There is also the fact that the eyes resolution drops off towards the edge. This makes the effect even harsher in the corner of your eye. As your eye moves from ball to ball your brain will be processing the new higher resolution versions based on the previous versions you saw in the corner of your eye. That effect fades away but your eye is actually always moving doing something called saccades, on a small screen with many prominent points it will do it a lot.
With a big screen alot of that goes away. The gaps are larger. The brown fades more slowly from light to dark so is percieved as a stronger color. Objects are larger so saccades will be less effective because they will be searching fewer objects rather than many in a tight screen. Lastly the lower resolutions at the edge of your eye will pick up more brown as well.
So there most definitely is physical aspects.
I also see an "egg" illusion where it looks like the lower left of the ball is actually flat but the rest is a dome.
/e all of the physical stuff has to do with magnification of the image (or incoming light) onto the retina
I look forward to a robot future where us humans can have a joke and catch out robots by enjoying these optical illusions knowing 'they' don't get it.
I think this might be the same biological reason that we can't perceive much (or any) colour in low light, rods vs cones.
TL;DR our retinas are not CCDs they are a patchwork of two discrete components.
That's the point my dude.
Humans see an optical illusion, robots do not. Meaning ML algos that care about seeing things as humans do have a conundrum.
A human can tell ML that the balls in the example are either perceived red (illusion) or reality (brown). The computer will use that training model for future decisions.
This question also applies to audio illusions, such as the (in)famous Laurel/Yanny clip.
It’s really not a particularly interesting illusion.
In contrast, here the issue is undoubtedly in how the brain interprets the signal data, i.e., an illusion.
It’s not right to say that the balls are “brown”, when they are in fact striped brown and red/green/blue. It’s like saying that a zebra is black if you just ignore the white.
Can it be that such an illusion is learned?
But, by default, I do not fixate on any ball. I take in the gestalt composition, and in this mode I perceive a field with three classes of balls with different tints. This happens as soon as I reframe my attention, even right after I have just sequentially confirmed their color as above.
There was also one interesting comment in the Twitter thread, posting a version that desaturated only the color stripe that overlaps the ball (at a bounding box rather than right at the circular edge of the ball). In this version, the gestalt composition shows me the same tint on all balls, and instead I see three classes of tinted tile in the background behind the balls.
For example, paralyzed babies will also be blind, even if their bodies are moved by someone else.