Wednesday Is Indigo Blue

How the extraordinary multisensory phenomenon of synesthesia has changed our traditional view of the brain.

A person with synesthesia might feel the flavor of food on her fingertips, sense the letter “J” as shimmering magenta or the number “5” as emerald green, hear and taste her husband''s voice as buttery golden brown. Synesthetes rarely talk about their peculiar sensory gift—believing either tha...