Number of Fingers and Grasping Orientation Influence Human Performance During Haptic Rotation

This research examines two factors whether they have an influence on human performance during haptic rotation. The first one is the number of fingers used to perform the haptic rotation. The second one is the grasping orientation of the fingers on the rotary knob. Twenty blindfolded participants had to rotate a rotary knob 90 degrees counterclockwise around its own axis. In the first part of the experiment we varied the number of fingers conducting the rotation from two to five. In the second part four different grasping orientations were evaluated: vertical, horizontal, oblique and unfamiliar. To determine the performance, we calculated two measures, the accuracy and the precision based on the rotation angles. The first part of the evaluation showed, that the number of fingers involved in the rotation had a significant influence on the accuracy, while more fingers lead to a better accuracy. Precision was not dependent on the number of fingers. The second evaluation showed that the grasping orientation had no effect on the accuracy. However, there was a significant impact of the grasping position on the precision. The vertical grasping orientation led to a better precision than the horizontal or unfamiliar grasping position.