Image source: University of Rostock, Germany
David Katz was born on October 1, 1884, as the seventh of eight children of his parents in Kassel, Germany, where he attended the local Realgymnasium. As a child and student, he became a talented amateur painter, interested in color and other sensory abilities. In 1902, he began studying at the nearby University of Göttingen. There he became interested in psychology taught by G. E. Müller. In 1906, he obtained a Ph.D. degree in psychology, physics, and philosophy, and in 1907, he assumed the position of assistant to Müller. In 1911, he was named a professor, based on his work on color phenomenology [1]. From 1914 to 1918, he was a volunteer soldier in the German Army. In 1919, he received an invitation from the University of Rostock to assume a then new professorship in psychology. In the same year, he married the psychologist Rosa Heine with whom he had two sons. Over the years, they both were active in a wide field of psychology, including that of children and animals and had a number of well-known students. In 1929, Katz was for a time a guest professor in Maine in the USA. Shortly after Hitler’s move to power in 1933, Katz and his wife were officially retired from their positions. In the same year, Katz with the help of a colleague moved to England, followed a year later by his wife and sons. In 1937, Katz received an invitation to fill the first professorship in psychology in Sweden at the University of Stockholm. Here he was broadly active in many fields of psychology. In 1952, already retired, he received an honorary professorship from the University of Hamburg. On February 2, 1953, he died in Stockholm. Katz produced over 200 research papers and books, most in the general field of psychology [2].
57.1 Katz and Phenomenology of Color Vision
Beginning with his dissertation, Katz was specifically interested in the phenomenology of vision, including shape, structure, space, color, and movement, to the exclusion of related physics and psychophysics. He defined three appearance modes of colors: film colors, surface colors, and volume colors. Film colors are those experienced when looking into the black tube of a spectroscope and seeing spectral colors, having a slightly spongy appearance without having a specific location in space. Surface colors are those commonly referred to as object colors. Volume colors he defined as those of colored glasses or gelatins. An important concept in his work was the subjective gray we experience either with closed eyes in the absence of strong light or with open eyes in a completely dark room. Another one was the reduction screen, a black sheet of paper with a small hole through which a small section of a colored object could be viewed and the resulting film color appearance compared to the surface color without the screen. Katz and his students performed many experiments related to color appearance involving illumination changes, surround and shadow effects, monocular versus binocular vision, exposition time, color constancy and lack thereof, light and dark adaptation, color and depth contrast effects, the effects of chromatic illumination, to name a few. He introduced novel concepts, translated as “pronouncedness” and “insistence,” to describe nuanced phenomenological color effects. A key subject was the problem of definition of the “true” color of an object. To measure phenomenological magnitudes, he used innovative disk mixture methodology.
In his book, Katz discussed his agreements and disagreements with other researchers and their findings, such as Hering and of his time K. Bühler, A. Gelb, E. Jaensch, J. von Kries, and E. G. Müller. An important psychological concept of that period was Gestalt psychology based on the idea that, as its primary formulator M. Werthheimer expressed it, “the brain is holistic” by considering the total amount of information received. Together with self-organizing tendencies, this results in “the whole is greater than its parts.” Katz published a textbook on the subject in 1944, issued in several editions and multiple languages [3].
Katz’s book of 1911 was issued in a revised and updated version as Der Aufbau der Farbwelt (The constellation of the world of colors) in 1930 [4]. After he moved to London, a shortened, translated version was published in 1935 in England as The world of colour [5].