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
flagFinland
96%
0%
0%
3%
29
flagSpain
84%
0%
10%
5%
38
flagNorway
78%
8%
8%
3%
56
flagPoland
75%
10%
8%
5%
19596
flagthe Netherlands
73%
8%
15%
1%
69
flagGermany
72%
9%
8%
7%
275
flagFrance
72%
8%
9%
8%
74
flagthe United Kingdom
71%
8%
12%
5%
573
flagItaly
70%
17%
8%
4%
47
flagthe United States
69%
9%
11%
6%
991
flagCanada
69%
13%
11%
4%
68
flagAustralia
69%
10%
7%
12%
56
flagRepublic of Ireland
68%
8%
10%
10%
70
flagDenmark
65%
10%
20%
3%
29
flagthe United Arab Emirates
64%
14%
10%
10%
28
flagBelgium
64%
12%
16%
4%
25
flagSweden
63%
18%
13%
4%
22
flagUnknown
60%
15%
17%
6%
58
flagIndia
57%
9%
17%
12%
233
flagthe Philippines
47%
7%
15%
30%
40

Gender

men75%
women75%
square
75%
75%
rhomboid
10%
10%
concave square
8%
7%
concave rhomboid
5%
5%

Language versions

question
answers
results
flag
How is this polygon called? (the one over the circles)
1928
66%

Details

Author: Debbie Fox
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