The basic color wheel is designed around the idea of the three primary colors-red, yellow and blue. But when this wheel is filled in with secondary and tertiary colors, it becomes obviously divided between a cool side-the greens, blues and violets-and a warm side-the yellows, reds and oranges. Playing warm and cool hues off of each other is an effective eye-grabbing device.
Because warm/cool contrasts command attention, I often use them near my center of interest. This works because the human eye has two types of cells that perceive color. “Rod” cells are sensitive to light and dark, while “cone” cells transmit color. Placing a warm color next to a cool color causes the cone cells to vibrate. This visual stimulation compels the viewer’s eye to focus on vibrating areas, then move around the painting to more restful areas.