Subliminal self-help auditory tapes: an empirical test of perceptual consequences (Appraisal of claims of subliminal effects of commercially available tapes)

Canadian Journal of Behavioural Science, Jan 1995 by Moore, Timothy E

Almost all of the dozens of tapes examined for this study shared a common format in that the only consciously perceivable sounds on the tapes consisted of music, ocean waves, and the occasional bird cry. The tapes from Company A, however, differed from the others in that speech - like sounds were sometimes noticeable. It was therefore possible that participants listening to these tapes would respond discriminatively on the basis of consciously perceivable words or phrases.

Procedure

Participants were tested individually in a quiet basement laboratory. Sound excluding headphones eliminated any extraneous noises. Successive 5 - second samples from two different tapes were presented, and subjects were asked to identify their respective sources (i.e., "Was it tape A or tape B?"). Subjects were given a fairly complete explanation about the purpose of the study. Recorded instructions to all participants included the following information:

You will be participating in research that investigates subliminal perception. We are studying peoples' ability to make decisions about information that they may have received without any conscious awareness. To do so, we are asking you to participate in an auditory discrimination test. What I mean by that is that you will be asked to identify which of two different sound tracks you are hearing from one trial to the next. You will be wearing ear phones. Five - second passages from one of two different cassette tapes will be transmitted on each test trial. Your task is to determine which is which. The order of presentation is random. You will be informed about the correctness of your choice after each trial by means of a message on the screen. The tapes will sound similar, if not identical, to one another, but they differ in terms of the subliminal messages that each contains. Thus, even though they sound similar, it is possible that they are discriminably different in some subtle way. If so, you may be able to distinguish one from the other. Even if you are not sure which is which, please make a decision on each trial".

After detailing the procedure, subjects were shown the packaging labels from the tapes, which included all the affirmations claimed by the manufacturer to be present on the tapes(f.2). This information remained available to subjects throughout the testing. Before the discrimination trials began, subjects first listened to 10 seconds from each tape while a message on the screen indicated which tape was being presented.

On each trial, subjects heard a 5 - second sample from either of the two tapes. They indicated their decision as to which tape they had heard by pressing one of two paddle buttons connected directly to the computer. Immediate feedback as to the correctness of their decision was given via the CRT display. Approximately 2 seconds elapsed between feedback presentation and the onset of the next trial.

All subjects received 400 discrimination trials, presented in two blocks of 200 trials each. During each block, both tapes played continuously, while the computer randomly selected 5 - second segments(f 3) from one tape or the other. A different random order was used in each trial block for each subject. Blocks were separated by approximately 3 minutes while the tapes were rewound. The 10 - second sample was included at the beginning of each block. At the end of each block, the computer printed a summary on the screen informing the subject of the number of correct responses during that block.