Seeing Numbers, Tasting Words

From Wiki­pedia:

Syn­es­thesia […] is a neur­o­lo­gic­ally based phe­nomenon in which stim­u­la­tion of one sensory or cog­nitive pathway leads to auto­matic, invol­un­tary exper­i­ences in a second sensory or cog­nitive pathway. People who report such exper­i­ences are known as synesthetes.

I’m always looking for more inform­a­tion on syn­aes­thetic exper­i­ences as its a phe­nomenon that seems very dif­fi­cult to effect­ively describe, or portray. A few weeks ago I saw a pretty good doc­u­mentary exploring the science behind the phe­nomenon (the tran­script is avail­able on the BBC’s Science website, but not the pro­gramme itself), but I watched it I was left wanting to know more, just as I had been left wanting to know more after I was first intro­duced to synath­aesia in sec­ondary school by Miss Porter, my Media Studies teacher. Let me know if you’ve come across any good books, doc­u­ment­aries, or articles.