text: The Mona Lisa demonstration is really intended to bring a smile to your face, while it shows just how much this computer can do. Imagine a computer that knows when youre happy or sad. For example, if you smile when a Web ad appears on your screen, a similar ad might follow. But if you frown, the next ad will be different. A classroom computer could recognize when a student is becoming confused or bored, Dr. Huang predicts. Then it could modify the lesson, like an effective human instructor. The same technology can make computer-animated faces more expressive for video games or video surgery. Most human communication is nonverbal, including emotional communication, notes Dr. Huang. So computers need to understand that, too.