Influence of stimulus velocity profile on rhythmic visuomotor coordination.

Every day, we visually coordinate our movements with environmental rhythms. Despite its ubiquity, it largely remains unclear why certain visual rhythms or stimuli facilitate such visuomotor coordination. The goal of the current study was to investigate whether the velocity profile of a rhythmic stimulus modulated the emergence and stability of this coordination. We examined both intended (Experiment 1) and unintended or spontaneous coordination (Experiment 2) between the rhythmic limb movements of participants and stimuli exhibiting different velocity profiles. Specifically, the stimuli oscillated with either a sinusoidal (harmonic), nonlinear Rayleigh, or nonlinear Van der Pol velocity profile, all of which are typical of human or biological rhythmic movement. The results demonstrated that the dynamics of both intended and unintended visuomotor coordination were modulated by the stimulus velocity profile, and that the Rayleigh velocity profile facilitated the coordination, suggesting a crucial role of the slowness to the endpoints or turning points of the stimulus trajectory for stable coordination. More generally, these findings open promising research directions to better understand and improve coordination with artificial agents and people with social deficits.