Figure 1.

Measured belt movement and its reliability metrics for the slow (left) and fast (right) protocols. The curves represent the mean and between-participant standard deviation (shaded area; note that the standard deviations are extremely small). Only the backward perturbations are shown, since the patterns are identical in both directions. Dashed vertical lines show the target values of the peak displacement, velocity, and acceleration based on programmed control signals of the belt. Time zero indicates the identified start of the perturbation. Note that the time scales are the same for both protocols, but the vertical scales differ. The observed values are presented as the mean and within-participant standard deviation of the peak values. SEM_{within−participant}, within-participant standard error of measurement; SEM_{between days}, between-day standard error of measurement.