Fig. 2.

Normalized COM velocity vs. normalized COM position at FSLO in the ML direction for single (●) and multiple (■) step responses at (a) perturbation level 3, (b) level 4, and (c) level 5. Mean for each group (○ and □) are also indicated. Error bars are SEM. The solid line indicates the BOS stability boundary based on the actual BOS width. The two dashed lines indicate the functional stability boundaries for single and multiple step responses. Since the functional boundaries vary between subjects, the average for all subjects within the group was shown here. (a) ^*p = 0.013, ^†p = 0.004; (b) ^*p = 0.045.