Karl Ewald Konstantin Hering was born on August 5, 1834 in Alt-Gersdorf, Kingdom of Saxony. He was a German physiologist whose research focused on color vision and spatial perception. In his earlier years he studied at the University of Leipzig and later became a professor at Charles University in Prague.

Herings main contribution to Color theory originated with his disagrement with th leading theory developed by Thomas Young and Hermann Von Helmholtz, which stated that the human eye perceives all colors in terms of three primary colors: Red, Green, and Blue. Instead Hering believed that the visual system worked based on the system of color opponency, a proposal that is now widely recongized as correct.

Thomas Young And Hermann Von Helmholtz





Hering looked more at qualitative aspects of color and said there were six primary colors, coupled in three pairs: red-green, yellow-blue and white-black. Any receptor that was turned off by one of these colors, was excited by its coupled color. This results in six different receptors. It also explained afterimages. His theory was rehabilitated in the 1970s when Edwin Land developed the Retinex theory that stated that whereas Helmholtz's colors hold for the eye, in the brain the three colors are translated into six.

Edwin Land

Edwin Land

Afterimage

Stare at the plus sign on the left for about 30 seconds. As you do this you probably will see some colors around the blue and green circles. After about 30 seconds, shift your gaze to the plus sign on the right. What did you see?

Afterimage

You probably saw a yellow and desaturated reddish circle. Did you notice that they were not there before you tried this experiment? Furthermore, unlike the colored circles on the left, the ones you saw on the right moved around as your eyes moved, which proves that these perceptions are the result of afterimages in your visual system and not some trick of the stimulus presentation on the right.


-In 1861 Hering described optical illusion which now bears his name , Hering illusion.
-He also developed Herings law of equal innervation to describe the conjugancy of saccactes in animals.
- In 1878, the physiologist Ewald Hering published his On the Theory of Sensibility to Light in Vienna, which opposed the purely phenomenal or physical understanding of colours.




-Hering wrote: "Yellow can have a red or green tinge, but not a blue one; blue can have only either a red or a green tinge, and red only either a yellow or a blue one. The four colours can with complete correctness therefore be described as simple or basic colours, as Leonardo da Vinci has already done. Language, too, has simple descriptions of them, and not expressions borrowed from coloured natural bodies."

Ewald Hering invented this apparatus for the detection of color-blindness. The subject looked down the main tube and saw a circular field, half red and half green. By moving reflecting screens the subject could change the hue of one half, the brightness of the other, and the saturation of both together. Subjects were asked to make the two halves match. If the match could be accomplished, the subject was deemed to be colour-blind.

Herings Color Blind Apparatus

Herings Color Blind Apparatus

The color opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cones and rods in an antagonistic manner. The three types of cones have some overlap in the wavelengths of light to which they respond, so it is more efficient for the visual system to record differences between the responses of cones, rather than each type of cone's individual response. The opponent color theory suggests that there are three opponent channels: red versus green, blue versusyellow, and black versus white. Responses to one color of an opponent channel are antagonistic to those to the other color. Ewald Hering proposed opponent color theory in 1872. He thought that the colors red, yellow, green, and blue are special in that any other color can be described as a mix of them, and that they exist in opposite pairs. That is, either red or green is perceived and never greenish-red; although yellow is a mixture of red and green in the RGB color theory, the eye does not perceive it as such.

Hering Opponent Colors Diagrams

Hering was not a very popular man, but he was an important medical scientist, recognized for his thoroughness and stubbornness. His research concerns the normal and pathological physiology of the nervous system, muscles, heart, vessels and the autonomous nervous system. His work on the automatic regulation of the circulation by the pressoreceptor nerves earned him a recommendation for the Nobel Prize for physiology or medicine. However, he did not receive it.