Fig. 3. Histograms of swing amplitudes of all steps (with exception of gap-crossing steps and tentative steps) observed during undisturbed walking (left) and gap crossing (right). (A) Front legs, (B) middle legs, (C) hind legs, (D) pooled data of all leg pairs. The broken lines mark the threshold of 8.5 mm that separates short steps from normal walking steps (as indicated).