[d4mi3n]

I was in bed reading this with an eye closed and was very confused until I discovered the illusion works for me only when I watch it with both eyes open.

I found this surprising—I know three dimensional optical illusions depend on focus and perspective, but I was unaware two dimensional optical illusions were as well.

[soxocx]

Thats interesting. I see it with either or both eyes.

[jareklupinski]

I... only see it happening with either both eyes or my right eye...

My left eye is immune? This is uncanny...

[meitham]

I’m the opposite! My right eye alone can’t see it, but can do with both or left only!

[yazzku]

Sounds like your perception can't exactly be pigeonholed.

Boom, baby.

[867-5309]

your taxi to the nearest wormhole awaits..

[bmitc]

The illusion is much less if I zoom in and even less if I close one eye, so maybe they had their device up close to their face?

[soxocx]

You are right. If I tilt the screen while changing distance to the screen and keep blinking with my eyes while I do this, I, besides looking like a maniac, can weaken the effect and even make it disappear entirely.

[PyWoody]

Try closing one eye and tilting your head 90°

[kerpotgh]

I can see it irrespective of how many eyes are open or any tilt angle.

[javawizard]

So you can see it with zero eyes open? ;)

I also see it with any number (>= 1) of eyes open and at any angle. Wonder if GP's phone was on night shift or something similar - the article mentions that color changes impact the illusion's visibility.

[d4mi3n]

No night shift, for what it’s worth. Another commenter mentioned astigmatism, which I do have. I was not wearing my glasses at the time.

Curious to see if anybody with expertise on the topic of optics or visual perception chimes in with some insight.

[kerpotgh]

Interesting, I have astigmatism so I tried it without my glasses and with both one and two eyes open at different angles and I still see the illusion (with no change in intensity of the “bobbing”)

[yazzku]

Can you see it with three eyes opened?

[labster]

I can’t but I’ll ask my yoga guru tomorrow.

[Daub]

As a one-eyes person, the illusion works fine for me. However, it ceases to work in the periphery of my vision.

[aendruk]

Astigmatism? My eyes blur at different angles so various anisotropies show up only when one is closed.

[d4mi3n]

I do have an astigmatism in my right eye—which was also closed. First time I’ve had this happen with an optical illusion, though.

[stouset]

I let out a verbal "what the fuck" when I tried this. Same exact thing as you, it's absolutely striking.

[d4mi3n]

I was confused as well. First impression: nothing. Get up and look with both eyes and there it was. Interesting stuff.

[kolinko]

For me, if I focus intensely on the head, the neck stops moving. When I relax, and the reference naturally changes to the lines in the background, the neck begins moving again.

[stefncb]

For me it weakens with one eye closed, but I still see it.

[IshKebab]

Worked a bit better for me with one eye closed. Weird.