This post is inspired by a cool Twitter thread I saw about how our eyes trick us during the saccades that occur when we move our eyes from place to place e.g. when reading, which you can find here. It's called saccadic masking or chronostasis, and it's an interesting example of how what our eyes detect and what we actually experience visually are quite different.
I then saw another thread (which I can't currently find) that mentioned akinetopsia (not being able to see movement) and simultanagnosia (only being able to see one thing at a time) and so here I am looking at unusual eye disorders that are down to the counterintuitive ways our brains process vision.
I'll be doing two posts on this: Part 1 is just about Aphantasia, which I have, and Part 2 will be about other interesting visual/cortical disorders.
Aphantasia is the lack of a 'mind's eye' or the inability to voluntarily visualise. I have it, and it means I can't picture anything in my head, from a simple red triangle to someone's face. I was interested to read that it's defined as inability to voluntarily visualise - that's mostly true for me as I can't voluntarily visualise, but I also rarely visualise even involuntarily i.e. in my dreams.
It's incredibly understudied but that's starting to change. The revival in interest in it appears to have come from a man who went to his doctor saying he had lost his ability to visualise after a minor surgical procedure and then was profiled in the New York Times, leading a lot of people to say how could someone not visualise but also some people to say wait, I've never been able to do that! It's odd that scientists (apart from someone in the 1800s) never actually discovered congenital aphantasia until someone lost the ability.
It's a really fascinating subject because everyone assumes other people are just the same as them since it's such a private experience. I always thought counting sheep was just metaphorical and that you weren't supposed to actually picture them, or that when you were told to visualise during meditation (argh) it was also just a metaphor or something. It did make meditation very frustrating - we'd go on school retreats and they'd lead us down memory lane with 'Imagine you're walking up to a door. What colour is the door? You walk in and see photos on the wall. What's happening in the photos?' I guess people must have been actually seeing things in their heads while they narrated this but I was seeing absolutely nothing and having to just lie there and make up answers like 'OK I guess the door can be red' even though I couldn't actually see the door at all.
For a great long explanation of this, I recommend this post by a man with aphantasia.
There's a really interesting link to blindsight [ability of cortically blind people to respond to/locate objects they can't consciously see] there in my experience - I can't visualise (most of the time - I tend to get one involuntary image in my head right before I go to sleep some nights, and I occasionally dream in pictures) but I could still reasonably accurately tell you how many windows (etc.) were in X room of my house. It's sort of like a coordinate system in my head, where I could imagine walking into that room and having a sense for how far away or near the windows were to me in each position without ever actually seeing anything.
The way I 'see' things is interesting albeit difficult to explain. Say I'm trying to picture a graph of y = x^2, which is a parabola opening upwards centred on the y-axis. I can't see it in my head in any normal sense of the word 'see' - there is no colour, no form, no anything visual. However, I have recently enough picked up a skill with which I can imagine that I am a point on the line and so I can trace out the line in my head purely through imagining motion, but there'll be no visual image, just the sensation of movement. That doesn't scale well; I could draw out a triangle or a rectangle, but it will only exist in the place where I currently am in the motion so there's no actual trace left of it so there'll never be a full shape. I can sort of imagine moving as a different shape, so instead of being a point I could be a square and by moving that could create the sense of a cube. But there still won't be anything you'd actually associate with a picture, no boundaries/colour/lines. And that approach only really works with simple geometric shapes because I can't exactly imagine myself as a travelling point to picture someone's face; the whole face needs to exist at once, whereas the y = x^2 curve can just exist as an infinite series of points.
Scientists asked that guy who'd lost his ability to say which letters of the alphabet had low-hanging tails e.g. j, g, and were suprised to find out he could do it even though he couldn't visualise. I can do it too - I would run through the alphabet in my head (without seeing anything visually) and either do it just by knowing it because I've already classified them while learning to read, or imagine I'm a point moving along the letters.
It feels like there's just no screen there. The information must be there because I can recognise people (usually - I'm not brilliant at it) without having to run through a checklist, but there's no 'screen' in my head for me to assemble that information visually. When I try to remember what someone close to me looks like, all I have is words I've specifically thought of while looking at them so 'brown hair' 'tall' and my emotional response to that. If I want to think 'is X person pretty?' I have to think back to the last time I saw them and remember what my response was then - I can't just picture them and judge how I feel now about how they look.
However, the screen must exist because I do get a flash of mental vision some nights before I go to sleep and because sometimes some things in my dreams are visual.
Super interesting stuff and I hope they do more research on it soon. I feel like it should maybe be classed as a disability; it certainly made organic chemistry very difficult as that's all pictures and I can't remember pictures at all. I remember in primary school we had to look at a picture for X seconds and then had Y seconds to write down as many things as we could remember from the picture and maybe where they were; I think now people must have done that by snapshotting the picture in their heads and holding it in memory to look at it, but I had to just name the things and memorise the list of names, so 'socks, slide, tree, cat, blanket'. It's also very annoying that basically all the words we use for imagining (including that word itself) are based on vision, e.g. 'visualise the future', 'picture this'. I can still imagine, just in words, concepts and feelings (sometimes sounds) rather than images.
Someone said recently 'but you must be able to visualise, you read all the time!' [this was after I brought it up and was in response to an English student who'd said they couldn't do it either], which was funny but also fascinating because clearly our reading experiences are very different. I definitely miss out on some parts of books because I basically just skim the descriptive bits since I can't visualise them. So I hate books that constantly visually describe the surroundings and will only read it in case there's information there that I might need, so if it describes a uniform in great detail and mentions they've a knife in one pocket, I'll only remember the knife because that might be relevant later. And I draw and paint (though not brilliantly), either by looking up and down at the thing I want to draw a lot, or if I'm drawing from memory (because I can't looking at it in my head) I either use a geometric shape or draw a little bit, see if that's recognisable as the shape I want to draw, and if so keep going in that way.
It's definitely an interesting thing to find out about, and a great opportunity to think about how other people think.
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