shapes + colors = mood?

I sort of already knew that some colors and shapes can affect how you feel. My room is dark blue and white and I always feel calm when I'm in it, so I kind of knew that blue was calming. But I didn't realize the amount of thought that went into the choosing of McDonald's colors. Red makes you hungry and yellow makes you anxious that you want to get out of there fast; so you're hungry for their food but you want to leave ASAP. As for shapes, it makes more sense to me that people draw certain shapes when they're in a certain mood rather than shapes causing the mood, but I can still see how that happens.