Experimental setup.

<p>The subplot A consists of a picture of the SENLY platform. The subplot B represents the 10 types of perturbations. Each perturbation involved the combination of longitudinal (i.e., North, <i>N</i> or South, <i>S</i>) and transversal (i.e., East, <i>E</i>, or West, <i>W</i>) movements of the belt provided while participants were walking steadily. Five perturbations were delivered on the left foot (i.e., <i>NL</i>, <i>NW</i>, <i>W</i>, <i>SW</i>, <i>SL</i>) and five on the right foot (i.e., <i>NR</i>, <i>NE</i>, <i>E</i>, <i>SE</i>, <i>SR</i>). The subplot C shows an example of the reconstruction of the biomechanical model of a representative subject. The vertexes of each polygon and the dots represent respectively the markers position and the <i>CoM</i> of each body segment with the corresponding acronyms.</p

The table shows the Mean Detection Time (<i>MDT</i>), <i>Sensitivity</i>, <i>Specificity</i> and <i>Accuracy</i> for the all-segments combination (<i>ALL</i>) and the reduced-segments combinations chosen after the <i>Ranking</i>.

<p>The accounted combinations are feet (<i>F</i>), hands (<i>H</i>), and feet-hands (<i>F-H</i>). The p-values are related respectively to the two-ways ANOVA (i.e., effect of the direction and side of the perturbation) and the t-tests (i.e., difference of each reduced-segments combination with respect to the all-segments one) on the <i>MDT</i> obtained for each subject and each type of perturbation (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092037#s2" target="_blank"><i>Materials and Methods</i></a>). When a p-value is statistically significant (<i>p</i><0.05), it is highlighted in bold.</p

Total Segment Weight.

<p>The Figure shows the mean and one standard deviation (error bar) of the Total Segment Weight (<i>TSW</i>) of each body segment that is the cumulative weight of the accounted segment on the <i>ICs</i> extracted. The <i>TSW</i> was normalized and expressed as a percentage. The 15 segments are: head/neck (<i>H/N</i>), chest (<i>T</i>), abdomen/pelvis (<i>P</i>), upper arms (<i>LA</i> and <i>RA</i>), forearms (<i>LFA</i> and <i>RFA</i>), hands (<i>LH</i> and <i>RH</i>), thighs (<i>LT</i> and <i>RT</i>), shanks (<i>LS</i> and <i>RS</i>) and feet (<i>LF</i> and <i>RF</i>). See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092037#pone.0092037.s001" target="_blank">Appendix S1</a> for further details.</p

Mean Detection Time.

<p>The Figure shows the Mean Detection Time (<i>MDT</i>) obtained for each type of perturbation (i.e., <i>NR</i>, <i>NE</i>, <i>E</i>, <i>SE</i>, <i>SR</i>, <i>NL</i>, <i>NW</i>, <i>W</i>, <i>SW</i>, <i>SL</i>) averaged across all participants (dark gray area) plus one standard deviation (light gray area) considering the all-segments (<i>ALL</i>), the feet (<i>F</i>), the hands (<i>H</i>) and the feet-hands (<i>F-H</i>) combinations. All the values are expressed in <i>ms</i>.</p