We like attractive faces turned toward us, and less attractive faces turned away from us. But then, he notes, our brain chemistry can break all the rules and make us drawn to one person, even if their visage is not perfect. Perrett spoke about his work with The Los Angeles Times.
Q: The work in your lab has produced some general rules of attractive faces. What are they?
A: One rule is symmetry - it does make faces more attractive. But it's a small factor. Another rule is averageness. That may seem contradictory, but we like to choose things that are familiar to us.
Another rule applies to female faces - you can make them more attractive (in computer models) by making them more feminine. For instance, you can make lots of structural changes - taking a broader chin and more prominent eyebrow bones and changing them to a smaller chin and a less prominent eyebrow bones. You can also create a smaller nose and larger eyes. In male faces, you can make them more rugged or masculine, but not all women will agree that the increased masculinity is more attractive.
There are also clues to health in the face. For instance, skin colour - this is not about dark skin or light skin, but rather about redness and yellowness. Ruddiness can tell you about the blood circulation, whether it's poor or good. Yellowness in the skin reveals a plant-based diet.
Q: Do people seek symmetrical partners?
A: Everyone seems to like symmetry, but not everyone likes it as much. For instance, women who find themselves attractive seek more symmetrical men. So the degree to which symmetry matters to someone depends on what they think of themselves.
Symmetry is less important to some people; it actually explains very little about the range of attractiveness in people.
Q: Your research also reveals that not everyone plays by the same rules or focuses on the same things. Can you talk about that?
A: Beauty is in the eye of the beholder. There are so many reasons why we're attracted to one face versus another. The family - particularly parents - affects us. Especially if we get along with our parents, we tend to (but don't always) choose partners that resemble the opposite-sex parent. .
There's also a lot of social learning from peers. If we see our peers giving a lot of attention to one person, then that person might become more appealable in our eyes. We can see that in the influence of Hollywood stars.
The experiences you have with someone - friendship, or more intimate - really affects how you see them. No matter what their face, the chemicals in our brain can lock us onto one person.
Q: You have also charted attractiveness over time. You've written: "We're at our cutest at about 8 months of age, and after that it's all downhill." Explain.
A: One way to chart this is to play around with faces of babies (on the computer). You can expand the forehead and reduce the size of the chin.
By 8 months of age, human babies have a massive forehead and a really diminutive chin - and that's the point at which most people find babies most attractive. After 8 months, the face grows relatively quickly. That gives rise to a less and less cute configuration. We find infants cute and we want to take care of them.