Includes bibliographical references and index.

"As humans, we are highly tuned to faces. We are very good at finding faces in our visual environment, we enjoy looking at them, and even find it difficult to ignore them. One reason for this is that we can extract a wealth of social signals by looking at someone's face. Hairstyle, facial hair and bone structure, for example, can convey a person's gender. Hair colour, skin complexion and adiposity provide clues to age. Facial expressions can convey a person's emotional state, and the direction a person's eyes are pointing indicates what holds their focus of attention in the immediate environment. Most importantly, however, our faces indicate who we are: they provide the primary visual means by which people can be identified, and for distinguishing one person from another"-- Provided by publisher.