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Parapsychology >> Subliminal Persuasion
stimulus discrimination, subliminal perception, logical contradiction, methodological difficulties

Why are some experts skeptical about subliminal influence?

Author: Todd I. Stark

© 2/1999 ToddStark@AOL.COM

There was once a
legitimate scientific controversy over whether subliminal perception really occurs or
not.  The question was whether someone can perceive something unconsciously. 
All kinds of experiments were performed to try to prove that we were perceiving something
without awareness of it.

Researchers flashed
messages very rapidly, and their test subjects did not report seeing anything.  Then,
the researchers tested their subjects about whether they "saw" the material they
didn't "see."  They found that it seemed to be detected, but they couldn't
agree on whether it had really been seen or not, or even whether the subjects were lying,
or somehow mistaken, about having not seen the flashed images. 

The semantic and methodological difficulties made the
topic almost a joke, except to a few dedicated researchers. Scientists studying perception
at this point could reasonably have concluded that "subliminal perception" was
an oxymoron.

Foremost and influential among the early critics was href="/perl/,1960">Charles Eriksen (1960, 1962), who pointed out
several significant weaknesses in the concept. His critique was devastating, but not
entirely conclusive. For one thing, he regarded subliminal perception as a logical
contradiction rather than an empirical question. For another, he did not make any
distinction between a verbal report of stimulus discrimination and conscious
of the stimulus.

Eriksen considered experiments "failed" if the
subject was aware of the stimulus by virtue of discriminating it in a test. He considered
the report of a subject that they didn't see the stimulus to be irrelevant. href="/perl/, 1959">(Eriksen, 1959). That distinction turned out later
to be critical to our understanding of perception, in order to explain things like
illusions and perceptual bias as well as subliminal perception. The criticisms of Eriksen
and others (Goldiamond, 1958) were
instrumental in later improvements in methodology, and the eventual acceptance of the

So the experiments all "failed" in some
sense, whether introspective or behavioral measures of unconscious perception were being
attempted.  The failures were more a matter of ambiguous interpretation and failure
to integrate with existing conceptual modeslthan lack of results, however. 

Many people who followed the early subliminal
research credulously believed the exaggerated claims about the effectiveness of
Vicary's "eat popcorn" projector, though Vicary himself
claimed that it was a very weak
influence technique
. So to the more knowledgeable student of psychology in the 1960's,
aware of the controversy in subliminal perception, it appeared that the topic of
subliminal influence was dead.  It appeared to be a hoax that had been debunked, in
contrast to alarmist claims by some authors.  This was partly true, but not quite the
whole story.

About 10 years after Eriksen's devastating critiques,
N.F. Dixon published a comprehensive summary of the research up to that point href="/perl/, 1971"> (Dixon, 1971). Dixon relied on much the same data as
Eriksen, but interpreted it differently, concluding that without doubt information was
being processed without awareness, but that it was simply a matter of responses to
external stimuli that for whatever reason we did not notice.

This lent some scientific credibility to the claims of href="/perl/ (1973). Subliminal Seduction">Wilson Bryan Key, who triggered
a wave of paranoia over subliminal influence. Key followed and built upon the fears
created by social critic href="/perl/, Vance, (1957). The Hidden Persuaders,">Vance Packard,
who had earlier warned about the use of psychoanalysts by advertisers to craft
advertisements. The wave of fear continues to this day.

The subliminal perception
research has shifted direction over the years, and now it has become obvious that the
human mind does process information unconsciously as well as consciously.  We have
also discovered that unconscious information processing has some different characteristics
from conscious information processing, both cognitively and affectively (thinking and

Normally, when we observe a scene, we notice
a figure against a background. We can only notice one interpretation at a
time, as demonstrated by a number of different perceptual illusions, such as reversible
figures. In bringing the scene to awareness, the mind patterns and groups the stimuli,
according to how we interpret the whole scene.
This is a well-accepted principle of
psychology. (Hilgard et. al, 1975).

What the early subliminal experiments showed was that we
perceive patterns in the ground as well as in the figure, even though we may not notice
the patterns in the ground. (Paul &
Fisher, 1959
; Eagle, Wolitzky & Klein,
). Unconscious (or "preconscious") processing of perceptual features
does not require the degree of patterning of figure-ground organization that conscious noticing
requires. This is what makes unconscious processing so different from conscious thought.

The preconscious processing involves association by
similarity of features, rather than by the meaning we would assign if we had noticed the
background image. This is the "primary process" which psychoanalysts attribute
to the "unconscious mind."

Unnoticed words can undergo some lexical and semantic
analysis (though limited), and unnoticed words or images can trigger temporary
motivational states or influence preferences in ambiguous decisions, and can appear as
related images in dreams or free association. This was the basis of the later claims that
advertisers could embed pictures in an ad that would have an influence on us. But the
question has always been just how strong or lasting an influence this is, and how much
could be done with it.

The foundations of this research appeared in the 1970's
with a mainstream revival of a vanguard movement that was sometimes known as the New
. (Erdelyi , 1974) The
New Look movement arose from the pioneering work of Jerome Bruner and others in the 1940's
and 50's who studied the effect of needs and values on perception. href="/perl/ & Klein, 1960, on New Look">(Bruner & Klein, 1960).

Probably the most influential series of subliminal
perception experiments in cognitive science were carried out by Marcel, using pattern
masking to demonstrate semantic priming (Marcel,
. Criticisms of Marcel's work href="/perl/ critical issues, 1992">(Merikle, 1992) were met by
subsequent improvements in methodology, until even the critics were convinced of the
reality of subliminal perception. (Merikle, 1998).

Unfounded claims of scientific evidence by
advertisers selling subliminal audiotapes have contributed to the lingering atmosphere of
skepticism, as have the silly claims of a global conspiracy to cover up positive research

Finally, we should not discount the raw fear many people
feel in considering the possibility that unseen or unheard messages could influence
them.  This could be reason enough for skepticism, but not reason enough to avoid
studying and building upon the extant research.

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