The neural basis governing the temporal formation of the human postural response is not well understood. It has been shown that postural control can be modeled using a simple feedback controller (Kuo 1995) and that the entire timecourse of EMG activity can be reconstructed using feedback on CoM kinematics in cats (Lockhart et al. 2005, SfN abstract). Specifically, acceleration and velocity feedback are important in the temporal formation of the EMG waveform during postural responses in cats. Our goal was to determine whether similar sensory feedback pathways are responsible for the temporal patterning of postural responses in humans. We hypothesize that the initial burst of EMG activity is formed by feedback on perturbation acceleration (acc) and velocity (vel). Since these characteristics typically covary, we attempted to delineate their individual effects. Subjects were perturbed during quiet stance with three different sets of anterior-posterior support surface translations with distinguishable acc and ...