Do control variables exist?Nicholas G. Hatsopoulos &William H. Warren -1995 -Behavioral and Brain Sciences 18 (4):762-762.detailsWe argue that the concept of a control variable (CV) as described by Feldman and Levin needs to be revised because it does not account for the influence of sensory feedback from the periphery. We provide evidence from the realm of rhythmic movements that sensory feedback can permanently alter the frequency and phase of a centrally generated rhythm.