Popular Science (Feb. 9) -- Chinese police officers are using facial-recognition sunglasses. Software that powers facial recognition generally uses a two-step process, says David Alexander Forsyth, a professor of computer science at Illinois and an artificial intelligence expert. Step one is to find the faces in the image. Step two is to try to match the faces to any in its database. “Turns out, that’s a harder problem,” Forsyth says of the second step. To algorithms, “people tend to look like each other.”