Fisher’s demonstrations were decidedly on the informal side, and a generation ago experimental psychologists would have reacted to these data with a torrent of methodological criticisms. At that time, the smart money was aligned against the reality of subliminal effects. In more recent years, however, there has been a veritable sea change in the mainstream, and these types of effects, in a variety of guises, are readily accepted and produced in the laboratory (e.g., Bergh & Chart and, 1999; Bornstein & Pittman, 1992; Redeye, 1970, 1996).
The change in the Zeitgeist from extreme skepticism to everyday acceptance has not yet been fully harmonized in the scientific literature. This may be seen in a special issue of Psychology and Marketing (Moore, 1988), devoted to subliminal advertising, in which the contributing experts simultaneously question the effectiveness of (gizmo) subliminal advertising while underscoring the reality of subliminal perception effects in the laboratory.
In recent times, the focus in the experimental psychology of subliminal processes has been shifting from the methodological to the conceptual. A wide band of subliminal effects, including those of the P ¨toll-Fisher variety, can be reliably produced with rigorous methodology. But what do we mean by “subliminal” in these cases? For example, if the subject fails to report a stimulus (e.g., bird), does this mean that the subject has no awareness of the stimulus?
Is awareness an either-or state? Is there, in other words, a true threshold or limen such that a stimulus intensity below this limen fails to produce awareness but at or above this limen yields awareness? Almost all contemporary experimental psychologists would now espouse the position that there is no true limen except as a statistical abstraction.
As the stimulus is gradually intensified, the probability of its perception increases gradually (in an oval fashion). There is no step-function cleaving perception into two distinct states, detect and no detect. Thus, if we hew to the classic threshold or limen concept, we must adopt a statistical conception (e.g., the threshold/limen is the stimulus value at which the probability of detection reaches,