I've discovered a couple of things about how we see that can be used in painting. One is if you want a birch tree, for example, to glow blue you don't have to paint the whole thing blue. It's better to lay on blue paint selectively, then let the eye do the work of spreading the color, making it more vital and alive.
The other thing is that when colors are closer together in value (lightness and darkness), our brains can't interpret where the objects are as readily as if there was greater value contrast. This causes the things in the painting we're looking at to shift forward and back as the brain tries to determine what is where, creating a rustling effect, like we would feel in the woods.
