Café wall
Richard Gregory & Priscilla Heard; observed by Steve Simpson
Perfectly parallel mortar lines seem to slope.
Size & geometry / 1889 / 1892
Jastrow curves
Identical curved pieces seem to have different sizes.
TRY THIS
Compare the two curved bands. Their placement puts the long edge of one next to the short edge of the other. Align the shapes mentally or trace them to check.
THE IMAGE IN THIS ARCHIVE
Fibonacci.
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What is Jastrow curves?
Identical curved pieces seem to have different sizes.
What should I look for in Jastrow curves?
Compare the two curved bands. Their placement puts the long edge of one next to the short edge of the other. Align the shapes mentally or trace them to check.
What explains Jastrow curves?
The arrangement encourages comparisons between unequal neighboring edges rather than corresponding parts of the identical shapes. That describes an important influence, but the broader perceptual mechanism is still debated.
Another way to see it
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Ebbinghaus circles
Traditionally Hermann Ebbinghaus; popularized by E. B. Titchener
The neighbors change the size of the circle you see.