The human face is a remarkable piece of work. The astonishing variety of facial features helps people recognize each other and is vital to the formation of complex societies. So is the face's ability to send emotional signals, whether through an unconscious red face or the artifice of a false smile. People spend much of their waking lives reading faces, for signs of attraction, hatred, trust and fraud. They also spend plenty of time trying to hide true feelings or intentions.
Technology is rapidly catching up with the human ability to read faces. In America facial recognition is used by churches to track worshippers' attendance; in Britain, by retailers to spot past shoplifters. In China, it confirms the identities of ride-hailing drivers, permits tourists to enter attractions and lets people pay for things with a smile. Apple's new iPhone is expected to use it to unlock the home screen.
Set against human skills, such applications might seem incremental(增值的). Some breakthroughs, such as flight or the Internet, obviously transform human abilities; facial recognition seems merely to encode(编码)them. Although faces are unique to individuals, they are also public, so technology does not, at first sight, interfere with something that is private. And yet the ability to record, store and analyze images of faces cheaply, quickly and on a vast scale promises one day to bring about fundamental changes to opinions of privacy, fairness and trust.
Start with privacy. One big difference between faces and other biometric data, such as fingerprints, is that they work at a distance. Anyone with a phone can take a picture for facial-recognition programs to use. Facebook's bank of facial images cannot be used by others, but the Silicon Valley giant could obtain pictures of visitors to a car showroom, say, and later use facial recognition to serve them ads for cars. Law-enforcement agencies now have a powerful weapon in their ability to track criminals, but at enormous potential cost to citizens' privacy.
The face is not just a name-tag. It displays a lot of other information—and machines can read that, too. Again, that promises benefits. Some firms are analyzing faces to provide automated diagnoses of rare genetic conditions, far earlier than would otherwise be possible. Systems that measure emotion may give autistic(孤独症的)people a grasp of social signals they find difficult.
