THE RELATION BETWEEN MUSIC and motion has been a topic of much theoretical and empirical research. An important contribution is made by a family of computational theories, so-called kinematic models, that propose an explicit relation between the laws of physical motion in the real world and expressive timing in music performance. However, kinematic models predict that expressive timing is independent of (a) the number of events, (b) the rhythmic structure, and (c) the overall tempo of the performance. These factors have no effect on the predicted shape of a ritardando. Computer simulations of a number of rhythm perception models show, however, a large effect of these structural and temporal factors. They are therefore proposed as a perception-based alternative to the kinematic approach.Received February 25, 2004, accepted June 26, 2004 T HE RELATION BETWEEN MUSIC and motion has been studied in a large body of theoretical and empirical work. (See Shove and Repp [1995] for a partial overview.) However, it is very difficult to specify-let alone validate-what is the nature of this longassumed relationship (Clarke, 2001;Honing, 2003). An important contribution to this topic is made by a family of computational theories, so-called kinematic models, that propose an explicit relation between the laws of physical motion (elementary mechanics) in the real world and expressive timing in music performance (Sundberg & Verillo, 1980;Kronman & Sundberg, 1987;Longuet-Higgins & Lisle, 1989;Feldman, Epstein, & Richards 1992;Todd, 1992;Epstein, 1994;Todd, 1995;Friberg & Sundberg, 1999). A large number of these theories focus on modeling the final ritard, the typical slowing down at the end of a music performance, especially in music from the Western Baroque and Romantic periods. But this characteristic slowing down can also be observed in, for instance, Javanese gamelan music or some pop and jazz genres. These models were