ble to induce subliminality without gizmos but it is not possible to have gizmo subliminality without psychological subliminality. When P ¨otzl (1917) or Fisher (1954, 1956, 1988) flashed their stimuli and subsequently evaluated soft cognition like fantasy, word-associations, and dreams, they were drawing on the effects not only of the tachistoscope but also of psychological processes that piggybacked on them, such as forgetting. It may be that the tachistoscope functions mainly to speed up psychological degradation of the input. It has been shown with two children (Erdelyi, 1996) that repeated recalls of a story over periods of months can yield the very types of effects (emergence and recovery,
Displacements, condensations, symbolic representations) as those found by P ¨otzl and Fisher in dreams and fantasy following tachistoscopic presentation of the stimulus. The tachistoscopic degradation may be thought of as giving the psychological process a head start. Instead of having to wait for days or weeks for forgetting (and other possible psychological processes) to take their toll on the stimulus, a tachistoscopic flash degrades the stimulus immediately and can produce effects in a brief laboratory session.
There is no general rule that subliminal effects are more powerful than supraliminal ones. It is the case, however, that subliminal communications are sometimes more effective or that they produce different (and more desired) effects than their clearly conscious counterparts. In the various examples of jokes, ads, and art considered previously, we saw that defensive considerations often dictate the mitigation of raw information.
Were the communications not toned down by the various techniques of psychological subliminality, untoward emotional reactions might result in the rejection of the communications, which typically involve primitive (sexual, aggressive) impulses about which we are inevitably ambivalent. We tend simultaneously to be attracted to and repelled by such content.
Subliminalizing the message allows us to have our cake and eat it too: The taboo can be partaken of without full awareness and, therefore, responsibility. Such ambivalence is consistent with the realities of the brain. Different subsystems of the brain represent different neurological constituencies