Same here. I think it was actually this meme that did it. I saw people commenting that they could not and I'm like "ha yeah, of course you can't, who can do that?". The lots of people are like, yeah, I can create a complex 3d shape in my mind and manipulate it, turn it, get closer, etc. I'm like WTF who are these megamind savants who can do this. Turns out, most people.

I felt very alone and very incapable after that realization.

It's like knowing a cow is the room next door. You are aware of the cow but you can't see it. If someone says the cow is brown, you are now aware the cow in the room next door is a brown cow but you can't see it because it's in another room. Except the other room is your mind.

I don't need to see a cow to imagine it in the next room. Same concept.

It's easy to figure out if you have aphantasia. Think of a cow. Do you see a cow?

It's not a condition or a disability, it's just a different way that some brains work. Don't fall into the trap of - it's outside the majority so it must be a deficiency. Most people with aphantasia don't even know they have it.

Also, strangely I can rotate a cow in my mind, but there is no visual feedback. I "feel" the cow rotating. I choose where in the physical space to project the imagined cow and there is the imagined "physical" sensation of the cow spinning as if it's an extension of my mind. I can imagine sound as well. But I don't see anything.

I got recommended a video that introduced the term to me and it was a very jarring realization.

Personally I've always struggled with expressing my thoughts in general. Before I learned about aphantasia I had started saying it was like I think in concepts instead of words or pictures. I know what I'm thinking and it's not like it's a vague idea, but for whatever reason actually translating it into a real language is really hard for me. I have an easier time writing out my thoughts than I do speaking them at least.

The most I can visualize are a few 'vivid' images that I spent a lot of time curating, usually from listening to music or remembering a dream I wrote down. Even then, When I try to think about those little exceptions, it's still only a tiny fraction of the whole image that I can really come up with. Thinking about it now, it's super weird to describe! I got super intro writing after I figured out I had aphantasia (shattered my hopes of being able to draw. But that doesn't mean aphantasic people can't draw. I just learned how to draw incorrectly and it screwed me over) and I like to think I'm decent at describing visuals despite all this.

To use the gif as an example, I can really only imagine the frame, moving images are practically impossible for me. And it's really only the sillohuete I can make out.

I also realized I'm face blind too, and part of me wonders how much that correlates to aphantasia