david branganna krasno lee edwardsamanda gorlick cogs 175 6/2/06

David Brang Anna KrasnoLee Edwards Amanda Gorlick

Cogs 1756/2/06

Outline

• 1. Lee - Synesthesia Primer– What it is, relation to consciousness

• 2. David– Video, demographics, evidence, theories

• 3. Anna– Acquired synesthesia, developmental vs. acquired

• 4. Amanda– Conscious understanding - closing remarks

What is Synesthesia?

• Perceptual phenomenon• Grapheme Color• Inducer and concurrent• Developmental synesthetes• No Comorbidity with mental

illness

Correlates to Consciousness

• Can be thought of as an altered state• The world is perceived differently,

relative to non-synesthetes• Cross modal integration• Relevance

Demographics• The majority of synesthetes

report the experience since childhood

• Occurs in at least 1/2000 individuals

• More common in children than adults

• More common in women• Has a genetic basis to it• Theorized 50 separate forms of

synesthesia

Evidence as a Phenomenon

• Test/retest reliability• Similar reports across

cultures and time• PET studies• fMRI studies• Synesthetic Stroop Test

Theories

• Learned association• Awareness• Neural Connectivity

– Neonatal– Cross-wiring

• Disinhibited feedback• Gamma-Binding

Acquired

• Brain damage• Retinitis pigmentosa• Sensory deafferentation• Drugs• Meditation

Developmental vs. AcquiredDevlopmental Acquired

Involuntary Transient experience

Synthetic Perception and Conception

Perception only

Consistent across lifetime

Not verifiable over time

Part of normal consciousness

Not brought into self-awareness

Often unreported Novelty of event communicated

Pop-out Effects

Towards a Conscious Understanding

• Booba and kiki– “Conceptual rightness”

• Synesthesia is present and suppressed in normal individuals, but has the potential to rise to consciousness

• Only consistently part of consciousness in developmental synesthetes

Conclusion

• Altered state is unique to the baseline state of each individual

• Umbrella including autism and other developmental disorders

• Personal reality

References• Baron-Cohen, Simon. (1996) “Is there a normal phase of synesthesia in

development? Psyche, 2(27)• Calkins, M.W. (1893). “A statistical study of pseudo-chromesthesia and of

mental-forms.” American Journal of Psychology, 5, 439-66.• Cytowic, R.E. (1989). “Synesthesia: A Union of the Senses.” Springer Verlag.• Galton, F. (1880). “Visualized numerals.” Nature, 21: 252-256. • Grossenbacher, P.G. & Lovelace, C.T. (2001). “Mechanisms of synesthesia:

cognitive and physiological constraints.” TRENDS in Cognitive Sciences, 5: 36-41.

• Hubbard, Edward M. and V.S. Ramachandran. (2005) “Neurocognitive Mechanisms of

• Synesthesia.” Neuron, 48:509-520.• Lynn C. Robertson & Noam Sagiv (Eds). Synesthesia: Perspectives from

Cognitive Neuroscience. New York: Oxford University Press, 2005. • Maurer, D. et al., (1999). “Cross-modal transfer of shape is difficult to

demonstrate in one-month-olds.” Child Development, 70 (5), 1047-57.

References• Nunn, J.A. et al., (2002). “Functional magnetic resonance imaging of

synesthesia: activation of V4/V8 by spoken words.” Nature Neuroscience, 5: 371-375.

• Paulesu, E. et al. (1995). “The Physiology of Coloured Hearing: A PET activation study of colour-word synaesthesia.” Brain, 118, 661-676.

• Ramachandran, V.S. and Hubbard, E.M. (2003). “Hearing colors, tasting shapes.” Scientific American. May 2003, 53-59.

• Ramachandran, V.S. & Hubbard, E.M. (2000). “Psychophysical investigations into the neural basis of synaesthesis.” The Royal Society, 268: 979-983.

• Rich, A.N, Bradshaw, J.L., J.B. Mattingley. (2004). “A Systematic, largescale study of synesthesia: Implications for the role of early experience in lexical-colour associations.” Cognition. 20(11): 1-32.

• Snyder, S.H. (1986). Drugs and the Brain. New York: Scientific American Library.

• Van Leeuwen, T. (2004) “The neural basis of synesthesia.” <http://bar.psych.ubc.ca/PDF/VanLeeuwen04_synpaper.pdf> May 28, 2006.

• Walsh, R. (2005). “Can synesthesia be cultivated?: Indications from surveys of meditators.” Journal of Consciousness Studies, 12, 5-17.