Which lines are parallel?

blue and red only
green and red only
green, blue and red
none
This is a well known Zöllner il­lu­sion, first de­scribed in 1860. It may be caused by this im­pres­sion of depth. The black lines are par­al­lel, too!

Answers distribution

blue and red only
green and red only
green, blue and red
none
answers
flagCroatia
0%
6%
86%
6%
15
flagSpain
5%
10%
80%
0%
20
flagAustralia
0%
4%
79%
15%
44
flagthe United Arab Emirates
13%
9%
72%
4%
22
flagthe United Kingdom
4%
8%
71%
14%
335
flagPoland
5%
9%
69%
15%
10423
flagFrance
0%
6%
69%
18%
43
flagUnknown
3%
6%
69%
21%
33
flagNorway
4%
14%
66%
14%
21
flagItaly
6%
13%
65%
13%
29
flagthe United States
5%
7%
64%
20%
757
flagGermany
4%
14%
64%
14%
149
flagIndonesia
0%
0%
64%
35%
14
flagFinland
14%
21%
64%
0%
14
flagthe Philippines
3%
3%
59%
29%
27
flagCanada
5%
10%
57%
23%
56
flagthe Netherlands
10%
5%
56%
24%
37
flagIndia
6%
11%
54%
23%
199
flagRepublic of Ireland
5%
10%
51%
32%
37
flagSouth Africa
0%
31%
43%
18%
16

Gender

men67%
women72%
blue and red only
5%
4%
green and red only
10%
7%
green, blue and red
67%
72%
none
15%
15%

Language versions

question
answers
results
flag
Which lines are parallel?
1533
63%

Details

Author: globalquiz.org
Illustration: globalquiz.org
tools
Should this question be improved? Improve it.
Globalquiz questions are translated by users for other users. Translate this question.