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%
87%
6%
16
flagSpain
4%
8%
78%
4%
23
flagAustralia
0%
6%
77%
15%
45
flagFrance
0%
6%
72%
17%
47
flagthe United Kingdom
4%
7%
71%
14%
382
flagthe United Arab Emirates
10%
7%
71%
7%
28
flagPoland
4%
9%
69%
15%
12859
flagUnknown
2%
7%
68%
21%
532
flagIndonesia
0%
0%
66%
33%
15
flagthe United States
5%
7%
64%
20%
791
flagNorway
4%
16%
64%
16%
25
flagGermany
5%
14%
62%
16%
167
flagItaly
9%
12%
62%
15%
32
flagCanada
4%
9%
59%
22%
62
flagthe Philippines
3%
6%
58%
27%
29
flagSweden
11%
0%
58%
29%
17
flagthe Netherlands
8%
6%
54%
26%
46
flagIndia
6%
11%
53%
23%
210
flagRepublic of Ireland
7%
10%
52%
30%
40
flagSouth Africa
0%
31%
43%
18%
16

Gender

men68%
women73%
blue and red only
4%
4%
green and red only
9%
6%
green, blue and red
68%
73%
none
17%
14%

Language versions

question
answers
results
flag
Which lines are parallel?
1627
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.