If you stare at a white square on a dark background, then look at a white sheet you will see a fuzzy black square.
When we see white, receptors in the back of the eye create chemicals which tells the brain it is looking at white
These receptors are used at night, and are called rods. Each time you look at white, the white receptor rods are 'used'. It takes a few moments for them to regenerate.
If you look at the white for a while, all the white rods are used. While they are regenerating, the brain uses what is there- the black ones! So it sees a fuzzy black after image.
If you stare at a grey square, on a dark background, there is no after image.
Our brain is very happy to use some of the black and white rods, to tell it it is seeing grey. One doesn't wear out, and all is happy. Our brain loves grey.
Our brain loves to compensate for what we see - it tries to make grey in our brain, by thinking of the contrasting colours it is experiencing
Grey brings balance to our lives
We often feel comfortable with contrasting colours in an environment
Even when we are determined to have an harmonious colour scheme we feel the urge to put just a little of the contrasting scheme.
-maybe a scatter cushion, or subconsciouly we want to put a green plant in a beige (pale red-orange) room.
A really popular colour scheme is a harmonious contrast scheme.
As we mix the primary paint colours together they become greyer. The tone becomes less intense, as the primary colours are mixed.
Most people react favourably to a 'toned' down colour scheme. It is suitable in most situations.
If, however, an impact is required then primary and secondary colours will be used.
The more 'pure' the colour the more desire for the human brain to need an alternative.
This can be achieved as demonstrated above by adding a contrasting (or complementry) colour.
Having an environment, or graphic that is only exposed for a short time also is effective.
Using a mostly neutral scheme (beiges, greys, taupes) with highlights of a primary or secondary colour is often observed
There have been a number of academics trying to depict how colours are mixed to make grey.
An interesting one is the colour triangle - prepared by Josef Alberu and Sewell Sillman Yale university. The primary colours are in the corners, the secondary are between these and the grey is when they are mixed in perfect proportions.