Why many scientists are skeptical against subliminal effects?

There was already a legitimate scientific discussion over whether subliminal effects indeed takes place or not. The main question was whether people can perceive unconsciously. Many types of experiments were developed to demonstrate that we are perceiving something without being aware of it.

Scientific researchers flashed words very fast, and the test subjects could not see anything. After that, the researchers also tested the subjects to verify whether they perceived somehow the material they could not "see." They discovered that the material could be detected, however they couldn't reach a conclusion on whether it have been seen, or whether they were somehow mistaken, or the test subjects were lying about not having seen the flashed words.

The methodological and semantic difficulties have made this topic a joke, except perhaps to a handful dedicated researchers. These researcher are studying perception and could have come to the conclusion that "subliminal perception" is actually an oxymoron.

First of all and highly influential among the critics is Charles Eriksen, who discovered several weaknesses in this concept. The critique was devastating, however not completely conclusive. On the one hand, he regarded subliminal effects as a somehow logical contradiction in terms rather than an scientific question. On the other hand, he could not see any difference between first normal verbal reports of discrimination of stimuli and second conscious awareness of this stimulus.

Charles Eriksen considered experiments in the field as "failed" if the test subject were somehow aware of these stimulus by discriminating them in a verbal test. He deemed irrelevant the report of test subjects that claimed that they couldn't see these stimulus. This basic differenciation turned out to be essential to our dicernment of perception, so to explain processes like perceptual bias and illusions or subliminal effects. The criticisms of Charles Eriksen and others was essential for later improvements in the methodology, and for the acceptance of these phenomena.

So we can say that the experiments actually "failed" in many cases, whether behavioral measures or introspective of unconscious effects were tested. All these failures were principally a problem of ambiguous interpretations and the failure to integrate existing models and not an abscense of results.

Several people who actually followed the first subliminal research believed the affirmation about the effects of Vicary's "drink coca-cola" projecto. Although Vicary himself estated that it was just a very tiny effect. So to all those more knowledgeable students of psychology and cognitive sciences in the 60's, mostly aware of this controversy in subliminal effects, it all appeared that the main topic of subliminal effects was actually dead. Now, it looked like an urband legend that had been refuted, in contrast to some claims by some minor authors. This was partially true, but not completely the whole picture.

About a decade after Charles Eriksen's harsh critiques, N.F. Dixon also published a summary ofall the research up to that date. Dixon relied on the same information as Eriksen did, however interpreted it quite differently, concluding that without many doubts data was processed without awareness, however that it was a matter of reactions to stimuli that for some reason we could not notice.

This gave some credibility to the affirmations of Wilson Key, who set off a huge wave of fear about subliminal effects. This was built upon the fears created by social critic V. Packard, who had warned against the usage of psychology by advertising companies to produce advertisements. The wave of paranoia continues until this day.

The subliminal effect research has shifted its direction over time, and nowadays it is obvious that the mind do processes data consciously as well as unconsciously. Indeed, we have also discovered that conscious data processing has some distinct characteristics from u conscious data processing, both affectively and cognitively (feeling and thinking).

When we observe some scene, we can notice some figure against a screen background. We can notice just one interpretation at a given time, as demonstrated by different perceptual illusions, like reversible figures. If we bring the scene to our awareness, our mind patterns the stimuli, according to the way we interpret the scene. This is a well-stablished principle of psychology.

However, what the subliminal experiments has demonstrated was that we indeed perceive patterns in the figureas well as in the ground , al though we may not notice the patterns in the ground. Unconscious processing of features does not actually require patterning of figure-ground organizations that conscious processing requires. This is what makes unconscious perception so distinct from conscious processing.

The unconscious processing also involves associations by similarity, rather than only by the meaning we could assign a message if we noticed the background of the image. This is known as "primary process" which psychologists attribute to our "unconscious mind."

Some unnoticed words can actually undergo semantic and lexical analysis (although this is limited), or unnoticed images can trigger motivational states or even influence preferences in case of ambiguous decisions. This is the basis of the later affirmation that advertising companies could have embedded images in some ads that would have some influence on us. However the question is how lasting or how strong an influence like this can be, and how much can be reach with it.

We must remember that the foundations of this theory appeared in the early 70's with a revival of a movement that was known as New Look. This New Look arose from the work of J. Bruner and others in the 40's and late 50's who studied the effect of values and needs on our perception.

The most influential studies of subliminal effects experiments in science were accomplished by M. Marcel, using masking to demonstrate lexical priming. Criticisms of Marcel's work were met by improvements in his methodology, until the critics could be convinced of the possibility of subliminal perception.

Unfounded accusations of some scientific evidence by companies selling subliminal tapes have contributed to the atmosphere of skepticism, as have the claims of a conspiracy to cover up research data.

We should not just discount the fear people feel in considering the possibility that unheard or unseen messages can influence them. All this could be a reason for skepticism, however not a reason to avoid building and studying upon the research.