Models of interlimb coordination--equilibria, local analyses, and spectral patterning: comment on Fuchs and Kelso (1994).

This article is a comment on A. Fuchs and J. A. S. Kelso's (1994) theoretical note on models of interlimb coordination. The generality of the order parameter equation derived by H. Haken, J. A. S. Kelso, and H. Bunz (HKB; 1985) for correlated limb movements is underscored through the correct and nonintuitive predictions it makes about steady state behavior. Local and global dynamical models are contrasted, and experimental situations in which local models are pragmatic alternatives to global models, like the HKB equation, are described. Questions are raised about the basis for interpreting detuning in HKB as a simple frequency difference and about the ability of the system of coupled nonlinear oscillators proposed by A. Fuchs and J. A. S. Kelso (1994) to model fully the experimental findings on the spectrum of relative phase.