Performers use physical gestures in numerous ways. They can be used to communicate musical expression, generate sound production, facilitate technical movements while playing or singing, regulate temporal aspects of performance, and provide musical and social cues to co-performers and others, including audiences. Performers' physical gestures are personal as well as musical and social, that is, they convey information about the performer, such as his/her character, emotions and feelings as well as messages about the music. In terms of cognitive and information-processing theories, such a combined gestural rhetoric might be understood as being part of a shared internal representation of the music. Such representations are generated through the anticipation of auditory and motor images in rehearsal and performance. There are numerous reports of research on chamber ensemble rehearsal that provide insight into the ways in which student and professional musicians work together.