Having finished "Harry Potter and the Half-Blood Prince," I'm now reading a fascinating nonfiction book by Richard Cytowic, MD, called "The Man Who Tasted Shapes." It's about synesthesia, a rare condition -- exhibited by only about 10 people in a million -- where the senses are commingled in such a way that people hear colors or (as the book title suggests) taste shapes. The condition is involuntary and consistent, not a result of drug use or delusion, and seems to be a subjective experience.
Given the rarity of the condition (and the likely reticence to discuss it), it's not surprising that I've never known or met any synesthetes. But I would love to hear a firsthand account or description of what their reality is like. Anyone have any experience with this phenomenon? Please feel free to comment.