For those interested, here is a piece about a chromosomal region linkage.
The 2nd study in the link is particularly interesting!
It's odd that they quoted very different rates of synesthaesia in the general population in the different articles. Is it 4% or 0.05%?
They talk about one specific sensation being interpreted as another in the brain. For me, it is more than that. Sounds are sometimes associated with colours, but almost always with textures, and sometimes even with tastes. I'm not saying I actually taste something when I hear a sound, but , when I replay the sound in my head, I am strongly reminded of a taste or a texture sometimes, as though the memory of the sound triggers my memory of that taste or texture. However, if I hear a loud enough sound or one that isn't really loud but comes all of a sudden when it's otherwise quiet, I will actually see a flash of coloured light, but it's not so much the colour as the shape (e.g a jagged lightning bolt vs. a round shape, depending on the nature of the sound). Music can make me visualise entire scenes if I let my mind relax.There are some sounds that I really can't stand because the texture they evoke is unpleasant, either disgusting or painful. I hate it when people sniff or eat noisily. Ugh.
Not only that, but different emotions are different colours and patterns, and I feel strong emotions more in my body than in my head, if that makes any sense. Also, everything is numbers and patterns, not actual numbers, like 45 or anything like that, but it's like everything is a number in a mathematical system that exists only inside my head.
Does anyone else experience anything like that? Is that even considered synaesthesia?
It's not surprising that the autistic brain, which tends to have more connections, is also prone to synaesthesia, which is associated with extra neural connections.
I'm diagnosed and it pretty much permeates a lot of things. The thing you are describing with textures and shapes is a thing that I also get strongly. I'd recommend reading Olga Bogdashina's Sensory Perceptual Issues in Autism and Asperger Syndrome- Different Perceptual Worlds. It really makes a lot of sense. She goes into a lot of detail about our senses and there are a lot of descriptions from people on the spectrum. That book stopped me from feeling like I was losing my mind after my diagnosis and led to my diagnosis of synaesthesia.
I think every article I have read about synaesthesia has quoted a different percentage for people with it.
After reading a number of books about it, I think every sensation you describe can be attributed to your synaesthesia/autism. I am by no means an expert.
Taste doesn’t figure with me, but I have heard of it. The texture of sounds is interesting, my synaesthesia responds to timbre and tone, so an instrument played with a bow, like a violin or cello, appears as a frayed dark line that moves continuously in a 3D environment, the colour usually red or orange but changing in hue as the music changes. A piano is represented as a more solid shape, usually from velvet blue to steely blue depending on the piano, so sometimes soft, sometimes hard. Yesterday a sudden burst of thunder looked similar to a fast moving, dark billowing cloud. My favourite music I visualise a bit like an internal video. It’s difficult to describe accurately.