Speed and walking trajectories.

<p><b>A:</b> One representative subject showing instantaneous velocity for the 6 trials performed with the eyes closed and the control trial performed with open eyes (<b>A1</b>). <b>A2:</b> An enlarged view of the speed profile during the first 25 m (same subject shown in A1). X-2SD (vertical dotted line) indicates the mean position value on the x-axis at which the deviation occurs (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0043861#pone-0043861-g001" target="_blank">Figure 1A</a>). <b>B1:</b> Plot of the final position on the x-axis (X final) versus the position value on the x-axis at which deviation occurs (X-2SD) for all trajectories (n = 88). <b>B2:</b> Plot of the final position on the x-axis (X final) versus the mean speed.