There is a line on the inside and outside of the circles where the colors go in and out of sync with the circle as the arrows change directions - it snaps between trailing by half the length of the color segments, going being ahead by the same amount, or in sync.
When the outer edge of a part of the circle is trailing and the inner edge is ahead, the circle appears to move outwards; reverse this and it appears to move inwards. The parts where the circle appears to be moving up/down/left/right have one side set to the 'outwards' motion, the opposite side set to the 'inwards' motion, and the other sides in sync.
The human visual cortex has so, so many edge cases like this. It's wonderful!
what I found fascinating is that the effect is maintained even when you're not focused (like lens focus, not attention focus) on the circles. If you let your eyes relax their focus to a point beyond the screen, the blurry circles maintain the illusion.
And bonus points if you find the focal point where a third circle is in the middle which is a composite of both the left and right circles, and... it doesn't move. I don't know how to better explain the effects of letting your eyes wander out of focus and the artifacts it creates in your vision, but I'm sure someone will get it.
Feels almost normal on the left/right moving ones, but when the grow/shrink stage comes my brain has no idea what to do with the arrows. The arrows looked like they were both pointing in and out, sometimes flipping between them really fast.
Somehow the right side is slightly out of focus, but the left is sharp. I think I had each eye at a different focal point. Is that possible? lol
It sure is. It’s also quite interesting that i have to get very close to the screen to create that third circle, but then can get quite far without loosing it, even when looking at the right or left circle.
Yeah, my first guess is the movement of that faint inner line triggers the Parasol cells or some other movement detection cells in our retina (https://en.wikipedia.org/wiki/Parasol_cell).
This needs a memetic hazard warning! I had just eaten, and the linked illusion caused me instant nausea/motion sickness, which has not gone away after hiding the browser tab.
It's possible to suggest a direction for the spinning dancer illusion.[1]
I don't have an example for you that actually has cues included, but you can do it with some success in your own mind. Decide you want to see it spinning clockwise, then look at it. Now look away, and tell yourself it's going to be spinning anti-clockwise, then look at it again.
I now that's not quite what you wanted, but I imagine you could achieve a similar result by showing a clockwise/anticlockwise cue on the image itself.
Either the compression is changing the circles a bit, or they do in fact move - I’ve held a piece of paper covering all but a slight edge of a circle (obscuring everything else) and I can see the edge expanding/moving ever so slightly.
Still not enough to call BS on the illusion, but it might actually help “augment” it a bit.
Part of what you think are compression artifacts-- the thin layer of "wrong" pixels-- are actually key to the illusion. That being said, yes there are still some compression issues.
I love how the compression artifacts are acting like a magician's sleight of hand, obscuring the changes to the border of the circle that create the illusion.
> Part of what you think are compression artifacts
I know what are compression artefacts and what is part of the illusion, no need to explain that to me. I just wanted to see the less compressed version.
It's a nice effect and others might find your comment useful, I just wanted to say that there was no reason to address your explanation to me.
You downvoted me, why don’t you try for yourself? Keep them covered for a minute so you’re sure that your brain isn’t messing with you, then look again and you’ll see it.
Me too, and I'm pretty sure they actually do move. When I place something on my screen covering the arrows, I can see circles moving (since the shape of the gap between covering and edge of circle changes).
I consider a loss of a pixel on one side simultaneous with the addition of a pixel on the other side as "moving". Loss and addition here meaning "change in color"
When the outer edge of a part of the circle is trailing and the inner edge is ahead, the circle appears to move outwards; reverse this and it appears to move inwards. The parts where the circle appears to be moving up/down/left/right have one side set to the 'outwards' motion, the opposite side set to the 'inwards' motion, and the other sides in sync.
The human visual cortex has so, so many edge cases like this. It's wonderful!