Subliminal deceptions - effectiveness of audio tapes with alleged subliminal messages

Science News, August 25, 1990 by Bruce Bower

Subliminal deceptions

Audio cassettes with subliminal messages -- purportedly producing everything from quick weight loss to peace of mind -- haul in $50 million annually. But two new studies suggest the tapes do not work as advertised and in some cases may not even contain subliminal suggestions.

Anthony G. Greenwald of the University of Washington in Seattle and his colleagues studied 237 volunteers who listened to commercially available subliminal tapes aimed at improving either memory or self-esteem. Messages lurked behind audible sounds of ocean waves. The researchers reversed labels on half of the cassettes so that the memory-oriented tapes carried self-esteem labels and vice versa. The remaining cassettes carried accurate labels. Each volunteer completed a series of memory and self-esteem tests before and after using a subliminal tape for mone month.

People who listened to memory tapes showed no more memory improvement than did those who listened to self-esteem tapes; people who used self-esteem tapes reported no more improvement in self-esteem than did volunteers in the memory group. Nevertheless, those who used self-esteem tapes labeled as memory boosters contended that only their memories had improved, while those who used memory tapes labeled as self-esteem enhancers said that only their self-esteem had increased.

At the end of the study all participants scored higher on both memory and self-esteem tests, regardless of which tape they had heard or how it was labeled. These improvements may have been stimulated by the memory, and self-esteem tests administered at the study's outset, Greenwald asserts.

"Placebo" effects critically influence customer satisfaction with subliminal tapes, since many of the mass-marketed cassettes-apparently contain no subliminal message, contends Philip M. Merikle of the University of Waterloo in Ontario. Merikle conducted an acoustic analysis of four subliminal tapes purchased from four different companies. In searching the background sounds for unique energy patterns previously associated with speech, he found no evidence of embedded words or phrases in any of the tapes.

In another test, he asked 24 volunteers to listen to a subliminal tape and a "placebo" tape with no embedded message. Both were supplied by a commercial vendor. Even after 300 trials, participants could not reliably distinguish the "real" tape from the placebo. This, he says, suggests the subliminal tape offered no unconsciously perceived message.