Why the same circle looks smaller among big ones: the Ebbinghaus illusion and size contrast
30seconds
Two identical orange circles, one ringed by big circles and one by small ones, and your eyes insist they differ. That is the Ebbinghaus illusion: your visual system judges size relative to the neighbours, not like a ruler.
Match the circles yourself, then see how far off you were. Squeeze the ring in and out to find out that distance matters too, and read how susceptibility varies between adults, children and brains.
Deep dive · 4 min
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