(Investigator 195, 2020 November)


Magnetic tape recording apparatus dates back to the latter part of the last century. The idea of storing electrical information was expressed as early as 1888 by Oberlin Smith in an article in The Electrical World.

Although research continued, little was heard by the public of further developments until 1927, when J. A. O'Neill received the first U.S. patent for a magnetic tape. The 1960s saw the first audiocassette recorders on the market, providing a convenient medium for subliminal tapes.

Over the past three decades, the sale of subliminal tapes has burgeoned into a multi-million dollar business. The claims made by promoters regarding the efficacy of subliminal tapes as therapeutic devices have not been substantiated however.


Promoters of subliminal tapes claim that by listening to tape recordings of messages over which a covering sound has been recorded, the subconscious mind can be influenced in a required direction. Consideration of how the brain works however, shows this to be false. Background noises, if they persist long enough, are considered by the brain to be an irritant and are "edited out". The background noises used in subliminal tapes such as rainfall, crashing waves and "nature" sounds, cover a wide frequency spectrum close to what we call "white noise". After a while the sounds simply become background noise and the brain starts the editing process. You become less sensitive to noise and off to sleep you go. Whether or not there is also a message on the tape is immaterial. If you can't hear it, it won't register.

The applications, according to promoters however, are endless, ranging from losing weight to attracting infinite riches.


The tapes can be listened to at any time during the day or during sleep at night.


The promoters and the products promise short-cuts to success and instant panaceas for whatever ails one, ranging from giving up bad habits to building self-confidence, and from improving one's memory to psychic healing. The result has been an industry whose reputation is built to a large extent on worthless testimonials and questionable advertising.

The sale of subliminal audiotapes in America alone exceeds $50 million annually. One auditory tape sold by Potentials Unlimited actually offers to cure deafness.

The grandiose claims made for the products are such that few people, if any, bother to enquire what evidence there is, other than personal testimonials, to support the claims made. Recommendations by those who have used them are suspect due to psychological pressures making it difficult to admit that they have been conned.

There are many reasons why users of subliminal tapes are sincere in their praise. First, there is the desire for self improvement which motivates the purchase, and an implied commitment to the undertaking. This can of itself bring about change and become self-fulfilling. Second, there is the phenomenon known as "effort justification." Research has shown that the harder we work at something, the more we like it. Having purchased and utilised a subliminal tape for some time, most people would justify its use by finding some sort of change in their lives with which to rationalise the purchase.

There is also the placebo effect
a strong expectation by the tape user based on the belief that subliminal messages are potent (Pratkanis, 1992). This misconception was born of a hoax in the 1950s, when it was claimed that imperceptibly brief insertions in a film impelled viewers to increase their consumption of popcorn and Coca-Cola. Cinema runs at 24 frames per second. The countdown numbers that we see at the beginning of a reel are only one frame and can be seen clearly. The Coca Cola message which must have been longer would also have been clearly seen.

In 1958, the Canadian Broadcasting Corporation conducted a test of subliminal persuasion in which the message "phone now" was flashed subliminally on the screen 352 times. Telephone company records indicated no increase in phone calls.

In a study by Greenwald et al (1991), participants were given two disparate tapes
one containing a subliminal suggestion for improving memory, the other for enhancing self-esteem. The tapes were deliberately mixed up so that half the participants received the memory tape instead of the self esteem tape and vice versa. After five weeks of daily home listening there was no discernible change in self-esteem or memory improvement although the participants believed there was. Pratkanis dubbed this an "illusory placebo effect" placebo because it was based on expectations, illusory because no objective improvement occurred.

These results were replicated by Greenwald et al and Auday et al (1991).


Auday, B.C., Mellett, ].L., and Williams, P.M. 1991. Self-improvement using subliminal self-help audiotapes: Consumer benefit or consumer fraud? Paper presented to the Western Psychological Ass., San Francisco. Apri11991.

Chirgwin, Richard. 1990. Subliminal sounds, the Skeptic, 10(4):28-9. Australian Skeptics Inc. NSW

Greenwald, A.G., Spangenberg, E.R., Pratkanis, A.R., and Eskenazi, J. 1991. Double-blind tests of subliminal self-help audiotapes. Psychological Science. 2(2):119-122.

Lippman, Susannah. 1994. The Truth About Subliminal Tapes, Earth Star Publishing, Jolimont, 6913.

Pratkanis, AR. 1992. The Cargo-cult science of subliminal persuasion. The Skeptical Inquirer. 16(3):260-272.

_________________ and Greenwald, A.G. 1988. Recent perspectives on unconscious processing: Still no marketing applications. Psychology and Marketing, 5(4):337-353.

From: Edwards, H. 1999 Alternative, Complementary, Holistic & Spiritual Healing, Australian Skeptics Inc.