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%
26
flagSpain
83%
0%
10%
5%
37
flagNorway
80%
9%
9%
1%
55
flagPoland
74%
10%
8%
5%
18779
flagthe Netherlands
74%
9%
14%
1%
63
flagGermany
71%
9%
8%
7%
252
flagFrance
71%
8%
10%
7%
67
flagCanada
71%
12%
12%
3%
66
flagthe United States
70%
9%
10%
6%
968
flagthe United Kingdom
70%
8%
12%
6%
524
flagAustralia
69%
10%
7%
12%
56
flagItaly
69%
19%
9%
2%
42
flagRepublic of Ireland
68%
7%
10%
10%
67
flagDenmark
67%
10%
17%
3%
28
flagBelgium
66%
12%
12%
4%
24
flagSweden
65%
20%
10%
5%
20
flagthe United Arab Emirates
60%
17%
8%
13%
23
flagIndia
57%
10%
16%
12%
227
flagUU
56%
21%
21%
0%
37
flagthe Philippines
50%
7%
15%
26%
38

Gender

men75%
women75%
square
75%
75%
rhomboid
10%
11%
concave square
8%
7%
concave rhomboid
5%
5%

Language versions

question
answers
results
flag
How is this polygon called? (the one over the circles)
1865
66%

Details

Author: Debbie Fox
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