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.

Answers distribution

square
rhomboid
concave square
concave rhomboid
answers
flagNorway
80%
6%
7%
5%
77
flagSpain
78%
0%
16%
6%
50
flagSwitzerland
78%
4%
11%
4%
42
flagthe Netherlands
76%
8%
12%
1%
111
flagPoland
74%
10%
8%
5%
31474
flagthe United Kingdom
72%
7%
12%
6%
777
flagGermany
72%
9%
8%
7%
393
flagItaly
72%
12%
8%
6%
62
flagthe United Arab Emirates
72%
10%
8%
8%
48
flagCroatia
72%
10%
10%
0%
37
flagSweden
70%
8%
12%
10%
50
flagthe United States
69%
10%
11%
6%
1139
flagFrance
69%
9%
12%
7%
91
flagCanada
69%
12%
12%
3%
79
flagAustralia
68%
11%
7%
13%
69
flagUnknown
67%
15%
9%
7%
1878
flagDenmark
67%
11%
17%
2%
34
flagRepublic of Ireland
66%
7%
10%
13%
90
flagIndia
55%
10%
16%
13%
280
flagthe Philippines
48%
8%
16%
26%
49

Gender

men72%
women76%
square
72%
76%
rhomboid
12%
10%
concave square
8%
7%
concave rhomboid
6%
5%

Language versions

question
answers
results
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How is this polygon called? (the one over the circles)
2303
65%

Details

Author: Debbie Fox
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