A champagne glass illusion.

Abstract

The high hat illusion found in Professor Carr's Psychology: A Stitdy of Mmtd Life (1925, pp. 157-158) strudc me at first sight as a very effective fusion of MiillerLyer's paradox ( 1889) and William Wundt's horizontal-vertical illusion ( 1859). On second thought, I realized that it was not only the best textbook illustration I had ever come across on that subject, bur it was much more than just a case of peripheral fusion of illusions, for the central factor of mental set or expectancy plays a predominant role there. We all have seen so many felt or straw hats in the past that we are accustomed to their standard low level on the top. So in contrast to our stereotyped memory image, the high hat pictured in the illustration produces an impressive effect of looking indeed very much taller than usual. For the same reason, a concave facial mold displayed on an optician's counter once looked like a real convex face to me at a distance. We tend to see what we expect to see. When the figure stays clear in the open, our memory image may magnify the difference by contrast as in the case of the high hat. But when the exposure is too brief or when the object is too far away to permit a clear look or close examination, are may ignore reality and interpret the ambiguity according to our expecrancy, as in the case of the concave facial mold. Ever since my Chicago days (1926-31), I have been looking for a perhaps less central and more peripheral illustration of combining the two famous illusions among familiar objects. Finally, I hit upon the idea of a wine vessel which is depicted in the following figure. Hold the figure upright and compare the relative length of the brim and the stem. Which appears longer' Are they equal? In fact, the brim is longer.