Relations between normal thumb forces and the fingers at various torque levels: (upper) index finger, (bottom) little finger. Filled symbols represent supination torques, and unfilled symbols represent pronation. Lower, middle, and upper refer to the different thumb positions. (Reprinted from Zatsiorsky, V. M., F. Gao, and M. L. Latash. Prehension synergies: effects of object geometry and prescribed torques. Exp. Brain Res. 148:77–87, 2003. Copyright © 2003 Springer-Verlag. Used with permission.)