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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Answers by country

Poland

69%

12%

30458

France

68%

20%

Switzerland

64%

23%

Greece

64%

14%

Austria

63%

12%

Germany

62%

10%

18%

387

the United Kingdom

62%

16%

10%

260

Canada

62%

12%

11%

the Netherlands

62%

20%

Singapore

61%

23%

15%

the United States

60%

12%

17%

1013

Unknown

60%

19%

Indonesia

57%

26%

10%

Australia

55%

15%

13%

16%

Republic of Ireland

48%

14%

18%

Malaysia

47%

13%

21%

17%

Pakistan

47%

33%

India

46%

15%

19%

15%

413

the Philippines

41%

13%

16%

24%

the United Arab Emirates

37%

25%

14%

17%

Which area is brighter?

Both are the same

It depends on the order of seeing

How many dots at the intersections are black?

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?

None of them

Both are larger