(Vokey and Read, 1985) mention the "fallacy that presence implies effectiveness" — that "advocates appear to believe that demonstrating the existence of the messages is not merely necessary to the argument but is sufficient as well". They present Gary Greenwald and Bryan Wilson Key as proponents of this fallacy.
Greenwald presents a collection of reversed recordings of rock music to demonstrate the existence of backward messages. From these demonstrations and the alleged presence and presumed effectiveness of subliminal messages in other media such as advertising, Greenwald concludes that listening to such music is having a detrimental effect on young people.
Bryan Wilson Key, the major proponent of the claim that advertisers have
resorted to "subliminal advertising" to influence the buying public, provides an extensive litany of subliminal messages in various print, film, and television
media. Like Greenwald, he presents the "exposed" messages as proof not only that the respective media contain such messages but also that the messages have the intended effect.
As stated by (Vokey and Read, 1985), even if such messages exist, "it does not follow that the messages must be effective".
They tested this by recording sets of messages that had meaning, playing them in reverse to listeners, then asking the listeners to perform tasks that would be influenced by the messages had the listeners been affected by the content of the backward messages.
Taken together with the results of the other tasks, we could find no evidence that our listeners were influenced, consciously or unconsciously, by the content of backward messages.
In a different setting, (Schwartz and Froufe, 2001) studied the effect of intentionally inserted subliminal messages (not backmasked, but present in the signal at a low level) for the goal of improving self-esteem. They found that "there were no statistically significant differences between the placebo group and the subliminal group".
Schwartz, Cecilia, and Manuel Froufe. "Subliminal messages for increasing self-esteem: Placebo effect." The Spanish journal of psychology 4, no. 1 (2001): 19.
Vokey, John R., and J. Don Read. "Subliminal messages: Between the devil and the media." American Psychologist 40, no. 11 (1985): 1231.