Comment by tasty_freeze | Hacker News Reader

Comment by tasty_freeze | Hacker News Reader

Parent Full thread

I've read a number of times about aphantasia, but I'm still unsure about things. For instance, if I'm asked to think of a cup in my minds eye, I would say yes, I can. Therefore I don't have aphantasia. But it is not at all like looking at a real cup or a picture of a cup. It is far more liminal and fleeting.

One bit of evidence of this is when I tried LSD a few times in the past, I don't get CEV (closed eye visuals), while some people report rich, colorful scenery. All the same, I do get visual impressions without actually seeing anything. For instance, while listening to a particular song it generated nothing but blackness in my minds eye, yet all the same I had the impression of looking at glossy flower made of hard glass. I was getting the interpretive conclusion of vision without any of the other information flow that comes along with actually seeing the object.

When I visualize things in my mind, it is kind of like that too -- I can describe what I'm seeing but I don't really see it.

I don't know how much LSD you did or what your body weight was or anything else that might be chemically relevant. But I would be deeply surprised by an individual being immune to the closed eye hallucinations.

When you look at a lightbulb for a moment and then close your eyes, do you get the after image? The "closed eye hallucinations" are just that normal after image chopped up in frequency space. LSD exposes the fact that a lot of what the brain does can be understood in terms of analog signal processing. The most reliable way to get a high quality viewing of the crystal patterns is with TV static. Baring that, any randomized constant texture such as a carpet will suffice. The reason is because random noise evenly fills up the entire spectrum in frequency space, so whatever frequencies are cut, de-phased, or otherwise affectef are guaranteed to be present in an image of pure noise. Another reliable glitch is that all lines below a certain thickness will tend to wobble or drift in and out of visibility. Again, construct a line as a really thin gaussian wave packet and see what happens when the high frequency terms pick up phase drift.

LSD hallucinations have nothing to do with aphantasia.

I got vivid, rich, and colorful closed-eye imagery from psilocybin (20-20mg) and no open-eye visuals from it. LSD was the reverse -- obvious open eye visuals, no closed eye visuals (up to 200ug).

LSD was brought up because of the specific experience of having visual impressions of things without actually seeing anything. My sober "minds eye" is like that too -- I can describe what I've been asked to conjure, but I don't really see it.

Maybe because its a class of things, you can't visualise 'furniture', but you can visualise instance such as an office chair, or dinning table.

My description is poor, office chair is also a class, but it not the top class ... I dunno read about this once anyway, didn't make it up, honest!

Reply on news.ycombinator.com