What is Heymans (1896) explanation of the Muller Lyer illusion?

-- Martha Davis (jstupot@hotmail.com), March 04, 2002

Answers

I do not know. He was from Groningen in the Netherlands (the Advanced Psychological Research Institute there is names after him). The original paper is in German -- Heymans, G. (1896). Untersuchungen über das "optischen Parodoxen". Zeitschrift für Psychologie, 9, 221-225. I have not been able to locate a translation. There is a drawing of Heymans' Muller-Lyer apparatus on p. 411 of E. B. Titchener's _Experimental Psychology_ (Instructor's Manual, Quantitative), and several mention of him but no description of the research itself. He seems to have been "nulling" the illusion (by extending the short-looking line until it appears to be equal to the long-looking line), and possibly linking the effect to Fechner's psychophysical law, but I cannot be sure. There is only the briefest mention of Heymans in Boring's 1929 _History of Experimental Psychology_, and no mention in the 1950 edition. There is a little more about him in Gardner Murphy's _Historical Introduction to Psychology_, but it is about his personality and sex-diff. work in the 20th early century. I can find nothing about him in a variety of perception texts, illusion texts, and dictionaries/encyclopedias of psychology. My best advice at this point would be to check the APA/Oxford _Encyclopedia of Psychology_ at your local college library. Sorry I couldn't be more help.

-- Christopher Green (christo@yorku.ca), March 04, 2002.