Eight primary colours


By means of the combination of three dimensional polar parameters, 8 colours are defined and placed in the genetic semantic space.  That these colours are primary is confirmed by different sources. From linguistics we know, thanks to the research by Berlyn and Kay (1969), that primary colours are first mentioned in the evolution of colour naming. The researchers confirm that cross-culturally between 7 to 12 primary colours are named initially. Following the evolution we get a colour range of dark (black) and bright (white), red, yellow/green, blue, brown, purple/pink/orange/gray (Kay, 1975).

RGB signal digitized in the retinal ganglion cells.

From biology, there is the function of the retinal ganglion cells that confirm the selection of the eight primary colours.  The retinal ganglion cells are situated in the innermost layer of the retina, which receive information from the light and colour-sensitive rods and cones in the outer layer of the retina. These stimuli are converted into an electric digital signal via the retinal ganglion cells. After digitizing the analogue RGB system, the retina distinguishes between 6 primary colours that interact as antagonists, where blue is opposite to yellow, green to red and dark to light. Purple and brown are generated by the simultaneous stimulation of these cells.

Black and white are regarded as full-fledged colours because both black and white are considered as such in linguistics, biology and in psychology. Heller (1989) “We connect black and white with a symbolism that can not be compared with any other colour.” Black and white are achromatic colours.