Ewald Hering
| Ewald Hering | |
|---|---|
 | |
| Born |
August 5, 1834 Alt-Gersdorf, Saxony |
| Died |
January 26, 1918 Leipzig, Saxony |
| Nationality | Germany |
| Fields | physiology |
| 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.
Born in Alt-Gersdorf, Kingdom of Saxony, Hering studied at the University of Leipzig and became a professor at Charles University in Prague.
Color theory
Hering disagreed with the leading theory developed mostly by Thomas Young, James Clerk Maxwell and Hermann von Helmholtz.[1] 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 evidences 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 Helmhotlz were right.
Binocular perception
Hering studied binocular perception.[2] 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.
Eye movements
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).
Other research
In 1861 Hering described an optical illusion which now bears his name – Hering illusion.
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").[1]
References
Further reading
- Turner RS (1993). "Vision studies in Germany: Helmholtz versus Hering". Osiris 8 (1): 80–103. doi:10.1086/368719. PMID 11639585.
- 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.
External links
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