About thirty years ago, the present author began to investigate the ptlJblems of visual perception (12,13,14).Sinte then, he has been persuing an active research program, conducting a large number of studies which covered various fields of PfYChology such as geometrical illusions, spatial anisotropy, spatial induction, successive cOfllparison, memory, etc.His earlier works were mainly concerned with the field of spatial induction, and the results of studies were published in a series under the title "Confributions to the study of psycho-physiological induction (15)." .After these experimental investigations the author proposed the psycho-physiological induction theory for the explanation of various kinds of perceptual phenomena.The theory was stated as follows: the areas surrounding the stimulated part of the retirut undergo a change in excitability when a light stimulates one part of the retina.(Strictly speaking, the retinocerebral nerve-system is activated.For the sake of brevity of description, however, the term retina is here used.)Such a excitability appears as various ~nsory or perceptual properties such as sensitivity, brightness, color, spatial extent, protensity, etc.The present author called the phenomenon" Psycho-physiological induction (16)."24.Yokose, Z. Theoretical formula of vector-field and its experimental proof.Psychologid, 1957,1,17-21_