Synesthesia

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Synesthesia

• Patricia Averill, C. Dillon Martin Hall

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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

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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 oclock), Feb (12), etc...
• Robert (apple pie), Jane (orange juice)

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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

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Types of Synesthesia

• Grapheme Color

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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!"

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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

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Types of Synesthesia

• Music Color

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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

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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)

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Types of Synesthesia

• Lexical Gustatory

Absolute - Tangerines Gallery - White
Chocolate Register - Pork Pie Filling Academy
- Thin Chocolate Bar Rent - Cabbage Accept - Egg
Yolk, Hard Require - Milk, Condensed Acid - Acid
Drops Gate - Bacon, Cold Reservations - Mars
Bar Acquire - Milk, Condensed Gillian
- Tongues Reserve  - Mars Bar   Acrobat - Choc.
biscuit thick  Glad - Potato, Sliced Adams
- Tomatoes, Tinned Glasgow  -  Milk 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 -CarrotsGreat -Grapes Roger
- Pork Pie Filling Aeroplane - Chocolate,
Dark Greed - Cabbage Rope - Bread Crust Grimsby
- Fruit Gum, Horrible Ross - Cornflakes, mlk
sgr Grip - Grape Skin Route - Pickled
Beetroot Ago - Meat Loaf Group - Grape Agree
- Cabbage Guess - wafer biscuits Safety - Toast
lightly butterd



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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

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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

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Historical Theories about Synesthesia

• Is it learned?
• once suggested that colored fridge magnets caused
  a learned association
• doesnt explain forms other than Grapheme
  Color
• Doesnt explain historical accounts before the
  prevalence of colored fridge magnets

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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

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Two Main Types Of Synesthesia

• Lower Level
• Fusiform Gyrus
• Higher Level
• Angular Gyrus

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Lower Level Synesthesia
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Higher Level Synesthesia
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Low Level Synesthesia Pop-Out Effects
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Low Level Synesthesia Pop-Out Effects
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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 lower level synesthetes, the Roman numeral
  will not appear in color

5 and V
For Example
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Fusiform GyrusThe Cross Activation Hypothesis
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Angular GyrusConcept Metaphor
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Booba Kiki Experiment
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Synesthesia as an Altered State?

• Lack of Pruning (Selectively or Globally)
• Artists and Poets
• Greater prevalence among them
• Relation to metaphor?
• Schizophrenics

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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

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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

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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

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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/w
  iki/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/prese
  ntations/ramachandran/player.html
• Duffy, P. L. (2001). Blue Cats and Chartreuse
  Kittens How Synesthetes Color their Worlds. New
  York Henry Holt Company