The primary metric chosen for the experiments was the degree to which subjects could achieve an even distribution of grasping forces among the fingers. The metric is computed as fs = 3 Xi=1 abs(fi − fa) (1) where fa is the average force and, again, i = 1, 2, 3 for the index, middle and ring fingers, respectively. Subjects were asked to maintain an even force balance for 5 seconds after lifting the object and the value of fs was recorded continuously during this time. If the subject dropped the object or was unable to hold the object for 5 seconds, a failure event was noted.