The principles of psychology . the theory of identical retinal points, andwhy Hering, the greatest champion of this theory, lays somuch stress upon it. It is an immediate consequence of the laiv of identical pro- * These two observations prove the law of identical direction only forobjects which excite the fovese or lie in the line of direct looking. Ob-servers skilled in indirect vision can, however, more or less easily verify thelaw for oiitlying retinal points. TEE PERCEPTION OF SPACE. 225 jection of images on geometrically similar points that imagesivhichfall upon geometrically
The principles of psychology . the theory of identical retinal points, andwhy Hering, the greatest champion of this theory, lays somuch stress upon it. It is an immediate consequence of the laiv of identical pro- * These two observations prove the law of identical direction only forobjects which excite the fovese or lie in the line of direct looking. Ob-servers skilled in indirect vision can, however, more or less easily verify thelaw for oiitlying retinal points. TEE PERCEPTION OF SPACE. 225 jection of images on geometrically similar points that imagesivhichfall upon geometrically points of the two retinceshould be projected in dispaeate directions, and that their objectsshould consequently appear in two places, or look the parallel rays from a star falling upon two eyeswliicli converge upon a near object, O, instead of beingparallel, as in tlie previously instanced case. If SL and SRin Fig. 55 be tlie parallel rays, each of tliem will fall uponthe nasal half of the retina which it Fig. 55, But the two nasal halves are disparate, geometricallysymmetrical, not geometrically similar. The image on theleft one will therefore appear as if lying in a direction left-ward of the Cyclopean eyes line of sight; the image of theright one will appear far to the right of the same star will, in short, be seen double,— homonymously double. Conversely, if the star be looked at directly with parallelaxes, O will be seen double, because its images will affectthe outer or cheek halves of the two retinae, instead of oneouter and one nasal half. The position of the images willhere be reversed from that of the previous case. The right 226 PSTCHOLOGT. eyes image will now appear to the left, the left eyes to theright—the double images will be heteronymous. The same reasoning and the same result ought to applywhere the objects place with respect to the direction of thetwo optic axes is such as to make its images fall not on non-similar reti
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpsychology, bookyear1
