Fleeting glances

Since replacing my eyes’ lens there have been a few times – every week or two, call it – when I see an hallucination out of the corner of an eye.

They move. Fast. And are gone.

What was that?? A rabbit? A car? A leaf falling where it shouldn’t?

They always seem like … something. Something identifiable.

But then they are gone and forgotten.

Nothing to see here, folks. Move on.

Coupled with more apparent oddities of new lenses – weird depth perception, fluid focus, bright blue world – these hallucinations do show that vision is not a camera.

So, now I wonder – just where in the brain is our GPU? Hey, it’s no new story that what we see in our mind’s eye is highly processed. But some gizmo has to render that highly processed information back in to pixels. That gizmo is impressive. And it’s not surprising the works of such a gizmo would be gummed up when its raw input is changed.

(Yes. I also believe that “gizmo” is a misleading representation of this aspect of the vision system’s architecture. It might make more sense to think of the image in our head as being heavily shopped. With parts of the image variably selected from many shopped alternatives.)

3 thoughts on “Fleeting glances

  1. Saw an eye guy very recently. Cataracts replaced with CrystaLens implants.

    Much of my recent time has been taken by machine vision and machine learning. So I view these “fleeting glances” as an interesting cognitive thing.

    Given that there was a recent, sudden change in what raw data comes in from my retinas, one would expect there to be miscues at various levels of image processing. As in, say: It used to be that some combination of light and shade in a given context meant the odds of seeing an object of type A were good. But, now the light and shade combos coming in are simply different. And the brain hasn’t learned that interpreting them as A is now bogus.

    Scary, when driving. Lucky they are rare. How often *does* one see a wandering giraffe on the freeway? 🙂

  2. Oh. These “fleeting glances” are not floaters. Nothing like ’em.

    Floaters are just stable noise. You can watch them and play with them.

    These “fleeting glances” are apparent, actual things. Like, “Hey, was that a dark, green, pygmy elephant over there?” But it wasn’t. It was just a shadow. It was just some unconscious mis-speculation about what’s in the field of vision that somehow made it in to consciousness.

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