This is something that we encounter a lot but we don’t think about how it happens. The first part of the brief tells us to find or paint a large area of bright colour, stare at it for 30 seconds and then close your eyes and wait for an after image to appear. Because I chose red the after image that appeared was the complimentary colour green.
From there I painted an isolated square of my most vivid and intense pigment, which happened to be fluorescent pink, I did the same with this then after 30 seconds I shifted my gaze to a white space on the same paper, the after image that appeared was an intense turquoise, Its complimentary colour.
These effects are caused by the stimulation and exhaustion of the receptors in the retina. By Exhausting the receptors for red, for example, only the remaining combinations of colours that mix to produce blue green are seen when you turn from looking at red to looking at white.
White light, as Newton showed, is made up of all the colours of the spectrum. The human eye has full colour discrimination through the rod and cone cells. The rod cells in the Retina distinguish light and dark, while the three types of cone cells respond to red, green and violet which make up colours.