This article is from the magazine Les Indispensables de Sciences et Avenir n°210 dated July/September 2022.
In his autobiography, Vladimir Nabokov writes that he “colourful hearing”. It poetically evokes the colors taken by the letters of the alphabet: “The [lettres] yellows include various e’s and i’s, a creamy d, a golden y and a u, the alphabetical value of which I can only express as ‘copper with an olive sheen’.” The human being, generally, strictly separates the sensations procured by his five senses. But if, like the American writer, you see colors when you mention a letter or listen to a sound, you are probably a synesthete… like 3% – at least – of the population. .
“I was born on a blue day”
For the synesthete, sensory information spontaneously associates with, or triggers, a sensory perception of another order. Two, three, or even more senses may be involved. The most common synesthesias are related to language (letters, words, numbers, quantities, symbols and divisions of time).