One thing I’m very interested in are the unexpected and “bizarre” colors you mention some synaesthetes perceiving– colors that are only describable by their relation to other stimuli (ie. a word or sound). The idea that the brain can perceive a color that it cannot label or identify in any other way implies, to me, that it is quite literally “reading” an outside, objective stimuli directly (rather than processing it and creating a subjective model). For a number of philosophical reasons this strikes me as very significant: in essence we are capable of perceiving data that we cannot yet conceive of! Jonah Lerner, in Proust Was a Neuroscientist (highly recommended btw), writes about the ability of the auditory cortex to rewire itself after being exposed to new data– as was seen in Stravinsky’s Rite of Spring, which once caused riots in the streets and is now seen as comparatively tame.

Thanks so much for the link– and I’d love hearing about any other studies you work on!