We work through an example of Yellow light to help clarify the concepts associated with trichromacy. Let us assume that a set of Yellow wavelengths (in the range of 577-597 nm) enters the eye and strikes the retina. Light with these wavelengths then activates the Red and Green sets of cones to produce the physiological response of electrical messages. e optical nerve sends the electrical messages to the brain. e brain then recognizes that Red and Green cones were simultaneously activated and interprets this to mean that the color Yellow was observed. e lack of
response from the Blue cones conrms this interpretation even further. Figure 2.7 diagrams these trichromacy concepts for a Yellow light example. As we noted in Section 2.4 when describing opponent processing color theory, we do not see Yellow and Blue together. is is the psychological response to the Yellow light .