When you hear the word love, does it taste like fresh ink and soft paper? When you see the number 4, does it burn a deep orange in your mind's eye? Does the letter E glow lime green above the page ...

In the 19th century, they called it “colored hearing”—letters and words, when spoken, took on mental weight and shimmered with color in the mind’s eye. For Miss C., who was interviewed in 1892, “n” ...

You’ve probably heard of synesthesia, the condition that makes people involuntarily associate something with a sense that wouldn’t normally be associated otherwise. For instance, some synesthetes ...