Transcript Group 7: Synesthesia

Synesthesia
Patricia Averill, C. Dillon Martin Hall
Presentation Outline
•
•
•
Description
• Definition
• Types, common and otherwise
• Population prevalence
Theories
• Historical Theories
• Neural correlates for Synesthesia
Evidence for Synesthesia as an ASC
• Neuroimaging
• “Pop-out” Effects
• Further Discussion
Synesthesia Defined
• A neurological condition where an observed
stimulus in one sensory modality is involuntarily
associated with a particular stimulus in another
sensory modality
• For Example:
• 1 2 3 4 5 etc...
• Jan (11 o’clock), Feb (12), etc...
• Robert (apple pie), Jane (orange juice)
Types of Synesthesia
• Grapheme
Color
• Letters/Numbers on a page appear to
be shaded by or are associated with
specific colors
• One of the more common forms
• No consistency for grapheme/color
associations across synesthetes
Types of Synesthesia
• Grapheme
Color
Types of Synesthesia
• Grapheme
•
Color
"I was sitting with my family around the dinner table and I don't know
why I said it but I said, "The number five is yellow." There was a
pause and my father said, "No, it's yellow-ochre." And my mother
and brother looked at us like, 'this is a new game, would you share
the rules?' I was dumbfounded. So I thought, "Well." At that time in
my life I was having trouble deciding whether the number two was
green and the number six blue, or the other way around. And I said
to my father, "Is the number two green?" and he said, "Yes,
definitely. It's green." Then he took a long look at my mother and
brother and became very quiet. Thirty years after that, he came to
my house and said, "you know, the number four *is* red, and the
number zero is white. And," he said, "the number nine is green." I
said, "Well, I agree with you about the four and the zero, but nine is
definitely not green!"
Types of Synesthesia
• Music
Color
• Tones or other aspects of musical notes
(key, timbre, etc.) are associated with
specific colors
• Less common than G
C
• Some consistency across synesthetes,
as higher notes appear to be more
brightly colored
Types of Synesthesia
• Music
Color
Types of Synesthesia
• Music
Color
• " The sounds of musical instruments will sometimes
make me see certain colors, about a yard in front of me,
each color specific and consistent with the particular
instrument playing; a piano, for example, produces a
sky-blue cloud in front of me, and a tenor saxophone
produces an image of electric purple neon lights"
-SD
Types of Synesthesia
• Lexical
Gustatory
• Words and names are associated with a
taste or combinations of tastes
• Rare
• Rhyming and syntactic associations
common enough to be occasionally
predictable (e.g. Tony Macaroni, or
Blue Inky flavor)
Admit Smarties
Global Pear Drops
Reveal Meat Jelly, Cold
Adrian Watery, Incomplete
Go Meat Loaf
Reward Turkish Delight
Adventure Mashed vegetables
Good Custard
Risk Milky
Advert Beef Burgers
Gordon Dirt
Robert Jam
? Sandwiches
Grab Bacon, Thick
Robin Jam Sandwiches
Advice Carrots
Great Grapes
Types of Synesthesia
• Lexical
Roger Pork Pie Filling
Aeroplane -
Gustatory
Prevalence of Synesthesia
• Early Data
• between “1 in 20” and “1 in 20,000”
• Questionable collection methods relying on
self-reporting
• Recent Data
• Prevalence of “1 in 23” suggested by
random population study
• Simner et al
Prevalence of Synesthesia
• Tends to cluster in families
• Strongly suggests genetic origin
• Likely “X-linked”, as no father-to-son
transmission ever recorded
• Slightly more common in women than in
men
• 1.1 : 1 ratio, Simner et al
Historical Theories about
Synesthesia
• Is it learned?
• once suggested that colored
fridge magnets caused a
learned association
• doesn’t explain forms other
than Grapheme
Color
• Doesn’t explain historical
accounts before the
prevalence of colored fridge
magnets
Historical Theories about
Synesthesia
• Is it just an overly vivid imagination?
• As with all ASCs, difficult to tell apart from
actual subjective experience
• Test- retest reliability
• Synesthetes: 90% over one year
• Non-synesthetes: 30-40%
• Stroop Effect
Two Main Types Of
Synesthesia
• Lower Level
• Fusiform Gyrus
• Higher Level
• Angular Gyrus
Lower Level Synesthesia
Higher Level Synesthesia
Low Level Synesthesia:
Pop-Out Effects
Low Level Synesthesia:
Pop-Out Effects
Other Effects
• Lower the Contrast
• Colorblind Synesthetes
• Roman Numerals (A Concept)
• Higher level synesthetes will see 5 in the
same color as the Roman numeral V
For Example: 5 and V
• For lower level synesthetes, the Roman
numeral will not appear in color
Fusiform Gyrus
The Cross Activation Hypothesis
Angular Gyrus
Concept & Metaphor
Booba Kiki Experiment
Synesthesia as an Altered
State?
• Lack of Pruning (Selectively or Globally)
• Artists and Poets
• Greater prevalence among them
• Relation to metaphor?
• Schizophrenics
LSD
• The threshold dosage level for an effect
on humans is of the order of 20 to 30 µg
(LSD is extremely potent)
• Doses can be as high as 1,200 µg but
higher doses come with the increased
risk of “bad trips”
• LSD affects a large number of the G
protein coupled receptors, including all
dopamine receptor subtypes, all
adrenoreceptor subtypes and most
serotonin receptor subtypes
• Initially used for psychotherapy
Sensory Effects of LSD
• Users experience Synesthesia
• “LSD does not produce hallucinations in the strict sense,
but instead illusions and vivid daydream-like fantasies.”
• Visual Effects
• movement of static surfaces (walls breathing)
• geometric patterns and an intensification of colors
and brightness
• Schizophrenics do not experience the effects of LSD
Alternate States and
Additional Questions
•
Could LSD be the gateway to the synesthesiac
experience/consciousness?
•
Are synesthetes experiencing the world at a level of
consciousness different from the rest of us?
• Do we all have synesthesia at some level?
• Booba/Kiki
• Metaphor
•
What about schizophrenics…
•
•
they lack the ability to comprehend metaphor
they do not experience the synesthesic effects of LSD
Sources
•
Ramachandran, V. S. & E. M. Hubbard (2001), "Synaesthesia: A window into perception,
thought and language", Journal of Consciousness Studies 8(12): 3-34
•
Simner, J.; C. Mulvenna & N. Sagiv et al. (2006), "Synaesthesia: The prevalence of
atypical cross-modal experiences", Perception 8(35): 1024-1033
•
Wannerton, J. I., “The World of Synaesthesia”, http://www.wannerton.net/
•
Synesthesia - Wikipedia, http://en.wikipedia.org/wiki/Synesthesia
•
Ramachandran, V. S. and Hubbard, Ed (2003), Hearing Colors, Tasting Shapes, Scientific
American, Vol 288 Issue 5 (May 2003), 42-49.
•
Ramachandran, V. S. and Hubbard, E.M. (2001). Psychophysical investigations in to the
neural basis of synaesthesia. Proceedings of the Royal Society, 268, 979-983.
•
Ramachandran, V. S., Lecture,
http://www.nyas.org/ebriefreps/ebrief/000500/presentations/ramachandran/player.html
•
Duffy, P. L. (2001). Blue Cats and Chartreuse Kittens: How Synesthetes Color their Worlds. New
York: Henry Holt & Company