Color is among the most familiar of our sensations, and at the same time also one of the most foreign. Whereas any child can tell you that Big Bird is yellow, any philosophy major can just as easily put you in a state of profound existential unease by informing you that, in actuality, nothing is yellow, that yellowness is a consistent illusion woven by brains doing their best to provide us with a map of our surroundings based on a very limited sampling of the electromagnetic radiation around us.
Just like the image of yourself in a mirror, yellow exists only in your head.
“It’s all lies!,” however, doesn’t quite do as an explanation of our experience of color, and in the early 19th century scientists started developing our first scientifically robust theories of how color works, both on the physical level of the biology of the eye, and the mental level, in the interpretation of the light taken in by the retina. Within a century, two rival schools of color theory had risen, positing seemingly mutually contradictory explanations for our sensation of color, which one individual, who also happened to be one of her era’s most significant logicians and feminists, managed to reconcile through the daring use of evolutionary theory. She was Christine Ladd-Franklin (1847-1930), America’s first woman psychologist, and an individual who never did anything by halves.
Part of the explanation for Ladd-Franklin’s unique sense of intellectual self-determination can be found in her upbringing. Born in Connecticut to a merchant father and an avidly feminist mother, her youth corresponded to the blossoming of American feminism as a movement. The great Seneca Falls Convention that established property rights, education, and suffrage as major goals for the women’s movement met the year after Ladd-Franklin’s birth, in 1848, and at the age of five young Christine was taken by her mother to hear a speech by the women’s right activist (and attendee at the first Women’s Rights National Convention in 1850) Elizabeth Oakes-Smith (1806-1893).
Ladd-Franklin was brought up to expect great things of herself, and brook no restriction on the exercise of her mind or capacities, and when it was announced in 1861 that a college for women was being established by Matthew Vassar, she set herself fully to the task of convincing her family that she be allowed to attend. Her mother had passed away in 1860, and shortly thereafter she was shipped off to live with relatives, of whom the most important to convince were her Aunt, who had money, her grandmother, who had moral authority, and her father, who had the ultimate say in her life’s course. The Aunt was all in, and offered to finance Ladd-Franklin’s way. The grandmother was reluctant, feeling that Christine would be too old upon graduating to find a good marriage, but Ladd-Franklin assured her that, as there was nobody of their immediate circle that she wanted to marry, and that her ordinary looks weren’t likely to win many suitors anyway, she wouldn’t miss out on any marriage prospects by leaving home. Somehow “I’m not good-looking enough to marry” convinced her grandmother, and after some initial profound resistance from her father, he was also swayed by her will to attend, and in 1866 she joined Vassar’s second class, graduating in 1869 in mathematics.
While at Vassar, she had the opportunity to study with Maria Mitchell (for more about whom, see the Astronomy volume of this series), the most famous woman scientist in America at the time, and was inspired by the idea of pursuing a life in scientific research, but upon graduation she came up against the realities of American life for an educated young woman. Teaching was still the expected career for a college graduate, and Ladd-Franklin, for nearly a full dismal decade, fell into the profession. She despised the work, stating with her characteristic directness, “Teaching I hate with a perfect hatred.” Fortunately, the galloping pace of late nineteenth century American higher education came to her rescue again, and in 1876 Johns Hopkins University admitted its first graduate students to pursue their PhDs. She wrote to a professor there, James J. Sylvester, for permission to attend the university. Fortunately, he was already well acquainted with her, through her publication of a series of solutions to mathematical problems posed by the Educational Times, and prodded Johns Hopkins into allowing her to attend his classes.
The exceptional nature of her work as a student, and her clear gift for both mathematics generally and logic specifically, compelled the university to allow her to take classes from other professors besides Sylvester, and by 1882 she had completed all of the work required for the awarding of a PhD, but was ultimately denied the degree she had earned on account of her gender (in fact, Johns Hopkins would not get around to awarding her that degree until forty-four long years later, on the occasion of its 50th Anniversary).
The same year she completed her work at Johns Hopkins, Ladd-Franklin married mathematician Fabian Franklin, and in the next two years gave birth to two children, only one of whom survived past infancy. Sometime during these years, her attention swung from her purely logical exercises to psychology, and particularly to the study of vision. In 1887 she wrote a paper on the subject of horopters, which are the sets of all points in a plane that make the same angle with your eyes as a point you are actively focusing on. This was a topic that had been worked on previously by two figures whose research would play a large role in Ladd-Franklin’s life, Hermann von Helmholtz and Ewald Hering, and which Ladd-Franklin proposed an experimental method for determining in her 1887 work.
That paper represented the first time an American woman had published a piece of psychological research, and is the source of her claim to being America’s first woman psychologist. As interesting as horopters are, however, the real drama in the late 19th century study of vision came with the nature of color, which Ladd-Franklin would study in Germany from 1891 to 1892 at Göttingen and Berlin. At the time, two warring clans of color theorists had arrayed themselves behind two (on the surface at least) quite different theories. The Young-Helmholtz Theory, first proposed by Thomas Young in 1802 and then elaborated upon by Helmholtz in 1850, held that the eye distinguishes color through the use of three different types of cones, one that is receptive to long wavelengths of light (like red), one responsive to short wavelengths (like violet or blue), and one responsive to intermediate wavelengths (like green), and that the brain tells us what color we are seeing at a location by interpreting the different degrees of activation of each of those three cone types, with white being the result of equal stimulation of all three.
It was a solid theory, but its detractors believed that it did not explain yellow well (which they believed was a fundamental color and not a mix of red and green), and more convincingly that it did not explain why color blind people, supposedly deficient in one of their cone types, still managed to see white perfectly well. These people turned towards the rival theory of Ewald Bering, who hypothesized that color works through sets of opposed colors, red-green, yellow-blue, and white-black. We are only capable of processing one or the other of each set of opposed colors, Bering hypothesized, a limitation which he used to explain why we can imagine a “reddish-blue” color or a “yellowish green” color, but not a “reddish green” or “yellowish blue” one.
This “tetrachromatic” theory put yellow back in an elemental position, which fans of yellow were super excited about, but had problems of its own in terms of what shades of red and green he had to pick as the fundamental ones in order to make the combinational math come out right. From our perspective today, we know that both theories were in fact, in their essences, correct, and that Young-Helmholtz explains our experiencing of light at the retinal level, while Bering explains how that information is processed by the brain. At the time, however, there seemed to be no common ground between them, until Ladd-Franklin published her seminal paper, “A New Theory of Light Sensation,” in 1892.
Ladd-Franklin sought to synthesize these two views, which she saw the clear merits of, and used the still-controversial (particularly in America) theory of evolution (which had only been published in 1859) to provide the explanatory mechanism for her theory. She noticed that certain types of color-blindness were more common than others, and held that the explanation for that fact lay in the evolution of the physical structures underpinning our sense of sight. She theorized that animals first developed a general black-white sense of color that allowed them to binarily detect light as either Present or Not Present. Eventually, we evolved the ability to detect two different bands of radiation, with one receptor for detecting long wavelengths (yellow), and another for short (blue). Later still, another refinement of our color senses evolved, with our yellow receptors splitting into long-wave specialists (red) and mid-wave specialists (green).
Further, Ladd-Franklin theorized, the eye still carries with it vestiges of its evolutionary past, with the highly developed central regions of the retina carrying the recently-evolved tri-color receptors, while as you work out towards the edges you travel back in time, arriving at the purely light-dark sensing rods towards the periphery of the retina. It was an elegant theory that allowed the retention of the best elements of Young-Helmholtz and Bering, and explained why red-green color blindness is more common than blue-yellow color blindness, the former being a more recent, and therefore less stable, addition to our optical repertoire.
The evolutionary theory of color was a major result which put her in the front rank of American scientists, earning her election to the American Psychological Association in 1893, and invitations from around the world to talk on the subject of color. Though a worldwide scientific figure, however, Ladd-Franklin had perpetual difficulty finding a professional position equal to her accomplishments. First at Johns Hopkins, then at Columbia, she had to fight to obtain guest-lecturing positions that amounted to something on the order of one class a semester, often without pay. Part of the explanation for her troubles might have lain with her outspoken feminist beliefs. Unlike the crop of women psychologists who would follow in her wake, and who grew up in a more Victorian atmosphere, Ladd-Franklin’s early life was full of the fire of the early women’s movement and the crucible of the Civil War, and she was not afraid to confront important members of the psychological establishment when she believed them to be in error, particularly castigating Edward Titchener for his decision to exclude women from his important Society of Experimental Psychologists on the grounds that the presence of women would prevent the men from being allowed to smoke, and would restrain them from using the full spectrum of vigorous and emphatic language they wanted to employ.
Though lacking in official position, however, Ladd-Franklin was a well-known presence in American life, publishing hundreds of articles, letters, and reviews on logic, color, politics, and feminism, as well as her book, Colour and Colour Theories, which presented all of her mature thought on the subject of color, and served as a classic in the field for decades thereafter. That book was published in 1929, the year before Ladd-Franklin's death in New York at the age of 82, and it is to be hoped that the almost universal praise for the volume was some solace at her life’s close for the professional career that never became what it ought to have been, the decade spent teaching when all she wanted to do was learn, and the years of frustration trying to make American science live up to its best ideals of open discourse and equal opportunity.
FURTHER READING:
There is, almost inexplicably for an individual of her high level of achievement in so many areas, no single volume devoted to the life of Christine Ladd-Franklin. Both Untold Lives: The First Generation of American Women Psychologists (1987) by Scarborough and Furumoto and Women in Psychology: A Bio-Bibliographic Sourcebook (1990) have nice chapters devoted to her, with Untold Lives focusing more on her struggles against Titchener, and the Sourcebook more on her scientific output. Her book, Colour and Colour Theories is available in reprint editions, and is also available to peruse online for free, which is more than can be said for a number of her key articles in psychology, which Science and the American Psychological Association have locked away behind hefty paywalls. If you’re really good at deciphering early twentieth century handwriting, Ladd-Franklin’s diaries from 1866 to 1873 have been scanned and made available online as well, which covers her Vassar years and early mathematical work rather than her psychological studies.
And if you want to read about more great women in the history of psychology and neuroscience, keep your eyes peeled for my History of Women in Psychology and Neuroscience, which is coming in the Spring of 2024 from Pen and Sword books!