The most important thing to know about colors, and our emotional response to them, has to do with colors’ saturation and brightness. Saturation is how pure a color is. Less saturated colors are more grayish, so khaki green is less saturated than Kelly green. Brightness is, as you’d expect, basically how light a color seems. Colors that are less saturated but bright, such as a bright sage green, are relaxing, and those that are more saturated and less bright, such as sapphire blues, are more energizing to look at.
Colors are called “warm” (reds and oranges) and “cool” (blues and greens) for a reason: When we’re in a space where the walls are painted in warm colors, we actually feel that the temperature there is warmer than we do in similar spaces painted cool colors. This makes warm colors good options for a vestibule in a cool climate—the temperature inside the building will seem even more comfortable as people enter from the cold—or in a room that’s hard to heat. Cool colors are good choices in entryways to buildings in warm climates, and in rooms that have a tendency to be warm, perhaps because of sunlight flowing into them.
We are drawn to warm colors, such as reds and oranges, so they’re good colors to put at the end of a longish hallway or to use to draw people toward a particular section of a large space.
Putting a light color on a wall makes that wall seem a little further away than it actually is, while darker colors on walls make them seem slightly closer than their true position. So you can use colors to change the apparent shapes of rooms—for example, pulling in the far walls of a long thin space. You can make places where lots of people will gather, such as family rooms, seem larger by painting the walls light colors and make boudoirs feel cozier by painting the walls darker colors.
Cool and Soothing Colors: located on the left side of the color wheel, provide a sense of calm and feelings of trust:
Green conveys a sense of renewal and growth. It’s also one of nature's most prominent colors and blends easily with any room.
Blue is generally a peaceful color. Light blue can make a room appear bright and refreshing, while a deep blue creates a sense of dignity.
Violet combines the calm of blue and the energy of red. Violet is often used in bedrooms to communicate an air of serenity.
Pastel colors are the result of adding a large amount of white to colors. They create a comfortable, airy feeling in any room.
Neutral colors include shades of white, beige, taupe, gray and black. Neutral colors are the easiest colors to use for one obvious reason: they blend with most surroundings. Neutral colors can also be stylish and dramatic. For instance, black and white are neutral colors that create a wonderful palette for additional colors.
"If you choose neutral colors, use bold-colored accessories to accent the walls and add interest. When you’re ready for a change, simply change out the accessories."