The Influence of Retinal Adaptation and Location on the “Empfindungszeit.”
1950 年 52 巻 3-4 号 p. 397-405
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1950 年 52 巻 3-4 号 p. 397-405
“Empfindungszeit” (“E. Z.”) for a wide range from the center to the periphery of the retina was measured by a modified Hazelhoff's method under various states of adaptation.
(1) It was proved that our method satisfied the necessary conditions for measuring the “E. Z.” that an observer could make his gaze follow a fixation point travelling at a constant speed.
(2) The speed of the eye movement has no influence on the “E. Z.” within the range of the speed from 10° to 44° per sec. in visual angle in the horizontal direction.
(3) At a constant intensity of a light stimulus, light adaptation causes an elongation of the “E. Z.”, and the ratio of the “E. Z.'s” determined predominantly by the cone function at two different retinal parts remains constant irrespective of adaptation.
(4) Under dark adaptation, the value of the “E. Z.” at a high in-tensity of the stimulus shows two minima at the fovea and about 30° peri-phery and two maxima at about 10° parafovea and the extreme periphery, while the value of the “E. Z.” at a low intensity of the stimulus shows only a minimum at about 30° periphery.
(5) The question whether cones or rods predominate for the “E. Z.” seems to depend on the ratio of the densities of rods and cones of the retinal area stimulated. The shortest “E. Z.'s” determined by the cone function and by the rod function are obtained at the fovea and at about 30° peri-phery respectively, and the former is shorter than the latter.
We wish to thank Prof. K. Motokawa for his advice and helpfulness.
