Synesthesia (sin-es-thee-zha) is one of the strangest and most interesting things the brain can do. People with synesthesia experience their senses tangled together - when one sense gets a signal, another fires too. It happens involuntarily, automatically, and the connections are usually consistent across a person’s entire life.
The most common types include grapheme-color synesthesia, where every letter or number has a specific color (A is permanently red, 7 is always blue). Chromesthesia - where sounds trigger colors - is also well known, especially among musicians. Some synesthetes “taste” words, “see” months in three-dimensional space around them, or experience touch on their bodies when they see someone else being touched.
About 4% of the population - roughly 1 in 25 - has some form of synesthesia. It often runs in families, suggesting a genetic basis. Famous synesthetes include musicians Pharrell Williams and Billie Eilish, painter Wassily Kandinsky, and physicist Richard Feynman, who saw equations in colors. For them, the world has extra layers.
