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Comment by hn8788 | Hacker News Reader

A quick search online brings up multiple articles dating back a few years with examples of the same thing. It's not "an impossible feat".

https://www.bbc.com/future/article/20160229-the-sea-nomad-ch...

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The headline is not acuratly representing the contents of the article. The full quote which is where the "once thought an impossible feat" part comes from:

> That makes D.W. different from other people who have demonstrated the ability to change their pupil size, Strauch told Live Science. What's more, that he can feel the muscles in the pupils directly "is astonishing, as it was thought to be impossible."

What's new isn't controlling the pupils but to "feel the muscles directly". Not sure how that part is verified though.

Yeah. I've been able to do this for years. Not immediately, but with some concentration and focus when standing in front of a mirror. Works probably 75-80% of the time.

So, "impossible feat"... how would they even think that?

If it takes time and is not wholly reliable, it sounds like you might be using one of the "indirect methods" they mentioned in the article.

I can change the focal point of my eyes on command to a far away point or a close one, and I have noticed that this reliably makes my pupil get slightly larger or smaller.

Yeah, the article mentions that as the early way the man learned to do it, before being able to directly control the muscle.

That's neat. I wonder if the pupil is actually changing size, or if it's the changing shape of the lens that is making it appear so. If you look into a camera lens as the focus is changed, the inner parts of the camera do appear to change size.

The eye's lens is behind the iris (unlike a camera which is typically the other way around), so the optics shouldn't affect the apparent pupil size.

Whoa. I had no idea. Thanks for informing me! That's so weird. I had always assumed that the curved front surface of the eye was the lens.

You're not wrong - the cornea (front of the eye) has about 3x the refractive power of the lens. Both function as converging lenses, and the only difference is that the refractive power of the lens can be changed.

...until age 45 to 50ish, when the lens hardens into a focus close to infinity and you start to need reading glasses. (presbyopia)

It's the accommodation reflex [0] at work here - pupillary constriction goes hand in hand with a shortening of the focal length of the lens, and the eyes also converge together. This is a brainstem level response, so I doubt there'd be any easy way to dissociate these movements consciously.

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

Interesting, this makes sense. Thanks for figuring it out

This guy can “tremble” his pupil. It’s not the same at all.

I knew a dozen kids in middle school who would do that. I got to the point I can do it sometimes.

I recently discovered / figured this out as well, while practicing meditation. I have found it's a great way to relax my eyes periodically while staring at a screen.

Still can't move my eyebrows independently though.

It sounds similar to how I learned to move my toes independently. It's harder than you'd think and takes a lot of focus. I don't think it's indirect control.

Nope. They only thing I focus on when doing that is changing the pupil size.

First line of the paper:

> Direct control of the pupillary musculature is deemed impossible (Loewenfeld, 1993).

Also, from the abstract, they tested to rule out "increases in arousal by increased mental effort". This is a different phenomenon than what you are discussing.

I hadn’t heard of this being an impossible feat before and I likewise don’t see why it would be. I remember from Kahneman’s work on human biases and fast/slow thinking that they used pupil dilation as a great proxy for how much conscious concentration someone is using. So I don’t see why controlling it would be such an impossible thing.

Similarly, I can stop hiccups mentally. It's just a little trick of concentration while focusing on the right thing.

But it says "once thought an impossible feat". That's cromulent journalism; helps disseminate the idea that it isn't.

This was the first thing that came to mind. They show the children controlling their pupils. https://youtu.be/YIKm3Pq9U8M

And to confirm, I knew someone in school who could do this, though I was never able to do it myself despite some notable time wasted in front of the mirror.

if a hundred people on a population of 8 billion can do it, on command, at will, immediately, it's an impossible feat.

It's not the act of changing the pupil size that's the impossible feat, it's the "doing it instantly, on command" part that's the impossible feat. Even if lots of people can change their pupil size, virtually no one can with the snap of their fingers.

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