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Comment by personjerry | Hacker News Reader

The most verifiable part if you want to check it out yourself:

Look at a mirror (not your phone camera), and look at your eyes. Now move your eyes, and try to see the movement of your own eyes. You can't.

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This phenomenon made me convinced I was unable to move my eyes as a child. I thought I had some strange condition where I could move my focus without my eyeballs moving.

I remember my elementary school teacher saying "don't roll your eyes at me" and me trying to explain I couldn't move my eyes and her awkwardly going "right..." Then continued to believe it for another few years.

> move my focus without my eyeballs moving

This is a thing!

https://en.wikipedia.org/wiki/Visual_spatial_attention

I discovered this when I accidentally performed an experiment that showed how paying attention to a bright light in my peripheral vision without moving my eyes caused my pupils to constrict. That was after I became aware that my pupil size affected how blurry things were from nearsightedness (the same effect as in cameras).

https://en.wikipedia.org/wiki/Pupillary_light_reflex#Cogniti...

It's amazing how much our brain does in the background to smooth out processing because it can't handle all of the data coming in. This example several others (the one where you look at the center dot and all others disappear - briefly mentioned in this twitter thread also, the one where you stare between two sets of rapidly updating photos of celebrities..but after a few, your brain gives up and just sort of makes them all look like ogres, etc).

Awesome stuff and I will always do every one of these silly things.

If you watch your eyes in the mirror and move your head, your eyes appear to do an incredible job of tracking using eye muscles. Are they actually? Or are they actually tracking jerkily and it appears smoothed due to saccadic masking?

Tracking smoothly. Copied from my other comment in this thread:

When you're focusing/tracking something your eyes do a different type of movement called smooth pursuit [0].

To see this in action, look around normally - notice your eyes move and then stop, taking in "still frames".

Next, look at your finger and move your finger around. Notice that your eyes smoothly follow the finger around.

[0]: https://en.wikipedia.org/wiki/Smooth_pursuit

That's cool! I really can't track around the room smoothly, despite "trying" hard to do so! Grr....

Haha yes this has annoyed me since I was a kid!

It is possible to train yourself to do that. I'd suggest starting with the corners of the room, horizontally, where the ceiling meets the wall. Taking your eyes slightly out of focus helps too. You will fail often. The goal is to minimize saccades.

If you are not following a pre-existing "line", it gets exponentially harder.

Thanks for the info. The part about needing catch-up saccades above a certain speed is particularly interesting.

I used to play with this as a kid. I have eye floaters[0] that tend to drift down to the bottom of my eyes, so I would saccade my eyes up to bring them to the center of my vision, then focus on the floaters and smoothly watch them on the way down (which actually just kept them centered since I was matching the tracking rate to their falling speed). I was kind of a weird kid.

[0]: https://en.wikipedia.org/wiki/Floater

I did the same thing in much the same way … So there’s at least two of us mate.

If I get really close to the mirror, so close I can barely focus, look at my dominant eye, then look at the general direction of my non dominant eye, but trying to focus some distant object, I can see it moving.

As a follow up, watch someone else doing the same thing. You'll be able to see their eye movements, but not your own.

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