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
82%
0%
12%
5%
40
flagCzech Republic
81%
11%
3%
3%
27
flagNorway
78%
8%
8%
3%
56
flagPoland
75%
10%
8%
5%
20172
flagthe Netherlands
75%
8%
15%
1%
72
flagGermany
72%
9%
8%
7%
281
flagFrance
72%
8%
10%
8%
75
flagthe United Kingdom
71%
8%
12%
5%
582
flagthe United States
70%
9%
11%
5%
1016
flagItaly
70%
16%
8%
4%
48
flagAustralia
69%
10%
7%
12%
56
flagCanada
68%
13%
13%
4%
69
flagthe United Arab Emirates
67%
12%
9%
9%
31
flagRepublic of Ireland
66%
8%
9%
13%
75
flagBelgium
64%
12%
16%
4%
25
flagUnknown
63%
12%
15%
6%
77
flagDenmark
63%
13%
20%
3%
30
flagIndia
55%
9%
17%
13%
243
flagthe Philippines
47%
7%
16%
28%
42

Gender

men76%
women75%
square
76%
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)
1977
65%

Details

Author: Debbie Fox
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