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. Author manuscript; available in PMC: 2018 Feb 26.
Published in final edited form as: IEEE Trans Neural Syst Rehabil Eng. 2016 Aug 26;25(8):1132–1142. doi: 10.1109/TNSRE.2016.2603340

Fig. 1.

Fig. 1

(A) We used a virtual reality environment to perturb optical flow with systematic changes in the driving frequencies of perceived mediolateral motion. In addition to normal, unperturbed walking, our five primary conditions (B) consisted of two sinusoidal driving frequencies each, for which we prescribed 0.326 m amplitudes and f equaled 0.05, 0.10, 0.20, 0.30, and 0.40 Hz (Pair 1-5). (C) Subjects also walked with larger combinations of these driving frequencies. Two of these conditions included 5 driving frequencies with amplitudes of 0.19 m (Set 1: {f}, Set 2: 3.1·{f}) and one included all 10 driving frequencies with amplitudes of 0.09 m (Set 3).