I don't know about alert level colour codes. I do understand that our senses are usually just monitoring changes.
Most sounds that are constant we blank out, if our eyes didn't move in small jumps constantly our vision would fade right out and there are optical illusions that demonstrate this.
http://www.planetperplex.com/en/color_illusions.html

I have no doubt you would get a rush of colours after being blindfolded for a while Dwest. It would probably last until your optical nerves got used to the colours again and renormalized them.
I will have to check this out and see if it is a real effect or just imaginary.