Experimental examination of vibrating-method based on kappa-sensitivity and its application to geometrical illusions

Abstract

The response in the center of the human fovea changes from On-type to Off-type as the inducing figure approachtes the fovea (this Journal, 1967, 38, 1-13). This findings could explain why the sensitivity measured in terms of light threshold decreases while that of CFF increases as the inducing figure approaches the test figure. On the basis of the results the present writer proposed a hypothesis that light sensitivity possesses two aspects of τ and κ. Furthermore, the following four methods have been devised to prove the hypothesis experimentally.Vibrating method 1. When a geometrical illusion figure is adequately vibrated in the direction of the appearance of illusion, the amount of illusion increases.Vibrating method 2. When grating lines are adequately vibrated in the face of a geometrical figure, they are deformed according to the characteristic of the figure.Vibrating method 3. When a small circle is adequately vibrated in the face of a geometrical figure, it is deformed from a circle to an ellipse.Flickering method. When one of two figures in the midst of binocular rivalry is flickered, the other is often disappeared immediately after the appearance of the flickering figure. The flickering method was designed to measure its flickering effect on the disappearance of the continuous figure.The present study is related to Vibrating method 2. First some experiments were conducted to test whether or not the deformation of the grating lines depends mainly upon the characteristic of figure on the following various conditions; (1) binocular vision and monocular vision, (2) illuminance of figure, (3) observing distance, (4) distance between grating lines and figure, (5) length of grating lines, (6) conditions of vibrations of grating lines, (7) observing time, (8) fixation point, (9) white-black relations between grating lines and figure, (10) number of grating lines, and (11) width of grating lines. Then some experiments were conducted to examine the relationship between the deformations of the grating lines and the following geometrical illusions; (1) Muller-Lyer, (2) Ponzo, (3) Zollner, (4) Hering, (5) Wundt, (6) Hofler, (7) Pisco, and so on. The results obtained are shown in Figs. 3-6.