This is a study of two attempts to develop quantitative models of timing in music performance, one based on connectionism and the other involving the autocorrelation function. The former is concerned with the ‘quantization problem’ of interpreting durations of time from a musical performance as note shapes which represent duration in music notation. The latter is an attempt to represent what makes such performances ‘‘expressive ’. These models were derived by Peter Desain, but there is a paucity of validating data in the published literature. Attempts to collect additional data have revealed significant shortcomings in both models, as well as methodological flaws. The most important problem is that the attempt to solve the quantization problem lacks any representation of high-level structure. As a result, if the music itself tends to be based on relatively irregular rhythmic patterns, the connectionist model can distort even a metronome-perfect performance, rather than recognizing the correct temporal patterns. Attempts are made to explain how these shortcomings may have arisen.