Traffic lights are recognized only by the placement of the lights. Most color blind people don't tell others of their situation. Psychological and Social Effects of Color People have known for a long time that color has an effect on people. Some color combinations can make people active and edgy. Some can put you into such a relaxed state that we will fall asleep.
Colors are Symbolic Different cultures apply very different meanings to color.
Here, we often use red to symbolize danger. In some places, red symbolizes prosperity and joy. In other cultures, white is symbolic of death and mourning. Colors are often highly political and religious. Here green is symbolic of nature, fertility, growth, and poison.