Comparing this second-to-last frame with the last one I think helps make the reasoning behind the illusion clear. The fake shadow is what causes us to perceive A as being darker than B, based on our intuition about how the physical world should work. If just that small portion of the image is covered, we can easily see how they are actually the same color.
shreyaskompalli
This entire illusion was incredible; before looking at the last slide, I tried covering the shadowed parts with my thumb to see if I could compare the A and B colors. However, I found that the illusion was only truly broken if I carefully covered ALL of the shadow; if even a small amount was peeking out, my brain would still adjust and view A and B as different colors.
Comparing this second-to-last frame with the last one I think helps make the reasoning behind the illusion clear. The fake shadow is what causes us to perceive A as being darker than B, based on our intuition about how the physical world should work. If just that small portion of the image is covered, we can easily see how they are actually the same color.
This entire illusion was incredible; before looking at the last slide, I tried covering the shadowed parts with my thumb to see if I could compare the A and B colors. However, I found that the illusion was only truly broken if I carefully covered ALL of the shadow; if even a small amount was peeking out, my brain would still adjust and view A and B as different colors.