Abstract: An improved music generation system that facilitates artistic expression by non-musician and musician performers in both individual and group performance contexts. Mappings are provided between 1) gestures of a performer as indicated by manipulation of a user input device, 2) displayed motion of a graphic object, and 3) global features of a musical segment. The displayed motions and global features are selected so as to reinforce the appearance of causation between the performer's gestures and the produced musical effects and thereby assist the performer in refining his or her musical expression. The displayed motion is isomorphically coherent with the musical segment in order to achieve the appearance of causation. The global features are segment characteristics perceivable to human listeners. Control at the global feature level in combination with isomorphic visual feedback provides advantages to both non-musicians and musicians in producing artistic effect.