The horizontal blue bars in this version of what is called the “café wall illusion” are parallel. Yes they are. Check with your ruler.
The café wall illusion, also known as the Münsterberg illusion, is a geometrical-optical illusion in which the parallel straight dividing lines between staggered rows with alternating dark and light "bricks" appear to be sloped, not parallel as they really are. The illusion was first described by Hugo Münsterberg in 1894. It has been rediscovered several times, including under the name kindergarten illusion in 1898 by A.H. Pierce, and under its current name in 1973 by Richard Gregory. According to Gregory, this effect was observed by a member of his laboratory, Steve Simpson, in the tiles of the wall of a café at the bottom of St Michael's Hill, Bristol. Also, Professor Akiyoshi Kitaoka, whose Rotating Snakes illusion was featured in [RR#2: 64] has created multiple versions of the illusion that include the contrasting targets.
This excellent version of the illusion, crediting both Richard Gregory and Akiyoshi Kitaoka, was created in 2017 by Victoria Skye, a professional illusion artist, magician and entertainer based in Atlanta, Georgia.
Skye’s Cafe wall illusion is comprised of perfectly aligned horizontal and vertical bars and diamond patterns. The design’s patterns are in parallel rows in both directions but it’s the way they interact with each other that makes the illusion look so believable. Interviewed by Interesting Engineering after she won second Best Illusion of the Year award in 2017, she explained just how the eyes are tricked into seeing inclined lines instead of the real straight figures:
“The scientists say that the reason the illusion exists has to do with how the white and black edges interact in opposite directions along the straight edge, tricking the brain into thinking there is a slant in the line. If you blur the image, the effect disappears because you cannot resolve the tiny white-black interactions once they are blurred, so the brain is no longer led down the garden path”.
Set out below in the gallery is the same image, but with the chequerboard diamonds removed. Also explained in 2017 competition video HERE.
Parallel order is restored.
Story Idea: Remo Giuffré
_____________________________
References
wikipedia.org/wiki/Cafe_wall_illusion
victoriaskye.com
illusionoftheyear.com/2017/10/skye-blue-cafe-wall-illusion
interestingengineering.com/culture/incredible-optical-illusion-deceiving-fools-creator
psy.ritsumei.ac.jp/akitaoka/cafewalle
Images
1. Skye Café Wall by Victoria Skye, 2017
2. Skye Café Wall with chequerboard diamonds removed
3. Victoria Skye
4. Richard Gregory visits the original café wall on St Michael's Hill, Bristol, in February 2010. Photo credit: Steven Battle.
5. Video: Skye Blue Cafe Wall Illusion via The Illusion Contest
6. Architecture inspired by the café wall illusion at Melbourne Docklands
