Johann Joseph on Geometrical-Optical Illusions: A Translation and Commentary

Nicholas J. Wade (Lead / Corresponding author), Dejan Todorović, David Phillips, Bernd Lingelbach

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
239 Downloads (Pure)


The term geometrical-optical illusions was coined by Johann Joseph Oppel (1815-1894) in 1855 in order to distinguish spatial distortions of size and orientation from the broader illusions of the senses. We present a translation of Oppel's article and a commentary on the material described in it. Oppel did much more than give a name to a class of visual spatial distortions. He examined a variety of figures and phenomena that were precursors of later, named illusions, and attempted to quantify and interpret them.

Original languageEnglish
Pages (from-to)1-18
Number of pages18
Issue number3
Early online date23 Jun 2017
Publication statusPublished - Jun 2017


  • Oppel
  • geometrical-optical illustions
  • orientation
  • size
  • area
  • contrast
  • bisection


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