The Psychological and Physiology of Color by Sarwar Nassiry 
The human brain is able to distinguish over two hundred shades of white, able to see the same color no matter the light source, to say color is essential to our perception is no slight exaggeration.

The human eye is the organ which gives us the sense of sight, allowing us to learn more about the surrounding world than we do with any of the other four senses.  We use our eyes in almost every activity we perform, whether reading, working, watching television, writing a letter, driving a car, and in countless other ways.    

Most people probably would agree that sight is the sense they value more than all the rest.

The eye allows us to see and interpret the shapes, colors, and dimensions of objects in the world by processing the light they reflect or emit.  The eye is able to see in bright light or in dim light, but it cannot see objects when light is absent.


What is Color? 

Color is our perception of different wavelengths of light.  
Light visible to humans ranges in wavelength form 380 nanometers (nm) for violet light to 760 nm for red light.


Cone Photoreceptors  


We have three types of cone photoreceptors.
Each cone type responds to a different range of wavelengths within the visible light spectrum.


Blue-sensitive cones are maximally stimulated by blue and violet light. 


Green-sensitive cones are maximally stimulated by light in the yellow to green range. 


Red-sensitive cones are most stimulated by light in the red to yellow range.


Color vision in humans is based on the additive color theory.
This theory states that all perceivable colors can be made by mixing different amounts of red, green, and blue light,
the primary colors of the additive color system.

Equal amounts of the three primaries give the sensation of white,
while the absence of additive primaries is black.

The additive color wheel. 
The three additive primaries are at the center.

Pyschological Effects

Does color have effect on our emotions and behavior? The answer is yes. The findings are inconclusive. Our reactions to colors are led by a combination of biological, physiological, psychological, social and cultural factors.

Warm Colors

Generally include magenta, red, orange, yellow, and yellow-green. They speed up our perception of time and produce feelings that are warm, cozy, and inviting. These colors are associated with excitement, happiness and comfort. 

Cool Colors

Generally include violet, blue, light blue, cyan and sea green. Emotions associated with these colors range from calm and peace to sadness, withdrawal and repression.

Do different colors affect your mood?

Colors often have different meanings in various cultures.
And even in Western societies, the meanings of various colors have changed over the years.
But today in the U.S., researchers have generally found the following to be accurate.



Black is the color of authority and power. It is popular in fashion (black-tie-affair). 

Black also implies submission. Priests wear black to signify submission to God.
Some fashion experts say a woman wearing black implies submission to men.

People wear black in times of mourning (funerals).

Black is a controversial color. It can represent evil and reliability, authority and despair, and evil characters and yet prudence. 

Too much black can inhibit growth and positive change because of its passivity.   


White symbolizes innocence and purity. White is a strange color in the sense that it is all of the colors together reflected, that's why it is considered a summer color. White is a neutral color. However, white shows dirt and is therefore more difficult to keep clean than other colors. Doctors and nurses wear white to imply sterility.

White brings calmness to the heart and ameliorates despair.  It stands for freedom and independence but too much can make you feel isolated.   

 The most emotionally intense color, red stimulates a faster heartbeat and breathing. It is also the color of love. Red commands attention. Red gives the impression of seriousness and dignity, represents heat, fire and rage, it is known to escalate the body's metabolism.

Using too much red should be done with caution because of its domineering qualities. Red is the most powerful of colors. 

The color of the sky and the ocean, blue is one of the most popular colors. It causes the opposite reaction as red. Peaceful, tranquil blue causes the body to produce calming chemicals.  Blue lowers blood pressure and thus relaxes the nervous system.

Deep blue stimulates the pituitary gland, which then regulates our sleep patterns. This deeper blue also has proved to help the skeletal structure in keeping bone marrow healthy.

Blue surroundings, if not too dark, increase productivity. Studies show that students score higher, weightlifters lift heavier weights in blue rooms. People retain more when reading information written in blue text.

Darker shades of blue can also be cold and depressing.


Currently the most popular decorating color, green symbolizes nature. It is the easiest color on the eye and can improve vision. It is a calming, refreshing color. People waiting to appear on TV sit in "green rooms" to relax. Hospitals often use green because it relaxes patients. Brides in the Middle Ages wore green to symbolize fertility. Dark green is masculine, conservative, and implies wealth. However, seamstresses often refuse to use green thread on the eve of a fashion show for fear it will bring bad luck. 


Cheerful sunny yellow is an attention getter. While it is considered an optimistic color, people lose their tempers more often in yellow rooms, and babies will cry more. It is the most difficult color for the eye to take in, so it can be overpowering if overused. Yellow enhances concentration, hence its use for legal pads. It also speeds metabolism.  


Purple is a mixture of blue and active red.  It can represent coolness, mist, and shadows.  It can symbolize royalty, purple connotes luxury, wealth, and sophistication. It is also feminine and romantic. However, because it is rare in nature, purple can appear artificial.  


Solid, reliable brown is the color of earth (trees and wood) and is abundant in nature, giving us a sense of familiarity. Light brown implies genuineness while dark brown is similar to wood or leather. It represents conservancy and humility and is one of the most neutral colors.  Brown can also be sad and wistful. Men are more apt to say brown is one of their favorite colors.

What is Color Blindness

Color blindness, visual defect resulting in the inability to distinguish colors.

About 8% of men and 0.5% of women experience some difficulty in color perception. Color blindness is usually an inherited sex-linked characteristic, transmitted through, but recessive in, females.

Acquired color blindness results from certain degenerative diseases of the eyes.

Most of those with defective color vision are only partially color-blind to red and green. Those who are completely color-blind to red and green see both colors as a shade of yellow.

Completely color-blind individuals can recognize only black, white, and shades of gray.

Color index, in astronomy, is difference in an object's brightness as recorded between any two well-defined bands of the electromagnetic spectrum by using optical filters of different colors. If blue and red filters are used, then the color index B-R would be zero for a white star (spectral class A0). The color index is positive for stars redder than a white star and negative for stars bluer than a white star. In effect, measuring the color index is equivalent to measuring the difference between the amount of blue light and red light that the star radiates. Although a star's true color might be changed as its light travels through clouds in interstellar space, the color index is an important indicator of the temperature of a star, gas cloud, or galaxy.