While most perceptions of color are subjective, some color effects have universal meaning. 

• Colors in the red area of the color spectrum are known as warm colors and include red, orange, and yellow. These warm colors evoke emotions ranging from feelings of warmth and comfort to feelings of anger and hostility.
• Colors on the blue side of the spectrum are known as cool colors and include blue, purple, and green. These colors are often described as calm, but can also call to mind feelings of sadness or indifference.
  

• Red was used to stimulate the body and mind and to increase circulation.
• Yellow was thought to stimulate the nerves and purify the body.
• Orange was used to heal the lungs and to increase energy levels.
• Blue was believed to soothe illnesses and treat pain.
• Indigo shades were thought to alleviate skin problems.

"Given the prevalence of color, one would expect color psychology to be a well-developed area. Surprisingly, little theoretical or empirical work has been conducted to date on color's influence on psychological functioning, and the work that has been done has been driven mostly by practical concerns, not scientific rigor."

Andrew Elliot and Markus Maier, researchers.

Most psychologists view color therapy with skepticism and point out that the supposed effects of color are often grossly exaggerated. Also, one’s feelings about color are often deeply personal and rooted in their own experience or culture.

Much of the evidence in this emerging area is anecdotal at best, so more scientific research is needed to gain a better understanding of color psychology.