Make-up makes women appear younger by increasing the contrast between facial features and skin tone, new research claims.
The study by a professor from Gettysburg College in Pennsylvania suggests the changing contrasts of facial features is one of the cues people unconsciously use to decipher a woman's age.
The discovery of this cue to age perception may partly explain why cosmetics are worn the way they are, the study claims.
Cosmetics are commonly used to increase aspects of facial contrast, such as the redness of lips.
Scientists propose that this can partly explain why make-up is worn the way that it is - shades of lipstick that increase the redness of the lips are making the face appear younger, which is related to healthiness and beauty.
"Unlike with wrinkles, none of us are consciously aware that we're using this cue, even though it stares us in the face every day," said Richard Russell, a professor of psychology at Gettysburg.