Abstract

The numerous inaccuracies of the current nomenclature of optical-geometrical illusions are set forth. The Oppel-Kundt display cannot be found either in Oppel (1855) or in Kundt (1863): it is by Ebbinghaus (1908); Poggendorff illusion was first depicted by Hering (1861); Loeb's illusion (1892) is ignored in the cases of misalignment; the current display of Müller-Lyer was outlined by Brentano (1892) and ameliorated by Heymans (1896); Baldwin (1895) never presented the optical-geometrical illusion that bears his own name; Ebbinghaus' - or Titchener's - illusion is by Thiéry (1896); Münsterberg simply reported a figure found in Heymans (1897); Ponzo's illusion, in its current form, cannot be found in his works (1912, 1928). Besides, current nomenclature, based on author's name, neglects the fact that some authors presented many and different illusive figures (for instance: Delboeuf: 108; Müller-Lyer: 65; Lipps: 183), so that any reference to the authors is useless. A nomenclature centred on figures, and not on authors is suggested: each figure would be identified by a string of characters bearing the name of the author, the year of publication and the number of the figure in the text (or the number of the page that contains the figure). Some considerations follow, on the necessity of an Atlas of optical-geometrical illusions.