Cross correlation results for participants’ postural sway.

<p>The figure shows grand averaged cross correlation curves for participants’ postural sway data for each of the VISUAL INTERACTION conditions (OO, BO, OB, and BB) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0137126#pone.0137126.g001" target="_blank">Fig 1</a> for the test conditions). Curves are plotted for postural sway along an Anterior-Posterior (AP) axis and for the Near DISTANCE condition only. The x-axis represents “time lag (ms)” centered around 0 up to ± 5000 ms, and the y-axis represents the “correlation value”. The solid lines indicate the means of each condition and the pale color areas standard error of the mean (SEM). Colored crosses over the lines indicate the peak of the curves at the time point around 0 ms, before and after 0 ms, with respect to the lag-0 time point (0 ms) for the OO, BO, and OB conditions, respectively. The horizontal line of the cross indicates SEM for the time lag of the peaks. The vertical line of the cross indicates SEM for the amplitude (correlation value) of the peaks. This suggests full synchronization of postural sway (with no time lag) between paired participants when they both had their eyes open (the OO condition). When only one of the paired participants had her eyes open, postural sway was synchronized, but occurred slightly earlier (the BO condition) or later (the OB condition) than the lag-0 time. The BB condition had no apparent peak in the correlation curve, showing that postural sway did not synchronize when paired participants were both blindfolded. (See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0137126#pone.0137126.s003" target="_blank">S1 Fig</a>) for the results for the Near DISTANCE condition along a Left-Right (LR) axis as well as the results for the Far DISTANCE condition along both AP and LR axes).