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STUDY
Vokey & Read
Upcoming
• Memes (Richard Dawkins) next class
• Idea journals due next class
• Review session Monday next week
11am (probably in this classroom – stay
tuned for details)
• Final exam Tuesday/Wednesday next
week
Two Themes
• What were the two themes of this
article?
Two Themes
• What were the two themes of this
article?
1. Do so-called subliminal messages work?
2. Is it possible that not all “messages” were
put there by evil rock stars (or Satan)?
Subliminal Messages
• What two kinds of subliminal messages
do the authors investigate?
Subliminal Messages
• What two kinds of subliminal messages
do the authors investigate?
– “backmasking” - backwards messages in
songs
Subliminal Messages
• What two kinds of subliminal messages
do the authors investigate?
– “backmasking” - backwards messages in
songs
– words embedded in the background of
images
Backmasking
• “Backmasking” is not backward masking
(if you’re going to argue that some
perceptual phenomenon is the work of
Satan, at least get the name right)
Backmasking
• “Backmasking” is not backward masking
(if you’re going to argue that some
perceptual phenomenon is the work of
Satan, at least get the name right)
• controversy in the 80’s - subliminal
“backmasked” messages in rock music
Backmasking
• Examples of Gary Greenwald’s
demonstrations (warning: you are about
to hear a backmasked “message”)
Forward
Backward
Does Backmasking Work?
• What can subjects tell about backwards
messages?
Does Backmasking Work?
• What can subjects tell about backwards
messages?
– Sex of the speaker
– Language (barely)
– Different speaker (barely)
Does Backmasking Work?
• What don’t backwards messages
convey?
Does Backmasking Work?
• What don’t backwards messages
convey?
–Meaning
Does Backmasking Work?
• Some Examples of the experiments that
Vokey & Read did:
• Subjects were presented with various
phrases played backward. Subjects were
unable to:
– Accurately discriminate between questions and
declarations
– Sort sentences into the category of message (i.e.
satanic, christian, nursery rhymes, etc.)
Does Backmasking Work?
• The meaning of backmasked messages
is not consciously perceived (sufficiently
to enable performance on these tasks).
• Might such messages still influence
behavior?
Does Backmasking Work?
• Priming by backmasked message?
Does Backmasking Work?
• Priming by backmasked message?
• Subjects presented with passages that use
the less common of two homophones tend to
use that word when asked to spell it
– e.g. climbing Mt. Everest is an incredible feat
Does Backmasking Work?
• Priming by backmasked message?
• Subjects presented with passages that use the less
common of two homophones tend to use that word
when asked to spell it
– e.g. climbing Mt. Everest is an incredible feat
• Subjects heard backwards sentences containing
uncommon words
If backwards messages have
subliminal influence, what would you
predict?
Does Backmasking Work?
• Priming by backmasked message?
• Result: there was no biasing of the less
frequent homophone by exposure to it
in a backward message
Does Backmasking Work?
• Priming by backmasked message?
• Result: there was no biasing of the less
frequent homophone by exposure to it
in a backward message
• Interpretation: backmasked messages
are not effective at influencing behavior
Does Backmasking Work?
• Priming by backmasked message?
• What are some counterarguments one
might make?
Does Backmasking Work?
• Priming by backmasked message?
• What are some counterarguments one
might make?
– Perhaps repeated exposure is necessary
Does Backmasking Work?
• Priming by backmasked message?
• What are some counterarguments one
might make?
– Perhaps repeated exposure is necessary
– Null findings do not prove the absence of
an effect
Does Backmasking Work?
• Priming by backmasked message?
• What are some counterarguments one
might make?
– Perhaps repeated exposure is necessary
– Null findings do not prove the absence of
an effect
• one needs to know the statistical power
Are All Subliminal Messages
Intentionally Inserted?
• These messages tend not to be clear
and obvious
Are All Subliminal Messages
Intentionally Inserted?
• These messages tend not to be clear
and obvious
• Could it be that our brains mistakenly
see or hear messages that aren’t really
there?
Are All Subliminal Messages
Intentionally Inserted?
• These messages tend not to be clear
and obvious
• Could it be that our brains mistakenly
see or hear messages that aren’t really
there?
• Do brains make stuff up!?
Are All Subliminal Messages
Intentionally Inserted?
• These messages tend not to be clear
and obvious
• Could it be that our brains mistakenly
see or hear messages that aren’t really
there?
• Do brains make stuff up!?
Absolutely! All the time.
Are All Subliminal Messages
Intentionally Inserted?
• Is there really a dog
or are the spots
enough like a dog for
your brain to fill in the
rest?
Are All Subliminal Messages
Intentionally Inserted?
• Some other examples brains making
guesses with your perception
• Missing fundamental, color constancy, Kaniza
triangle,the blindspot, illusory conjunctions,
misinformation effect, false memories
Subliminal “Messages” Where
you Least Expect Them
• How did Vokey and Read test the idea
that subliminal messages might just be
a case of mistaken perception?
Subliminal “Messages” Where
you Least Expect Them
• They examined passages from various
sources (Jabberwokey and the 23rd
Psalm) played backwards to identify
candidate messages
The “subliminal” message is:
Subliminal “Messages” Where
you Least Expect Them
• They examined passages from various
sources (Jabberwokey and the 23rd
Psalm) played backwards to identify
candidate messages
The “subliminal” message is: “saw a girl with a weasel in her mouth”
Subliminal “Messages” Where
you Least Expect Them
• Listeners were given each passage
(backwards) and asked to listen for 12
possible messages
• Listeners detected “messages” in the
appropriate passage
Subliminal “Messages” Where
you Least Expect Them
• Interpretation: Your brain is remarkably
good at “active construction” of patterns
amid a background of noise.
Subliminal “Messages” Where
you Least Expect Them
• Interpretation: Your brain is remarkably
good at “active construction” of patterns
amid a background of noise.
• Creative listening by (well-meaning?)
public censors can go very wrong
Subliminal “Messages” Where
you Least Expect Them
• Consider the trial of Judas Priest
– Band sued for inserting the message “do it”
which allegedly lead to the suicide of two
teens
Listen for “Do It”
The “do its”
Subliminal “Messages” Where
you Least Expect Them
• Consider the trial of Judas Priest
– Band sued for inserting the message “do it”
which allegedly lead to the suicide of two
teens
• Band acquitted on the basis of expert
testimony
Expert Testimony !
Subliminal “Messages” Where
you Least Expect Them
• With enough creativity
and patience one can
see “subliminal
messages” just about
anywhere:
Subliminal “Messages” Where
you Least Expect Them
• Our perceptual mechanisms are great at extracting
meaningful images from noisy stimuli. For example the famous face on Mars:
Viking, 1976
Subliminal “Messages” Where
you Least Expect Them
• Given a clearer picture it looks a lot less
like a face:
Mars Global
Surveyor, 2001