AboutFace is a user-dependent system that is able to learn patterns and discriminate the different facial movements characterizing confusion and interest. The system uses a piezoelectric sensor to detect eyebrow movements and begins with a training session to calibrate the unique values for each user. After the training session, the system uses these levels to develop an expression profile for the individual user. The system has many potential uses, ranging from computer and video-mediated conversations to interactions with computer agents. This system is an alternative to using camera-based computer vision analysis to detect faces and expressions. Additionally, when communicating with other people, users of this system also have the option of conveying their expressions anonymously by wearing a pair of glasses that conceals their expressions and the sensing device.