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

RESULTS

Twenty - one subjects were tested on the pair of tapes from Company A, and 16 subjects for each of the pairs from Companies B and C. The male/female breakdown for the three groups was 12/9, 7/9, and 8/8 respectively. For companies B and C, tapes within each pair were identical with respect to tone, speed, volume, and supraliminal content. Consequently, better than chance identification accuracy would indicate that subjects were responding discriminatively to the subliminal content, thereby providing evidence for subliminal perception. One could theoretically expect above chance performance on Company A tapes if listeners had been able to exploit the non - subliminal information contained in the audible portions of the speech signal.

Although Company A claims that the listener "will not consciously hear any spoken words on the tapes", most participants indicated that they heard what sounded like an electronically modified voice at different times during the testing. Single words or phrases were reported by a minority of listeners. For example, the phrase 'stop smoking' and the word 'eating' were each reported four times. No detectable speech sounds were reported for participants who listened to tapes from Companies B or C.

A group mean of 100 represents a chance level of accuracy for each block. The data were analyzed in a 3(Group) x 2(Sex) x 2(Blocks) analysis of variance. There were no main effects and no interactions (F's

DISCUSSION

Inasmuch as reliable evidence for subliminal perception has only been found under conditions that permit stimulus discriminability, the tapes tested here did not meet this minimal condition for demonstrating subliminal perception. Because the sample of tapes used in this study may not have been representative of all commercially marketed self - help tapes, the preceding conclusion may not apply to the entire population of such devices. It is noteworthy, however, that one of the pairs of tapes contained a 'subliminal' signal that was often detectable and occasionally intelligible. Subjects were nevertheless unable to make the necessary discrimination. It is important to emphasize that even if the tapes had been found to contain discriminable messages, it would not follow that those messages would have any motivational impact. The failure of these materials to provide subjects with sufficient information to permit discrimination makes it most improbable that there could be any behavioural consequences.

An advocate of the effectiveness of the tapes might argue that the preceding test is irrelevant because participants were not using the tapes under typical conditions, nor were they motivated to change the behaviours the tapes were designed to remedy. The intended therapeutic effects, however, are purportedly brought about by the perception (albeit unconscious) of specific affirmations contained on the tapes. If the subliminal content induces the requisite semantic activity, then respondents should be able to exploit that information when engaged in a forced - choice task. If, after 400 trials (with feedback on each trial), respondents are nevertheless at chance in distinguishing one tape from the other, it is a reasonable inference that the messages did not trigger any perceptual activity - conscious or otherwise.