What Is Synesthesia? The Neuroscience Behind Hearing Color

You Should Know: During the Wicked press tour, Cynthia Erivo revealed she has synesthesia, a neurological phenomenon where the senses cross wires. When she hears a musical note, she sees a color. Billie Eilish, Pharrell Williams, Lady Gaga, and Kanye West have said the same.

Going Deeper: There are around 80 known forms of synesthesia, but the most common are grapheme-color (letters and numbers appear colored) and chromesthesia (sound triggers color, what Erivo has). Scientists say it shows up in 2-4% of the population, though many people don’t actually know it’s an unusual experience when it happens to them. The neuroscience behind it is the cross-activation between adjacent brain regions (the area that processes letters is right next to the one that processes color, and there are more connections than usual between the two) and disinhibited feedback, where high-level connections fire more freely than normal. It’s also genetic.

Takeaway: This is a neurological wiring difference in some people’s brains. Synesthetes have sensory blending that’s involuntary, consistent, present from childhood, and stable over time.

Bottom Line: When Erivo says she sees blue when Jennifer Lawrence sings a note, she means it literally.