Cone vision can differentiate colors while Vision 20/20 Protocol Ebook Review rod vision cannot. The reason for this difference is that all rods respond in the same way to light exposure. However, there are three different types of cones. One type responds most strongly to red light and less strongly to other colors (called red cones). A second type responds most strongly to green light and less strongly to other colors (called green cones). The third type responds most strongly to blue light and less strongly to other colors (called blue cones). Each speck of color we look at will cause numerous red, green, and blue cones to send signals to the brain. The brain uses the ratio of red cone signals: green cone signals: blue cone signals to determine what color that speck actually is. Each shade of color has a slightly different ratio.
However, some individuals inherit a genetic defect involving one of the three types of cones. As a result, that type of cone does not function properly. The brain now receives signals from only two types of cones. It still uses the ratio of signals to determine colors. But, because of the missing information, several different colors now produce the same ratio. Therefore, the individual sees them as the same color. The most common type of colorblindness is called red-green colorblindness. In this case, the genetic defect results in the person having difficulty distinguishing among certain shades of red and green. However, there are also other types of colorblindness.
Color blindness occurs in males much more frequently than in females. This is because of the location of the genes which are responsible for cone vision. The explanation requires some basic information about genes.