Four timed tasks were performed, with both arm systems. In order to complete these tasks, different combinations of all of the available DOFs were required. A cubicle reach and retrieve test was developed consisting of 15 cubicles, containing 15 one-inch (2.5cm) cubes, positioned on an adjustable height table (fig 3A). Before timed testing began, the subject would reach, grasp and place the 1-inch cubes on the table from as many cubicles as he was able to reach successfully, without moving his feet, thus defining the workspace to be used for the timed test. The time to grasp a 1-inch cube, place it on the table and activate a buzzer was recorded. The score consisted of the average time per successful reach and retrieval for all blocks in the workspace. A second timed task involved individually retrieving 11 plastic cups from an inverted stack and positioning them in a prescribed pyramid arrangement; 4 upside-down cups on the bottom row, building up to 1 on the top. The final eleventh cup was placed upright on top of the top upside-down cup of the pyramid. The time required to stack the cups was recorded, as was the time required to unstack the cups (fig 3B). The Box and Block test of gross manual dexterity12 required the subject to move 1-inch cubes from 1 compartment to another. This standard test was altered to increase the test interval from 60 seconds to 120 seconds (fig 3C). For the Clothespin Relocation Task, using a Rolyan Graded Pinch Exerciserg commonly found in the occupational therapy setting, the time was recorded for the subject to move 3 clothespins from a horizontal bar to a vertical bar (fig 3D). The subject’s performance of these tasks using his 3-DOF prosthesis was compared with that of the 6-DOF prosthesis.