Fig. 4.

a–c Relationships among forces at the VF level. a Normal forces of the virtual finger and the thumb for a representative subject. The data for both the clockwise and counterclockwise torques are shown. All coefficients of correlation were 1.00. b Tangential forces of the thumb versus tangential forces of the virtual finger for the same subject. The coefficients of correlation ranged from −0.95 to −1.00, while all error-corrected coefficients of correlation were −1.00. c Tangential forces of the thumb versus tangential forces of the virtual finger for all six subjects. Note the differences among the subjects in the location and the width of the clusters