I really dislike hearing about the calculating geniuses who can “see” or “visualize” or perceive numbers and sequences in their heads as shapes or colors. Because, for me, that doesn’t happen.
I am a synesthete, but my sixth sense doesn’t make any logical sense. Some words have genders. Some have movements. None have shapes. Most have colors. For the most part, I just say I have grapheme/color synesthesia, though words like “exotic” or “spasm” or “extreme” have movements, the number 2 is lavender and most definitely female, and the capital letter D is absolutely a jerk. Occasionally, I will get hints of colors or shapes from music, but rather rarely.
But there’s no pattern. 3 is yellow, much like C. 4 is sort of burgundy-red-orange. 5 is darker blue. 6 is maroon. 7 is green. 13 is ochre. Sounds don’t have colors. Certain letters’ colors can be variable. Some words have dominant letters, which determine their colors, other times they have letters that would be dominant but aren’t, and for some I can perceive multiple colors at once, and sometimes colors are completely unrelated to the letters!
But I can’t multiply using colors. Or divide. Or add. All I can do is recall sequences of numbers and letters with relative ease.
So I can recall license plates and a little bit of Pi, and sometimes it’s helpful for remembering words in other languages or poems, but, for the most part, it’s useless except for conversation and argument with other synesthetes–is S red or purple?