- Zöllner illusion
The Zöllner illusion is a classic
optical illusion named after its discoverer, German astrophysicistJohann Karl Friedrich Zöllner . In1860 , Zöllner sent his discovery in a letter to physicist and scholarJohann Christian Poggendorff , editor of "Annalen der Physik und Chemie", who subsequently discovered the relatedPoggendorff illusion , in the original drawing ( [http://gallica.bnf.fr/ark:/12148/bpt6k151955/f687.table Table VIII Figure 4] ) of Zöllner. [cite journal
title = Ueber eine neue Art von Pseudoskopie und ihre Beziehungen zu den von Plateau und Oppel beschrieben Bewegungsphaenomenen
author = Zöllner F
journal = Annalen der Physik
volume = 186
issue =
pages = 500–25
year = 1860
url = http://gallica.bnf.fr/ark:/12148/bpt6k151955/f512.table
doi = 10.1002/andp.18601860712 ]In this figure the black lines seem to be unparallel, but in reality they are parallel. The shorter lines are on an angle to the longer lines. This angle helps to create the impression that one end of the longer lines is nearer to us than the other end. This is very similar to the way the
Wundt illusion appears. It may be that the "Zöllner illusion" is caused by this impression of depth.It is interesting to see what happens when the colours in this illusion are changed. If the illusion is printed in green on a red background and the red and green are equally bright, the illusion disappears.
This illusion is similar to the
Hering illusion , thePoggendorff illusion and theMüller-Lyer illusion . All these illusions demonstrate how lines can seem to be distorted by their background.External links
* [http://www.ritsumei.ac.jp/~akitaoka/zollnere.html Zöllner illusion] at Akiyoshi Kitayoka's illusion pages
References
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