Evolution of human colour vision that are found between 450 and 625. Individuals with various forms of colour blindness such as deuteranopia and protanopia are missing human middle wavelength sensitive or long wavelength sensitive opsins. Their minimum wavelength differences are <5 but only at around 500. Protanopes, who are missing long wavelength sensitive cones, are unable to distinguish between colours in the green-yellow-red section of the electromagnetic spectrum. They find yellow, red and orange colours to have much lower brightness when compared to a trichromat. The dimming of these colours can result in confusion in many cases, such as when attempting to identify red traffic
Colour centre the recognition of shapes, motion, and colour. V1 has multiple areas that are colour-sensitive, which indicates that colour processing is not limited to one area. According to a paper by Dr Robert Shapley, V1 has an important role in colour perception. fMRI experimental results showed that V1 has two kinds of colour sensitive neurons: single-opponent and double-opponent cells. These cells are integral in the opponent process of interpreting colour signals. Single-opponent neurons respond to large areas of colour. This is advantageous for recognizing large colour scenes and atmospheres. In comparison, double opponent cells respond to patterns, textures, and colour boundaries.