Gunnar Svaetichin

Gunnar Nils Toivo Svaetichin (13 January 1915 – 23 March 1981) was a Swedish-Finnish-Venezuelan physiologist who, in 1956, showed by examining the external layers of fish retinas that electroretinograms display particular sensitivity to three different groups of wavelengths in the areas of blue, green and red. This provided the first biological demonstration in support of the Young-Helmholtz trichromatic theory. He also gave name to the S-potential, which was the first experimental evidence that opponency existed in the visual system.

Born in Finland, he moved to Sweden in 1948, and from 1955 until his death, he worked as a researcher in Venezuela.