Color Blindness and Traffic Lights

Color Blindness is the inability to perceive the differences between some of the colors that other people can. Color blindness always pertains to the cone photoreceptors in the retina specifically (red, green and blue), which are capable of detecting the color frequencies of light. One of the implications of color blindness is in identifying the colors in a traffic light. The American traffic light always uses this pattern: The top light is red; the middle, yellow; and the bottom, green. Aside from the color scheme, some traffic signals use universal codes, pictograms, and warning signs to help color blind people.