Quoting myself from a thread on aphantasia several months ago:

… there are plenty of scientific experiments that show actual differences between people who report aphantasia and those who don't, including different stress responses to frightening non-visual descriptions, different susceptibility to something called image priming, lower "cortical excitability in the primary visual cortex", and more: https://en.wikipedia.org/wiki/Aphantasia

So we know that at least the people who claim to see nothing act differently. Could it just be that people who act differently describe the sensation differently, you might ask?

No, because there are actual cases of acquired aphantasia after neurological damage. These people used to belong to the group that claimed to be able to imagine visual images, got sick, then sought medical help when they could no longer visualize. For me, at least, that's pretty cut and dry evidence that it's not just differing descriptions of the same (or similar) sensations.

They absolutely exist. I have a VERY strong minds eye and can invent and watch movies if I want to. Once I was driving while my friend described a post-apocalyptic landscape. I was seeing that landscape and not the road. Suddenly (some part of my brain was still paying attention, thankfully) the road rushed back to me and I saw that the cars in front of me had stopped. I had to slam on the brakes to avoid an accident.

As possibly a tradeoff for this intense visual imagination, I have dyscalculia: I am unable to do more than simple calculations in my mind, and the more math I do the more my mind "closes up" and I feel a kind of pain and visceral frustration. There was nothing more frustrating growing up than people telling me I just needed to be patient or try harder, when nothing I did had any effect on my math ability.

As an adult I have worked around that disability by learning the fields of math that don't involve lots of numbers (discrete math is fine, algorithms are fine), and by learning non-numerical strategies for breaking down problems into smaller, more manageable calculations.

People are different, we have different cognitive abilities. Just like some people are blind or deaf, some people lack a visual imagination, an internal narrative, or the ability to manipulate numbers. I think this cognitive diversity is really quite fascinating.

As a kid, I had vivid mental images. That completely changed after a head injury in my early twenties. Now I can’t picture anything in my mind.

I believe the same injury also left me with anendophasia, meaning I don’t have an inner monologue.

Neither has negatively affected my work or daily life. I’ve just become what I’d call a 'generative thinker': I figure things out by doing. Ideas take shape as I speak, write, build, or work through them. Over time I've gotten increasingly better/faster at this. In some instances I believe it even makes me more productive..I don't overthink.

Here’s a helpful overview of anendophasia:

https://my.clevelandclinic.org/health/symptoms/anendophasia

And a few active communities for anyone interested:

Aphantasia: https://www.reddit.com/r/Aphantasia/

Anendophasia: https://www.reddit.com/r/Anendophasia/ https://www.reddit.com/r/silentminds/

I’ve lived with and without both mental imagery and an inner monologue, so for me, there’s no question that these differences are real.

I agree. The afterimage test was a major red flag for me. To see something in your “mind’s eye” has nothing to do with physical vision, yet the afterimage works by exhausting some of the eye’s physical cones. It’s a confusing non sequitur and totally unrelated to the subject at hand. I have always suspected that people with “aphantasia” simply misunderstand the idea of a “mind’s eye,” believing that others can somehow superimpose something onto their actual field of vision at will. Of course, this is not possible.

Edit: it’s also telling that this website sells an “Aphantasia Membership” for a monthly fee.

I'm going to second you for a different reason:

I guess one thing I don't really get or perhaps don't by about phantasia is that the way our whole visual field works in a big illusion: we can really only see a tiny fraction at the center of our vision with any meaningful detail and we don't even realize each eye has a blindspot.

Thus we can very easily believe we "see" something that we clearly do not see.

To make this into a more concrete test, there's a study that most people don't even remember what a bicycle looks like [1]. I'd ask somebody who insists they have phantasia to picture a bicycle, ask them if they see it clearly and in full detail as though it's in front of them, and then say great, how many gears do you see? Does it have a chain? Which way does the handlebar go? Please draw it.

Of course they don't need to draw a perfect bicycle, they could be imagining an imperfect bicycle, but I suspect what would happen is that they would be dynamically adding detail as you asked them (e.g. about the break cords) rather than having seen the whole thing in all of its detail at once. I think that's just an implausible amount of information to pull up for the average person in a moment and render.

1 - https://twistedsifter.com/2016/04/artist-asks-people-to-draw...

I think I've read the article differently to you. It does not say that the afterimage is a test. In fact it calls it an illusion.

> This afterimage illusion, while a product of perception, serves as a bridge to understanding visualization

The way that illusion works is simple. You expose your eye to green light without moving your gaze (stare at the dot). The green receptors in your eye become tired in the receptor pattern of the apple. Then, you switch to the white light which is broad spectrum. You fail to see the green, leaving red (blue is almost green, and our colour triangle is not equilateral). So, you see an afterimage of the apple but in red. This fades quickly as your green receptors recover from the overload. It has nothing to with aphantasia and the article does not claim it does.

It sounds like you have something less than full aphantasia. Remember it's a spectrum, not a binary.

For me with your triangle example, I know what the equilateral triangle and the parallelogram look like. I could describe them, or draw them, but the whole concept of a mind's eye is completely foreign to me. I don't have any ability to put something in my mind's eye and I guess I conceptually understand what people probably mean by "mind's eye" but I have no experience of it. I conceptually understand things, but there is no imagining happening for me.

A better example might be the brain teasers where you have a cube laid out in 2 dimensions, and you need to fold up that 2 dimensional cube and 'create' a 3d cube and manipulate that 3d cube to solve the brain teaser. From what I understand, most people can do this either completely in their head, or else in their head with some drawing.

The only way I can solve these is to draw the cube with pencil and paper and then use logic while looking at the drawing to figure out the answer. I just have zero ability to in any way create or manipulate a 3d cube in my head. If you took away my pencil and paper I would resort to trying to put together a chain of logic ... "if this side is X, then that side must be Y and the reverse side would be Z" but that quickly becomes confusing and hard to manage.

I also don't experience anything visual when I dream. This is actually how I found out I have aphantasia. I was trying lucid dreaming and none of the instructions made any sense. How am I supposed to fly when I don't have a body in the dream? How am I supposed to flip light switches when there are no light switches?

> If you tell me to imaging an equilateral triangle, I can put it there in my mind's eye, and if you tell me to attach another equilateral triangle to it I can see the resulting parallelogram.

For me, I can't. With the Apple example, I don't see (or imagine) anything. I know I am thinking of an Apple, and my thinking is also entirely verbal/monologue based so it's like a thought of "I am thinking of an Apple" there's no accompanying visualization, etc. When I'm really deep in thought I have subvocalizations too, slight movements of my mouth and tongue as if speaking the words of my internal monologue. To me the absence of language seems impossible to my mind.

I suspect being able to visualize something feels so natural to you you have a hard time imagining it could be otherwise. However, for folks like me it just doesn't happen.

When I dream I see the dreams just fine (so I think I understand what it is to have a minds eye) but can't reproduce any remotely similar thing while awake. Imagining sounds works fine and occurs not in my "real" hearing (so I get the distinction you're talking about with visual imagination) but with vision there's basically nothing for me.

I have 3 kinds of mental vision.

One, which some people call "phosphenes", is the ability to paint mental images on the field of vision that corresponds mentally to the signals I get from my retina. I can only see these kinds of images with my eyes closed and shielded from light. My ability to do this has waxed and waned over the years, and has never been good enough to create photographic imagery. At one point, I lost the ability to generate any colour, and I trained until I got colour back.

Two, the ability which seems to be called "phantasia". This is photographic mental imagery that runs on a separate channel from my visual channel, so I can consult this channel with my eyes open, and see things like people's faces. I couldn't do this at all a number of years ago, and was unaware that I was missing this ability. Then I discovered I had aphantasia, and I did some training which got me up to the level that the OP calls "hypophantasia", or maybe a bit better than that. I think that ability may have waned over the last few years since I last trained up.

The "afterimage test" is physically working at the phosphene level. It does not provide an accurate subjective experience of phantasia.

Three, the ability to visualize 3D geometric objects. It works great for wireframe polyhedra, and also works for maps that I hold in my head and use to navigate while driving. This ability has always been very strong, and I originally mistook this ability for phantasia. This is the ability I would use for your equilateral triangle example. I can position 3D objects in space relative to my body, rotate them, etc. Because I am strong at this ability, it is my job to efficiently pack luggage into the vehicle for camping trips. My partner is bad at this, but is much better at phantasia, and is a visual artist who can draw realistic faces.

What I wrote is based on personal experience. I am not selling anything. I know from internet forums that different people have different wiring in their brains. Some people have subjective experiences that other people have never encountered. It is impossible to prove the existence of first-person subjective experiences to a determined skeptic. The best you can do is collect field reports from a lot of people, compare them, find patterns, then make your own conclusions. This is called phenomenology.

> Can anyone confirm that they have this ability, which specifically is to superimpose imagined objects inside your actual field of vision? If the answer to this is yes, then okay, I guess I have aphantasia.

Yes, this is utterly trivial for me, but then I am hyperphantasic by any measure or definition.

It is also common to read people telling others to explicitly do this kind of superimposition (or "projection") in early psychological experiments, and meditative and/or spiritual and esoteric practices. It would be really odd for people to spontaneously just give such specific nonsense instructions if they couldn't just do it.

I have hypophantasia, so it's very easy to convince me that both exist (because I'm right in the middle between the two)

No, it's definitely akin to imagining a song for me. It is not confusable with actually seeing things.

"Exist" is probably the wrong framing. It doesn't seem unreasonable that such a phenomenon could occur after a traumatic brain injury, for instance. I'm sure there's some evidence of it, neurologically (like split-brain syndrome). But it's also true that people who say they "aphantasia", in 99.9% cases, don't experience that phenomenon.

I made a poll to see if anyone can (like D-Machine or jhedwards) actually see a superimposed image and not just "see" a superimposed image: https://news.ycombinator.com/item?id=49469365

Having been on the "vivid imagery" spectrum I could easily superimpose images onto my vision. Now, after covid infection some years ago, I have aphantasia, so I can tell you it's a very real thing. A lot of the stuff mentioned in that guide is very true as well, I lost the "feeling" of my childhood memories for instance.

As I understand it, many (most?) people with phantasia can't really superimpose images onto their vision like this, but needs to close their eyes to imagine something, but I for sure could. I was fully aware not directly seeing it, the image is composed in the mind after all, but I guess a good analogy is you "playing music" onto music you're listening to. It's composed together in your mind, but you're fully aware only parts of it is coming through you ear.

Last, since you can imagine images in your minds eye like you describe, you clearly do not have aphantasia...

Not sure about phantasia, but aphantasia exists. I don't know why you say it doesn't?

It exists. You're wrong. Update. Thanks.

You're absolutely right.

Nobody hallucinates or "sees" the object, it's like an object instantiation with default properties that you can name/describe, nothing more.

If you quiz someone long enough you can get them to acknowledge they don't see anything "in their head" whatever that means.

This nonsense makes me irrationally annoyed, I suspect because it's unfalsifiable attention seeking, some people I've met mention it every chance they get angling at it being some sort of disability. I get it, you don't see anything...I don't see anything either...nobody does.

I feel like there would be much more obvious practical differences if it was a real thing. The spectrum as described seems so different from one end to the other that we seemingly have people who can switch reality into a movie of their choosing on one side and people who can’t imagine like what a square is on the other. It seems like communication would necessarily have to be very different, books would be different depending on the authors phantasia, UI/UX would be different - it’s hard to believe everything is so homogenous if it’s really serving people with such different visual capacity.