Japanese Studies on the So-Called Geometrical-Optical Illusions

The so-called geometrical-optical illusion (geometrisch-optische Tauschung) was one of the most important problems of psychology during the second half of the last century. However, only a few of European and American psychologists today are seemingly studying it, while in Japan it has continuously interested psychologists for these three decades. As Boring (1942) said, "the problem of the geometrical illusions is not a special problem of space perception." They will serve as useful cues to discover the general laws. In the present paper, the important experimental works in Japan which have been done quantitatively through psychophysical methods will be mainly reviewed.** Theoretical works will be referred to only briefly.