Fig. 3.

Mean normalized step times (a, T _step) and step lengths (b, Y _step) for S ₁–S ₂₀ for the perturbation conditions. Note that following phase-advance (−60°) perturbations, a shorter-step response was observed (with both T _step and Y _step < 100% regardless of the cueing type); after phase-delay (+60°) perturbations, a longer-step response was observed (with both T _step and Y _step > 100% regardless of the cueing type). For both phase-shift directions, significant differences between cueing types for a given S _n are indicated by an open symbol for the T _step or Y _step that deviated most from 100%; initial step-time and step-length adjustments were faster and larger for the stepping stone (S) than metronome beep (M) conditions