The connection between frequency and color vision in humans is based on the response of specialized cells in the retina called cones. Cones are responsible for color perception and are sensitive to different ranges of light wavelengths. While it is true that color is associated with specific wavelengths, the perception of color is ultimately linked to the frequency of the light waves rather than the wavelength itself. This is because our visual system processes the frequency information carried by the light waves, not the actual physical properties of the waves.
The reason frequency is more relevant than wavelength for color vision is due to the way our eyes and brain process light. When light enters the eye, it interacts with the photopigments in the cones, specifically the three types of cones that are sensitive to different ranges of light. These cones are commonly referred to as "red," "green," and "blue" cones, based on their sensitivity to different parts of the spectrum.
The perception of color arises from the relative stimulation of these three types of cones. Different wavelengths of light correspond to different frequencies, and when these frequencies stimulate the cones in different proportions, we perceive different colors. For example, if light at a certain frequency stimulates the "red" cones more than the other types of cones, we perceive the color red.
In terms of why the model based solely on wavelength is not accurate for human vision, it is because our visual system does not directly perceive wavelength. Instead, our perception is based on the information encoded in the frequencies of light waves and the relative responses of the cones in our eyes. The brain interprets the information from the cones and constructs our experience of color based on the relative activity levels of the different cone types.
Therefore, while wavelength and frequency are related properties of light, it is the frequency that is directly linked to our perception of color, not the wavelength itself.