From: lippard@skyblu.ccit.arizona.edu (James J. Lippard)
Newsgroups: alt.atheism,alt.satanism
Subject: Re: Backward Masking
Date: 9 Apr 92 16:47:00 GMT
Article-I.D.: skyblu.9APR199209474857
 <ogorman.702753753@unix1.tcd.ie><8APR199215152365@skyblu.ccit.arizona.edu> <ROLFL.92Apr9072117@karl.uio.no>
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In article <ROLFL.92Apr9072117@karl.uio.no>, rolfl@karl.uio.no (Rolf Lindgren) writes...
>So far as backward masking goes: There's still the problem: Does it work?
>Is it possible to _change_people's_minds_ using BM?
> 
>Well, there's been done some research on subliminal messages, ie.
>(usually) visual messages that are displayed so fast that you're not aware
>you've seen them.
> 
>These messages have some effect on monopolistic competition. They can't
>make you buy soda pop, but they can direct your choice of brand if you
>were already going to buy...
> 
>I haven't got any sources though, this is what I heard at a lecture. 

I think that the evidence shows that overt advertising is far more effective
at this than subliminal messages.  

There is a psycholinguistics laboratory here at the University of Arizona
where one commonly used experimental design involves the use of a masked
prime.  A word is displayed on a computer screen for a very short period
of time, then replaced by a mask (usually another word), and then by
a test stimulus, for example, a word stem followed by dashes.  The subject
is instructed to complete the word stem.  The word which was initially
displayed (and followed by a mask--this, by the way, is what "backward
masking" means to psychologists) has a significant influence on how
the subject completes the word stem, even though the subject has no
memory of having seen the initial word.  (I've done this experiment
myself as a subject, and my subjective impression was that I saw
*something* very briefly, followed by the mask, but I couldn't tell
what it was that I saw, other than it was a word.)
    It turns out that if the initial word is presented for exactly
the same amount of time (around 50 ms) but without the mask, the word
is quite clearly and easily read.  If the amount of time the initial
word is presented is reduced so that it cannot be seen even without
the mask, then the priming effect disappears.

   This suggests that any subliminal effect in an advertisement which
is going to have an effect on the viewer is going to have to be a
masked stimulus.
   Let me describe one more interesting effect.  The mask itself
can be presented for a short time (around 50 ms) and followed by
yet another mask.  What happens?  The mask "unmasks" the first mask,
and the initial stimulus can be seen.  Somehow, an event later in
time undoes the effect of an event earlier in time.  (Similar
phenomena are described in Daniel Dennett's book, _Consciousness
Explained_.)

>--
>Rolf Lindgren		| 	"The opinions expressed above are 
>616 Bjerke Studentheim	|  	 not necessarily those of anyone"	
>N-0589 OSLO 5		|             rolfl@hedda.uio.no 

Jim Lippard              Lippard@CCIT.ARIZONA.EDU
Dept. of Philosophy      Lippard@ARIZVMS.BITNET
University of Arizona
Tucson, AZ 85721
Xref: sparky alt.atheism:8242 alt.satanism:1332