Since the 1950's, there has been enormous public concern over hidden messages in art, music, and advertising. Subliminal self-help tapes are a multi-billion dollar industry. Yet many psychologists claim that subliminal influence consists at best of uselessly weak effects.
This has variously been described as an elaborate hoax, as a scientific controversy, and as a conspiracy to hide the true story of subliminal persuasion. Is there a true story ? Who is telling it ?
Mosy scientists who study subliminal perception characterize it in terms of
temporary, weak, lexical priming effects. The people selling subliminal tapes take its effectiveness for granted, and sometimes even claim scientific support for their products. Authors like Bryan Wilson Key and Vance Packard helped inspire public scrutiny into advertising practices that could best be labelled as "sorcery" if they work. How big a deal is this subliminal sorcery, really ? Some years ago, the term subliminal came into popular usage to mean nearly any kind of deliberately hidden message.
A series of widely read books and articles made us aware of the possibility that unseen, unheard messages could influence how they think, feel, and act. This is a rightly frightening prospect, made more frightening by the increasing time we sit watching or listening to things produced by people we don't know, with motives we know all too well.
The question is not whether most advertisers would be willing to use "sorcery" to sell products, we know they would.
The real question is in two parts. Does it work ? And if so, is our freedom of thought threatened by it ?
Unfortunately, the issue has become extremely contentious. "Skeptics" claim that "believers" are paranoid alarmists. "Believers" countering that "skeptics" are guilty of complicity with a grand advertising conspiracy to subdue the public.
Many of the sources have claimed that (secret) research conducted by advertisers showed that subliminal influence was an effective tool. They also have claimed that advertisers have been using subliminal techniques on the public.
Reviews of published scientific papers do not support the claims that research had demonstrated subliminal advertising techniques to be broadly effective. That's where the conspiracy claims come in.
Of course it's possible that some "real" research into subliminal techniques is secret, and that no one else has used an effective technique in their testing. You have to evaluate the credibility of this argument for yourself. Even if it is not true today, it could some day become true.
Personally, I don't believe the arguments about conspiracies to hide research. The strongest reason is that so much research has been published about subliminal or marginal perception. There is no gap in this field, subliminal "masking" and "priming" techniques are today used fairly routinely in some kinds of experiments. The conspiracy would have had to be so elaborate and so selective that it just doesn't seem credible.
Then there's another possible resolution to the conflicting claims. "Skeptics" and "believers" may be talking about and emphasizing different things.
Careful experiments have demonstrated that human beings do process information unconsciously. Even more remarkably, evidence has also accumulated indicating that unconscious information processing, unconscious learning, and automatic responding are a normal part of our daily life. They are not effects limited to special states or contrived experimental conditions.
Subliminal experiments may be seen as artificial situations where these unconscious processes are isolated for study.
The experimental subliminal effects themselves are weak and usually relatively temporary. However, this is at least partly because the effect is isolated to purely unconscious influence. It is also at least partly because the influence effects in these experiments are usually not tailored to the personality stucture of the recipient. When stimuli are made more personally meaningful, we seem to get some more potent and more interesting effects.
Marginal perception of stimuli that are more personally meaningful, especially presented in a carefully crafted conscious communication context, can have more lasting and more significant effects on thinking, feeling, and behavior. This is a central principle in hypnotherapy. To combine consciously perceived messages with more subtle ones, reinforcing each other.
Subliminal "believers" interpret this to mean that the experimental conditions themselves make weak use of powerful subliminal effects. Subliminal "critics" interpret it to mean that even under the best conditions of contrived subliminal influence, the effect is still weak. They also point out the negligible support for the most popular form of claimed subliminal influence, subliminal audio tapes.
Both arguments have merit. Subliminal effects by themselves are relatively weak and temporary. They can potentially be used as part of a larger strategy of effective influence, however, just as other weak techniques can combine in their effects. Think about how effective the simple positive reinforcement of a product or candidate name can be, if repeated enough.
It boils down to whether subliminal effects themselves can be exploited under more natural conditions in a more powerful way. Again, here the evidence is weak specifically for subliminal effectiveness
Yet the advocates are persistent and persuasive. Sometimes they are often talking about real kinds of subtle influence that the critics don't really consider subliminal, or consider of secondary interest. And sometimes they are talking about situations where the subliminal effects need only play a secondary, reinforcing role.
Unconscious information processing effects and unconscious bias has always been used by skilled communicators, and can certainly be exploited by advertisers. This sort of influence is both more widespread and less novel than most of us would like to think about. Like hypnosis, it turns out to be largely a way to exploit the manner in which the human mind evolved to deal with the non-verbal subtleties of face-to-face communication.
The potential for propagandists to take advantage of our evolved mental blind spots has always been, and remains, a cause for concern, especially as technology improves our ability to exploit each other. But most forms of influence leave clues, especially if we remain educated about them and use our mind, rather than being paralyzed by fear of the unseen or the unheard.