Over at Neurophilosophy, Mo — who has just added Sunclipse to his blogroll! — gives us a nice summary of the neuropsychology of synaesthesia. What makes some people see letters in color, either indelibly in their visual field or vividly in their “mind’s eye”? What causes an association between colors and musical sounds, and why do people experience the “mirror touch” effect, in which a person feels a tactile sensation when they observe another individual being touched? Moreover, if — as it now appears — these phenomena are more common than previously expected, might they in fact be the extremes of a spectrum of variation?
This is all fascinating stuff, particularly to an associative grapheme-color and tone-color synaesthete like me! Does my fusiform gyrus have defective feedback between area V4 and adjacent patches of cortex, and where can I sign up to find out? (I note with detachment that Drs. Rouw and Scholte, who published the evidence for this connection, work at the University of Amsterdam, clearly an interesting place to poke the brain, one way or another.)