|Born||August 5, 1834
|Died||January 26, 1918
|Known for||color vision, binocular perception, eye movements|
Karl Ewald Konstantin Hering (August 5, 1834 – January 26, 1918) was a German physiologist who did much research into color vision, binocular perception and eye movements. He proposed opponent color theory in 1892.
Hering disagreed with the leading theory developed mostly by Thomas Young, James Clerk Maxwell and Hermann von Helmholtz. Young proposed that colors are based on three primary colors: red, green, and purple (or blue). Maxwell demonstrated that any color can be matched by a mix of 3 primary colors. This has been interpreted by Helmholtz as a proof that humans perceive colors through 3 types of receptors while white and black would reflect the amount of light.
Hering instead believed that the visual system worked based on a system of color opponency. He had little empirical evidence to support this claim. In this model colors are perceived through receptors sensitive to three couples of opponent colors: red-green, yellow-blue and white-black. Later on Erwin Schrödinger demonstrated that the first and the second model are mathematically equivalent.
But nowadays, we know that if the human possesses indeed 3 types of receptors as proposed by Young, Maxwell, and Helmholtz, they are then combined in 3 opponent channels as proposed by Hering. In their way, both Hering and Helmholtz were right.
According to Granzier and Gegenfurtner (2012), in 1878 Hering coined the term memory color for the color one experiences when looking at a black-and-white image of some object that has a typical colour, such as yellow from the image of a banana.
Hering studied binocular perception. He is famous for the Hering's law of visual direction which describes the perceived egocentric direction of an object in function of the direction of this object in the two retinaes of the two eyes.
The last main area of research of Hering was eye movements. He developed the Hering's law of equal innervation to describe the conjugacy of eye movements in animals. According to this law eye movements are always equal in intensity in the two eyes but not in direction. Eye movements can therefore be either conjugate (in the same direction such as saccades or smooth pursuit) or disjunctive (such as vergence eye movements).
In 1861, Hering described an optical illusion which now bears his name – Hering illusion. When two straight and parallel lines are presented in front of radial background (like the spokes of a bicycle), the lines appear as if they were bowed outwards. The Orbison illusion is one of its variants, while the Wundt illusion produces a similar, but inverted effect.
Hering first suggested the idea of organic memory in an 1870 lecture for the Imperial Academy of Science in Vienna. Hering took influence from the idea of inheritance of acquired characteristics and suggested that memories could be passed on through generations by germ cells.
The Hering–Breuer reflex is also named for him.
The Hering-Helmholtz controversy
Hering spent most his life arguing violently with Helmholtz. The controversy was not only scientific but also philosophical; Hering was a nativist, Helmholtz an empiricist. Helmholtz also came from a higher social class and was always considered a prodigy, while Hering had to go through a very hard time in his early career. Hering and Helmholtz disagreed on almost everything and the controversy lasted long after the end of both of their lives. Hering however was by far the most aggressive of the two, and was always prompt to point out any mistake that Helmholtz might have made, sometimes even going so far as to insult him ("It is likely that the great Helmholtz in his dozing state..."). Helmholtz's faction (though probably not Helmholtz himself) spread rumors which accorded to Hering the need for help to do his mathematical work and that he was clinically insane ("He has been, as I have heard, mentally ill").
- Handbuch der Physiologie (1879)
- On Memory and the Specific Energies of the Nervous System (1897)
- Turner, R. M. (1994). In the eye's mind: vision and the Helmholtz-Hering controversy. Princeton, N.J: Princeton University Press. ISBN 0-691-03397-8.
- Granzier, J. J., & Gegenfurtner, K. R. (2012). "Effects of memory colour on colour constancy for unknown coloured objects". i-Perception 3: 190–215. doi:10.1068/i0461.
- Hering, Ewald (1977). The theory of binocular vision. New York: Plenum Press. ISBN 0306310163.
- Stanley, Finger. (1994). Origins of Neuroscience: A History of Explorations Into Brain Function. Oxford University Press. p. 338. ISBN 978-0-262-01704-6
- Baumann C (June 1992). "[Ewald Hering's opponent colors. History of an idea]". Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft (in German) 89 (3): 249–52. PMID 1303712.
- Janko J (1995). "Mach and Hering's physiology of the senses". Clio Medica 33: 89–96. PMID 9061228.
- Otis, L (1994). Organic Memory: History and the Body in the Late Nineteenth and Early Twentieth Centuries. University of Nebraska Press. ISBN 0-8032-3561-5
- Turner RS (1993). "Vision studies in Germany: Helmholtz versus Hering". Osiris 8 (1): 80–103. doi:10.1086/368719. PMID 11639585.