symbols and colors

Color has evolved over the course of the ages to symbolize many different things. Through cultural and social construction, colors have taken on psychological properties of their own, but none of these properties are concrete. For different cultures and times, colors can have very different meanings. For instance, in the United States it is almost ingrained in our heads that weddings are associated with the color white, perhaps alluding to the virginal and pure. In Japan and other parts of Asia though, the color white was often worn at funerals.
Color theorist Faber Birren created categories for the varying levels of color symbolism. These included general appearance, mental associations, direct associations, objective impressions, and subjective impressions. Each color has not only one association, but many when viewed in different contexts. Red can symbolize St. Valentine's day, but it is also often associated with rage. Often green is associated with the eco-friendly movement, but it is also symbolic of money.
There are many people that believe that certain colors will yield a consistent and specific response from people. There are many psychologists though that have found through various studies that there is no clear response to color and that emotional responses to certain colors were inconsistent. Regardless of this information, many people used color to heal. Called "color consultants", these people try to alleviate stress through color. For instance, they've found that babies cry less when the color of there room is not yellow and prisoners are less violet when their rooms are pink. This is not a new fad though. For centuries, people have been using color to heal.

Source: http://en.wikipedia.org/wiki/Color_symbolism
http://www.princetonol.com/groups/iad/lessons/middle/color2.htm