A rather rare phenomenon of
synesthesia was first
studied on a large group of people in 6588 people. As a result, it turned out that most synesthetes have a common color perception of letters, which to some extent showed the commonality of the principles of the brain.
Synesthesia is a complex psychological phenomenon of human perception of various stimuli. Such people, perceiving by some sense organ a certain phenomenon (visual image, object, touch, memory), can simultaneously perceive the same as a completely different feeling. For example, while listening to music, synesthetes can perceive sounds of different tone and volume as colors of different shades or saturations. This phenomenon of “color hearing” is experienced by man involuntarily and described by the Japanese pianist and composer Hiromi Uehara. The question “what color is a cold water faucet” for people who do not possess synesthetic abilities most likely causes a real faucet handle with a blue indicator? Synesthetic, by contrast, is likely to experience blue. Although this can to some extent be explained by the logical “blue” color of water, and hot water is “red” as a designation for high temperature, for synaesthetics such objects involuntarily form a color sensation.
It is known that many of these people perceive the letters of the alphabet as colors. For example,
Y is usually yellow,
A is red, and
B is a blue “letter.” The research team set out to relate each letter of the English alphabet to a particular color, interviewing 6588 people who called themselves owners of synesthetic abilities. Each synesthetic responded with what color it "sees" the letter. The results were compiled into the following scheme:

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It is not difficult to see that the majority of synesthetes perceive the same letters as the same color. For example, the letter A is red (with some exceptions), and the consecutive letters E, F, G are green. Very curious is the fact that the color scheme of the children's alphabet by adults was painted in almost the same colors, which probably means that synesthesia is not really a rare phenomenon, but lost with age:
