[Solvency]

Am I alone in not understanding this black hole one... it's a sequence of three obviously distinct still images in which the black center is larger than the previous image.

Meanwhile, each image on its own is offering no kind of perceptive illusion to me...

[block_dagger]

Staring at any of them individually makes the central circle appear to grow. Bottom one is most effective for my eyes. Creepy!

[tstrimple]

For me it doesn’t seem to grow. But the blurred edges definitely show movement from my perception with both eyes open. If I close one eye the effect goes away altogether.

[gowld]

The intent is that the black hole grows while you stare at it.

Not all illusions work on everyone in every environment.

[albert_e]

Yes each image independently shows the illusion -- different images are only to provide a variation i guess, since some proportions work better for some people than others

I personally found the illusion not strong though definitely present

This similar illusion but done with different colors and patters was much more vivid and strong for me ...

check this out:

"Expanding Pupils" second image onwards

http://www.psy.ritsumei.ac.jp/~akitaoka/motion35e.html

[kazinator]

I don't intuitively understand any illusion. I don't have conscious introspection into what the layers of neurons are doing between the retina and conscious visual perception. The layers of neurons use certain indirect cues in order to detect size, depth and movement. Those cues do their job in most circumstances, but test cases can be constructed which falsely trigger those cues. That's just an intellectual generality that doesn't explain anything specific.

[btilly]

You should add shadow to the list of important cues. Something light in shadow can be the same color as something white in direct light. You can see that optical illusion in https://en.wikipedia.org/wiki/Checker_shadow_illusion.

My favorite example of where shadow matters is "the dress". As https://slate.com/technology/2017/04/heres-why-people-saw-th... explains, those whose brains assumed it was in shadow saw it as white and gold. Those whose brains thought it was in light saw it as blue and black. (It was actually a blue and black dress, in light. But the photo was taken in such a way that most people thought it was in shadow.)

[smeej]

This one drives me crazy because even having seen a picture of the same blue and black dress in direct light, my brain simply will not see this as anything but white and gold. I know I'm seeing it wrong and still can't see it right.

[phatskat]

Mine has changed over the years - usually I see blue and black, but occasionally I see white and gold.

[qwertywert_]

Open the image and F11 to full screen then just stare at the center.