I can’t speak to physical blindness, but I have aphantasia[0] which basically means I cannot voluntarily invoke my minds eye. Up until I found out about it last year, I thought that “visualizing” things was a metaphor for thinking, as I didn’t realize people could actually see things without looking at them.

There are varying degrees of aphantasia. For context, I am completely unable to “see” anything in my mind. I do not dream either. If I close my eyes and think of something, nothing happens visually, though I can more easily remember things about whatever it is. I would describe it more as complete emptiness, instead of darkness (as darkness implies there is something there at all). I have been like this since I was born.

One thing that stood out to me in GPs comment was that programmers tend to visualize code to reason about it. I asked a bunch of my friends after finding out my minds eye is blind and they all said they do it at least sometimes, some of them do it constantly.

I obviously don’t, but I can say that I have a very good memory (in general, but also for code), and often find myself capable of context switching between related bits of code faster than many of my peers. I rarely reach for a diagram for explanation, however I do use them very regularly for documentation and explaining designs because I find other people seem to be able to process that format better.

I don’t know if my aphantasia contributes to any of this, these are just things I’ve noticed I’m good at. One thing I am terrible at, however, is design.

[0] https://en.m.wikipedia.org/wiki/Aphantasia

> For context, I am completely unable to “see” anything in my mind. I do not dream either. If I close my eyes and think of something, nothing happens visually

Correct me if I'm wrong but I suspect a lot of self-diagnosed cases of aphantasia are due to the ambiguity of language (specifically, English)... Qualia lost in translation.

I suspect nobody really sees something visually when thinking/imagining something, in a sober waking state (barring maybe a few rare exceptions or psychotic disorders). If you would see something superimposed on your visual field, with closed eyes or not, that would be called hallucinating.

For me, "seeing it in my mind's eye" is a different kind of "seeing": there is no visual input.

Example: imagine a tree. Where are the branches? Where are the roots? Where are the leaves? What color do the leaves have? Etc... You can answer these questions, right? The place where you find the answers is where the mind's eye is. I've yet to meet someone who actually sees the tree with the same visual clarity as if looking at an actual tree.

Dreaming is somewhere in between for me: it's usually visual, but not of the same visual quality as waking life, except when lucid. A lot of people don't remember their dreams, but that doesn't mean they don't have them. Ask yourself right after waking up in REM sleep (don't even open your eyes if you can): what just happened? What were you thinking?

> I suspect nobody really sees something visually when thinking/imagining something,

I suspect that you may have some degree of aphantasia.

Visualizing something encumbers the same visual processing as sight does. Personally I have a hard time visualizing something and looking at something at the same time. I can only pay close attention to inside or outside, not both simultaneously. (Casual attention, like half-listening, is possible otherwise I'd be a terrible driver.)

To think of it another way: when you say "I've yet to meet someone who actually sees the tree with the same visual clarity as if looking at an actual tree," maybe you should ask some more. I can look at things, close my eyes, and continue studying them up to the limits of my memory and original attention.

Aphantasia seems to come in degrees, not a binary "have it"/"don't have it."

Perhaps... what I mean is this: close your eyes and visualize a tree. Do you literally see the tree in the darkness of your closed eyelids in front of you, visually? Even just vaguely? If not, then imho that's not really visual. I "see" the tree, but it's a different kind of seeing. Perhaps that's a degree of aphantasia, but how would I know? ;)

I do, but I haven't practised the skill much lately so it's not as vivid as it used to be.

It's more like a second virtual desktop than superimposed; it takes up the same coordinates, but there's a clear distinction between "real" and "imagined" objects (unless I'm particularly tired, but that's closer to "hallucinating" than "visualising").

I used to be able to visualise things in positions relative to real objects, but at the moment I can only manage floating in the air, such that focusing on the position of imagined objects de-focuses the background, either relative to my field of view (so it moves when I move my head) or in a defined position in space (so it doesn't move when I move my head – though obviously this is limited by my ability to instinctively judge positions and distances, so it often doesn't quite work right when things are moving in complex ways, or I'm moving fast).

That's blowing my mind right now. First I thought people who can visualize to the point of actually seeing what they visualize were pretty rare. For me what I visualize takes place in a mental space: it's a clear mental image, not a literal visual image.

Have you always been able to do this, because you mention practising this skill? Also, does this only happen after focussing on something, or does it happen spontaneously when thinking? I imagine it would be pretty distracting if someone says for example, "don't think of scary thing X", and then the scary thing manifests visually for you because you are thinking about it.

> I imagine it would be pretty distracting if someone says for example, "don't think of scary thing X", and then the scary thing manifests visually for you because you are thinking about it.

That sounds about right. For me, "don't think of a pink elephant" results in the image of a pink elephant, though if I'm not concentrating on its location it's just… somewhere.

> Have you always been able to do this, because you mention practising this skill?

I think I've always been able to do it – but I haven't been doing it as much since I stopped playing with toys, going outside and generally doing activities where such a thing would be useful, so it's less instinctive.

Uh yeah, same here. Like, I can remember what my daughter looks like as she sleeps in her crib, but visually what I see (with my eyes closed) is just blackness. I've always thought of it as something akin to a prerendering buffer or virtual display context in my mind. What the parent poster is saying makes me think that for them its more like experiencing an actual display, which seems like it would get really confusing layered onto the visual input from their eyes.

The only time I've ever experienced anything like that I was trying psychedelic mushrooms for the one (and so far, only) time, and so it was literally a hallucination.

That's an excellent analogy! The mental space is exactly like a prerendering buffer. When asleep and dreaming, there is no overriding visual input, so the stuff in the mental space gets rendered. And I guess some people can access this even when sensory input is present. That must be wild.

I had many conversations in the weeks following my original discovery, and this comment thread reflects them perfectly.

Me: There's no way everyone actually sees things and I made it 30 years without knowing.

Everyone else: Yeah I see things.

Me: but, like really see or just remember features?

Everyone else: <some variation of quality, but it was always described visually and everyone agreed it was basically like seeing>

I put "see" in quotes in my original comment simply because that is how everyone I spoke to described it; that it's clearly not physical vision, but it's also clearly a visual experience. I have absolutely zero visual experience when I close my eyes, and I never have, it is simply emptiness.

You seem to describe dreaming as if you experience that visually too, while not being able to do it while awake. It's worth noting that this is not uncommon for people with aphantasia, which is why it is the inability to _voluntarily_ invoke your minds eye. Many people can still dream visually, however I do not. I go to sleep and then simply wakeup with nothing but emptiness in between (not an experience of emptiness as time passes, but more like a time skip).

Yep, imagining/visualizing something goes without an actual visual experience for me. I've always assumed the same thing applies to most people, but I guess I do have some degree of aphantasia.

I can imagine something, but it's like rendering a layer with the opacity brought all the way down to 0, but my "mental computer" knows it's there and can tell its shape, color, all its features & details in 3D space... without seeing the actual visual image.

Dreaming on the other hand is usually multi-sensory and especially visual for me. Much like being awake or in a VR environment, but with internally generated input.

Have you spend time really consciously investigating your sleep? To the point of interrupting it with alarms etc..? I'm someone who's very interested in my dreams: for years, every night before sleep I wonder what I will dream, sometimes I get lucid during the dream, and when I awake my first instinct is to recall my dreams. I think this is why I dream so much. I wonder if the same thing applies to visualization and whether or not aphantasia is "curable" through consciously exercising visualization.

When I visualize some thing I don't literally see it in my field of view but I can still 'see' it. It's similar to audition(hearing in your mind). Read something out loud in your mind or play a song in your head. Its the same thing you don't literally hear it but you do 'hear' it.

Yes but that was my point: I suspect (I can't be sure of course) that this is a limit of the English language. We call it "seeing", but it's not. If it would be real seeing, you would visually see the thing you are visualizing in your field of view, as if it were literally there (like in a dream).

Hehe, perhaps no and this is the moment when you figure out that you have mild aphantasia. When people say they "count sheep jumping over a fence" it's not a metaphor.

That's kind of what I've been trying to figure out: when people say they count sheep, do they close their eyes and literally see sheep jumping over a fence as if watching a movie or wearing a VR headset? Even in low resolution... That would be pretty impressive... why would we still need movies and games then? ;)

Of course I can imagine sheep jumping over a fence, even in vivid detail, but this imagining is not really seeing visually like in real life, not even like in a dream. As I said, I would describe seeing things that aren't there (with closed eyelids or not) as hallucinating. Perhaps not being able to do that at will is aphantasia, I don't know, but it would blow my mind if it were

Generally when I’m idly visualising something it is ‘in my mind’s eye’ as you put it. But if I’m really focused and close my eyes then everything else seems to disappear and I’m ‘really’ seeing it, not on the inside of my eyelids but it encompasses my entire visual perception if that makes sense

More rarely I also get it with sounds and then it definitely does feel that the sound is originating externally to my mind

You’re right that these experiences are more like hallucinations but I think they are points on a spectrum rather than separate things

Aphantasia is a condition I have never heard about. Your experience and the description on Wikipedia lets me think I was born like this as well.

I had many arguments with my wife about how I did not have visual dreams and did not see anything when I close my eyes. When she says she sees stuff when she closes her eyes, I always assumed it was some sort of metaphor and it was usual for human beings not to see anything when their eyes are closed.

I think when I "visualize" something, not limited to math and code, I do not see anything per se. Mostly I think my thoughts are directed graphs whose nodes are concepts I have in memory.

May I ask how did you get a diagnosis? And did you learn anything of use thanks to this diagnosis?

Not OP but...

There isn't a scientific diagnosis, it's more of a self observation kind of thing right now. The reason is that there has been very little research into it so far. You may notice that the wikipedia article is extremely short and most of the references are news articles, opinion pieces, and blog entries. Personally, I've found that the realization has offered slightly new ways of approaching life. It's fun to explain to people how I think and how that may differ from them. Nothing truly changed except perspective.

For reference, I also think mostly in directed graphs. I'm also able to roughly draw a shape in my head, but its very quickly erased and is hyperlocal, like trying to draw in the air with a sparkler.

There is a subreddit, r/aphantasia, but I've found that it's mostly a mix of curious gawkers and bitter people claiming that having it has somehow deprived them of essential life experiences.

Not OP but this felt like a simple test - https://twitter.com/backus/status/1091203973246111744

There's the Vividness of Visual Imagery Quiz but that's self-administered and is a questionnaire.

hmmm... this is interesting.

I think I must have this too. E.g. if I close my eyes and try to visualise the face of someone that I hang out with every day, I can't do it.

If I try really hard, the best I can do is a flash of bits of some photographs I remember. It also starts to give me a headache. I think though, if I want to remember how something physically looks it helps to have my eyes open. Even then it's more like flashes than being able to actually see something.

Mostly when I "visualise" something e.g. the house where I live, I think in terms of how things are spatially connected to one another. It's more like a scene from the matrix - where what I'm remember are more the concepts of things and where they are spatially, rather than what things actually look like. This is pretty much also what happens when I'm coding - thinking in terms of concepts and how things are connected together spatially.

I find myself going quieter when I read faster. I do take pauses to think through what I’ve just read. You may want to try separating reading and thinking, and see if that helps you no longer need to think aloud reach word.

FYI that process is called "subvocalization" - I'm only passingly familiar, but if you search that term there's lots of literature about it.

Yes that's the one, I forgot what it was called. Always found this part interesting (from the wiki):

"This inner speech is characterized by minuscule movements in the larynx and other muscles involved in the articulation of speech. Most of these movements are undetectable (without the aid of machines) by the person who is reading."

Try gently pressing your finger against your larynx when you read in your head - you'll likely find you read faster - this works for me, although I tend not to bother.

Interesting tip, I will try it.

The worst thing about the inner voice is it's not just when reading, it won't be quiet at bed time. And I have a tendency to complete thoughts as words. Even if I know where it is leading, and what the conclusion is, it feels like I have to see it through and phrase it correctly in my head. I feel very uncomfortable leaving it hanging.

Exactly. Sometimes I even feel compelled to complete the sentence more than once (as if I wasn't paying attention enough the first time, so I feel the need to say it again). I think there is a subtle difference between that and "reading without production" (when I try it, it feels more like skimming text; I have to really try to pay attention). To me, reading/inner-speaking feels like engaging with the text; to only be able to "see" words would be lifeless (I'm assuming that some/many/most people can do both).

I also rely on the "inner voice" for reading and writing. But I can skip that when programming. I think it's related to how you learn that language in the early stage.

Could you expand on how you skip it for programming?

When I am designing the solution, I still have the inner voice. But when I'm implementing in code, I can do it almost "brain-lessly", even fine when listening to music.

I'm not sure how do I do that, but I guess because I do it a lot, so I can do it as familiar as walking?

Edit: Maybe because I didn't learn programming by listening to teacher, instead I learn from books and trials. I guess it's more like walking / playing sport, you don't need explicit inner voice to guide your body movement.

I have this inner voice when reading English, which is my second language. However, if I am reading stuffs in Chinese, I can skim through without the inner voice.

When I read Spanish (2nd language; not great at it) I sub-vocalize as I do in English. But if there is a long, complex word that I would have to laboriously "pronounce" (but I know exactly what it means ahead of time), I will treat it as a gestalt/symbol (so, it's like "cheating" on the vocalizing), so sub-vocalization isn't actually needed for comprehension, but I'm guessing is a parallel mental action/process (probably correlated with how we learn to read a language and personal characteristics). Maybe non-sub-vocalizing is really just suppressing this parallel processing workflow. (I'm wondering if people who "don't need to do this" could read backwords (accidental pun!) effectively.)