Synesthesia

1. Synesthesia • Patricia Averill, C. Dillon Martin Hall

2. 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

3. 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: • 12345 etc... • Jan (11 o’clock), Feb (12), etc... • Robert (apple pie), Jane (orange juice)

4. 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

5. Types of Synesthesia • Grapheme Color

6. 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!"

7. 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

8. Types of Synesthesia • Music Color

9. 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

10. 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)

11. 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 ?

12. 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

13. 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

14. 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

15. 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

16. Two Main Types Of Synesthesia • Lower Level • Fusiform Gyrus • Higher Level • Angular Gyrus

17. Lower Level Synesthesia

18. Higher Level Synesthesia

19. Low Level Synesthesia: Pop-Out Effects

20. Low Level Synesthesia: Pop-Out Effects

21. 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 5andV For Example:

22. Fusiform GyrusThe Cross Activation Hypothesis

23. Angular GyrusConcept & Metaphor

24. Booba Kiki Experiment

25. Synesthesia as an Altered State? • Lack of Pruning (Selectively or Globally) • Artists and Poets • Greater prevalence among them • Relation to metaphor? • Schizophrenics

26. 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

27. 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

28. 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

29. 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