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in the peripheryEwald HeringReprinted by permission of Open Court Publishing Company, a division ofCarcus Publishing Company, from Philosophical Portrait Series, © 1898 byOpen Court Publishing Company.EARLY DEVELOPMENTS IN PHYSIOLOGY AND THE RISE OF EXPERIMENTAL PSYCHOLOGY 243of the retina, night vision and movement perceptionare better than in the fovea. Ladd-Franklinassumed that peripheral vision (provided by therods of the retina) was more primitive than fovealvision (provided by the cones of the retina) becausenight vision and movement detection are crucial forsurvival. But if color vision evolved later than achromaticvision, was it not possible that color visionitself evolved in progressive stages?After carefully studying the established colorzones on the retina and the facts of color blindness,Ladd-Franklin concluded that color vision evolvedin three stages. Achromatic vision came first, thenblue-yellow sensitivity, and finally red-green sensitivity.The assumption that the last to evolve wouldbe the most fragile explains the prevalence of redgreencolor blindness. Blue-yellow color blindnessis less frequent because it evolved earlier and is lesslikely to be defective. Achromatic vision is the oldestand therefore the most difficult to disrupt.Ladd-Franklin, of course, was aware ofHelmholtz’s and Hering’s theories, and, althoughshe preferred Hering’s theory, her theory was notoffered in opposition to either. Rather, she attempted
to explain in evolutionary terms the origins
of the anatomy of the eye and its visual
abilities.
After initial popularity, Ladd-Franklin’s theory
fell into neglect, perhaps because she did not have
adequate research facilities available to her. Some
believe, however, that her analysis of color vision
still has validity (see, for example, Hurvich, 1971).
For interesting biographical sketches of LaddFranklin,
see Furumoto (1992) and Scarborough
and Furumoto (1987).
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