is the world’s largest and most important industry. Our standard of living improvements have been driven by the availability of useful work — by replacing drudgery with affordable energy.

Energy use also is behind what I believe to be the most serious environmental problem humankind has ever faced — global warming. Last year alone, our global energy system released an amount of CO2 that took nature 400,000 years to store. Two thirds of all US energy comes from fossil fuel.

The world would benefit from building electric and thermal generation options that reduce costs and reduce pollution. The prevailing energy mind-sets assume it is not possible to produce it cheaper and cleaner. The power system is large and ubiquitous, it must be economically optimal. Thus any changes that lower pollution must, by definition, raise the price of electricity.

The great bulk of the public is still in the mind-set but it is false. The power industry is governed by very strong rule-sets that make the delivery of electricity a monopoly — that ban private wires. Would be power entrepreneurs who seek to develop more efficient approaches can not, by law, deliver the product to their customers, except through monopoly wires. This blocks local generation, which blocks energy recycling. As a result, we burn double the fossil fuel that would be burned by an optimal system.

The presentation shown is about our business of recycling waste energy streams. The point is to demonstrate how critical thinking and refusal to accept existing mind-sets has identified ways to cut in half the fossil fuel used to generate electricity, while reducing average electric prices. But governments have enacted rule-sets that block such optimization.

The conclusion is to me, profound. Critical thinking is just as important in commercial enterprises as in science, education, and medicine. And the obsolete mind-sets and rule-sets have a great cost to the planet and to all of humanity.

The face of Jesus was “discovered” in a forkful of spaghetti in a Pizza Hut billboard advertisement in DeKalb County, Georgia, in May of 1991. Joyce Simpson said she was debating whether to quit her church choir as she was leaving a gas station when she felt compelled to look up. “And I saw Christ’s face,” she said (Guevara-Castro and Viele 1991). Subsequently, dozens of motorists claimed to have seen Jesus shrouded in spaghetti and tomato sauce on the chain’s billboard. God works in mysterious ways, but this tactic seems unnecessarily convoluted. On the other hand, compared to being abducted by aliens, seeing a face in a blob of spaghetti is small potatoes.

Sometimes perceptual illusions or faulty reasoning can have more pernicious consequences. For example, in 1986 a Philadelphia jury awarded a woman more than $900,000 in damages because she claimed her psychic powers had been damaged during a CAT scan conducted at Temple University Medical School (New York Times, March 29, 1986). Her complaint was supported by the “expert” testimony of a doctor. Unfounded fears are not unusual, but when they are accorded further esteem by a credulous judge or jury we risk surrender to the irrational. What the courts take seriously is believed to be serious by the common citizen. While science can supposedly provide some protection against litigious foolishness, sometimes science itself seems to be part of the problem.

How do scientific beliefs influence courtroom deliberations? More specifically, what happens to an extraordinary claim when it plays a pivotal role in a high-stakes criminal trial? Within the scientific community there are accepted methods and procedures for establishing the truth or falsity of an extravagant claim (Gardner 1981), but the courtroom is a different kind of forum. It is adversarial in nature. What happens to scientific consensus in court, especially if scientific information is distorted, misrepresented, or perhaps not science at all? Peter Huber has described what he calls “junk science” (Huber 1991), and according to Huber junk science may (and often does) wreak havoc with scientific integrity and with justice.

This article explores the issue of junk science in the context of a specific trial-the Judas Priest trial that unfolded in Reno, Nevada, in the summer of 1990. Two teenage boys, James Vance and Ray Belknap, had attempted suicide. At the time of the shootings, Belknap died instantly. Vance was severely injured but he lived, only to die of drug complications three years later. The plaintiffs (the boys’ parents) alleged that subliminal messages hidden in the heavy metal rock music that Vance and Belknap listened to contributed to their suicidal impulse. This trial is interesting for a number of reasons. First, it provides a classic example of junk science. Second, the trial established a legal precedent that has already influenced the ruling in a similar subsequent suit. Third, it provides a good forum for illustrating some important and often misunderstood aspects of subliminal perception.

Judas Priest was a British heavy metal rock band-one of the first of that genre. Their popularity peaked in the mid-70s. The album in question (Stained Class) was produced in 1978; the shootings took place in December 1985. It was alleged that a particular subliminal phrase in one of their songs ("Better by You Better Than Me") on the album triggered a suicidal impulse. The phrase at issue was “Do It.” In isolation, this phrase has little meaning unless there is some antecedent to which the “It” refers. Moreover, the antecedent could not have been anything that was audible on the record (or visible on the album cover), because such material would have been protected by the First Amendment. Consequently the plaintiffs were in the difficult position of having to acknowledge that the boys were suicidal to begin with, and that the subliminal phrase “Do It” triggered the already existing disposition.

First Amendment Protection and the Denial of Summary Judgment

The defendants denied any and all knowledge of subliminal messages, and they denied having engaged in any tricks or mischief during production of the record. Nevertheless, the case went to trial. The defense was unsuccessful in arguing that any and all speech (including subliminal speech) should enjoy First Amendment protection. In a pre-trial motion, Justice Jerry Carr Whitehead ruled that subliminal speech does not deserve protection because it does not perform any of the functions that free speech accomplishes. Since the recipient of a subliminal message is unaware of it, the message can’t contribute to dialogue, the pursuit of truth, the marketplace of ideas, or personal autonomy. There is no information exchange. No arguments are possible if recipients are unaware of the message’s presence. People also have a right, the judge added, to be free from unwanted speech. Since subliminal materials cannot be avoided, they constitute an invasion of privacy. For all these reasons, subliminals were not afforded First Amendment protection (Vance v. Judas Priest 1989b). This ruling makes logical sense if a subliminal message could have the power attributed to it by the plaintiffs. The plaintiffs thus achieved a major victory in getting the case to trial in the first place.

While First Amendment protection has never been absolute, the exceptions have been narrow and carefully limited. Speech that is obscene, libelous, or an incitement to lawlessness is not protected by the First Amendment. Justice Whitehead’s ruling provided another exception-subliminal speech. We may not have seen the last of trials concerning allegations about subliminal influences (Dee 1994). A few months after Judas Priest’s acquittal, Michael Waller, the son of a Georgia minister, shot himself in the head while listening to Ozzy Osbourne’s record Suicide Solution. 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.

Liability ‘Science’

If a car accident causes severe injury or death, it may be more appealing and more comforting to the driver if the cause of the accident can be attributed to a mechanical defect rather than to operator error. It may also be more appealing and more lucrative to lawyers interested in liability. Liability science often assumes that every ill has a distant cause-often a technological cause. Food additives, environmental toxins, and mechanical defects have all been alleged culprits in liability suits within the last two decades. The Judas Priest suit was a product liability case. An allegedly defective product was placed on the market and it caused harm. According to Timothy Post, one of the plaintiffs’ lawyers, the subliminal message triggered the suicides. The defense denied placing any subliminal messages, and further contended that subliminal stimuli are not capable of compelling any behaviors, let alone suicidal ones.

One of the threats to scientific integrity mentioned by Huber (1991) has to do with abandoning the usual scientific meaning of the term causality. From a scientific perspective, we typically want to understand a phenomenon by discovering all the causal factors that contribute to it. According to Huber, however, liability science has its own rules. Liability science likes to simplify matters. A specific potential cause is selected and other contributing factors are ignored. It is assumed that no other variables were operating except the one of interest. The standard scientific approach is abandoned. Multiple risks are disregarded-especially obvious, ubiquitous, taken-for-granted risks-and all attention is focused on remote and (perhaps) implausible causes that implicate negligence on the part of someone else.

There was some evidence of this approach-the tendency to subvert the meaning of causality-at the Judas Priest trial. In his final ruling, the judge explicitly stated “the deceased and their parents are not on trial. The court is not to judge the lives of the decedents or evaluate their families.” (Vance v. Judas Priest 1990, 2-3). The plaintiffs were obliged, however, to acknowledge some degree of risk, otherwise the “Do It’s” would have been meaningless. What were some of these risk factors? According to the clinical psychologist who testified for the defense, both boys had serious, long-term adjustment problems. Both were violent and abusive in their relationships. They felt socially alienated; they were emotionally distressed, often depressed, and impulsive. Vance once broke another student’s jaw in a fight at school. Both had a history of drug abuse, petty crime, school failure, and unemployment. Family backgrounds were violent and punitive. Belknap had attempted suicide before and had expressed suicidal intentions. Just prior to the shootings, Belknap gave out some of his Christmas presents early and indicated a desire for his sister to name her baby after him if anything happened to him. Most of these factors were mentioned by the judge in his final ruling. They were included “reluctantly” to show that the deceased were at high suicide risk (see Litman and Farberow 1994). Was this a reasoned departure from the “subverted causality” that often typifies liability cases? Who can say? The concession may simply have been an artifact of the logical necessity for the plaintiffs to recognize the high-risk status of the boys. At any rate, multiple causes were recognized, albeit somewhat grudgingly. The judge stated that “[t]here exist other factors which explain the conduct of the deceased independent of the subliminal stimuli. . . . [t]he deceased had propensities which made them a high suicide risk” (Vance v. Judas Priest 1990, 31-32).

The Plaintiffs’ Experts

The pursuit of isolated, distant, and mysterious causes for various mishaps sometimes results in a search for distant and mysterious experts. Experts are invited to provide support for the contentious claim. When courts are tolerant of a subverted sense of the meaning of causality, they may also be tolerant of fringe experts. There were several at this trial. One of them was Wilson Key. He is the man who pretty much single-handedly popularized the myth of subliminal advertising. He sees subliminal conspiracies everywhere (Key 1973, 1976, 1980, 1989), so it was not surprising that he was present to support the plaintiffs’ claims. While Key provided extensive pre-trial testimony, his contribution to the actual trial was negligible. It is possible that he undermined his own credibility with the court by opining that subliminal messages could be found on Ritz crackers, the Sistine Chapel, Sears catalogues, and the NBC evening news. He also asserted that “science is pretty much what you can get away with at any point in time.”

The most influential expert to testify for the plaintiffs was Howard Shevrin, whose credentials were unassailable. He has conducted research on subliminal influences for over twenty years and has a respectable track record of publications in peer-reviewed books and journals (e.g., Shevrin 1988). Shevrin’s argument was that subliminal commands are especially potent because the recipient is unaware of their source and attributes the directive or the imperative to himself-to his own inner motivational state. While there is a certain logic to this, Shevrin was hard-pressed to describe any research that supported his opinion. The argument also presupposes that a command or directive is inherently compelling-that because it is an imperative in a linguistic or syntactic sense, it compels compliance in a psychological sense. According to Shevrin, when we consciously experience a command, we can ignore or comply with commands as we see fit, but if the command is subliminal, it may become part of our ongoing stream of motives, feelings, and inner promptings. It can therefore add an increment to any current predisposition that may be present, such as suicide. The fallacy lies in assuming that an imperative message has some inherently motivating effect. His position also required the assumption that a suicidal disposition requires a trigger or precipitant in order to be acted on. This assumption does not square with the research literature on adolescent suicide (Maris 1981). Shevrin was nevertheless persuasive. He provided an apparently respectable conceptual framework for explaining how such a mysterious and almost magical force could operate.

The Defendants’ Experts

Three experts were called by the defense: myself, Anthony Pratkanis (a professor of social psychology from the University of California at Santa Cruz), and Don Read (a cognitive psychologist from the University of Lethbridge). I testified about methodological and interpretational flaws in some specific investigations of subliminal auditory stimuli (e.g., Borgeat and Chaloult 1985; Borgeat, Elie, Chaloult, and Chabot 1985; Henley 1975) and about the dubious empirical foundation underlying psychodynamic constructs. It was my opinion that there was no scientific support for the proposition that subliminal directives could induce behaviors of any kind, let alone suicide. Pratkanis reiterated some of the main points of my testimony regarding the history of research on subliminal influence, and described a recently conducted experiment (since published) showing that subliminal self-help tapes were ineffective (Pratkanis, Eskenazi, and Greenwald 1994). He also expressed additional misgivings about the validity of the Borgeat studies-studies Shevrin had cited as supportive of his position. Pratkanis resisted the intimation by the plaintiffs’ lawyers that scientific findings were not of an enduring nature-that what is known today may be abandoned and replaced by a new opinion tomorrow. Finally, Don Read provided an eloquent description of research on the comprehension and retention of reversed speech (see Vokey and Read 1985).

Scientific Opinion vs. Scientific Evidence

The judge may have been seduced by psychodynamics, but perhaps not entirely convinced. Although Shevrin was successful in helping obtain the exception to First Amendment protection, he did not prevail during the actual trial. The ruling about subliminal effects stated: “The scientific research presented does not establish that subliminal stimuli, even if perceived, may precipitate conduct of this magnitude. . . . [t]he strongest evidence presented at the trial showed no behavioral effects other than anxiety, distress or tension” (Vance v. Judas Priest 1990, 31). The judge’s conclusion about subliminal effects is not too far from the consensus to be found among most cognitive psychologists. Well-established subliminal effects are rather modest in their magnitude and nature-semantic activation of single words under highly constrained conditions (see Holender 1986). To quote from a recent influential review: “. . . unconscious cognition is severely limited in its analytic capability” (Greenwald 1992, 775).

At one point during pre-trial testimony, Bill Peterson (one of the defense counsels) asked Shevrin to describe the empirical basis for his opinion: “What experiments are you referring to when you say you’re referring to a body of literature, experiments on which you base your conclusion that subliminal messages may be sufficient to induce suicidal behavior?”

"I’m basing my opinion, my expert judgment, on a corpus of literature, on hundreds of experiments,” said Shevrin.

"Name one,” said Mr. Peterson (Vance v. Judas Priest 1989a, 138-139).

Shevrin eventually alluded to three or four studies (e.g., Kupper and Gerard 1990; Silverman 1982; Smith, Spence, and Klein 1959)-none of which demonstrated anything remotely close to subliminal commands influencing motives. In fact, very few published studies have attempted to use subliminal directives, and those that have used them produced singularly uncompelling evidence for subliminal influences on intentionality (e.g., Zuckerman 1960; see Moore [1982] for commentary).

Shevrin’s position was supportive of the plaintiffs’ claims. Moreover, if logically extended, it constitutes an endorsement of auditory subliminal self-help tapes. If Shevrin’s position were valid, subliminal self-help tapes should be effective for a substantial number of people. Users are predisposed and some may even be preoccupied with changing their behavior in the direction of the affirmations on the tapes. Those messages should, therefore, according to Shevrin’s logic, alter and increase the listeners’ inner motives. There is ample evidence, however, that subliminal self-help tapes are therapeutically useless (Greenwald, Spangenberg, Pratkanis, and Eskenazi 1991; Merikle 1988; Merikle and Skanes 1992; Moore 1988; Pratkanis, Eskenazi, and Greenwald 1994; Russell, Rowe, and Smouse 1991).

While Shevrin’s testimony may have been logical, it was not good science. The judge, to his credit, appears to have made a distinction between a scientific opinion based on personal conviction and the logic of psychodynamics, and one based on empirical support.

Pseudoscience

Up to this point, science has not fared badly. With respect to causality, the judge found that there were factors independent of the subliminal stimuli that made the decedents a high suicide risk. With respect to the scientific literature, he found that the research had not established that subliminal stimuli could have the sorts of effects postulated by the plaintiffs. There were other aspects of the case, however, in which scientific thinking fared less well. Pseudoscience sometimes plays a role in court because of dubious “experts” who are willing to attest to just about anything. In these situations, junk science appears in court because experts have been invited to educate the judge or jury. Another reason that junk science gets into court is because it already resides in court in the form of pre-existing beliefs about the phenomenon at issue.

The judge’s beliefs about subliminal perception are reflected in his ruling that denied summary judgment and in his final judgment. In the latter he provided what he called a “history of subliminal stimuli.” The title itself reveals some confusion. It is not the history of subliminal perception, nor the history of subliminal influences, but rather the history of subliminal stimuli. The difference is not irrelevant. Determining the subliminality of a stimulus requires some labor-intensive scientific analysis. The arbitrary and capricious use of the phrase “subliminal stimuli” by journalists (and some social scientists) has resulted in frequent reports of “subliminal” effects in the absence of any demonstration of subliminality.

What information formed the basis of the judge’s beliefs about subliminal perception? The references contained in his history essay consisted of several articles or book chapters from law journals, written by lawyers. He also cited information obtained from: Saturday Review, New York Times, Omni, Time, High Times, and TV Guide. The law articles, plus many of the magazine articles, contain numerous references to James Vicary and Wilson Key. Key’s expertise has already been described. Who was James Vicary? In September of 1957, James Vicary claimed to have conducted a study in Fort Lee, New Jersey, in which he projected the subliminal messages “Eat Popcorn” and “Drink Coke” onto a movie screen during movie showings to audiences (see Moore 1982; Pratkanis 1992; Rogers 1993). Initial press releases reported that over 45,000 people had been tested in this way and that on-site sales had increased dramatically. Five years later Vicary acknowledged that he had had only a small amount of data-too small to be meaningful. Soon after that he dropped out of sight completely. At best this so-called study was a shallow and meaningless empirical exercise. At worst, it was a complete fabrication (Rogers 1993). Media coverage was nevertheless heavy and continues to this day. Surveys have demonstrated that there is widespread belief in subliminal manipulation and that the techniques are “taught” in high school and college courses (Block and Vanden Bergh 1985; Synodinos 1988; Zanot, Pincus, and Lamp 1983).

Implicit, if not explicit, in both Vicary’s alleged demonstration, as well as media descriptions of the phenomenon, is the assumption that invisible or inaudible stimuli are inevitably unconsciously perceived. Portions of the judge’s ruling reflect this assumption. His historical review of subliminal stimuli is more a review of media coverage of the topic rather than a scientific history, let alone a recent scientific appraisal. This popular, simplified, and exaggerated notion of subliminal persuasion is reflected in some of the other rulings, and it is in these rulings that scientific truth fared less well. Here is what needed to be demonstrated by the plaintiffs:

1. An inaudible (but technically identifiable) “message” was physically present on the recording.
2. The message was deliberately placed there.
3. The message was subliminal.
4. The message contributed to the suicides.

As we have already seen, the judge rejected the fourth proposition, but what of the other three? The judge assumed that the technical presence of a “message” (item 1) was synonymous with its being subliminal (item 3). This assumption is the result of the mythological heritage of Vicary and all the media coverage since then. The judge’s ruling stated that “. . . the ‘Do It’s’ on the record were subliminal because they were only discernible after their location had been identified and after the sounds were isolated and amplified. The sounds would not be consciously discernible to the ordinary listener under normal listening conditions” (Vance v. Judas Priest 1990, 18). The problem is that sounds that are not consciously discernible are not necessarily unconsciously discernible either. Many stimuli are not consciously discernible because they fall outside the range of our sensory apparatus. Consequently they do not initiate any neurological activity-conscious or unconscious. The error consists of equating the physical presence of the signal with subliminality.

Physical Presence vs. Psychological Consequence

Empirical studies of subliminal perception indicate that, with rare exceptions, the phenomenon appears to be confined to a certain range of stimulus intensities (Cheesman and Merikle 1986). This range places the stimulus below a threshold of subjective or phenomenal awareness, but above an objective detection or discrimination threshold. In other words, subliminal perception is not perception in the absence of stimulus detection. It occurs when our introspective reports are at odds with or discrepant with objective measures of detection. It is not unusual for subjects to profess to be guessing or to claim ignorance of a stimulus’ identity when they are nevertheless making use of stimulus information. What this means is that no amount of expensive hardware or analyses of the signal can tell us if a signal is subliminal. Subliminality can only be determined by an analysis of the perceptual consequences of stimulation. Signal detection methods in which the human perceptual system is used as the measuring instrument might have provided a clearer picture of whether the recording in question actually contained a detectable message that could conceivably have influenced behavior (e.g., Merikle 1988; Moore 1995).

A physical analysis of the signal is not necessarily completely uninformative. Such an analysis could help determine the presence of a signal which might, after further analysis, turn out to be subliminal. The judge assumed that if an inaudible signal was present, that signal was therefore subliminal even though neither the plaintiffs nor the defense presented evidence establishing subliminality. It should be emphasized that even if subliminality had been established, it would not necessarily follow that the message would have the influence attributed to it by Shevrin. His claim, however, could have been obviated by the finding that the signal was not, in fact, subliminal.

Was the signal deliberately placed there? Who can say? The judge’s opinion was that the signal at issue was simply a coincidental convergence of a guitar chord with an exhalation pattern. Under what circumstances could one confidently infer purposeful deception? Conceivably, the length and complexity of an inaudible signal might guide decisions about whether its placement was accidental or deliberate. Walt Disney Inc. was recently accused of inserting the “subliminal” directive “All good teenagers take off your clothes” into the animated family film Aladdin. At around the same time the letters S-E-X were alleged to have been surreptitiously embedded in a scene from The Lion King (Globe & Mail, Nov. 7, 1995). Walt Disney Inc. has emphatically denied attempting any kind of subliminal titillation.

In March of 1994, someone discovered that Jessica Rabbit had no underwear for a very short time during the animated movie Who Framed Roger Rabbit? (Globe & Mail, March 17, 1994). In this example, there were at least three offending frames-unnoticeable unless the tape is advanced frame by frame. Were they deliberately planted there for some nefarious reason, or were the artists just saving some ink or playing a practical joke? It’s hard to know, but the physical presence of an uncovered Jessica tells us nothing about the perceptual or psychological consequences of her undressed state. It is probable that under normal viewing conditions the contents of the frames are completely and thoroughly masked by the subsequent material. In the absence of the appropriate tests, however, one cannot simply assert that stimuli are (or are not) subliminal. In none of these examples is it possible to know definitively if the signal or image was subliminal, nor if it was deliberately planted.

Perception is an active, constructive process. Consequently, people often see or hear what they are predisposed (or encouraged) to perceive (Vokey and Read 1985). A diligent search entailing the isolation and amplification of dozens of snippets from a three-minute heavy metal rock recording would probably yield some intelligible words or phrases that would not be intelligible under normal listening conditions. In fact, it would be surprising if a few such “discoveries” were not made. The fact that the signal in question on the Stained Class album was not contained on any particular track of the 24-track tape argues further against the possibility of deliberate chicanery.

Further Confusion

The two most credible witnesses testifying for the plaintiffs were, in the judge’s opinion, Shevrin and Mrs. Rusk. Mrs. Rusk was a guidance counselor at Vance’s school. Vance, the boy who survived the suicide attempt, was questioned about the circumstances of the shootings by Mrs. Rusk in the spring of 1986. Mrs. Rusk’s testimony was that Vance said, “We got a message. It told us just Do It . . . It [the record] was giving us the message to just Do It.” This statement reflects conscious awareness on Vance’s part of the presence and nature of the “Do It” message. Recall that Shevrin’s position was that the subliminal message “Do It” was influential precisely because it was subliminal. The boys were unaware of receiving the prompt from an external source and, therefore, misattributed its source or origin to their own inner motivation. These two pieces of testimony are logically contradictory. They cannot both be correct. If, as Shevrin claimed, the message was subliminal, the boys should have been oblivious to its presence and its meaning. It is the unconscious nature of the message which, according to Shevrin, affords it the exceptional influence he ascribed to it. On the other hand, if they could actually hear it, as Vance indicated to Mrs. Rusk, then the message was not, by definition, subliminal, and was thus (a) protected by the First Amendment, and (b) not especially influential. The judge seemed unaware of this logical conundrum: “This testimony [Mrs. Rusk’s] gives support to the premise that both James and Raymond subliminally perceived ‘Do It’ from the record” (Vance v. Judas Priest 1990, 30). In fact, Mrs. Rusk’s testimony refutes the notion that the signal was subliminal. Shevrin was well aware of this difficulty. When the plaintiffs’ lawyers suggested to him that Mrs. Rusk’s testimony supported the notion that the “message” had been retained in the boys’ memories, he expressed concern that Mrs. Rusk may have been influenced by media reports, and/or that she was having trouble recalling what Vance had reported to her. Apparently, the plaintiffs’ lawyers did not understand the logic of their own expert’s testimony. At this point one wonders who was minding the store.

Defining ‘Expertise’

At issue in this trial was the claim that a subliminal directive incited suicide. From a scientific perspective, this is an extraordinary and prima facie implausible proposition. There is not now, nor has there ever been, any reliable empirical evidence that subliminal stimulation can produce anything other than fairly brief and relatively inconsequential reactions. Further, there is no evidence whatsoever that subliminal directives can compel compliance, and no such evidence was presented at the trial. Perhaps with the help of the defendants’ experts, the judge came to realize that subliminal directives do not have the influence attributed to them by the plaintiffs. A more thorough grasp of the issue might have yielded a summary judgment, thereby precluding a long and expensive trial. By denying summary judgment, Justice Whitehead assumed the validity of the plaintiffs’ central claim-namely, that subliminal messages can influence human motivation.

There have been numerous legal commentaries on the Judas Priest ruling. Most of the post-trial controversy has concerned the question of First Amendment protection for subliminal messages. If such surreptitious manipulation is ineffective, then First Amendment protection from it becomes moot. Judging from legal scholars’ commentary on Justice Whitehead’s rulings, his understanding of the scientific issues was no worse than the rest of the legal community’s (cf. Blen 1992; Dee 1994; Locke 1991). Similar to the judge’s description of subliminal stimulation, legal commentators’ reviews contain copious references to Key, Vicary, and other nonscientists whose backgrounds are anything but scientific. Key’s books constitute quintessential pseudoscience; they contain no citations, no references, and no documentation for any of his proclamations. While Key’s testimony per se does not appear to have been of much significance at the trial, his extravagant and well-publicized claims had had twenty years to infiltrate the North American psyche (including the legal profession’s), where scientific literacy is not a dominant feature (Burnham 1987).

In the final analysis, however, it was not the obvious pseudoscience that misled the court as much as the misleading opinions of the well-qualified expert-Shevrin. His views, while imaginative and logical, were anomalous with prevailing scientific understanding of the phenomenon at hand. A long resume and a prestigious affiliation are no guarantee of a scientifically valid opinion. An expert whose testimony is unique, idiosyncratic, and unconfirmed by the broader scientific community is not educating the court in the way that Frye v. United States (1923) intended or that more recent rulings have encouraged (Daubert v. Merrell Dow Pharmaceuticals 1993; R. v. Mohan 1994). These recent rulings have emphasized the need for expert testimony to be reasonably well grounded in theories, methods, and procedures that have been accepted and validated by other scientists in the same field. It is not at all clear that Shevrin’s testimony met this standard. It is clear, however, that the courts are generally ill-prepared to meet the challenge of evaluating the scientific validity of expert evidence (Miller, Rein, and Baily 1994), especially in the social sciences (Richardson, Ginsburg, Gatowski, and Dobbin 1995). A rigorous application of Daubert’s admissibility criteria might well disallow any testimony based on Freudian principles because of its inherently unfalsifiable nature (Crews 1995). The need for systematic judicial education on scientific principles is now a recognized priority. Eventually, improved scientific understanding will result in more equitable court rulings. In the meantime, as long as the legal community’s scientific literacy skills are so little able to permit distinctions between sense and nonsense, the public will continue to be entertained by (and foot the bill for) trials like that of Vance v. Judas Priest.

References

• Blen, B. 1992. To hear or not to hear: A legal analysis of subliminal communication technology in the arts. Rutgers Law Review 44: 871-921.
• Block, M. P., and B. G. Vanden Bergh. 1985. Can you sell subliminal messages to consumers? Journal of Advertising 14: 59-62.
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Note

1. This paper is based, in part, on presentations at the annual conference of the Committee for the Scientific Investigation of Claims of the Paranormal, held in Seattle, Wash., June 25, 1994. (Symposium title: Influencing Beliefs in the Courtroom: Rules of Law, Expert Testimony, and Science), and at the Ontario Criminal Lawyers Association annual conference, Toronto, October 27, 1995 (Session title: Deceptive Research: Good Science/Bad Science).

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.”