Averages and coefficients of variation of normal force in the various conditions.

<p>Left panels: DS, DR, IS, and IR and right panels: C1S, C1R, C2S, and C2R indicate each condition. D, I, C1, and C2 mean discrimination task, identification task, 1^st control condition, and 2^nd control condition, and S and R mean smooth group and rough group. Error bars indicate the standard deviation. *indicates <i>p</i><0.05 and **<i>p</i><0.01 with Wilcoxon signed rank tests.