HardCash has been talking about how colors affect your perception, trying to tie it into trading...here is what I've dug up...
Researchers have found that while the eye responds better to black print on a white page for written text, for some reason, the response seems to be much better on a computer screen for a black background and white text.
They believe this is because while a book merely reflects ambient light (and who would read in ambient light that overwhelms their eyes?), a computer monitor actually generates light, and on a white background it's somewhat akin to staring at a lightbulb.
We have all heard the SAD stories (Seasonally Adjusted Depression) where a person is supposed to stare at a bright light for a set amount of time each day to help alleviate their depression. Well, this works by a form of sensory overload...the mind is tricked into thinking that it is sunny out, and releases the necessary neurotransmitters to give a 'sunny' disposition, as well.
So, while staring at a bright white computer screen may mentally stimulate you, it very well could overstimulate you (leading to impaired judgement in trading). The resulting losses would seriously depress you.
Conversely, a black background would not stimulate you, leaving you depressed anyway.
We just can't win, can we?
Seriously, though, research show that the color yellow is the hardest for the eye to perceive, and the color green is the easiest.
As for the mentally soothing or stimulating qualities of colors, they've found it to be more a factor of the color's brightness and saturation than the actual color. (i.e.: a bright red is mentally stimulating while a dull red is not, a dull blue is soothing while a bright blue is not).