Participants in a University of Nottingham study rated people with more red and yellow tones in their skin as being more attractive. Moreover, a study at the University of St. Andrews Perception Lab uncovered that people with rosier complexions were perceived as being healthier. The increased flow of oxygen and blood that leads to rosy blush on cheeks is associated with strong lungs and a healthy heart. A rosy complexion also mimics the healthy flush that comes from exercise and sexual activity, both of which tend to indicate strength and vitality. The reverse is also true; people suffering from respiratory and cardiac problems tend to look dull because their skin has fewer blood vessels.