questionedithistorytranslations

How is this polygon called? (the one over the circles)

square
rhomboid
concave square
concave rhomboid
In this Ehrenstein illusion the sides of a square placed inside a pattern of concentric circles take an apparent curved shape. But in reality, the sides are straight.
Debbie Fox
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Very interesting!
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Answers by country

square
rhomboid
concave square
concave rhomboid
answers
flagPoland
69%
12%
9%
7%
30549
flagFrance
68%
20%
4%
8%
25
flagSwitzerland
65%
4%
21%
4%
41
flagAustria
64%
8%
11%
11%
59
flagGermany
63%
10%
17%
7%
432
flagthe United Kingdom
62%
8%
17%
10%
269
flagCanada
62%
12%
12%
11%
72
flagGreece
61%
16%
9%
12%
31
flagSingapore
61%
23%
15%
0%
26
flagthe United States
60%
12%
16%
7%
1036
flagUnknown
59%
9%
11%
19%
42
flagthe Netherlands
59%
6%
18%
9%
32
flagIndonesia
57%
5%
26%
10%
19
flagAustralia
54%
14%
14%
15%
82
flagRepublic of Ireland
48%
14%
14%
18%
27
flagMalaysia
47%
13%
21%
17%
23
flagPakistan
47%
9%
33%
4%
21
flagIndia
46%
15%
19%
15%
417
flagthe Philippines
41%
13%
16%
24%
65
flagthe United Arab Emirates
36%
27%
13%
16%
36

Which area is brighter?

A
B
Both are the same
It depends on the order of seeing

How many dots at the intersections are black?

10%
25%
50%
None

The bright circle around the Sun seen in the picture is known as a halo. What causes it?

refraction of light in ice crystals
refraction in the lens of the eye or lens
refraction of light in water drops
reflections from the water surface

Which shape is larger?

A
B
None of them
Both are larger