Christine Ladd-Franklin

1847-1930
American psychologist, logician, and an internationally recognized authority on the theory of color vision.

Born in Windsor, Connecticut, Christine Ladd-Franklin spent her early childhood in New York City. Her father was a prominent merchant and her mother was a feminist. Following her mother's death when Ladd-Franklin was 13, she moved to Portsmouth, New Hampshire, to live with her paternal grandmother. Ladd-Franklin attended the Wesleyan Academy in Wilbraham, Massachusetts for two years, taking classes with boys preparing to enter Harvard University, and was the valedictorian of her graduating class in 1865. After graduating from Vassar College in 1869 with a primary interest in mathematics and science, she taught in secondary schools in Pennsylvania, New York, and Massachusetts for more than a decade and also published numerous articles on mathematics during this period. In 1878, she applied for admission to Johns Hopkins University for advanced study in mathematics. Because of her extraordinary intellectual ability, Ladd-Franklin was awarded the stipend of a fellow, although not the actual title because women were not permitted to pursue graduate study at the time. Despite completing requirements for the doctorate in 1882, she was denied the degree until 1926.

At the completion of her fellowship in 1882, Ladd-Franklin married Fabian Franklin, a mathematics professor at Johns Hopkins University, and gave birth to two children, one of whom died in infancy. Atypical for married women of the time, and without a formal academic affiliation, she continued to publish scholarly papers, several of which appeared in the American Journal of Mathematics. After hearing Charles S. Peirce (1839-1914) lecture at Johns Hopkins, Ladd-Franklin became interested in symbolic logic and wrote a paper, "The Algebra of Logic," that was published in 1883 in a book of

Christine Ladd-Franklin (Archives of the History of American Psychology. Reproduced with permission)

essays by Peirce and his students. In her paper, praised as a landmark achievement by Harvard philosopher Josiah Royce (1815-1916), Ladd-Franklin reduced all syllogisms to a single formula, in which the three parts form an "inconsistent triad."

Ladd-Franklin's mathematical interests ultimately led her to make important contributions to the field of psychology. In 1886, she became interested in the geometrical relationship between binocular vision and points in space and published a paper on this topic in the first volume of the American Journal of Psychology the following year. During the 1891-92 academic year, Ladd-Franklin took advantage of her husband's sabbatical leave from Johns Hopkins and traveled to Europe to conduct research in color vision in the laboratories of Georg Müller (1850-1934) in Göttingen, and Hermann von Helmholtz (1821-1894) in Berlin, where she also attended lectures by Arthur König. In contrast to the prevailing three-color and opponent-color explanations of color vision, Ladd-Franklin developed an evolutionary theory that posited three stages in the development of color vision. Presenting her work at the International Congress of Psychology in London in 1892, she argued that black-white vision was the most primitive stage, since it occurs under the greatest variety of conditions, including under very low illumination and at the extreme edges of the visual field. The color white, she theorized, later became differentiated into blue and yellow, with yellow ultimately differentiated into red-green vision. Ladd-Franklin's theory was well-received and remained influential for some years, and its emphasis on evolution is still valid today.

After returning to the United States, Ladd-Franklin taught, lectured, and pursued research. She continued publishing and presented papers at meetings of both the American Philosophical Association and the American Psychological Association, as well as at international congresses. She lectured in philosophy and logic at Johns Hopkins between 1904 and 1909, and served as an associate editor in those fields for Baldwin's Dictionary of Philosophy and Psychology. Moving to New York City with her husband in 1910 when he became an associate editor of the New York Evening Post, Ladd-Franklin began lecturing at Columbia University. She published an influential paper on the visual phenomenon known as "blue arcs" in 1926, when she was in her late seventies, and in 1929, a year before her death, a collection of her papers on vision was published under the title Colour and Colour Theories. In her writings and active correspondence with colleagues, Ladd-Franklin challenged the mores of the day, championing the cause of women in matters of equal rights, access to education and the professions, and the right to vote.