The mathematical theory of communication.

Facial appearance changes with age and health affecting skin color as well as facial and head hair. Yet somehow the brain is able to see past shared structure and dynamic deformations to focus on subtle details that distinguish one face from another. This article argues that the brain takes an efficient approach to this problem using prior knowledge about the structure of faces in its analysis. It employs intrinsic norms to focus on subtle variations in the shared face configuration that (...) differentiate one face from another. The study reviews evidence that the brain uses multiple norms to extract face identity that these norms are shaped by visual experience, and that norm-based coding is well-suited to meeting the challenges of image-based face perception mentioned above. By encoding faces with reference to stored perceptual norms the visual system can focus on what is unique to each individual, allowing for the discrimination of thousands of faces despite their similarity. (shrink)