Characterization of studied variables.

RM-ANOVA: repeated-measure analysis of variance; Correlation: spearman correlation between each variable and the materials' pleasantness levels; v: exploration velocity; fN: normal force component; fT: tangential force component; μ: dynamic coefficient of friction; α: decay coefficient of friction-induced vibrations in the spatial domain; β: the offset of friction-induced vibrations in the spatial domain.