Normalized PFM patterns as a function of probe electrode for pTPEL8, α = 0 (upward triangles), pTPEL8, α = 0.5 (circles), and pTPEL8, α = 1 (downward triangles) for each subject. The centroid of each pattern is indicated by the corresponding symbol near the x-axis. The width at 75 % of the peak amplitude of each pattern is shown in the unit of electrode spacing.