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Subliminal FAQ
by Todd Stark

"What are subliminal messages, and how do they affect us ?"

The term subliminal was controversial for a long time, and is today
commonly used in a number of different ways.

There have been many methodologically sound scientific experiments
performed over the years to test the limits of perception in various ways
and determine whether messages can be concealed from our awareness, yet
still influence our behavior.

Many of the influences that are branded as "subliminal" by popular
literature are simply messages that are encoded in non-obvious ways, or
played backwards, or such as images hidden in larger pictures, or subtle
non-verbal messages in body language.

Hidden images can sometimes affect us on an emotional level, although the
effect is very general, and unconcealed images are generally more
effective and therefore are more commonly used in advertising today.

Messages played backwards might conceivably be recognized, but have
never been found to have any special power to influence us.

More interestingly, we are particularly well adapted to interpret human
body language, and there are indeed a number of undetected signals that
we send each other that can have social consequences.

This has some applicability to hypnosis theory, but would require a
separate article.

The type of "subliminal" messages most closely related in popular
literature to hypnosis are the "too brief" or "too faint" messages.
These are closer to actually being "subliminal" by virtue of being
flashed too briefly or played too softly (or acoustically masked in
some manner) to recognize consciously.

For this case, the quick answer is that certain subliminal perception
phenomena,especially visual, are real and replicable in experiments.

The practical difficulties in using them make it extremely unlikely
that they are widely used today as propaganda tools, but some experts
contend that this possibility exists at least in the future.

Experiments so far demonstrate that a certain limited amount of
language processing can occur with very brief exposures, that
momentary emotional responses can be created and even built into
temporary motivational states from briefly flashed messages, and that
repeated exposure to an arbitrary picture flashed briefly can influence
us to prefer that picture over others in subsequent tests.

The effects are still subtle enough however that they are not
particularly alarming, nor do they appear to pose any great threat to
our autonomy, particuarly as compared to more powerful non-subliminal
forms of propaganda.  Those very important forms of influence are
described in great detail in two excellent books:  Robert Cialdini's
classic Influence, and Pratkanis and Aronson's "Age of Propaganda."
Here are more details about subliminal influence:

1.  There is scientific evidence for perception without awareness of
various types. Most of the evidence concerns visual images flashed at 
approximately5ms duration, which is sufficiently brief that  most people do not
report awareness of the image.  Some of it concerns "hidden" phalluses
or other sexual symbols in visible images.  There is evidence that such
images actually were used at one point by advertisers, but no evidence
that it was as effective or more so than easily visible sensuous
images.

The subliminally flashed message type of research began in the 1950's,
when the tachistoscope (image flashing device) first began to be used
widely for research purposes.  At that time, many claims were made
for subliminal effects which turned out later to be false or greatly
exaggerated.  The most famous "study" conducted by marketing
consultant James Vicary actually turned out to be a probable hoax.
However, later work did verify that it is possible to perceive various
kinds of stimuli without awareness, and that under the right conditions,
they might be able to have lingering effects on us.  The most detailed
and scholarly reviews of this work that I've seen so far were published
by Robert Bornstein at the University of Gettysburg.

2.  There are two types of subliminal visual effect studied :  the
effects of "mere exposure" on attitude toward an image, and the effects
of drive-related stimuli on temporary motivation.

These are reviewed in great detail by Robert Bornstein, as above. A 
psychoanalyst named Silverman was able to demonstrate that he could produce 
therapeutically useful temporary motivational effects usingFreudian 
drive-related fantasy messages that were not perceivedconsciously.
Bornstein and others have been able to show that subliminal exposure
to an image can increase our preference in picking that image out of
a group of images.

3.  There is no replicable evidence that useful verbal hypnotic
suggestions can be delivered in this manner, and much evidence that
the most effective hypnotic suggestions require active attention and
more sophisticated language processing, as well as establishing
appropriate expectations and psychological state.  This is true even
if aspects of our experience are "unaware" because of the focused
attention during hypnosis.  The unawareness is for a different reason
in hypnosis and subliminal messages, and has very different
psychological properties.

Subliminal perception provides a "weak signal" that can have subtle
influence but is not generally interpreted as a command in any way,
thus limiting what can be done in this way.  Also, complex subliminal
phrases are not processed, only simple one and two word phrases.
Subliminally delivered (briefly flashed) visual messages do bypass
critical analysis in some sense, as hypnotic suggestions do, and are
processed with some degree of lexical analysis, but the amount of
processing is limited by the brief exposure.  The strongest effects
are Silverman's drive-related motivational effects, and Bornstein and
Zajonc's mere exposure effects.

4.  There is no replicable experimental support at this time for the
claimed effectiveness of commercial subliminal audiotapes, although
there is much less research here than with tachistoscopic subliminal
images.  Every carefully conducted independent study performed so far
on subliminal audio tapes has found any behavioral effect to be either
explained entirely by expectancy, or mediated by expectancy to the
point where the effect was negligible if the person was not already
motivated to change their behavior.

So, the strongest subliminal self-help effect shown is at best
reinforcement of existing motivation.   The value of such an effect
is questionable except in very specialized uses because of the fact
that non-subliminal reinforcement methods are generally far more
effective.

The best known writings in this area are by perceptual psychologists
Timothy Moore, and (Anthony Greenwald, and Sean Draine), who have
separately reviewed the evidence around commercial subliminal
audiotapes and performed independent research as part of their work
in perception, and all come to similar conclusions.  So far, they have
not found any evidence with any brands tested for a replicable
perception effect, much less a lasting effect on behavior.

Commenting on the above situation, Robert Bornstein, an advocate of
subliminal mere exposure and subliminal psychodynamic drive stimulus
effects, agrees that subliminal "Eat Popcorn, Drink Coke" type
messages simply don't work the way it was claimed.  Which implies
that he believes that the kind of messages ostensibly delivered by
subliminal audiotapes also do not work.  He believes however that
messages could potentially be crafted, with much more sophisticated
technology and influence techniques (not arbitrary suggestion), that
would influence our attitudes and motivations in subtle ways.

It is my own opinion after reviewing the claims by subliminal
audiotape manufacturers in great detail and following up on the
references they provide that none of them has yet demonstrated the
efficacy of their product beyond expectation effects (placebo), and
that giving them great leeway in interpreting their own evaluations,
we find only a subtle effect on behavior at best.

Also, I have found no good evidence that we can learn new concepts
subliminally.  The two known subliminal perception effects for
tachistoscopic experiments have to do so far with altering our
attitude toward an image or producing temporary emotional responses,
thus potentially influencing cognitive processes in subtle and
somewhat unpredictable ways.

Some of the better published resources :

London psychology professor Norman Dixon's "Subliminal Perception:
The Nature of a Controversy," 1971, from McGraw Hill reviews all of
the pertinent research as of 1971.
Bornstein, R. F., & Pittman, T.S. (Eds.) (1992). Perception without
awareness: Cognitive, clinical and social perspectives. NY: Guilford
Press.

A review can also be found in the popular cognitive psychology text:
Eysenck M & Keane M, "Cognitive Psychology: A Student's Handbook,"
1990, pp. 77-84.

A recent Science article describes evidence for momentary (100 mS)
subliminal priming using visually masked words and a new response
window technique : Greenwald, Draine, and Abrams, (1996) "Three
Cognitive Markers of Unconscious Semantic Activation," _Science_,
Vol. 273, No. 5282, issue 20, pp. 1699-1702.

A previous experiment used physiological markers to show evidence
of subliminal perception of drive-related (emotional) stimuli;
Masling, Bornstein, Poynton, Reed, Katkin, (1991), "Perception
without awareness and electrodermal responding.  A strong test
of subliminal psychodynamic activation effects."  Journal of Mind
and Behavior, 12, 33-48.

Here are some web resources :

Greenwald and Draine technical articles on Sean Draine's page :
        http://weber.u.washington.edu/~scd/psych/papers.html
A non-technical article on a skeptics page :
        http://psg.com/~ted/bcskeptics/meetings/Mt940907.html
A page of related references :
        http://www.utexas.edu/coc/adv/research/biblio/Subliminal.html
A critical review online (mine): 
        http://www.actwin.com/NLP/random/sublm00.htm
Pages related to Robert Bornstein and mere exposure :
        http://www.gettysburg.edu/~ptaylor/bbornste/sheet.html
        http://www.gettysburg.edu/~s366165/BORN2.html
        http://www.gettysburg.edu/~s366165/EXPO.html
        http://www.gettysburg.edu/~s365942/SUBLIM2.html
        http://www.gettysburg.edu/~s334383/PSYCHPRO.html